Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
  • H04N21/80—Generation or processing of content or additional data by content creator independently of the distribution process; Content per se
  • H04N21/85—Assembly of content; Generation of multimedia applications
  • H04N21/854—Content authoring
  • H04N21/8545—Content authoring for generating interactive applications
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
  • H04N21/20—Servers specifically adapted for the distribution of content, e.g. VOD servers; Operations thereof
  • H04N21/23—Processing of content or additional data; Elementary server operations; Server middleware
  • H04N21/231—Content storage operation, e.g. caching movies for short term storage, replicating data over plural servers, prioritizing data for deletion
  • H04N21/23106—Content storage operation, e.g. caching movies for short term storage, replicating data over plural servers, prioritizing data for deletion involving caching operations
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
  • H04N21/20—Servers specifically adapted for the distribution of content, e.g. VOD servers; Operations thereof
  • H04N21/23—Processing of content or additional data; Elementary server operations; Server middleware
  • H04N21/234—Processing of video elementary streams, e.g. splicing of video streams or manipulating encoded video stream scene graphs
  • H04N21/2343—Processing of video elementary streams, e.g. splicing of video streams or manipulating encoded video stream scene graphs involving reformatting operations of video signals for distribution or compliance with end-user requests or end-user device requirements
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
  • H04N21/20—Servers specifically adapted for the distribution of content, e.g. VOD servers; Operations thereof
  • H04N21/23—Processing of content or additional data; Elementary server operations; Server middleware
  • H04N21/24—Monitoring of processes or resources, e.g. monitoring of server load, available bandwidth, upstream requests
  • H04N21/2402—Monitoring of the downstream path of the transmission network, e.g. bandwidth available
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
  • H04N21/40—Client devices specifically adapted for the reception of or interaction with content, e.g. set-top-box [STB]; Operations thereof
  • H04N21/47—End-user applications
  • H04N21/478—Supplemental services, e.g. displaying phone caller identification, shopping application
  • H04N21/4781—Games

Definitions

• the present disclosure relates generally to the field of data processing systems that improve a users' ability to manipulate and access audio and video media.
• cassette tapes for taping their own records purely for convenience, but increasingly consumers (e.g., students in a dormitory with ready access to each others' record collections) would make pirated copies. Also, consumers would tape music played over the radio rather than buying a record or tape from the publisher.
• An avid consumer of media may have a stack of devices connected to TVs and computers in various rooms of the house, resulting in a "rat's nest" of cables to one or more TV sets and/or personal computers (PCs) as well as a group of remote controls.
• PCs personal computers
• the term "personal computer” or “PC” refers to any sort of computer suitable for us in the home or office, including a desktop, a Macintosh® or other non-Windows computers, Windows-compatible devices, Unix variations, laptops, etc.
• These devices may include a video game console, VCR, DVD player, audio surround- sound processor/amplifier, satellite set-top box, cable TV set-top box, etc.
• a consumer may own both a HD- DVD and a Blu-ray DVD player, or both a Microsoft Xbox® and a Sony Playstation® video game system. Indeed, because of incompatibility of some games across versions of game consoles, the consumer may own both an XBox and a later version, such as an Xbox 360®. Frequently, consumers are befuddled as to which video input and which remote to use. Even after a disc is placed into the correct player (e.g., DVD, HD-DVD, Blu-ray, Xbox or Playstation), the video and audio input is selected for that the device, and the correct remote control is found, the consumer is still faced with technical challenges.
• the correct player e.g., DVD, HD-DVD, Blu-ray, Xbox or Playstation
• the user may need to first determine and then set the correct aspect ratio on his TV or monitor screen (e.g., 4:3, Full, Zoom, Wide Zoom, Cinema Wide, etc.).
• the user may need to first determine and then set the correct audio surround sound system format (e.g., AC-3, Dolby Digital, DTS, etc.).
• the consumer is unaware that they may not be enjoying the media content to the full capability of their television or audio system (e.g., watching a movie squashed at the wrong aspect ratio, or listening to audio in stereo rather than in surround sound).
• IPTV Internet Protocol Television
• the local device may not have the hardware capability to support the new format, which would mean that the consumer would have to purchase an upgraded local media device.
• the local device may not have the computational capability to decode the video, or it may not have the hardware to output the video in the new format (e.g., assuming stereoscopy is achieved through 120fps video synchronized with shuttered glasses, with 60fps delivered to each eye, if the consumer's video hardware can only support 60fps video, this option would be unavailable absent an upgraded hardware purchase).
• Modern video game applications are largely divided into four major non-portable hardware platforms: Sony PlayStation® 1, 2 and 3 (PSl, PS2, and PS3); Microsoft Xbox® and Xbox 360®; and Nintendo Gamecube® and WiiTM; and PC-based games.
• Sony PlayStation® 1, 2 and 3 PSl, PS2, and PS3
• Microsoft Xbox® and Xbox 360® and Nintendo Gamecube® and WiiTM
• PC-based games are different than the others so that games written to run on one platform usually do not run on another platform.
• Each platform is sold to the consumer as a "console” (i.e., a standalone box attached to a TV or monitor/speakers) or it is a PC itself.
• the video games are sold on optical media such as a Blu-ray DVD, DVD-ROM or CD-ROM, which contains the video game embodied as a sophisticated real-time software application.
• optical media such as a Blu-ray DVD, DVD-ROM or CD-ROM, which contains the video game embodied as a sophisticated real-time software application.
• home broadband speeds have increased, video games are becoming increasingly available for download.
• Portable devices such as cellular (“cell”) phones and portable media players also present challenges to game developers.
• Increasingly such devices are connected to wireless data networks and are able to download video games.
• cell phones and media devices in the market, with a wide range of different display resolutions and computing capabilities.
• graphics acceleration hardware like a Graphics Processing Unit (“GPU"), such as devices made by NVIDIA of Santa Clara, CA. Consequently, game software developers typically develop a given game title simultaneously for many different types of portable devices. A user may find that a given game title is not available for his particular cell phone or portable media player.
• GPU Graphics Processing Unit
• multiple games can fill up small disk drives, such as those sold with portable computers or with video game consoles.
• games or MMOGs require an online connection for the game to be playable, the piracy problem is mitigated since the user is usually required to have a valid user account.
• linear media e.g., video and music
• each video game experience is unique, and can not be copied using simple video/audio recording.
• MMOGs can be shielded from piracy and therefore a business can be supported.
• Vivendi SA' s "World of Warcraft” MMOG has been successfully deployed without suffering from piracy throughout the world.
• many online or MMOG games, such as Linden Lab's "Second Life” MMOG generate revenue for the games' operators through economic models built into the games where assets can be bought, sold, and even created using online tools.
• mechanisms in addition to conventional game software purchases or subscriptions can be used to pay for the use of online games.
• MMOGs online game operator still face remaining challenges. Many games require substantial local (i.e., in-home) processing resources for online or MMOGs to work properly. If a user has a low performance local computer (e.g., one without a GPU, such as a low-end laptop), he may not be able to play the game. Additionally, as game consoles age, they fall further behind the state-of- the-art and may not be able to handle more advanced games. Even assuming the user's local PC is able to handle the computational requirements of a game, there are often installation complexities.
• a low performance local computer e.g., one without a GPU, such as a low-end laptop
• driver incompatibilities e.g., if a new game is downloaded, it may install a new version of a graphics driver that renders a previously-installed game, reliant upon an old version of the graphics driver, inoperable.
• a console may run out of local disk space as more games are downloaded.
• Complex games typically receive downloaded patches over time from the game developer as bugs are found and fixed, or if modifications are made to the game (e.g., if the game developer finds that a level of the game is too hard or too easy to play). These patches require new downloads. But sometimes not all users complete downloading of all the patches. Other times, the downloaded patches introduce other compatibility or disk space consumption issues.
• Online or MMOG games may also narrow the market of users that can play the games.
• technically-knowledgeable users are increasingly reverse-engineering local copies of games and modifying the games so that they can cheat.
• the cheats maybe as simple as making a button press repeat faster than is humanly possible (e.g., so as to shoot a gun very rapidly).
• the cheating can reach a level of sophistication that results in fraudulent transactions involving assets of actual economic value.
• an online or MMOGs economic model is based on such asset transactions, this can result in substantial detrimental consequences to the game operators.
• the single optical drive or single disk drive typically available on a PC or game console is usually much slower than the RAM, and typically can not keep up with the maximum data rate that the GPU can accept in rendering polygons and textures.
• Current games typically load most of the polygons and textures into RAM, which means that a given scene is largely limited in complexity and duration by the capacity of the RAM.
• this may limit a PC or a game console to either a low resolution face that is not photoreal, or to a photoreal face that can only be animated for a limited number of frames, before the game pauses, and loads polygons and textures (and other data) for more frames.
• a soccer video game may allow the players to choose among a large number of players, teams, stadiums and weather conditions. So, depending on what particular combination is chosen, different polygons, textures and other data (collectively "objects") may be required for the scene (e.g., different teams have different colors and patterns on their uniforms). It may be possible to enumerate many or all of the various permutations and pre-compute many or all of the objects in advance and store the objects on the disk used to store the game. But, if the number of permutations is large, the amount of storage required for all of the objects may be too large to fit on the disk (or too impractical to download). Thus, existing PC and console systems are typically constrained in both the complexity and play duration of given scenes and suffer from long load times for complex scenes.
• the database is at risk of being pirated once it has been downloaded to the local user.
• a user wants to download a database simply for the sake of evaluating it to see if it suits the user's needs (e.g., if a 3D costume for a game character has a satisfactory appearance or look when the user performs a particular move).
• a long load time can be a deterrent for the user evaluating the 3D database before deciding to make a purchase.
• Similar issues occur in MMOGs, particularly as games that allow users to utilize increasingly customized characters.
• OS operating system
• the OS graphical requirements are limited to a large degree by a least common denominator of computers that the OS is targeted for, which typically includes computers that do not include a GPU. This severely limits the graphics capability of the OS.
• battery-powered portably computers e.g., laptops
• Portable computers typically include software that automatically lowers processor activity to reduce power consumption when the processor is not utilized. In some computer models the user may lower processor activity manually.
• Such applications have a much more limited target audience than a general purpose OS (or general purpose productivity application, like Microsoft Office) and typically sell in much lower volume than general purpose OS software or general purpose application software.
• the potential audience is further limited because often times it is difficult for a prospective user to try out such computationally-intense applications in advance. For example, suppose a student wants to learn how to use Maya or a potential buyer already knowledgeable about such applications wants to try out Maya before making the investment in the purchase (which may well involve also buying a high-end computer capable of running Maya).
• High-priced applications also create more incentive for individuals and businesses to use pirated copies of the application software.
• high- end application software suffers from rampant piracy, despite significant efforts by publishers of such software to mitigate such piracy through various techniques.
• users cannot obviate the need to invest in expensive state-of-the-art PCs to run the pirated copies. So, while they may obtain use of a software application for a fraction of its actual retail price, users of pirated software are still required to purchase or obtain an expensive PC in order to fully utilize the application.
• the same is true for users of high-performance pirated video games.
• a video game demo is often a full-fledged version of the game with some features disabled, or with limits placed on the amount of game play. This may involve a long process (perhaps hours) of downloading gigabytes of data before the game can be installed and executed on either a PC or a console. In the case of a PC, it may also involve figuring out what special drivers are needed (e.g., DirectX or OpenGL drivers) for the game, downloading the correct version, installing them, and then determining whether the PC is capable of playing the game.
• special drivers e.g., DirectX or OpenGL drivers
• This latter step may involve determining whether the PC has enough processing (CPU and GPU) capability, sufficient RAM, and a compatible OS (e.g., some games run on Windows XP, but not Vista).
• a compatible OS e.g., some games run on Windows XP, but not Vista.
• a significant drawback to this approach is that for a user to view the recorded game, the user must possess a video game client computer capable of playing the game and must have the video game application running on that computer, such that the gameplay is identical when the recorded game state is replayed. Beyond that, the video game application has to be written in such a way that there is no possible execution difference between the recorded game and the played back game.
• game graphics are generally computed on a frame- by- frame basis.
• the game logic sometimes may take shorter or longer than one frame time to compute the graphics displayed for the next frame, depending on whether the scene is particularly complex, or if there are other delays that slow down execution (e.g., on a PC, another process may be running that takes away CPU cycles from the game applications).
• a "threshold" frame that is computed in slightly less than one frame time (say a few CPU clock cycles less) can eventually occur.
• the rate of computed frames may be 53 fps when the game was recorded, but 52 fps when the game is replayed, which can make the difference between whether the basketball is blocked from going into the basket or not, resulting in a different outcome.
• using game state to record video games requires very careful game software design to ensure that the replay, using the same game state information, produces the exact same outcome.
• Another prior art approach for recording video game is to simply record the video output of a PC or video game system (e.g., to a VCR, DVD recorder, or to a video capture board on a PC). The video then can be rewound and replayed, or alternatively, the recorded video uploaded to the Internet, typically after being compressed.
• a disadvantage to this approach is that when a 3D game sequence is played back, the user is limited to viewing the sequence from only the point of view from which the sequence was recorded. In other words, the user cannot change the point of view of the scene.
• this delay is tolerable in certain situations (e.g., to watch a game player's accomplishments that occurred at a prior time), it eliminates the ability to watch a game live (e.g., a basketball tournament, played by champion players) or with "instant replay" capability as the game is played live.
• a game live e.g., a basketball tournament, played by champion players
• Another prior art approach allows a viewer with a television receiver to watch video games live, but only under the control of the television production crew.
• Some television channels in both the US and in other countries provide video game viewing channels, where the television viewing audience is able to watch certain video game users (e.g., top-rated players playing in tournaments) on video game channels. This is accomplished by having the video output of the video game systems (PCs and/or consoles) fed into the video distribution and processing equipment for the television channel. This is not unlike when the television channel is broadcasting a live basketball game in which several cameras provide live feeds from different angles around the basketball court. The television channel then is able to make use of their video/audio processing and effects equipment to manipulate the output from the various video game systems.
• the television channel can overlay text on top of the video from a video game that indicates the status of different players (just as they might overlay text during a live basketball game), and the television channel can overdub audio from a commentator who can discuss the action occurring during the games.
• the video game output can be combined with cameras recording video of the actual players of the games (e.g., showing their emotional response to the game).
• a given television channel broadcasting a full- screen image of a video game to the entire television viewing audience shows only one video game at a time. This severely limits a television viewer's choices. For example, a television viewer may not be interested in the game(s) shown at a given time. Another viewer may only be interested in watching the game play of a particular player that is not featured by the television channel at a given time. In other cases, a viewer may only be interested in watching a how an expert player handles a particular level in a game. Still other viewers may wish to control the viewpoint that a video game is seen from, which is different from that chosen by the production team, etc.
• a television viewer may have a myriad of preferences in watching video games that are not accommodated by the particular broadcast of a television network, even if several different television channels are available.
• prior art video game television channels have significant limitations in presenting video games to television viewers.
• a user may call up a game developer's customer service line and leave a message stating that when playing the game, the screen started to flash, then changed to a solid blue color and the PC froze. That provides the SQA team with very little information useful in tracking down a bug.
• Some games or applications that are connected online can sometimes provide more information in certain cases.
• a "watchdog" process can sometimes be used to monitor the game or application for "crashes". The watchdog process can gather statistics about the status of the game or applications process (e.g., the status of the stack, of the memory usage, how far the game or applications has progressed, etc.) when it crashes and then upload that information to the SQA team via the Internet.
• FIG. 1 illustrates a prior art video gaming system such as a Sony
• Playstation® 3 Microsoft Xbox 360®, Nintendo WiiTM, Windows-based personal computer or Apple Macintosh.
• CPU central processing unit
• GPU graphical processing unit
• I/O input/output
• the prior art video gaming system of Figure 1 also is shown including an optical media drive 104 (e.g., a DVD-ROM drive); a hard drive 103 for storing video game program code and data; a network connection 105 for playing multi-player games, for downloading games, patches, demos or other media; a random access memory (RAM) 101 for storing program code currently being executed by the CPU/GPU 100; a game controller 106 for receiving input commands from the user during gameplay; and a display device 102 (e.g., a SDTV/HDTV or a computer monitor).
• an optical media drive 104 e.g., a DVD-ROM drive
• a hard drive 103 for storing video game program code and data
• a network connection 105 for playing multi-player games, for downloading games, patches, demos or other media
• RAM random access memory
• game controller 106 for receiving input commands from the user during gameplay
• a display device 102 e.g., a SDTV/HDTV or a computer monitor.
• Some systems attempt to overlap the loading of the program code concurrently with the gameplay, but this can only be done when there is a known sequence of events (e.g., if a car is driving down a road, the geometry for the approaching buildings on the roadside can be loaded while the car is driving). For complex and/or rapid scene changes, this type of overlapping usually does not work. For example, in the case where the user is in the midst of a battle and RAM 101 is completely filled with data representing the objects within view at that moment, if the user moves the view rapidly to the left to view objects that are not presently loaded in RAM 101, a discontinuity in the action will result since there not be enough time to load the new objects from Hard Drive 103 or Optical Media 104 into RAM 101.
• disk storage devices can be manufactured with a relatively large storage capacity (e.g., 50 gigabytes or more), they still do not provide enough storage capacity for certain scenarios encountered in current video games. For example, as previously mentioned, a soccer video game might allow the user to choose among dozens of teams, players and stadiums throughout the world. For each team, each player and each stadium a large number of texture maps and environment maps are needed to characterize the 3D surfaces in the world (e.g., each team has a unique jersey, with each requiring a unique texture map).
• One technique used to address this latter problem is for the game to pre-compute texture and environment maps once they are selected by the user. This may involve a number of computationally-intensive processes, including decompressing images, 3D mapping, shading, organizing data structures, etc. As a result, there may be a delay for the user while the video game is performing these calculations. On way to reduce this delay, in principle, is to perform all of these computations - including every permutation of team, player roster, and stadium - when the game was originally developed.
• the released version of the game would then include all of this pre-processed data stored on optical media 104, or on one or more servers on the Internet with just the selected pre-processed data for a given team, player roster, stadium selection downloaded through the Internet to hard drive 103 when the user makes a selection.
• pre-loaded data of every permutation possible in game play could easily be terabytes of data, which is far in excess of the capacity of today's optical media devices.
• the data for a given team, player roster, stadium selection could easily be hundreds of megabytes of data or more. With a home network connection of, say, lOMbps, it would take longer to download this data through network connection 105 than it would to compute the data locally.
• Figure 1 is that over the years video games tend to become more advanced and require more CPU/GPU processing power. Thus, even assuming an unlimited amount of RAM, video games hardware requirements go beyond the peak level of processing power available in these systems. As a result, users are required to upgrade gaming hardware every few years to keep pace (or play newer games at lower quality levels).
• One consequence of the trend to ever more advanced video games is that video game playing machines for home use are typically economically inefficient because their cost is usually determined by the requirements of the highest performance game they can support.
• an XBox 360 might be used to play a game like "Gears of War", which demands a high performance CPU, GPU, and hundreds of megabytes of RAM, or the XBox 360 might be used to play Pac Man, a game from the 1970s that requires only kilobytes of RAM and a very low performance CPU. Indeed, an XBox 360 has enough computing power to host many simultaneous Pac Man games at once.
• Video games machines are typically turned off for most of the hours of a week. According to a July 2006 Nielsen Entertainment study of active gamers 13 years and older, on average, active gamers spend fourteen hours/week playing console video games, or just 12% of the total hours in a week.
• Video game consoles also incur costs associated with almost any consumer electronic device. For instance, the electronics and mechanisms of the systems need to be housed in an enclosure. The manufacturer needs to offer a service warranty. The retailer who sells the system needs to collect a margin on either the sale of the system and/or on the sale of video game software. All of these factors add to the cost of the video game console, which must either be subsidized by the manufacturer, passed along to the consumer, or both.
• piracy is a major problem for the video game industry.
• the used game market reduces revenue for the video game industry.
• a user When a user has become tired of a game, they can sell the game to a store which will resell the game to other users. This unauthorized but common practice significantly reduces revenues of game publishers.
• a reduction in sales on the order of 50% commonly occurs when there is a platform transition every few years. This is because users stop buying games for the older platforms when they know that the newer version platform is about to be released (e.g., when Playstation 3 is about to be released, users stop buying Playstation 2 games).
• the loss of sales and increased development costs associated with the new platforms can have a very significant adverse impact on the profitability of game developers.
• Fast action video games require very low latency between the time the user performs an action with the game controller and the time the display screen is updated showing the result of the user action. Low latency is needed so that the user has the perception that the game is responding "instantly". Users may be satisfied with different latency intervals depending on the type of game and the skill level of the user. For example, 100ms of latency may be tolerable for a slow casual game (like backgammon) or a slow-action role playing game, but in a fast action game a latency in excess of 70 or 80ms may cause the user to perform more poorly in the game, and thus is unacceptable.
• the latency through the Internet varies based on the route that the data is given and the delays it incurs as it is routed.
• round-trip latency is also incurred due to the speed of light traveling through the optical fiber that interconnects most of the Internet. For example, for each 1000 miles, approximately 22ms is incurred in round-trip latency due to the speed of light through the optical fiber and other overhead.
• Additional latency can occur due to the data rate of the data streamed through the Internet. For example, if a user has DSL service that is sold as "6Mbps DSL service", in practice, the user will probably get less than 5Mbps of downstream throughput at best, and will likely see the connection degrade periodically due to various factors such as congestion during peak load times at the Digital Subscriber Line Access Multiplexer (DSLAM). A similar issue can occur reducing a the data rate of a cable modem is used for a connection sold as "6Mbps cable modem service" to far less than that, if there is congestion in the local shared coaxial cable looped through the neighborhood, or elsewhere in the cable modem system network.
• DSL service Digital Subscriber Line Access Multiplexer
• UDP User Datagram Protocol
• the data packets will pass through without incurring additional latency, but if there is congestion (or other impediments) and only 3.5Mbps is available to stream data to the user, then in a typical situation either packets will be dropped, resulting in lost data, or packets will queue up at the point of congestion, until they can be sent, thereby introducing additional latency.
• Different points of congestion have different queuing capacity to hold delayed packets, so in some cases packets that can't make it through the congestion are dropped immediately. In other cases, several megabits of data are queued up and eventually be sent.
• Latency is also incurred by the time required to compress video in the server and decompress video in the client device. Latency is further incurred while a video game running on a server is calculating the next frame to be displayed.
• motion JPEG is an intraframe-only lossy compression algorithm that is characterized by low-latency. Each frame of video is compressed independently of each other frame of video.
• a client device When a client device receives a frame of compressed motion JPEG video, it can immediately decompress the frame and display it, resulting in very low latency. But because each frame is compressed separately, the algorithm is unable to exploit similarities between successive frames, and as a result intraframe-only video compression algorithms suffer from very high data rates. For example, 60 fps (frames per second) 640x480 motion JPEG video may require 40Mbps (megabits per second) or more of data. Such high data rates for such low resolution video windows would be prohibitively expensive in many broadband applications (and certainly for most consumer Internet-based applications). Further, because each frame is compressed independently, artifacts in the frames that may result from the lossy compression are likely to appear in different places in successive frames. This can results in what appears to the viewer as a moving visual artifacts when the video is decompressed.
• Other compression algorithms such as MPEG2, H.264 or VC9 from Microsoft Corporation as they are used in prior art configurations, can achieve high compression ratios, but at the cost of high latency.
• Such algorithms utilize interframe as well as intraframe compression. Periodically, such algorithms perform an intraframe-only compression of a frame. Such a frame is known as a key frame (typically referred to as an "I" frame). Then, these algorithms typically compare the I frame with both prior frames and successive frames. Rather than compressing the prior frames and successive frames independently, the algorithm determines what has changed in the image from the I frame to the prior and successive frames, and then stores those changes as what are called "B" frames for the changes preceding the I frame and "P" frames for the changes following the I frame.
• I frame is typically much larger than a B or P frame (often 10 times larger), and as a result, it takes proportionately longer to transmit at a given data rate.
• the transmission channel has a maximum data rate of 2Mbps.
• Mb Megabits
• each frame needs to decompressed and displayed at a regular interval (e.g., 60 fps).
• a regular interval e.g. 60 fps.
• An interframe video compression system as described above using a large percentage of the bandwidth of the transmission channel will be subject to long latencies due to the large size of an I frame relative to the average size of a frame.
• prior art interframe compression algorithms achieve a lower average per-frame data rate than intraframe-only compression algorithms (e.g., 2Mbps vs. 40Mbps)
• the P and B frames are all much smaller than the I frames.
• Video compression algorithms utilizing the GOP structure described above have been largely optimized for use with live video or motion picture material intended for passive viewing.
• the camera whether a real camera, or a virtual camera in the case of a computer-generated animation
• scene is relatively steady, simply because if the camera or scene moves around too jerkily, the video or movie material is (a) typically unpleasant to watch and (b) if it is being watched, usually the viewer is not closely following the action when the camera jerks around suddenly (e.g., if the camera is bumped when shooting a child blowing out the candles on a birthday cake and suddenly jerks away from the cake and back again, the viewers are typically focused on the child and the cake, and disregard the brief interruption when the camera suddenly moves).
• 3D high action video games are characterized by constant motion (e.g., consider a 3D racing, where the entire frame is in rapid motion for the duration of the race, or consider first-person shooters, where the virtual camera is constantly moving around jerkily).
• Such video games can result in frame sequences with large and frequent peaks where the user may need to clearly see what is happening during those sudden motions.
• compression artifacts are far less tolerable in 3D high action video games.
• the video output of many video games by their nature, produces a compressed video stream with very high and frequent peaks.
• Peak bandwidth requirements can also be accommodated by residential broadband infrastructure if special accommodations are made. For example, on a cable TV system, digital video traffic can be given dedicated bandwidth which can handle peaks, such as large I frames. And, on a DSL system, a higher speed DSL modem can be provisioned, allowing for high peaks, or a specially- graded connection can provisioned which can handle a higher data rates. But, conventional cable modem and DSL infrastructure attached to the general Internet have far less tolerance for peak bandwidth requirements for compressed video.
• FIG. 1 illustrates an architecture of a prior art video gaming system.
• FIGS. 2a-b illustrate a high level system architecture according to one embodiment.
• FIG. 3 illustrates actual, rated, and required data rates for communication between a client and a server.
• FIG. 4a illustrates a hosting service and a client employed according to one embodiment.
• FIG. 4b illustrates exemplary latencies associated with communication between a client and hosting service.
• FIG 4c illustrates a client device according to one embodiment.
• FIG 4d illustrates a client device according to another embodiment.
• FIG 4e illustrates an example block diagram of the client device in
• FIG 4f illustrates an example block diagram of the client device in
• FIG. 5 illustrates an example form of video compression which may be employed according to one embodiment.
• FIG. 6a illustrates an example form of video compression which may be employed in another embodiment.
• FIG. 6b illustrates peaks in data rate associated with transmitting a low complexity, low action video sequence.
• FIG. 6c illustrates peaks in data rate associated with transmitting a high complexity, high action video sequence.
• FIGS. 7a-b illustrate example video compression techniques employed in one embodiment.
• FIG. 8 illustrates additional example video compression techniques employed in one embodiment.
• FIGS. 9a-c illustrate example techniques employed in one embodiment for alleviating data rate peaks.
• FIGS. 10a-b illustrate one embodiment which efficiently packs image tiles within packets.
• FIGS, lla-d illustrate embodiments which employ forward error correction techniques.
• FIG. 12 illustrates one embodiment which uses multi-core processing units for compression.
• FIGS. 13a-b illustrate geographical positioning and communication between hosting services according to various embodiments.
• FIG. 14 illustrates exemplary latencies associated with communication between a client and a hosting service.
• FIG. 15 illustrates an example hosting service server center architecture.
• FIG. 16 illustrates an example screen shot of one embodiment of a user interface which includes a plurality of live video windows.
• FIG. 17 illustrates the user interface of Figure 16 following the selection of a particular video window.
• FIG. 18 illustrates the user interface of Figure 17 following zooming of the particular video window to full screen size.
• FIG. 19 illustrates an example collaborative user video data overlaid on the screen of a multiplayer game.
• FIG. 20 illustrates an example user page for a game player on a hosting service.
• FIG. 21 illustrates an example 3D interactive advertisement.
• FIG. 22 illustrates an example sequence of steps for producing a photoreal image having a textured surface from surface capture of a live performance.
• FIG. 23 illustrates an example user interface page that allows for selection of linear media content.
• FIG. 24 is a graph that illustrates the amount of time that elapses before the web page is live versus connection speed.
• Figures 2a-b provide a high-level architecture of two embodiments in which video games and software applications are hosted by a hosting service 210 and accessed by client devices 205 at user premises 211 (note that the "user premises" means the place wherever the user is located, including outdoors if using a mobile device) over the Internet 206 (or other public or private network) under a subscription service.
• the client devices 205 may be general-purpose computers such as Microsoft Windows- or Linux-based PCs or Apple, Inc.
• Macintosh computers with a wired or wireless connection to the Internet either with internal or external display device 222, or they may be dedicated client devices such as a set- top box (with a wired or wireless connection to the Internet) that outputs video and audio to a monitor or TV set 222, or they may be mobile devices, presumably with a wireless connection to the Internet.
• client devices such as a set- top box (with a wired or wireless connection to the Internet) that outputs video and audio to a monitor or TV set 222, or they may be mobile devices, presumably with a wireless connection to the Internet.
• any of these devices may have their own user input devices (e.g., keyboards, buttons, touch screens, track pads or inertial-sensing wands, video capture cameras and/or motion-tracking cameras, etc.), or they may use external input devices 221 (e.g., keyboards, mice, game controllers, inertial sensing wand, video capture cameras and/or motion tracking cameras, etc.), connected with wires or wirelessly.
• the hosting service 210 includes servers of various levels of performance, including those with high- powered CPU/GPU processing capabilities.
• a home or office client device 205 receives keyboard and/or controller input from the user, and then it transmits the controller input through the Internet 206 to the hosting service 210 that executes the gaming program code in response and generates successive frames of video output (a sequence of video images) for the game or application software (e.g., if the user presses a button which would direct a character on the screen to move to the right, the game program would then create a sequence of video images showing the character moving to the right).
• This sequence of video images is then compressed using a low-latency video compressor, and the hosting service 210 then transmits the low-latency video stream through the Internet 206.
• the home or office client device then decodes the compressed video stream and renders the decompressed video images on a monitor or TV. Consequently, the computing and graphical hardware requirements of the client device 205 are significantly reduced.
• the client 205 only needs to have the processing power to forward the keyboard/controller input to the Internet 206 and decode and decompress a compressed video stream received from the Internet 206, which virtually any personal computer is capable of doing today in software on its CPU (e.g., a Intel Corporation Core Duo CPU running at approximately 2GHz is capable of decompressing 72Op HDTV encoded using compressors such as H.264 and Windows Media VC9).
• home client devices 205 do not require any specialized graphics processing units (GPUs), optical drive or hard drives, such as the prior art video game system shown in Figure 1.
• GPUs graphics processing units
• hard drives such as the prior art video game system shown in Figure 1.
• the hosting service 210 provides software development tools to the game or application software developers (which refers generally to software development companies, game or movie studios, or game or applications software publishers) 220 which design video games so that they may design games capable of being executed on the hosting service 210.
• Such tools allow developers to exploit features of the hosting service that would not normally be available in a standalone PC or game console (e.g., fast access to very large databases of complex geometry ("geometry" unless otherwise qualified shall be used herein to refer to polygons, textures, rigging, lighting, behaviors and other components and parameters that define 3D datasets)).
• game or application software developers which refers generally to software development companies, game or movie studios, or game or applications software publishers
• Such tools allow developers to exploit features of the hosting service that would not normally be available in a standalone PC or game console (e.g., fast access to very large databases of complex geometry ("geometry" unless otherwise qualified shall be used herein to refer to polygons, textures, rigging, lighting, behaviors and other components and parameters that define
• the hosting service 210 collects a subscription fee from the end user and pays a royalty to the developers 220, as shown in Figure 2a.
• the developers 220 collects a subscription fee directly from the user and pays the hosting service 210 for hosting the game or application content.
• a latency of 70-80ms(from the point a input device is actuated by the user to the point where a response is displayed on the display device) is at the upper limit for games and applications requiring a fast response time.
• this is very difficult to achieve in the context of the architecture shown in Figures 2a and 2b due to a number of practical and physical constraints.
• the connection is typically rated by a nominal maximum data rate 301 to the user's home or office.
• a nominal maximum data rate 301 may be more or less strictly enforced, but typically the actual available data rate is lower for one of many different reasons. For example, there may be too much network traffic at the DSL central office or on the local cable modem loop, or there may be noise on the cabling causing dropped packets, or the provider may establish a maximum number of bits per month per user.
• the maximum downstream data rate for cable and DSL services typically ranges from several hundred Kilobits/second (Kbps) to 30 Mbps.
• the actual available max data rate 302 may fluctuate over time.
• the data rate 303 required to sustain a given level of quality at given number of frames-per-second (fps) at a given resolution (e.g., 640 x 480 @ 60 fps) for a certain amount of scene complexity and motion rises above the actual available max data rate 302 (as indicated by the peak in Figure 3) then several problems may occur. For example, some internet services will simply drop packets, resulting in lost data and distorted/lost images on the user's video screen.
• FIG. 4a illustrates an architecture of the hosting service 210 according to one embodiment.
• the hosting service 210 can either be located in a single server center, or can be distributed across a plurality of server centers (to provide for lower latency connections to users that have lower latency paths to certain server centers than others, to provide for load balancing amongst users, and to provide for redundancy in the case one or more server centers fail).
• the hosting service 210 may eventually include hundreds of thousands or even millions of servers 402, serving a very large user base.
• a hosting service control system 401 provides overall control for the hosting service 210, and directs routers, servers, video compression systems, billing and accounting systems, etc.
• the hosting service control system 401 is implemented on a distributed processing Linux-based system tied to RAID arrays used to store the databases for user information, server information, and system statistics.
• the various actions implemented by the hosting service 210 unless attributed to other specific systems, are initiated and controlled by the hosting service control system 401.
• the hosting service 210 includes a number of servers 402 such as those currently available from Intel, IBM and Hewlett Packard, and others. Alternatively, the servers 402 can be assembled in a custom configuration of components, or can eventually be integrated so an entire server is implemented as a single chip. Although this diagram shows a small number of servers 402 for the sake of illustration, in an actual deployment there may be as few as one server 402 or as many as millions of servers 402 or more.
• the servers 402 may all be configured in the same way (as an example of some of the configuration parameters, with the same CPU type and performance; with or without a GPU, and if with a GPU, with the same GPU type and performance; with the same number of CPUs and GPUs; with the same amount of and type/speed of RAM; and with the same RAM configuration), or various subsets of the servers 402 may have the same configuration (e.g., 25% of the servers can be configured a certain way, 50% a different way, and 25% yet another way), or every server 402 may be different.
• the servers 402 are diskless, i.e., rather than having its own local mass storage (be it optical or magnetic storage, or semiconductor-based storage such as Flash memory or other mass storage means serving a similar function), each server accesses shared mass storage through fast backplane or network connection.
• this fast connection is a Storage Area Network (SAN) 403 connected to a series of Redundant Arrays of Independent Disks (RAID) 405 with connections between devices implemented using Gigabit Ethernet.
• RAID Redundant Arrays of Independent Disks
• a SAN 403 may be used to combine many RAID arrays 405 together, resulting in extremely high bandwidth — approaching or potentially exceeding the bandwidth available from the RAM used in current gaming consoles and PCs.
• RAID arrays based on rotating media such as magnetic media
• RAID arrays based on semiconductor storage can be implemented with much lower access latency.
• some or all of the servers 402 provide some or all of their own mass storage locally.
• a server 402 may store frequently-accessed information such as its operating system and a copy of a video game or application on low-latency local Flash-based storage, but it may utilize the SAN to access RAID Arrays 405 based on rotating media with higher seek latency to access large databases of geometry or game state information on a less frequent bases.
• the hosting service 210 employs low-latency video compression logic 404 described in detail below.
• the video compression logic 404 may be implemented in software, hardware, or any combination thereof (certain embodiments of which are described below).
• Video compression logic 404 includes logic for compressing audio as well as visual material.
• control signal logic 413 on the client 415 transmits control signals 406a-b (typically in the form of UDP packets) representing the button presses (and other types of user inputs) actuated by the user to the hosting service 210.
• the control signals from a given user are routed to the appropriate server (or servers, if multiple servers are responsive to the user's input device) 402. As illustrated in Figure 4a, control signals 406a may be routed to the servers 402 via the SAN.
• control signals 406b may be routed directly to the servers 402 over the hosting service network (e.g., an Ethernet- based local area network). Regardless of how they are transmitted, the server or servers execute the game or application software in response to the control signals 406a-b.
• the hosting service network e.g., an Ethernet- based local area network
• the server or servers execute the game or application software in response to the control signals 406a-b.
• various networking components such as a firewall(s) and/or gateway(s) may process incoming and outgoing traffic at the edge of the hosting service 210 (e.g., between the hosting service 210 and the Internet 410) and/or at the edge of the user premises 211 between the Internet 410 and the home or office client 415.
• the graphical and audio output of the executed game or application software i.e., new sequences of video images — are provided to the low-latency video compression logic 404 which compresses the sequences of video images according to low-latency video compression techniques, such as those described herein and transmits a compressed video stream, typically with compressed or uncompressed audio, back to the client 415 over the Internet 410 (or, as described below, over an optimized high speed network service that bypasses the general Internet).
• Low- latency video decompression logic 412 on the client 415 then decompresses the video and audio streams and renders the decompressed video stream, and typically plays the decompressed audio stream, on a display device 422 Alternatively, the audio can be played on speakers separate from the display device 422 or not at all. Note that, despite the fact that input device 421 and display device 422 are shown as free-standing devices in Figures 2a and 2b, they may be integrated within client devices such as portable computers or mobile devices.
• Home or office client 415 may be a very inexpensive and low-power device, with very limited computing or graphics performance and may well have very limited or no local mass storage.
• each server 402, coupled to a SAN 403 and multiple RAIDs 405 can be an exceptionally high performance computing system, and indeed, if multiple servers are used cooperatively in a parallel-processing configuration, there is almost no limit to the amount of computing and graphics processing power that can be brought to bear. And, because of the low-latency video compression 404 and low-latency video compression 412, perceptually to the user, the computing power of the servers 402 is being provided to the user.
• the image on display 422 is updated in response to the button press perceptually with no meaningful delay, as if the game or application software were running locally.
• a home or office client 415 that is a very low performance computer or just an inexpensive chip that implements the low- latency video decompression and control signal logic 413, a user is provided with effectively arbitrary computing power from a remote location that appears to be available locally. This gives users the power to play the most advanced, processor- intensive (typically new) video games and the highest performance applications.
• FIG. 4c shows a very basic and inexpensive home or office client device 465.
• This device is an embodiment of home or office client 415 from Figures 4a and 4b. It is approximately 2 inches long. It has an Ethernet jack 462 that interfaces with an Ethernet cable with Power over Ethernet (PoE), from which it derives its power and its connectivity to the Internet. It is able to run Network Address Translation (NAT) within a network that supports NAT.
• PoE Power over Ethernet
• NAT Network Address Translation
• the client 465 contains control signal logic 413 (of Figure 4a) that is coupled to a Bluetooth wireless interface, which interfaces with Bluetooth input devices 479, such as a keyboard, mouse, game controller and/or microphone and/or headset.
• client 465 is capable of outputting video at 120fps coupled with a display device 468 able to support 120fps video and signal (typically through infrared) a pair of shuttered glasses 466 to alternately shutter one eye, then the other with each successive frame.
• the effect perceived by the user is that of a stereoscopic 3D image that "jumps out" of the display screen.
• One such display device 468 that supports such operation is the Samsung HL-T5076S. Since the video stream for each eye is separate, in one embodiment two independent video streams are compressed by the hosting service 210, the frames are interleaved in time, and the frames are decompressed as two independent decompression processes within client 465.
• the client 465 also contains low latency video decompression logic 412, which decompresses the incoming video and audio and output through the HDMI (High-Definition Multimedia Interface),connector 463 which plugs into an SDTV (Standard Definition Television) or HDTV (High Definition Television) 468, providing the TV with video and audio, or into a monitor 468 that supports HDMI. If the user's monitor 468 does not support HDMI, then an HDMI-to-DVI (Digital Visual Interface) can be used, but the audio will be lost. Under the HDMI standard, the display capabilities (e.g. supported resolutions, frame rates) 464 are communicated from the display device 468, and this information is then passed back through the Internet connection 462 back to the hosting service 210 so it can stream compressed video in a format suitable for the display device.
• HDMI High-Definition Multimedia Interface
• HDMI-to-DVI Digital Visual Interface
• Figure 4d shows a home or office client device 475 that is the same as the home or office client device 465 shown in Figure 4c except that is has more external interfaces. Also, client 475 can accept either PoE for power, or it can run off of an external power supply adapter (not shown) that plugs in the wall.
• video camera 477 uses client 475 USB input, video camera 477 provides compressed video to client 475, which is uploaded by client 475 to hosting service 210 for use described below.
• a low-latency compressor utilizing the compression techniques described below.
• client 475 In addition to having an Ethernet connector for its Internet connection, client 475 also has an 802.1 Ig wireless interface to the Internet. Both interfaces are able to use NAT within a network that supports NAT. [0124] Also, in addition to having an HDMI connector to output video and audio, client 475 also has a Dual Link DVI-I connector, which includes analog output (and with a standard adapter cable will provide VGA output). It also has analog outputs for composite video and S-video.
• the client 475 has left/right analog stereo RCA jacks, and for digital audio output it has a TOSLINK output.
• USB jacks to interface to input devices.
• Figure 4e shows one embodiment of the internal architecture of client 465. Either all or some of the devices shown in the diagram can be implemented in an Field Programmable Logic Array, an custom ASIC or in several discrete devices, either custom designed or off-the-shelf.
• Ethernet with PoE 497 attaches to Ethernet Interface 481. Power
• Bus 480 is a common bus for communication between devices.
• Control CPU 483 (almost any small CPU, such as a MIPS R4000 series CPU at 100MHz with embedded RAM is adequate) running a small client control application from Flash 476 implements the protocol stack for the network
• Ethernet interface i.e. Ethernet interface
• Hosting Service 210 also communicates with the Hosting Service 210, and configures all of the devices in the client 465. It also handles interfaces with the input devices 469 and sends packets back to the hosting service 210 with user controller data, protected by Forward Error Correction, if necessary. Also,
• Control CPU 483 monitors the packet traffic (e.g. if packets are lost or delayed and also timestamps their arrival). This information is sent back to the hosting service 210 so that it can constantly monitor the network connection and adjust what it sends accordingly. Flash memory 476 is initially loaded at the time of manufacture with the control program for Control CPU 483 and also with a serial number that is unique to the particular Client 465 unit. This serial number allows the hosting service 210 to uniquely identify the Client 465 unit.
• Bluetooth interface 484 communicates to input devices 469 wirelessly through its antenna, internal to client 465.
• Video decompressor 486 is a low-latency video decompressor configured to implement the video decompression described herein. A large number of video decompression devices exist, either off-the-shelf, or as
• IP Intellectual Property
• the output of the video decompressor is coupled to the video output subsystem 487, which couples the video to the video output of the HDMI interface 490.
• the audio decompression subsystem 488 is implemented either using a standard audio decompressor that is available, or it can be implemented as
• IP or the audio decompression can be implemented within the control processor
• the device that implements the audio decompression is coupled to the audio output subsystem 489 that couples the audio to the audio output of the
• Figure 4f shows one embodiment of the internal architecture of client 475.
• the architecture is the same as that of client 465 except for additional interfaces and optional external DC power from a power supply adapter that plugs in the wall, and if so used, replaces power that would come from the Ethernet PoE 497.
• the functionality that is in common with client 465 will not be repeated below, but the additional functionality is described as follows.
• CPU 483 communicates with and configures the additional devices.
• WiFi subsystem 482 provides wireless Internet access as an alternative to Ethernet 497 through its antenna. WiFi subsystems are available from a wide range of manufacturers, including Atheros Communications of Santa
• USB subsystem 485 provides an alternative to Bluetooth communication for wired USB input devices 479.
• USB subsystems are quite standard and readily available for FPGAs and ASICs, as well as frequently built into off-the-shelf devices performing other functions, like video decompression.
• Video output subsystem 487 produces a wider range of video outputs than within client 465. In addition to providing HDMI 490 video output, it provides DVI-I 491, S-video 492, and composite video 493. Also, when the
• DVI-I 491 interface is used for digital video
• display capabilities 464 are passed back from the display device to the control CPU 483 so that it can notify the hosting service 210 of the display device 478 capabilities.
• All of the interfaces provided by the video output subsystem 487 are quite standard interfaces and readily available in many forms.
• Audio output subsystem 489 outputs audio digitally through digital interface 494 (S/PDIF and/or Toslink) and audio in analog form through stereo analog interface 495.
• the round trip latency between a user's action using input device 421 and seeing the consequence of that action on display device 420 should be no more than 70-80ms. This latency must take into account all of the factors in the path from input device 421 in the user premises 211 to hosting service 210 and back again to the user premises 211 to display device 422.
• Figure 4b illustrates the various components and networks over which signals must travel, and above these components and networks is a timeline that lists exemplary latencies that can be expected in a practical implementation. Note that Figure 4b is simplified so that only the critical path routing is shown. Other routing of data used for other features of the system is described below.
• Double-headed arrows (e.g., arrow 453) indicate round-trip latency and a single -headed arrow (e.g., arrow 457) indicate one-way latency, and " ⁇ " denote an approximate measure. It should be pointed out that there will be real-world situations where the latencies listed can not be achieved, but in a large number of cases in the US, using DSL and cable modem connections to the user premises 211, these latencies can be achieved in the circumstances described in the next paragraph. Also, note that, while cellular wireless connectivity to the Internet will certainly work in the system shown, most current US cellular data systems (such as EVDO) incur very high latencies and would not be able to achieve the latencies shown in Figure 4b.
• EVDO EVDO
• a user control signal is sent to client 415 (which may be a standalone device such a set-top box, or it may be software or hardware running in another device such as a PC or a mobile device), and is packetized (in UDP format in one embodiment) and the packet is given a destination address to reach hosting service 210.
• the packet will also contain information to indicate which user the control signals are coming from.
• the control signal packet(s) are then forwarded through Firewall/Router/NAT (Network Address Translation) device 443 to WAN interface 442.
• Firewall/Router/NAT Network Address Translation
• WAN interface 442 is the interface device provided to the user premises 211 by the User's ISP (Internet Service Provider).
• the WAN interface 442 may be a Cable or DSL modem, a WiMax transceiver, a Fiber transceiver, a Cellular data interface, an Internet Protocol-over-powerline interface, or any other of many interfaces to the Internet.
• Firewall/Router/NAT device 443 (and potentially WAN interface 442) may be integrated into the client 415.
• An example of this would be a mobile phone, which includes software to implement the functionality of home or office client 415, as well as the means to route and connect to the Internet wirelessly through some standard (e.g., 802.1 Ig).
• WAN Interface 442 then routes the control signals to what shall be called herein the "point of presence" 441 for the user's Internet Service Provider (ISP) which is the facility that provides an interface between the WAN transport connected to the user premises 211 and the general Internet or private networks.
• ISP Internet Service Provider
• the point of presence's characteristics will vary depending upon nature of the Internet service provided. For DSL, it typically will be a telephone company Central Office where a DSLAM is located. For cable modems, it typically will be a cable Multi-System Operator (MSO) head end. For cellular systems, it typically will be a control room associated with cellular tower. But whatever the point of presence's nature, it will then route the control signal packet(s) to the general Internet 410.
• MSO cable Multi-System Operator
• the control signal packet(s) will then be routed to the WAN Interface 441 to the hosting service 210, through what most likely will be a fiber transceiver interface.
• the WAN 441 will then route the control signal packets to routing logic 409 (which may be implemented in many different ways, including Ethernet switches and routing servers), which evaluates the user's address and routes the control signal(s) to the correct server 402 for the given user.
• the server 402 then takes the control signals as input for the game or application software that is running on the server 402 and uses the control signals to process the next frame of the game or application. Once the next frame is generated, the video and audio is output from server 402 to video compressor 404. The video and audio may be output from server 402 to compressor 404 through various means.
• compressor 404 may be built into server 402, so the compression may be implemented locally within server 402.
• the video and/or audio may be output in packetized form through a network connection such as an Ethernet connection to a network that is either a private network between server 402 and video compressor 404, or a through a shared network, such as SAN 403.
• the video may be output through a video output connector from server 402, such as a DVI or VGA connector, and then captured by video compressor 404.
• the audio may be output from server 402 as either digital audio (e.g., through a TOSLINK or S/PDIF connector) or as analog audio, which is digitized and encoded by audio compression logic within video compressor 404.
• video compressor 404 Once video compressor 404 has captured the video frame and the audio generated during that frame time from server 402, then video compressor will compress the video and audio using techniques described below. Once the video and audio is compressed it is packetized with an address to send it back to the user's client 415, and it is routed to the WAN Interface 441, which then routes the video and audio packets through the general Internet 410, which then routes the video and audio packets to the user's ISP point of presence 441, which routes the video and audio packets to the WAN Interface 442 at the user's premises, which routes the video and audio packets to the Firewall/Router/NAT device 443, which then routes the video and audio packets to the client 415.
• the client 415 decompresses the video and audio, and then displays the video on the display device 422 (or the client's built-in display device) and sends the audio to the display device 422 or to separate amplifier/speakers or to an amplifier/speakers built in the client.
• the round-trip delay needs be less than 70 or 80ms.
• the one-way transmission time to send the control signals 451 is typically less than lms, the roundtrip routing through the user premises 452 is typically accomplished, using readily available consumer-grade Firewall/Router/NAT switches over Ethernet in about lms.
• User ISPs vary widely in their round trip delays 453, but with DSL and cable modem providers, we typically see between 10 and 25ms.
• the round trip latency on the general Internet 410 can vary greatly depending on how traffic is routed and whether there are any failures on the route (and these issues are discussed below), but typically the general Internet provides fairly optimal routes and the latency is largely determined by speed of light through optical fiber, given the distance to the destination.
• the WAN Interface 441 to the hosting service 210 is typically a commercial-grade fiber high speed interface with negligible latency.
• the general Internet latency 454 is typically between 1 and 10ms.
• the one-way routing 455 latency through the hosting service 210 can be achieved in less than lms.
• the server 402 will typically compute a new frame for a game or an application in less than one frame time (which at 60fps is 16.7ms) so 16ms is a reasonable maximum oneway latency 456 to use.
• the compression 457 can be completed in lms.
• the compression may take as much as 6ms (of course even less optimized versions could take longer, but such implementations would impact the overall latency of the round trip and would require other latencies to be shorter (e.g., the allowable distance through the general Internet could be reduced) to maintain the 70-80ms latency target).
• the round trip latencies of the Internet 454, User ISP 453, and User Premises Routing 452 have already been considered, so what remains is the video decompression 458 latency which, depending on whether the video decompression 458 is implemented in dedicated hardware, or if implemented in software on a client device 415 (such as a PC or mobile device) it can vary depending upon the size of the display and the performance of the decompressing CPU. Typically, decompression 458 takes between 1 and 8ms. [0150] Thus, by adding together all of the worst-case latencies seen in practice, we can determine the worst-case round trip latency that can be expected to be experience by a user of the system shown in Figure 4a.
• the video compressor 404 and video decompressor 412 from Figure 4a in the client 415 require the video compressor 404 and video decompressor 412 from Figure 4a in the client 415 to generate a packet stream which very particular characteristics, such that the packet sequence generated through entire path from the hosting service 210 to the display device 422 is not subject to delays or excessive packet loss and, in particular, consistently falls with the constraints of the bandwidth available to the user over the user's Internet connection through WAN interface 442 and Firewall/Router/NAT 443. Further, the video compressor must create a packet stream which is sufficiently robust so that it can tolerate the inevitable packet loss and packet reordering that occurs in normal Internet and network transmissions.
• one embodiment takes a new approach to video compression which decreases the latency and the peak bandwidth requirements for transmitting video.
• an analysis of current video compression techniques will be provided with respect to Figure 5 and Figures 6a-b. Of course, these techniques may be employed in accordance with underlying principles if the user is provided with sufficient bandwidth to handle the data rate required by these techniques.
• audio compression is not addressed herein other than to state that it is implemented simultaneously and in synchrony with the video compression. Prior art audio compression techniques exist that satisfy the requirements for this system.
• Figure 5 illustrates one particular prior art technique for compressing video in which each individual video frame 501-503 is compressed by compression logic 520 using a particular compression algorithm to generate a series of compressed frames 511-513.
• This technique is "motion JPEG” in which each frame is compressed according to a Joint Pictures Expert Group (JPEG) compression algorithm, based upon the discrete cosine transform (DCT).
• JPEG Joint Pictures Expert Group
• DCT discrete cosine transform
• Various different types of compression algorithms may be employed, however, while still complying with these underlying principles (e.g., wavelet-based compression algorithms such as JPEG-2000).
• One problem with this type of compression is that it reduces the data rate of each frame, but it does not exploit similarities between successive frames to reduce the data rate of the overall video stream.
• motion JPEG may only compress the stream by a factor of 10, resulting in a data stream of 90 KB/frame.
• VC9, MPEG2 and MPEG4 are all more efficient at compressing a video stream because they exploit the similarities between successive frames. These techniques all rely upon the same general techniques to compress video. Thus, although the H.264 standard will be described, but the same general principles apply to various other compression algorithms. A large number of H.264 compressors and decompressor are available, including the x264 open source software library for compressing H.264 and the FFmpeg open source software libraries for decompressing H.264.
• Figures 6a and 6b illustrate an exemplary prior art compression technique in which a series of uncompressed video frames 501-503, 559-561 are compressed by compression logic 620 into a series of "I frames” 611, 671; "P frames” 612-613; and “B frames” 670.
• the vertical axis in Figure 6a generally signifies the resulting size of each of the encoded frames (although the frames are not drawn to scale).
• video coding using I frames, B frames and P frames is well understood by those of skill in the art.
• an I frame 611 is a DCT-based compression of a complete uncompressed frame 501 (similar to a compressed JPEG image as described above).
• P frames 612-613 generally are significantly smaller in size than I frames 611 because they take advantage of the data in the previous I frame or P frame; that is, they contain data indicating the changes between the previous I frame or P frame.
• B frames 670 are similar to that of P frames except that B frames use the frame in the following reference frame as well as potentially the frame in the preceding reference frame.
• the desired frame rate is 60 frames/second
• each I frame is approximately 160 Kb
• the average P frame and B frame is 16 Kb and that a new I frame is generated every second.
• This data rate falls well within the maximum data rate for many current broadband Internet connections to homes and offices.
• This technique also tends to avoid the background noise problem from intraframe-only encoding because the P and B frames track differences between the frames, so compression artifacts tend not to appear and disappear from frame-to-frame, thereby reducing the background noise problem described above.
• One problem with the foregoing types of compression is that although the average data rate is relatively low (e.g., l.lMbps), a single I frame may take several frame times to transmit.
• a 2.2 Mbps network connection e.g., DSL or cable modem with 2.2Mbps peak of max available data rate 302 from Figure 3a
• a 2.2 Mbps network connection would typically be adequate to stream video at 1.1 Mbps with a 160Kbps I frame each 60 frames. This would be accomplished by having the decompressor queue up 1 second of video before decompressing the video. In 1 second, 1.1Mb of data would be transmitted, which would be easily accommodated by a 2.2Mbps max available data rate, even assuming that the available data rate might dip periodically by as much as 50%.
• this prior art approach would result in a 1 -second latency for the video because of the 1- second video buffer at the receiver. Such a delay is adequate for many prior art applications (e.g., the playback of linear video), but is far too long a latency for fast action video games which cannot tolerate more than 70-80ms of latency.
• the video stream data rate 624 is below the available max data rate 621 except for the I frames, where the peak data rate required for the I frames 623 far exceeds the available max data rate 622 (and even the rated max data rate 621).
• the video stream data rate sequence 634 shown in Figure 6c is a sequence typical to what one would expect to see from video with far more action, such as might be generated in a motion picture or a video game, or in some application software.
• HDTV streams of 1920x1080 at 60fps are readily handled by modern computers and displays, and 2560x1440 resolution displays at 60fps are increasingly available (e.g., Apple, Inc.'s 30" display).
• a high action video sequence at 1920x1080 at 60fps may require 4.5 Mbps using H.264 compression for a reasonable quality level. If we assume the I frames peak at 1OX the nominal data rate, that would result in 45Mbps peaks, as well as smaller, but still considerable, P frame peak.
• CBR Constant Bit Rate
• the low-latency compression logic 404 employed in one embodiment uses several different techniques to address the range of problems with streaming low-latency compressed video, while maintaining high quality.
• the low-latency compression logic 404 generates only I frames and P frames, thereby alleviating the need to wait several frame times to decode each B frame.
• the low- latency compression logic 404 subdivides each uncompressed frame 701-760 into a series of "tiles” and individually encodes each tile as either an I frame or a P frame.
• the group of compressed I frames and P frames are referred to herein as "R frames" 711-770.
• each uncompressed frame is subdivided into a 4 x 4 matrix of 16 tiles.
• these underlying principles are not limited to any particular subdivision scheme.
• the low-latency compression logic 404 divides up the video frame into a number of tiles, and encodes (i.e., compresses) one tile from each frame as an I frame (i.e., the tile is compressed as if it is a separate video frame of 1716 th the size of the full image, and the compression used for this "mini" frame is I frame compression) and the remaining tiles as P frames (i.e., the compression used for each "mini" 1716 th frame is P frame compression).
• Tiles compressed as I frames and as P frames shall be referred to as "I tiles" and "P tiles", respectively. With each successive video frame, the tile to be encoded as an I tile is changed.
• tile 0 of uncompressed frame 701 is encoded as I tile Io and the remaining 1-15 tiles are encoded as P tiles P 1 through P 15 to produce R frame 711.
• tile 1 of uncompressed frame 701 is encoded as I tile I 1 and the remaining tiles 0 and 2 through 15 are encoded as P tiles, Po and P 2 through P 15 , to produce R frame 712.
• the I tiles and P tiles for tiles are progressively interleaved in time over successive frames.
• the process continues until a R tile 770 is generated with the last tile in the matrix encoded as an I tile (i.e., I 1S ).
• the process then starts over, generating another R frame such as frame 711 (i.e., encoding an I tile for tile 0) etc.
• the first R frame of the video sequence of R frames contains only I tiles (i.e., so that subsequent P frames have reference image data from which to calculate motion).
• the startup sequence uses the same I tile pattern as normal, but does not include P tiles for those tiles that have not yet been encoded with an I tile.
• the video decompression logic 412 running on the client 415 decompresses each tile as if it is a separate video sequence of small I and P frames, and then renders each tile to the frame buffer driving display device 422. For example, I 0 and P 0 from R frames 711 to 770 are used to decompress and render tile 0 of the video image. Similarly, I 1 and P 1 from R frames 711 to 770 are used to reconstruct tile 1, and so on. As mentioned above, decompression of I frames and P frames is well known in the art, and decompression of I tiles and P tiles can be accomplished by having a multiple instances of a video decompressor running in the client 415.
• each of the tiles illustrated in Figure 7a may be roughly 1Kb
• the P frame will be very small, if the prior frame is quite different from the next frame, the P frame will be very large. But because a P frame is largely derived from the previous frame, rather than from the actual frame, the resulting encoded frame may contain more errors (e.g., visual artifacts) than an I frame with an adequate number of bits. And, when one P frame follows another P frame, what can occur is an accumulation of errors that gets worse when there is a long sequence of P frames.
• errors e.g., visual artifacts
• a sophisticated video compressor will detect the fact that the quality of the image is degrading after a sequence of P frames and, if necessary, it will allocate more bits to subsequent P frames to bring up the quality or, if it is the most efficient course of action, replace a P frame with an I frame. So, when long sequences of P frames are used (e.g., 59 P frames, as in prior examples above) particularly when the scene has a great deal of complexity and/or motion, typically, more bits are needed for P frames as they get further removed from an I frame.
• P frames that closely follow an I frame tend to require less bits than P frames that are further removed from an I frame. So, in the example shown in Figure 7a, no P frame is further than 15 frames removed from an I frame that precedes it, where as in the prior example, a P frame could be 59 frames removed from an I frame. Thus, with more frequent I frames, the P frames are smaller.
• R frames can be configured in a variety of different ways, depending upon the nature of the video sequence, the reliability of the channel, and the available data rate.
• a different number of tiles is used than 16 in a 4x4 configuration.
• 2 tiles may be used in a 2x1 or 1x2 configuration
• 4 tiles may be used in a 2x2, 4x1 or 1x4 configuration
• 6 tiles may be used in a 3x2, 2x3, 6x1 or 1x6 configurations or 8 tiles may be used in a 4x2 (as shown in Figure 7b), 2x4, 8x1 or 1x8 configuration.
• the tiles need not be square, nor must the video frame be square, or even rectangular.
• the tiles can be broken up into whatever shape best suits the video stream and the application used.
• the cycling of the I and P tiles is not locked to the number of tiles.
• a 16- cycle sequence can still be used as illustrated in Figure 7b.
• Sequential uncompressed frames 721, 722, 723 are each divided into 8 tiles, 0-7 and each tile is compressed individually. From R frame 731, only tile 0 is compressed as an I tile, and the remaining tiles are compressed as P tiles. For subsequent R frame 732 all of the 8 tiles are compressed as P tiles, and then for subsequent R frame 733, tile 1 is compressed as an I tile and the other tiles are all compressed as P tiles.
• certain tiles may be sequenced with I tiles more often than other tiles if, for example, certain areas of the screen are known to have more motion requiring from frequent I tiles, while others are more static (e.g., showing a score for a game) requiring less frequent I tiles.
• each frame is illustrated in Figures 7a-b with a single I tile, multiple I tiles may be encoded in a single frame (depending on the bandwidth of the transmission channel).
• certain frames or frame sequences may be transmitted with no I tiles (i.e., only P tiles).
• each tile is compressed separately from the other tiles, as the tiles get smaller the encoding of each tile can become less efficient, because the compressor of a given tile is not able to exploit similar image features and similar motion from the other tiles.
• dividing up the screen into 16 tiles generally will result in a less efficient encoding than dividing up the screen into 8 tiles.
• the screen is divided into 8 tiles and it causes the data of a full I frame to be introduced every 8 frames instead of every 16 frames, it results in a much higher data rate overall. So, by introducing a full I frame every 16 frames instead of every 8 frames, the overall data rate is reduced. Also, by using 8 larger tiles instead of 16 smaller tiles, the overall data rate is reduced, which also mitigates to some degree the data peaks caused by the larger tiles.
• the compression logic 404 allocates an equal number of bits to each tile, then the tiles on the bottom half of the screen (tiles 4- 7) in uncompressed frame 721 in Figure 7b, will generally be compressed with higher quality than tiles than the tiles in the upper half of the screen (tiles 0-3) in uncompressed frame 721 in Figure 7b. If this particular game, or this particular scene of the game is known to have such characteristics, then the operators of the hosting service 210 can configure the compression logic 404 to allocate more bits to the tiles in the top of the screen than to tiles at the bottom of the screen.
• the compression logic 404 can evaluate the quality of the compression of the tiles after frames are compressed (using one or more of many compression quality metrics, such as Peak Signal-To-Noise Ratio (PSNR)) and if it determines that over a certain window of time, certain tiles are consistently producing better quality results, then it gradually allocates more bits to tiles that are producing lower quality results, until the various tiles reach a similar level of quality.
• PSNR Peak Signal-To-Noise Ratio
• the compressor logic 404 allocates bits to achieve higher quality in a particular tile or group of tiles. For example, it may provide a better overall perceptual appearance to have higher quality in the center of the screen than at the edges.
• the video compression logic 404 uses smaller tiles to encode areas of the video stream with relatively more scene complexity and/or motion than areas of the video stream with relatively less scene complexity and/or motion. For example, as illustrated in Figure 8, smaller tiles are employed around a moving character 805 in one area of one R frame 811 (potentially followed by a series of R frames with the same tile sizes (not shown)). Then, when the character 805 moves to a new area of the image, smaller tiles are used around this new area within another R frame 812, as illustrated. As mentioned above, various different sizes and shapes may be employed as "tiles" while still complying with these underlying principles.
• cyclic VP tiles described above substantially reduce the peaks in the data rate of a video stream, they do not eliminate the peaks entirely, particularly in the case of rapidly-changing or highly complex video imagery, such as occurs with motion pictures, video games, and some application software. For example, during a sudden scene transition, a complex frame may be followed by another complex frame that is completely different. Even though several I tiles may have preceded the scene transition by only a few frame times, they don't help in this situation because the new frame's material has no relation to the previous I tiles.
• the video compressor 404 will determine that many, if not all, of the P tiles are more efficiently coded as I tiles, and what results is a very large peak in the data rate for that frame.
• the rated maximum data rate 621 e.g., "6Mbps DSL”
• the rated maximum data rate 621 is essentially a marketing number for users considering the purchase of an Internet connection, but generally it does not guarantee a level of performance.
• a peak data rate 941 which is a data rate the channel is able to handle steadily.
• This rate can be determined by a number of techniques.
• One such technique is by gradually sending an increasingly higher data rate test stream from the hosting service 210 to the client 415 in Figures 4a and 4b, and having the client provide feedback to the hosting service as to the level of packet loss and latency. As the packet loss and/or latency begins to show a sharp increase, that is an indication that the available maximum data rate 922 is being reached.
• the hosting service 210 can gradually reduce the data rate of the test stream until the client 415 reports that for a reasonable period of time the test stream has been received with an acceptable level of packet loss and the latency is near minimal. This establishes a peak maximum data rate 941, which will then be used as a peak data rate for streaming video. Over time, the peak data rate 941 will fluctuate (e.g., if another user in a household starts to heavily use the Internet connection), and the client 415 will need to constantly monitor it to see whether packet loss or latency increases, indicating the available max data rate 922 is dropping below the previously established peak data rate 941, and if so the peak data rate 941.
• the client 415 finds that the packet loss and latency remain at optimal levels, it can request that the video compressor slowly increases the data rate to see whether the available maximum data rate has increased (e.g., if another user in a household has stopped heavy use of the Internet connection), and again waiting until packet loss and/or higher latency indicates that the available maximum data rate 922 has been exceeded, and again a lower level can be found for the peak data rate 941, but one that is perhaps higher than the level before testing an increased data rate. So, by using this technique (and other techniques like it) a peak data rate 941 can be found, and adjusted periodically as needed. The peak data rate 941 establishes the maximum data rate that can be used by the video compressor 404 to stream video to the user.
• the logic for determining the peak data rate may be implemented at the user premises 211 and/or on the hosting service 210.
• the client device 415 performs the calculations to determine the peak data rate and transmits this information back to the hosting service 210;
• a server 402 at the hosting service performs the calculations to determine the peak data rate based on statistics received from the client 415 (e.g., packet loss, latency, max data rate, etc).
• Figure 9a shows an example video stream data rate 934 that has substantial scene complexity and/or motion that has been generated using the cyclic VP tile compression techniques described previously and illustrated in Figures 7a, 7b and 8.
• the video compressor 404 has been configured to output compressed video at an average data rate that is below the peak data rate 941, and note that, most of the time, the video stream data rate remains below the peak data rate 941.
• a comparison of data rate 934 with video stream data rate 634 shown in Figure 6c created using I/P/B or VP frames shows that the cyclic VP tile compression produces a much smoother data rate.
• a server 402 (from Figures 4a and 4b) produces an uncompressed video output stream at a steady frame rate (at 60fps in one embodiment).
• a timeline shows each frame 961-970 output each 1160 th second.
• Each uncompressed video frame, starting with frame 961, is output to the low-latency video compressor 404, which compresses the frame in less than a frame time, producing for the first frame compressed frame 1 981.
• the data produced for the compressed frame 1 981 may be larger or smaller, depending upon many factors, as previously described.
• server 402 If the data is small enough that it can be transmitted to the client 415 in a frame time (1160 th second) or less at the peak data rate 941, then it is transmitted during transmit time (xmit time) 991 (the length of the arrow indicates the duration of the transmit time).
• server 402 produces uncompressed frame 2 962, it is compressed to compressed frame 2 982, and it is transmitted to client 415 during transmit time 992, which is less than a frame time at peak data rate 941.
• server 402 produces uncompressed frame 3 963.
• the resulting compressed frame 3 983 is more data than can be transmitted at the peak data rate 941 in one frame time.
• server 402 produces another uncompressed frame 4 964 and outputs it to video compressor 404 but the data is ignored and illustrated with 974.
• video compressor 404 is configured to ignore further uncompressed video frames that arrive while it is still transmitting a prior compressed frame.
• client 415' s video decompressor will fail to receive frame 4, but it simply continues to display on display device 422 frame 3 for 2 frame times (i.e., briefly reduces the frame rate from 60fps to 30fps).
• server 402 outputs uncompressed frame 5
• server 402 outputs frame 10 970, video compressor 404 compresses it into compressed frame 10 987, and it is transmitted during transmit time 997, and client 415' s decompressor decompresses frame 10 and displays it on display device 422 and once again the video resumes at 60fps.
• video compressor 404 drops video frames from the video stream generated by server 402, it does not drop audio data, regardless of what form the audio comes in, and it continues to compress the audio data when video frames are dropped and transmit them to client 415, which continues to decompress the audio data and provide the audio to whatever device is used by the user to playback the audio. Thus audio continues unabated during periods when frames are dropped. Compressed audio consumes a relatively small percentage of bandwidth, compared to compressed video, and as result does not have a major impact on the overall data rate. Although it is not illustrated in any of the data rate diagrams, there is always data rate capacity reserved for the compressed audio stream within the peak data rate 941.
• a high action video stream can be transmitted with low latency through the general Internet and through a consumer-grade Internet connection.
• a high action video stream can be transmitted without peaks so that multiple users (e.g., transmitting 1920x1080 at 60fps at 4.5Mbps) can use the LAN or shared private data connection without having overlapping peaks overwhelming the network or the network switch backplanes.
• the hosting service 210 initially assesses the available maximum data rate 622 and latency of the channel to determine an appropriate data rate for the video stream and then dynamically adjusts the data rate in response.
• the hosting service 210 may, for example, modify the image resolution and/or the number of frames/second of the video stream to be sent to the client 415.
• the hosting service can adjust the quality level of the compressed video.
• the video decompression logic 412 on the client 415 can scale up the image to maintain the same image size on the display screen.
• the hosting service 210 pauses the game.
• the hosting service reports to the other users that the user has dropped out of the game and/or pauses the game for the other users.
• the video decompression logic 412 is able to mitigate the visual artifacts.
• the entire screen is impacted, potentially causing the screen to completely freeze for a period of time or show other screen- wide visual artifacts.
• a lost/delayed packet causes the loss of an I frame
• the decompressor will lack a reference for all of the P frames that follow until a new I frame is received. If a P frame is lost, then it will impact the P frames for the entire screen that follow. Depending on how long it will be before an I frame appears, this will have a longer or shorter visual impact.
• a lost/delayed packet is much less likely to impact the entire screen since it will only affect the tiles contained in the affected packet. If each tile's data is sent within an individual packet, then if a packet is lost, it will only affect one tile.
• the duration of the visual artifact will depend on whether an I tile packet is lost and, if a P tile is lost, how many frames it will take until an I tile appears. But, given that different tiles on the screen are being updated with I frames very frequently (potentially every frame), even if one tile on the screen is affected, other tiles may not be. Further, if some event cause a loss of several packets at once (e.g., spike in power next to a DSL line that briefly disrupts the data flow), then some of the tiles will be affected more than others, but because some tiles will quickly be renewed with a new I tile, they will be only briefly affected.
• One embodiment attempts to reduce the effect of lost packets by intelligently packaging the compressed tiles within the TCP (transmission control protocol) packets or UDP (user datagram protocol) packets.
• tiles are aligned with packet boundaries whenever possible.
• Figure 10a illustrates how tiles might be packed within a series of packets 1001-1005 without implementing this feature. Specifically, in Figure 10a, tiles cross packet boundaries and are packed inefficiently so that the loss of a single packet results in the loss of multiple frames. For example, if packets 1003 or 1004 are lost, three tiles are lost, resulting in visual artifacts.
• FIG 10b illustrates tile packing logic 1010 for intelligently packing tiles within packets to reduce the effect of packet loss.
• the tile packing logic 1010 aligns tiles with packet boundaries.
• tiles Tl, T3, T4, T7, and T2 are aligned with the boundaries of packets 1001-1005, respectively.
• the tile packing logic also attempts to fit tiles within packets in the most efficient manner possible, without crossing packet boundaries.
• tiles Tl and T6 are combined in one packet 1001; T3 and T5 are combined in one packet 1002; tiles T4 and T8 are combined in one packet 1003; tile T8 is added to packet 1004; and tile T2 is added to packet 1005.
• a single packet loss will result in the loss of no more than 2 tiles (rather than 3 tiles as illustrated in Figure 10a).
• One additional benefit to the embodiment shown in Figure 10b is that the tiles are transmitted in a different order in which they are displayed within the image. This way, if adjacent packets are lost from the same event interfering with the transmission it will affect areas which are not near each other on the screen, creating a less noticeable artifacting on the display.
• FEC forward error correction
• One embodiment employs forward error correction (FEC) techniques to protect certain portions of the video stream from channel errors.
• FEC techniques such as Reed-Solomon and Viterbi generate and append error correction data information to data transmitted over a communications channel. If an error occurs in the underlying data (e.g., an I frame), then the FEC may be used to correct the error.
• FEC codes increase the data rate of the transmission, so ideally, they are only used where they are most needed. If data is being sent that would not result in a very noticeable visual artifact, it may be preferable to not use FEC codes to protect the data. For example, a P tile that immediately precedes an I tile that is lost will only create a visual artifact (i.e., on tile on the screen will not be updated) for l/ ⁇ O" 1 of second on the screen. Such a visual artifact is barely detectable by the human eye. As P tiles are further back from an I tile, losing a P tile becomes increasingly more noticeable.
• a tile cycle pattern is an I tile followed by 15 P tiles before an I tile is available again, then if the P tile immediately following an I tile is lost, it will result in that tile showing an incorrect image for 15 frame times (at 60 fps, that would be 250ms).
• the human eye will readily detect a disruption in a stream for 250ms. So, the further back a P tile is from a new I tile (i.e., the closer a P tiles follows an I tile), the more noticeable the artifact.
• the closer a P tile follows an I tile the smaller the data for that P tile.
• P tiles following I tiles not only are more critical to protect from being lost, but they are smaller in size. And, in general, the smaller the data is that needs to be protected, the smaller the FEC code needs to be to protect it.
• FEC 1101 contains error correction code for I tile 1100 and FEC 1104 contains error correction code for I tile 1103. In this embodiment, no FEC is generated for the P tiles.
• Ib FEC codes are also generated for P tiles which are most likely to cause visual artifacts if lost.
• FECs 1105 provide error correction codes for the first 3 P tiles, but not for the P tiles that follow.
• FEC codes are generated for P tiles which are smallest in data size (which will tend to self-select P tiles occurring the soonest after an I tile, which are the most critical to protect).
• the tile is transmitted twice, each time in a different packet. If one packet is lost/delayed, the other packet is used.
• 1113 are generated for audio packets, 1110 and 1112, respectively, transmitted from the hosting service concurrently with the video. It is particularly important to maintain the integrity of the audio in a video stream because distorted audio (e.g., clicking or hissing) will result in a particularly undesirable user experience.
• the FEC codes help to ensure that the audio content is rendered at the client computer 415 without distortion.
• the audio data is transmitted twice, each time in a different packet. If one packet is lost/delayed, the other packet is used.
• FEC codes 1121 and 1123 are used for user input commands 1120 and 1122, respectively (e.g., button presses) transmitted upstream from the client 415 to the hosting service 210. This is important because missing a button press or a mouse movement in a video game or an application could result in an undesirable user experience.
• the user input command data is transmitted twice, each time in a different packet. If one packet is lost/delayed, the other packet is used.
• the hosting service 210 assesses the quality of the communication channel with the client 415 to determine whether to use FEC and, if so, what portions of the video, audio and user commands to which FEC should be applied. Assessing the "quality" of the channel may include functions such as evaluating packet loss, latency, etc, as described above. If the channel is particularly unreliable, then the hosting service 210 may apply FEC to all of I tiles, P tiles, audio and user commands.
• the hosting service 210 may apply FEC only to audio and user commands, or may not apply FEC to audio or video, or may not use FEC at all.
• the hosting service 210 continually monitors the conditions of the channel and changes the FEC policy accordingly.
• the client 415 assesses how many frames are left before a new I tile will be received and compares it to the round-trip latency from the client 415 to hosting service 210. If the round- trip latency is less than the number of frames before a new I tile is due to arrive, then the client 415 sends a message to the hosting service 210 requesting a new I tile.
• This message is routed to the video compressor 404, and rather than generating a P tile for the tile whose data had been lost, it generates an I tile.
• the system shown in Figs. 4a and 4b is designed to provide a round-trip latency that is typically less than 80ms, this results in a tile being corrected within 80ms (at 60fps, frames are 16.67ms of duration, thus in full frame times, 80ms latency would result in a corrected a tile within 83.33ms, which is 5 frame times — a noticeable disruption, but far less noticeable than, for example, a 250ms disruption for 15 frames).
• Figure 12 illustrates one particular embodiment in which a multi- core and/or multi-processor 1200 is used to compress 8 tiles in parallel.
• a dual processor, quad core Xeon CPU computer system running at 2.66 GHz or higher is used, with each core implementing the open source x264 H.264 compressor as an independent process.
• each of the CPU cores can be replaced with an H.264 compressor implemented in an FPGA.
• cores 1201-1208 are used to concurrently process the I tiles and P tiles as eight independent threads.
• a PCI Express xl- based DVI capture card such as the Sendero Video Imaging IP Development Board from Microtronix of Oosterhout, The Netherlands is used to capture uncompressed video at 640x480, 800x600, or 1280x720 resolution, and the FPGA on the card uses Direct Memory Access (DMA) to transfer the captured video through the DVI bus into system RAM.
• DMA Direct Memory Access
• the tiles are arranged in a 4x2 arrangement 1205 (although they are illustrated as square tiles, in this embodiment they are of 160x240 resolution).
• Each instantiation of x264's is configured to compress one of the 8 160x240 tiles, and they are synchronized such that, after an initial I tile compression, each core enters into a cycle, each one frame out of phase with the other, to compress one I tile followed by seven P tiles, and illustrated in Figure 12.
• each frame time the resulting compressed tiles are combined into a packet stream, using the techniques previously described, and then the compressed tiles are transmitted to a destination client 415.
• the data rate of the combined 8 tiles exceeds a specified peak data rate 941, then all 8 x264 processes are suspended for as many frame times as are necessary until the data for the combined 8 tiles has been transmitted.
• client 415 is implemented as software on a PC running 8 instantiations of FFmpeg.
• a receiving process receives the 8 tiles, and each tile is routed to an FFmpeg instantiation, which decompresses the tile and renders it to an appropriate tile location on the display device 422.
• the client 415 receives keyboard, mouse, or game controller input from the PC's input device drivers and transmits it to the server 402.
• the server 402 then applies the received input device data and applies it to the game or application running on the server 402, which is a PC running Windows using an Intel 2.16GHz Core Duo CPU.
• the server 402 then produces a new frame and outputs it through its DVI output, either from a motherboard-based graphics system, or through a NVIDIA 8800GTX PCI Express card's DVI output.
• the server 402 outputs the audio produced by game or applications through its digital audio output (e.g., S/PDIF), which is coupled to the digital audio input on the dual quad-core Xeon-based PC that is implementing the video compression.
• a Vorbis open source audio compressor is used to compress the audio simultaneously with the video using whatever core is available for the process thread.
• the core that completes compressing its tile first executes the audio compression.
• the compressed audio is then transmitted along with the compressed video, and is decompressed on the client 415 using a Vorbis audio decompressor.
• the hosting service 210 server center 1300 is located in the center of the US (e.g., Kansas, Kansas, etc.), such that the distance to any point in the continental US is approximately 1500 miles or less, the round trip Internet latency could be as low as 32 ms.
• the worst-case latencies allowed for the user ISP 453 is 25ms, typically, we have observed latencies closer to 10- 15ms with DSL and cable modem systems.
• Figure 4b assumes a maximum distance from the user premises 211 to the hosting center 210 of 1000 miles.
• the hosting service 210 server centers, HS1-HS6, are strategically positioned around the United States (or other geographical region), with certain larger hosting service server centers positioned close to high population centers (e.g., HS2 and HS5).
• the server centers HS1-HS6 exchange information via a network 1301 which may be the Internet or a private network or a combination of both. With multiple server centers, services can be provided at lower latency to users that have high user ISP latency 453.
• the general Internet usually provides connections from one point to another with a fairly reliable and optimal route and latency that is largely determined by distance (especially with long distance connections that result in routing outside of the user's local area) such reliability and latency is by no means guaranteed and often cannot be achieved from a user's premises to a given destination on the general Internet.
• a user client 415 when a user client 415 initially connects to the hosting service 210 to play a video game or use an application, the client communicates with each of the hosting service server centers HS1-HS6 available upon startup (e.g., using the techniques described above). If the latency is low enough for a particular connection, then that connection is used. In one embodiment, the client communicates with all, or a subset, of the hosting service server centers the one with the lowest latency connection is selected. The client may select the service center with the lowest latency connection or the service centers may identify the one with the lowest latency connection and provide this information (e.g., in the form of an Internet address) to the client.
• This information e.g., in the form of an Internet address
• the client 415 may be redirected to the other hosting service server center.
• the game or application the user is running would be paused on the server 402 at the user's overloaded server center, and the game or application state data would be transferred to a server 402 at another hosting service server center.
• the game or application would then be resumed.
• the hosting service 210 would wait until the game or application has either reached a natural pausing point (e.g., between levels in a game, or after the user initiates a "save" operation in application) to do the transfer.
• the hosting service 210 would wait until user activity ceases for a specified period of time (e.g., 1 minute) and then would initiate the transfer at that time.
• the hosting service 210 subscribes to an Internet bypass service 440 of Figure 14 to attempt to provide guaranteed latency to its clients.
• Internet bypass services are services that provide private network routes from one point to another on the Internet with guaranteed characteristics (e.g., latency, data rate, etc.). For example, if the hosting service 210 was receiving large amount of traffic from users using AT&T's DSL service offering in San Francisco, rather than routing to AT&T's San Francisco-based central offices, the hosting service 210 could lease a high-capacity private data connection from a service provider (perhaps AT&T itself or another provider) between the San Francisco-based central offices and one or more of the server centers for hosting service 210.
• a service provider perhaps AT&T itself or another provider
• private data connection could be used instead.
• private data connections are generally more expensive than the routes through the general Internet, so long as they remain a small percentage of the hosting service 210 connections to users, the overall cost impact will be low, and users will experience a more consistent service experience.
• Server centers often have two layers of backup power in the event of power failure.
• the first layer typically is backup power from batteries (or from an alternative immediately available energy source, such a flywheel that is kept running and is attached to a generator), which provides power immediately when the power mains fail and keeps the server center running. If the power failure is brief, and the power mains return quickly (e.g., within a minute), then the batteries are all that is needed to keep the server center running. But if the power failure is for a longer period of time, then typically generators (e.g., diesel- powered) are started up that take over for the batteries and can run for as long as they have fuel. Such generators are extremely expensive since they must be capable of producing as much power as the server center normally gets from the power mains.
• batteries or from an alternative immediately available energy source, such a flywheel that is kept running and is attached to a generator
• each of the hosting services HS1-HS5 share user data with one another so that if one server center has a power failure, it can pause the games and applications that are in process, and then transfer the game or application state data from each server 402 to servers 402 at other server centers, and then will notify the client 415 of each user to direct it communications to the new server 402. Given that such situations occur infrequently, it may be acceptable to transfer a user to a hosting service server center which is not able to provide optimal latency (i.e., the user will simply have to tolerate higher latency for the duration of the power failure), which will allow for a much wider range of options for transferring users.
• users on the East Coast may be going to sleep at 11:30PM while users on the West Coast at 8:30PM are starting to peak in video game usage. If there is a power failure in a hosting service server center on the West Coast at that time, there may not be enough West Coast servers 402 at other hosting service server centers to handle all of the users. In such a situation, some of the users can be transferred to hosting service server centers on the East Coast which have available servers 402, and the only consequence to the users would be higher latency. Once the users have been transferred from the server center that has lost power, the server center can then commence an orderly shutdown of its servers and equipment, such that all of the equipment has been shut down before the batteries (or other immediate power backup) is exhausted.
• Figure 15 illustrates an embodiment of components of a server center for hosting service 210 utilized in the following feature descriptions. As with the hosting service 210 illustrated in Figure 2a, the components of this server center are controlled and coordinated by a hosting service 210 control system 401 unless otherwise qualified.
• Inbound internet traffic 1501 from user clients 415 is directed to inbound routing 1502.
• inbound internet traffic 1501 will enter the server center via a high-speed fiber optic connection to the Internet, but any network connection means of adequate bandwidth, reliability and low latency will suffice.
• Inbound routing 1502 is a system of network (the network can be implemented as an Ethernet network, a fiber channel network, or through any other transport means) switches and routing servers supporting the switches which takes the arriving packets and routes each packet to the appropriate application/game (“app/game”) server 1521-1525.
• a packet which is delivered to a particular app/game server represents a subset of the data received from the client and/or may be translated/changed by other components (e.g., networking components such as gateways and routers) within the data center.
• packets will be routed to more than one server 1521-1525 at a time, for example, if a game or application is running on multiple servers at once in parallel.
• RAID array 1511-1512 are connected to the inbound routing network 1502, such that the app/game servers 1521-1525 can read and write to the RAID arrays 1511-1512.
• a RAID array 1515 (which may be implemented as multiple RAID arrays) is also connected to the inbound routing 1502 and data from RAID array 1515 can be read from app/game servers 1521- 1525.
• the inbound routing 1502 may be implemented in a wide range of prior art network architectures, including a tree structure of switches, with the inbound internet traffic 1501 at its root; in a mesh structure interconnecting all of the various devices; or as an interconnected series of subnets, with concentrated traffic amongst intercommunicating device segregated from concentrated traffic amongst other devices.
• One type of network configuration is a SAN which, although typically used for storage devices, it can also be used for general highspeed data transfer among devices.
• the app/game servers 1521-1525 may each have multiple network connections to the inbound routing 1502.
• a server 1521-1525 may have a network connection to a subnet attached to RAID Arrays 1511-1512 and another network connection to a subnet attached to other devices.
• the app/game servers 1521-1525 may all be configured the same, some differently, or all differently, as previously described in relation to servers 402 in the embodiment illustrated in Figure 4a.
• each user, when using the hosting service is typically at least one app/game server 1521- 1525.
• app/game server 1521- 1525 For the sake of simplicity of explanation, we shall assume a given user is using app/game server 1521, but multiple servers could be used by one user, and multiple users could share a single app/game server 1521-1525.
• the user's control input, sent from client 415 as previously described is received as inbound Internet traffic 1501, and is routed through inbound routing 1502 to app/game server 1521.
• App/game server 1521 uses the user's control input as control input to the game or application running on the server, and computes the next frame of video and the audio associated with it. App/game server 1521 then outputs the uncompressed video/audio 1529 to shared video compression 1530. App/game server may output the uncompressed video via any means, including one or more Gigabit Ethernet connections, but in one embodiment the video is output via a DVI connection and the audio and other compression and communication channel state information is output via a Universal Serial Bus (USB) connection.
• the shared video compression 1530 compresses the uncompressed video and audio from the app/game servers 1521-1525. The compression maybe implemented entirely in hardware, or in hardware running software.
• each app/game server 1521-1525 There may a dedicated compressor for each app/game server 1521-1525, or if the compressors are fast enough, a given compressor can be used to compress the video/audio from more than one app/game server 1521-1525. For example, at 60fps a video frame time is 16.67ms. If a compressor is able to compress a frame in lms, then that compressor could be used to compress the video/audio from as many as 16 app/game servers 1521-1525 by taking input from one server after another, with the compressor saving the state of each video/audio compression process and switching context as it cycles amongst the video/audio streams from the servers. This results in substantial cost savings in compression hardware.
• the compressor resources are in a shared pool 1530 with shared storage means (e.g., RAM, Flash) for storing the state of each compression process, and when a server 1521-1525 frame is complete and ready to be compressed, a control means determines which compression resource is available at that time, provides the compression resource with the state of the server's compression process and the frame of uncompressed video/audio to compress.
• shared storage means e.g., RAM, Flash
• part of the state for each server's compression process includes information about the compression itself, such as the previous frame's decompressed frame buffer data which may be used as a reference for P tiles, the resolution of the video output; the quality of the compression; the tiling structure; the allocation of bits per tiles; the compression quality, the audio format (e.g., stereo, surround sound, Dolby® AC-3).
• the previous frame's decompressed frame buffer data which may be used as a reference for P tiles
• the resolution of the video output the quality of the compression
• the tiling structure the allocation of bits per tiles
• the compression quality the audio format (e.g., stereo, surround sound, Dolby® AC-3).
• the compression process state also includes communication channel state information regarding the peak data rate 941 and whether a previous frame (as illustrated in Fig 9b) is currently being output (and as result the current frame should be ignored), and potentially whether there are channel characteristics which should be considered in the compression, such as excessive packet loss, which affect decisions for the compression (e.g., in terms of the frequency of I tiles, etc).
• the peak data rate 941 or other channel characteristics change over time, as determined by an app/game server 1521-1525 supporting each user monitoring data sent from the client 415, the app/game server 1521-1525 sends the relevant information to the shared hardware compression 1530.
• the shared hardware compression 1530 also packetizes the compressed video/audio using means such as those previously described, and if appropriate, applying FEC codes, duplicating certain data, or taking other steps to as to adequately ensure the ability of the video/audio data stream to be received by the client 415 and decompressed with as high a quality and reliability as feasible.
• Some applications require the video/audio output of a given app/game server 1521-1525 to be available at multiple resolutions (or in other multiple formats) simultaneously. If the app/game server 1521-1525 so notifies the shared hardware compression 1530 resource, then the uncompressed video audio 1529 of that app/game server 1521- 1525 will be simultaneously compressed in different formats, different resolutions, and/or in different packet/error correction structures.
• some compression resources can be shared amongst multiple compression processes compressing the same video/audio (e.g., in many compression algorithms, there is a step whereby the image is scaled to multiple sizes before applying compression. If different size images are required to be output, then this step can be used to serve several compression processes at once).
• the compressed video/audio 1539 of all of the various resolutions and formats required for a given app/game server 1521-1525 (be it one or many) will be output at once to outbound routing 1540.
• the output of the compressed video/audio 1539 is in UDP format, so it is a unidirectional stream of packets.
• the outbound routing network 1540 comprises a series of routing servers and switches which direct each compressed video/audio stream to the intended user(s) or other destinations through outbound Internet traffic 1599 interface (which typically would connect to a fiber interface to the Internet) and/or back to the delay buffer 1515, and/or back to the inbound routing 1502, and/or out through a private network (not shown) for video distribution.
• the outbound routing 1540 may output a given video/audio stream to multiple destinations at once. In one embodiment this is implemented using Internet Protocol (IP) multicast in which a given UDP stream intended to be streamed to multiple destinations at once is broadcasted, and the broadcast is repeated by the routing servers and switches in the outbound routing 1540.
• IP Internet Protocol
• the multiple destinations of the broadcast may be to multiple users' clients 415 via the Internet, to multiple app/game servers 1521-1525 through via inbound routing 1502, and/or to one or more delay buffers 1515.
• the output of a given server 1521-1522 is compressed into one or multiple formats, and each compressed stream is directed to one or multiple destinations.
• the video output of multiple servers 1521- 1525 can be combined by the shared hardware compression 1530 into a combined frame, and from that point forward it is handled as described above as if it came from a single app/game server 1521-1525.
• each compressed video/audio output 1539 stream being routed to a user client 415 is also being multicasted to a delay buffer 1515.
• a directory on the delay buffer 1515 provides a cross reference between the network address of the app/game server 1521-1525 that is the source of the delayed video/audio and the location on the delay buffer 1515 where the delayed video/audio can be found.
• App/game servers 1521-1525 may not only be used for running a given application or video game for a user, but they may also be used for creating the user interface applications for the hosting service 210 that supports navigation through hosting service 210 and other features.
• a screen shot of one such user interface application is shown in Figure 16, a "Game Finder" screen. This particular user interface screen allows a user to watch 15 games that are being played live (or delayed) by other users.
• Each of the "thumbnail" video windows, such as 1600 is a live video window in motion showing one the video from one user's game.
• the view shown in the thumbnail may be the same view that the user is seeing, or it may be a delayed view (e.g., if a user is playing a combat game, a user may not want other users to see where she is hiding and she may choose to delay any view of her gameplay by a period of time, say 10 minutes).
• the view may also be a camera view of a game that is different from any user's view. Through menu selections (not shown in this illustration), a user may choose a selection of games to view at once, based on a variety of criteria.
• the user may select a random selection of games (such as those shown in Figure 16), all of one kind of games (all being played by different players), only the top-ranked players of a game, players at a given level in the game, or lower-ranked players (e.g., if the player is learning the basics), players who are "buddies" (or are rivals), games that have the most number of viewers, etc.
• games such as those shown in Figure 16
• all of one kind of games all being played by different players
• only the top-ranked players of a game e.g., players at a given level in the game, or lower-ranked players (e.g., if the player is learning the basics), players who are "buddies" (or are rivals), games that have the most number of viewers, etc.
• each user will decide whether the video from his or her game or application can be viewed by others and, if so, which others, and when it may be viewed by others, whether it is only viewable with a delay.
• the app/game server 1521-1525 that is generating the user interface screen shown in Figure 16 acquires the 15 video/audio feeds by sending a message to the app/game server 1521-1525 for each user whose game it is requesting from.
• the message is sent through the inbound routing 1502 or another network.
• the message will include the size and format of the video/audio requested, and will identify the user viewing the user interface screen.
• a given user may choose to select "privacy" mode and not permit any other users to view video/audio of his game (either from his point of view or from another point of view), or as described in the previous paragraph, a user may choose to allow viewing of video/audio from her game, but delay the video/audio viewed.
• a user app/game server 1521-1525 receiving and accepting a request to allow its video/audio to be viewed will acknowledge as such to the requesting server, and it will also notify the shared hardware compression 1530 of the need to generate an additional compressed video stream in the requested format or screen size (assuming the format and screen size is different than one already being generated), and it will also indicate the destination for the compressed video (i.e., the requesting server). If the requested video/audio is only delayed, then the requesting app/game server 1521-1525 will be so notified, and it will acquire the delayed video/audio from a delay buffer 1515 by looking up the video/audio's location in the directory on the delay buffer 1515 and the network address of the app/game server 1521-1525 that is the source of the delayed video/audio.
• the audio from 15 games all mixed simultaneously might create a cacophony of sound.
• the user may choose to mix all of the sounds together in this way (perhaps just to get a sense of the "din" created by all the action being viewed), or the user may choose to just listen to the audio from one game at a time.
• the selection of a single game is accomplished by moving the yellow selection box 1601 to a given game (the yellow box movement can be accomplished by using arrow keys on a keyboard, by moving a mouse, by moving a joystick, or by pushing directional buttons on another device such as a mobile phone). Once a single game is selected, just the audio from that game plays. Also, game information 1602 is shown.
• the publisher logo (“EA") and the game logo, "Need for Speed Carbon” and an orange horizontal bar indicates in relative terms the number of people playing or viewing the game at that particular moment (many, in this case, so the game is "Hot”).
• “Stats” are provided, indicating that there are 145 players actively playing 80 different instantiations of the Need for Speed Game (i.e., it can be played either by an individual player game or multiplayer game), and there are 680 viewers (of which this user is one).
• these statistics are collected by hosting service control system 401 and are stored on RAID arrays 1511-1512, for keeping logs of the hosting service 210 operation and for appropriately billing users and paying publishers who provide content.
• Some of the statistics are recorded due to actions by the service control system 401, and some are reported to the service control system 401 by the individual app/game server 1521-1525.
• the app/game server 1521-1525 running this Game Finder application sends messages to the hosting service control system 401 when games are being viewed (and when they are ceased to be viewed) so that it may update the statistics of how many games are in view.
• Some of the statistics are available for user interface applications such as this Game Finder application.
• the app/game server 1521-1525 requests from the app/game server 1521-1525 running the game selected to have a copy of the video stream for a full screen size (at the resolution of the user' s display device 422) of the game routed to it.
• the app/game server 1521-1525 running the game notifies the shared hardware compressor 1530 that a thumbnail-sized copy of the game is no longer needed (unless another app/game server 1521-1525 requires such a thumbnail), and then it directs it to send a fullscreen size copy of the video to the app/game server 1521-1525 zooming the video.
• the user playing the game may or may not have a display device 422 that is the same resolution as that of the user zooming up the game. Further, other viewers of the game may or may not have display devices 422 that are the same resolution as the user zooming up the game (and may have different audio playback means, e.g., stereo or surround sound).
• the shared hardware compressor 1530 determines whether a suitable compressed video/audio stream is already being generated that meets the requirements of the user requesting the video/audio stream and if one does exist, it notifies the outbound routing 1540 to route a copy of the stream to the app/game server 1521-1525 zooming the video, and if not compresses another copy of the video that is suitable for that user and instructs the outbound routing to send the stream back to the inbound routing 1502 and the app/game server 1521-1525 zooming the video.
• This server now receiving a full screen version of the selected video will decompress it and gradually scale it up to full size.
• Figure 18 illustrates how the screen looks after the game has completely zoomed up to full screen and the game is shown at the full resolution of the user' s display device 422 as indicated by the image pointed to by arrow 1800.
• the app/game server 1521-1525 running the game finder application sends messages to the other app/game servers 1521-1525 that had been providing thumbnails that they are no longer needed and messages to the hosting service control server 401 that the other games are no longer being viewed.
• the only display it is generating is an overlay 1801 at the top of the screen which provides information and menu controls to the user.
• the audience has grown to 2,503 viewers. With so many viewers, there are bound to be many viewers with display devices 422 that have the same or nearly the resolution (each app/game server 1521-1525 has the ability to scale the video for adjusting the fitting).
• the hosting service 210 may or may not allow the user to join the game for a variety of reasons. For example, the user may have to pay to play the game and choose not to, the user may not have sufficient ranking to join that particular game (e.g., it would not be competitive for the other players), or the user's Internet connection may not have low enough latency to allow the user to play (e.g., there is not a latency constraint for viewing games, so a game that is being played far away (indeed, on another continent) can be viewed without latency concerns, but for a game to be played, the latency must be low enough for the user to (a) enjoy the game, and (b) be on equal footing with the other players who may have lower latency connections).
• app/game server 1521-1525 that had been providing the Game Finder user interface for the user will request that the hosting service control server 401 initiate (i.e., locate and start up) an app/game server 1521-1525 that is suitably configured for playing the particular game to load the game from a RAID array 1511-1512, and then the hosting service control server 401 will instruct the inbound routing 1502 to transfer the control signals from the user to the app/game game server now hosting the game and it will instruct the shared hardware compression 1530 to switch from compressing the video/audio from the app/game server that had been hosting the Game Finder application to compressing the video/audio from the app/game server now hosting the game.
• the hosting service control server 401 initiate (i.e., locate and start up) an app/game server 1521-1525 that is suitably configured for playing the particular game to load the game from a RAID array 1511-1512, and then the hosting service control server 401 will instruct the inbound routing 1502 to transfer the control signals from the user to the app/game game server now hosting
• the vertical sync of the Game Finder app/game service and the new app/game server hosting the game are not synchronized, and as a result there is likely to be a time difference between the two syncs. Because the shared video compression hardware 1530 will begin compressing video upon an app/game server 1521- 1525 completing a video frame, the first frame from the new server may be completed sooner than a full frame time of the old server, which may be before the prior compressed frame completing its transmission (e.g., consider transmit time 992 of Figure 9b: if uncompressed frame 3 963 were completed half a frame time early, it would impinge upon the transmit time 992).
• the shared video compression hardware 1530 will ignore the first frame from the new server (e.g., like Frame 4 964 is ignored 974), and the client 415 will hold the last frame from the old server an extra frame time, and the shared video compression hardware 1530 will begin compressing the next frame time video from the new app/game server hosting the game.
• the hosting service control server 401 will then notify app/game game server 1521-1525 that had been hosting the Game Finder to switch to an idle state, until it is needed again. [0248] The user then is able to play the game.
• each of the segments of the game will load into the server at gigabit/second speed (i.e., 1 gigabyte loads in 8 seconds) from the RAID array 1511-1512, and because of the vast storage capacity of the RAID array 1511-1512 (since it is a shared resource among many users, it can be very large, yet still be cost effective) geometry setup or other game segment setup can be pre-computed and stored on the RAID array 1511-1512 and loaded extremely rapidly. Moreover, because the hardware configuration and computational capabilities of each app/game server 1521-1525 is known, pixel and vertex shaders can be pre-computed.
• the game will start up almost instantly, it will run in an ideal environment, and subsequent segments will load almost instantly.
• the user will be able to view others playing the game (via the Game Finder, previously described and other means) and both decide if the game is interesting, and if so, learn tips from watching others. And, the user will be able to demo the game instantly, without having to wait for a large download and/or installation, and the user will be able to play the game instantly, perhaps on a trial basis for a smaller fee, or on a longer term basis.
• the user will be able to play the game on a Windows PC, a Macintosh, on a television set, at home, when traveling, and even on a mobile phone, with a low enough latency wireless connection. And, this can all be accomplished without ever physically owning a copy of the game.
• the user can decide to not allow his gameplay to be viewable by others, to allow his game to be viewable after a delay, to allow his game to be viewable by selected users, or to allow his game to be viewable by all users.
• the video/audio will be stored, in one embodiment, for 15 minutes in a delay buffer 1515, and the user will be able to "rewind” and view his prior game play, and pause, play it back slowly, fast forward, etc., just as he would be able to do had he been watching TV with a Digital Video Recorder (DVR).
• DVR Digital Video Recorder
• this "3D DVR” capability will also be supported, but it will require the game to be designed to support it.
• the "DVR" capability using a delay buffer 1515 will work with any game or application, limited of course, to the video that was generated when the game or application was used, but in the case of games with 3D DVR capability, the user can control a "fly through” in 3D of a previously played segment, and have the delay buffer 1515 record the resulting video and have the game state of the game segment record.
• a particular "fly-through” will be recorded as compressed video, but since the game state will also be recorded, a different fly-through will be possible at a later date of the same segment of the game.
• users on the hosting service 210 will each have a User Page, where they can post information about themselves and other data.
• video segments from game play that they have saved. For example, if the user has overcome a particularly difficult challenge in a game, the user can "rewind" to just before the spot where they had their great accomplishment in the game, and then instruct the hosting service 210 to save a video segment of some duration (e.g., 30 seconds) on the user's User Page for other users to watch.
• some duration e.g. 30 seconds
• the app/game server 1521-1525 that the user is using to playback the video stored in a delay buffer 1515 to a RAID array 1511-1512 and then index that video segment on the user's User Page.
• the game state information required for the 3D DVR can also be recorded by the user and made available for the user's User Page.
• the Game Finder application will enable users to join games as spectators as well as players. From an implementation point of view, there is no difference to the hosting system 210 to if a user is a spectator instead of an active player.
• the game will be loaded onto an app/game server 1521-1525 and the user will be controlling the game (e.g., controlling a virtual camera that views into the world). The only difference will be the game experience of the user.
• Another feature of the hosting service 210 is the ability to for multiple users to collaborate while viewing live video, even if using widely disparate devices for viewing. This is useful both when playing games and when using applications.
• Such cameras and/or microphones combined with local video/audio compression capability (particularly employing the low latency video compression techniques described herein) will enable a user to transmit video and/or audio from the user premises 211 to the hosting service 210, together with the input device control data.
• a capability illustrated in Figure 19 is achievable: a user can have his video and audio 1900 appear on the screen within another user's game or application.
• This example is a multiplayer game, where teammates collaborate in a car race.
• a user's video/audio could be selectively viewable / hearable only by their teammates.
• the players would be able to talk or make motions to each other in real-time without perceptible delay.
• This video/audio integration is accomplished by having the compressed video and/or audio from a user's camera/microphone arrive as inbound internet traffic 1501. Then the inbound routing 1502 routes the video and/or audio to the app/game game servers 1521-1525 that are permitted to view/hear the video and/or audio. Then, the users of the respective app/game game servers 1521-1525 that choose to use the video and/or audio decompress it and integrate as desired to appear within the game or application, such as illustrated by 1900.
• FIG. 19 The example of Figure 19 shows how such collaboration is used in a game, but such collaboration can be an enormous powerful tool for applications.
• a large building is being designed for New York city by architects in Chicago for a real estate developer based in New York, but the decision involves a financial investor who is traveling and happens to be in an airport in Miami, and a decision needs to be made about certain design elements of the building in terms of how it fits in with the buildings near it, to satisfy both the investor and the real estate developer.
• the architectural firm has a high resolution monitor with a camera attached to a PC in Chicago
• the real estate developer has a laptop with a camera in New York
• the investor has a mobile phone with a camera in Miami.
• the architectural firm can use the hosting service 210 to host a powerful architectural design application that is capable of highly realistic 3D rendering, and it can make use of a large database of the buildings in New York City, as well as a database of the building under design.
• the architectural design application will execute on one, or if it requires a great deal of computational power on several, of the app/game servers 1521- 1525.
• Each of the 3 users at disparate locations will connect to the hosting service 210, and each will have a simultaneous view of the video output of the architectural design application, but it will be will appropriately sized by the shared hardware compression 1530 for the given device and network connection characteristics that each user has (e.g., the architectural firm may see a 2560x1440 60fps display through a 20Mbps commercial Internet connection, the real estate developer in New York may see a 1280x720 60fps image over a 6 Mbps DSL connection on his laptop, and the investor may see a 320x180 60fps image over a 250Kbps cellular data connection on her mobile phone.
• the architectural firm may see a 2560x1440 60fps display through a 20Mbps commercial Internet connection
• the real estate developer in New York may see a 1280x720 60fps image over a 6 Mbps DSL connection on his laptop
• the investor may see a 320x180 60fps image over a 250Kbps cellular data connection on her mobile phone.
• Each party will hear the voice of the other parties (the conference calling will be handled by any of many widely available conference calling software package in the app/game server(s) 1521-1525) and, through actuation of a button on a user input device, a user will be able to make video appear of themselves using their local camera.
• the architects will be able to show what the build looks like as they rotate it and fly by it next to the other building in the area, with extremely photorealistic 3D rendering, and the same video will be visible to all parties, at the resolution of each party's display device. It won't matter that none of the local devices used by any party is incapable of handling the 3D animation with such realism, let alone downloading or even storing the vast database required to render the surrounding buildings in New York City.
• the hosting service 210 enables an unprecedented opportunity for establishing video-rich community services on the Internet.
• Figure 20 shows an exemplary User Page for a game player on the hosting service 210.
• the User Page is an application that runs on one of the app/game servers 1521-1525. All of the thumbnails and video windows on this page show constantly moving video (if the segments are short, they loop).
• the user Using a video camera or by uploading video, the user (whose username is "KILLHAZARD") is able to post a video of himself 2000 that other users can view. The video is stored on a RAID array 1511-1512.
• KILLHAZARD When other users come to KILLHAZARD's User Page, if KILLHAZARD is using the hosting service 210 at the time, live video 2001 of whatever he is doing (assuming he permits users viewing his User Page to watch him) will be shown. This will be accomplished by app/game server 1521-1525 hosting the User Page application requesting from the service control system 401 whether KILLHAZARD is active and if so, the app/game server 1521-1525 he is using. Then, using the same methods used by the Game Finder application, a compressed video stream in a suitable resolution and format will be sent to the app/game server 1521-1525 running the User Page application and it will be displayed.
• a key advantage of this over prior art approaches is the user viewing the User Page is able to see a game played live that the user does not own, and may very well not have a local computer or game console capable of playing the game. It offers a great opportunity for the user to see the user shown in the User Page "in action" playing games, and it is an opportunity to learn about a game that the viewing user might want to try or get better at.
• the user viewing the buddy' s game does not own a copy of the came, nor the local computing/game console resources to play the game.
• the game viewing is effectively instantaneous.
• the video segments 2003 are all Brag Clips 2003 saved by KILLHAZARD from previous games that he has played. Number 2004 shows how many times a Brag Clip has been viewed, and when the Brag Clip is viewed, users have an opportunity to rate them, and the number of orange keyhole- shaped icons 2005 indicate how high the rating is.
• the Brag Clips 2003 loop constantly when a user views the User Page, along with the rest of the video on the page.
• the Brag Clip 2003 playback is implemented by the app/game server 1521-1525 loading the compressed video segment stored on a RAID array 1511-1512 when the user recorded the Brag Clip and decompressing it and playing it back.
• Brag Clips 2003 can also be "3D DVR" video segments (i.e., a game state sequence from the game that can be replayed and allows the user to change the camera viewpoint) from games that support such capability.
• the game state information is stored, in addition to a compressed video recording of the particular "fly through” the user made when the game segment was recorded.
• a 3D DVR Brag Clip 2003 will constantly loop the Brag Clip 2003 that was recorded as compressed video when the user recorded the "fly through” of the game segment.
• This 3D DVR Brag Clip 2003 capability is enabled by activating the game that is about to replay the recorded game state information on another app/game server 1521-1525. Since the game can be activated almost instantaneously (as previously described) it is not difficult to activate it, with its play limited to the game state recorded by the Brag Clip segment, and then allow the user to do a "fly through” with a camera while recording the compressed video to a delay buffer 1515. Once the user has completed doing the "fly through” the game is deactivated.
• DVR Brag Clip 2003 is no more effort than controlling the DVR controls of a linear Brag Clip 2003. They may know nothing about the game or even how to play the game. They are just a virtual camera operator peering into a 3D world during a game segment recorded by another.
• Brag Clips that is either recorded from microphones or uploaded.
• Brag Clips can be used to create custom animations, using characters and actions from games. This animation technique is commonly known as "machinima”.
• machineima This animation technique is commonly known as "machinima”.
• users As users progress through games, they will achieve differing skill levels. The games played will report the accomplishments to the service control system 401, and these skill levels will be shown on User Pages.
• Figure 21 illustrates an interactive advertisement where the user is to select the exterior and interior colors of a car while the car rotates around in a showroom, while real-time ray tracing shows how the car looks. Then the user chooses an avatar to drive the car, and then the user can take the car for a drive either on a race track, or through an exotic locale such as Monaco. The user can select a larger engine, or better tires, and then can see how the changed configuration affects the ability of the car to accelerate or hold the road. [0280] Of course, the advertisement is effectively a sophisticated 3D video game.
• RAID array 1511-1512 and the inbound routing 1502 can provide data rates that are so fast and with latencies so low that it is possible to design video games and applications that rely upon the RAID array 1511-1512 and the inbound routing 1502 to reliably deliver geometry on-the-fly in the midst of game play or in an application during real-time animation (e.g., a fly-through with a complex database.
• the RAID arrays 1511- 1512 can stream data in excess of Gigabit Ethernet speed, and with a SAN network, it is possible to achieve 10 gigabit/second speed over 10 Gigabit Ethernet or over other network technologies. 10 gigabits/second will load a gigabyte of data in less that a second. In a 60fps frame time (16.67ms), approximately 170 megabits (21MB) of data can be loaded. Rotating media, of course, even in a RAID configuration will still incur latencies greater than a frame time, but Flash-based RAID storage will eventually be as large as rotating media RAID arrays and will not incur such high latency. In one embodiment, massive RAM write-through caching is used to provide very low latency access.
• Figure 22 shows how a live performance captured using ContourTM Reality Capture Technology (subject of co-pending applications: "Apparatus and method for capturing the motion of a performer," Ser. No. 10/942,609, Filed September 15, 2004; “Apparatus and method for capturing the expression of a performer," Ser. No. 10/942,413 Filed September 15, 2004; “Apparatus and method for improving marker identification within a motion capture system," Ser. No. 11/066,954, Filed February 25, 2005; “Apparatus and method for performing motion capture using shutter synchronization," Ser. No. 11/077,628, Filed March 10, 2005; “Apparatus and method for performing motion capture using a random pattern on capture surfaces," Ser. No.
• Linear content is widely available to home and office users in many forms. Linear content can be acquired on physical media, like CD, DVD,
• HD-DVD and Blu-ray media can be recorded by DVRs from satellite and cable TV broadcast. And, it is available as pay-per-view (PPV) content through satellite and cable TV and as video-on-demand (VOD) on cable TV.
• PV pay-per-view
• VOD video-on-demand
• DVDs and other video optical media typically have interactive features not available elsewhere, like director's commentaries, "making of featurettes, etc.
• CDs but not all CDs are available online. And Web sites associating with television programming often have extra features, blogs and sometimes comments from the actors or creative staff.
• Hosting service 210 is well suited for the delivery of linear content in linking together the disparate forms of related content. Certainly, delivering motion pictures is no more challenging that delivering highly interactive video games, and the hosting service 210 is able to deliver linear content to a wide range of devices, in the home or office, or to mobile devices.
• Figure 23 shows an exemplary user interface page for hosting service 210 that shows a selection of linear content.
• the hosting system 210 is able to link together linear content with video game content dynamically, and in real-time. For example, if a user is watching a Quidditch match in a Harry Potter movie, and decides she would like to try playing Quidditch, she can just click a button and the movie will pause and immediately she will be transported to the Quidditch segment of a Harry Potter video game. After playing the Quidditch match, another click of a button, and the movie will resume instantly.
• a live sports event such as a basketball game
• the hosting service 210 may be streamed through the hosting service 210 for users to watch, as they would for regular TV.
• a video game of the game could come up with the players starting in the same position, and the users (perhaps each taking control of one player) could redo the play to see if they could do better than the players.
• the hosting service 210 described herein is extremely well-suited to support this futuristic world because it is able to bring to bear computing power and mass storage resources that are impractical to install in a home or in most office settings, and also it's computing resources are always up-to-date, with the latest computing hardware available, whereas in a home setting, there will always be homes with older generation PCs and video games. And, in the hosting service 210, all of this computing complexity is hidden from the user, so even though they may be using very sophisticated systems, from the user's point of view, it is a simple as changing channels on a television. Further, the users would be able to access all of the computing power and the experiences the computing power would bring from any client 415. [0303] MuLTiPLAYER GAMES
• the game is a multiplayer game
• it will be able communicate both to app/game game servers 1521-1525 through the inbound routing 1502 network and, with a network bridge to the Internet (not shown) with servers or game machines that are not running in the hosting service 210.
• the app/game game servers 1521-1525 will have the benefit of extremely fast access to the Internet (compared to if the game was running on a server at home), but they will be limited by the capabilities of the other computers playing the game on slower connections, and also potentially limited by the fact that the game servers on the Internet were designed to accommodate the least common denominator, which would be home computers on relatively slow consumer Internet connections.
• Each app/game game server 1521-1525 hosting a game for a user will be interconnected with other app/game game servers 1521-1525 as well as any servers that are hosting the central control for the multiplayer game with extremely high speed, extremely low latency connectivity and vast, very fast storage arrays.
• the app/game game servers 1521-1525 will be communicating among each other and communicating to any servers hosting the central control for the multiplayer game at gigabit/second speed with potentially only lms of latency or less.
• the RAID arrays 1511-1512 will be able to respond very rapidly and then transfer data at gigabit/second speeds.
• a user customizes a character in terms of look and accoutrements such that the character has a large amount of geometry and behaviors that are unique to the character, with prior art systems limited to the game client running in the home on a PC or game console, if that character were to come into view of another user, the user would have to wait until a long, slow download completes so that all of the geometry and behavior data loads into their computer.
• that same download could be over Gigabit Ethernet, served from a RAID array 1511-1512 at gigabit/second speed.
• the Hosting Service 210 is extremely well-suited for tournaments.
• the Hosting Service is 210 is able to broadcast the major tournaments to thousands of people in the audience at once.
• a Content Delivery Network such as Akamai or Limelight for mass distribution to many client devices 415.
• a similar level of efficiency can be gained when a CDN is used to show Game Finder pages of top player groupings.
• a live celebrity announcer can be used to provide commentary during certain matches. Although a large number of users will be watching a major tournament, and relatively small number will be playing in the tournament.
• the audio from the celebrity announcer can be routed to the app/game game servers 1521-1525 hosting the users playing in the tournament and hosting any spectator mode copies of the game in the tournament, and the audio can be overdubbed on top of the game audio.
• Video of a celebrity announcer can be overlaid on the games, perhaps just on spectator views, as well.
• HTTP Transfer Protocol
• Tl line which provided 1.5Mbps data rate symmetrically (i.e., with equal data rate in both directions).
• HTTP was not architected (nor has it been implemented) to effectively take advantage of these dramatic speed improvements.
• a web site is a collection of files on a remote server.
• HTTP requests the first file, waits for the file to be downloaded, and then requests the second file, waits for the file to be downloaded, etc.
• HTTP allows for more than one "open connection", i.e., more than one file to be requested at a time, but because of agreed-upon standards (and a desire to prevent web servers from being overloaded) only very few open connections are permitted.
• a typical commercial website is shown (this particular website was from a major athletic shoe brand).
• the website has 54 files on it.
• the files include HTML, CSS, JPEG, PHP, JavaScript and Flash files, and include video content.
• a total of 1.5MBytes must be loaded before the page is live (i.e., the user can click on it and begin to use it).
• Figure 24 shows the amount of time that elapses before the web page is live as the connection speed grows.
• a 1.5Mbps connection speed 2401 using a conventional web server with a convention web browser, it takes 13.5 seconds until the web page is live.
• the load time is reduced to 6.5 seconds, or about twice as fast.
• this web site will always take at least 5.4 seconds until it is live.
• Another factor is the server-side queuing; every HTTP request is added in the back of the queue, so on a busy server this will have a significant impact because for every small item to get from the web server, the HTTP requests needs to wait for its turn.
• the server control system 401 will attempt to communicate with the app/game server 1521-1525, and if successful, will collect whatever machine state is available. Whatever information is available, along with the video/audio recorded by the delay buffer 1515 will be sent to the software developer. [0325] Thus, when the game or application software developer gets notification of a crash from the hosting service 210, it gets a frame-by-frame record of what led up to the crash. This information can be enormous valuable in tracking down bugs and fixing them.
• FIG. 4a and 4b provide a variety of benefits for both end users and game and application developers.
• home and office client systems e.g., PCs or game consoles
• PCs within businesses are also typically used only a fraction of the hours of the week, especially non-portable desktop PCs often required for high-end applications such as Autodesk Maya.
• some businesses operate at all hours and on holidays, and some PCs (e.g., portables brought home for doing work in the evening) are used at all hours and holidays, most business activities tend to center around 9AM to 5PM, in a given business' time zone, from Monday to Friday, less holidays and break times (such as lunch), and since most PC usage occurs while the user is actively engaged with the PC, it follows that desktop PC utilization tends to follow these hours of operation.
• a high-performance server 402 with high performance dual CPUs and dual GPUs and a large quantity of RAM can be utilized by a businesses and schools from 9AM to 5PM on non-holidays, but be utilized by gamers playing a sophisticated video game in the evenings, weekends and on holidays.
• low-performance applications can be utilized by businesses and schools on a low-performance server 402 with a Celeron CPU, no GPU (or a very low-end GPU) and limited RAM during business hours and a low-performance game can utilize a low-performance server 402 during non-business hours.
• the exact peak user load on the system is difficult to estimate for many reasons: some users will play during off-peak times, there may be certain day times when there are clustering peaks of users, the peak times can be affected by the type of game played (e.g., children's games will likely be played earlier in the evening), etc. But, given that the average number of hours played by a gamer is far less than the number of hours of the day when a gamer is likely to play a game, only a fraction of the number of users of the hosting service 210 will be using it at a given time. For the sake of this analysis, we shall assume the peak load is 12.5%.
• resources may be allocated dynamically based on the game being played or the applications executed by users. So, a user selecting a low-performance game or application will be allocated a low-performance (less expensive) server 402, and a user selecting a high-performance game or applications will be allocated a high-performance (more expensive) server 402.
• a given game or application may have lower-performance and higher- performance sections of the game or applications, and the user can be switched from one server 402 to another server 402 between sections of the game or application to keep the user running on the lowest-cost server 402 that meets the game or application's needs.
• the RAID arrays 405 which will be far faster than a single disk, will be available to even low-performance servers 402, that will have the benefit of the faster disk transfer rates. So, the average cost per server 402 across all of the games being played or applications being used is much less than the cost of the most expensive server 402 that plays the highest performance game or applications, yet even the low-performance servers 402, will derive disk performance benefits from the RAID arrays 405.
• a server 402 in the hosting service 210 may be nothing more than a PC motherboard without a disk or peripheral interfaces other than a network interface, and in time, may be integrated down to a single chip with just a fast network interface to the SAN 403.
• RAID Arrays 405 likely will be shared amongst far many more users than there are disks, so the disk cost per active user will be far less than one disk drive. All of this equipment will likely reside in a rack in an environmentally-controlled server room environment. If a server 402 fails, it can be readily repaired or replaced at the hosting service 210.
• a PC or game console in the home or office must be a sturdy, standalone appliance that has to be able to survive reasonable wear and tear from being banged or dropped, requires a housing, has at least one disk drive, has to survive adverse environment conditions (e.g., being crammed into an overheated AV cabinet with other gear), requires a service warranty, has to be packaged and shipped, and is sold by a retailer who will likely collect a retail margin.
• a PC or game console must be configured to meet the peak performance of the most computationally-intensive anticipated game or application to be used at some point in the future, even though lower performance games or application (or sections of games or applications) may be played most of the time.
• Any game or applications on the hosting service 210 regardless of what type of server 402 is required for that game or applications, is available to the user, and all games and applications run nearly instantly (i.e., loading rapidly from the RAID Arrays 405 or local storage on a servers 402) and properly with the latest updates and bug fixes (i.e., software developers will be able to choose an ideal server configuration for the server(s) 402 that run(s) a given game or application, and then configure the server(s) 402 with optimal drivers, and then over time, the developers will be able to provide updates, bug fixes, etc.
• the user is likely to find that games and applications continue to provide a better experience (e.g., through updates and/or bug fixes) and it may be the case that a user discovers a year later that a new game or application is made available on the service 210 that is utilizing computing technology (e.g., a higher-performance GPU) that did not even exist a year before, so it would have been impossible for the user to buy the technology a year before that would play the game or run the applications a year later.
• computing technology e.g., a higher-performance GPU
• the data that is stored in RAID arrays 405 can be configured using prior art RAID configuration techniques well-known to those skilled in the art such that if a disk fails, no data will be lost, and a technician at the server center housing the failed disk will be notified, and then will replace the disk, which then will be automatically updated so that the RAID array is once again failure tolerant. Further, since all of the disk drives are near one another and with fast local networks between them through the SAN 403 it is not difficult in a server center to arrange for all of the disk systems to be backed up on a regular basis to secondary storage, which can be either stored at the server center or relocated offsite. From the point of view of the users of hosting service 210, their data is simply secure all the time, and they never have to think about backups. [0339] ACCESS TO DEMOS
• demo the verb form of "demo” means to try out a demonstration version, which is also called a “demo”, but as a noun
• hosting service 210 it is easy and convenient for users to try out demos. Indeed, all the user does is select the demo through a user interface (such as one described below) and try out the demo. The demo will load almost instantly onto a server 402 appropriate for the demo, and it will just run like any other game or application.
• the demo Whether the demo requires a very high performance server 402, or a low performance server 402, and no matter what type of home or office client 415 the user is using, from the point of view of the user, the demo will just work.
• the software publisher of either the game or application demo will be able to control exactly what demo the user is permitted to try out and for how long, and of course, the demo can include user interface elements that offer the user an opportunity to gain access to a full version of the game or application demonstrated.
• the hosting service 210 can employ various techniques to limit demo use for a given user. The most straightforward approach is to establish a user ID for each user and limit the number of times a given user ID is allowed to play a demo. A user, however, may set up multiple user IDs, especially if they are free. One technique for addressing this problem is to limit the number of times a given client 415 is allowed to play a demo. If the client is a standalone device, then the device will have a serial number, and the hosting service 210 can limit the number of times a demo can be accessed by a client with that serial number.
• a serial number can be assigned by the hosting service 210 and stored on the PC and used to limit demo usage, but given that PCs can be reprogrammed by users, and the serial number erased or changed, another option is for the hosting service 210 to keep a record of the PC network adapter Media Access Control (MAC) address (and/or other machine specific identifiers such as hard-drive serial numbers, etc.) and limit demo usage to it.
• MAC Media Access Control
• Another approach is to limit the number of times a demo can be played to a given IP address.
• IP addresses may be periodically reassigned by cable modem and DSL providers, it does not happen in practice very frequently, and if it can be determined (e.g., by contacting the ISP) that the IP is in a block of IP addresses for residential DSL or cable modem accesses, then a small number of demo uses can typically be established for a given home. Also, there may be multiple devices at a home behind a NAT router sharing the same IP address, but typically in a residential setting, there will be a limited number of such devices. If the IP address is in a block serving businesses, then a larger number of demos can be established for a business. But, in the end, a combination of all of the previously mentioned approaches is the best way to limit the number of demos on PCs.
• Such self- managed server centers are typically dedicated for a single business or school and as such, are unable to take advantage of the overlap of usage that is possible when disparate applications (e.g., entertainment and business applications) utilize the same computing resources at different times of the week. So, many businesses and schools lack the scale, resources or expertise to set up a server center on their own that has a LAN- speed network connection to each user. Indeed, a large percentage of schools and businesses have the same Internet connections (e.g., DSL, cable modems) as homes.
• Internet connections e.g., DSL, cable modems
• the hosting service 210 can be gradually updated over time as gaming requirements change, in contrast to the current situation where a completely new generation of technology forces users and developers to upgrade and the game developer is dependent on the timely delivery of the hardware platform.
• the video path for delay buffer and/or group video 1550 is a feedback loop where the multicasted streaming interactive video output of the app/game servers 1521- 1525 is fed back into the app/game servers 1521-1525 either in real-time via path 1552 or after a selectable delay via path 1551.
• This enables a wide range of practical applications (e.g. such as those illustrated in Figures 16, 17 and 20) that would be either impossible or infeasible through prior art server or local computing architectures.
• what feedback loop 1550 provides is recursion at the streaming interactive video level, since video can be looped back indefinitely as the application requires it. This enables a wide range of application possibilities never available before.
• Video streams are unidirectional UDP streams. This enables effectively an arbitrary degree of multicasting of streaming interactive video (in contrast, two-way streams, such as TCP/IP streams, would create increasingly more traffic logjams on the networks from the back- and- forth communications as the number of users increased). Multicasting is an important capability within the server center because it allows the system to be responsive to the growing needs of Internet users (and indeed of the world's population) to communicate on a one-to-many, or even a many-to- many basis. Again, the examples discussed herein, such as Figure 16 which illustrates the use of both streaming interactive video recursion and multicasting are just the tip of a very large iceberg of possibilities.
• the various functional modules illustrated herein and the associated steps may be performed by specific hardware components that contain hardwired logic for performing the steps, such as an application-specific integrated circuit ("ASIC") or by any combination of programmed computer components and custom hardware components.
• the modules may be implemented on a programmable digital signal processor ("DSP") such as a Texas Instruments' TMS320x architecture (e.g., a TMS320C6000, TMS320C5000, . . . etc).
• DSP programmable digital signal processor
• Embodiments may include various steps as set forth above.
• the steps may be embodied in machine-executable instructions which cause a general-purpose or special-purpose processor to perform certain steps.
• Various elements which are not relevant to these underlying principles such as computer memory, hard drive, input devices, have been left out of the figures to avoid obscuring the pertinent aspects.
• Elements of the disclosed subject matter may also be provided as a machine-readable medium for storing the machine-executable instructions.
• the machine-readable medium may include, but is not limited to, flash memory, optical disks, CD-ROMs, DVD ROMs, RAMs, EPROMs, EEPROMs, magnetic or optical cards, propagation media or other type of machine-readable media suitable for storing electronic instructions.
• the present invention may be downloaded as a computer program which may be transferred from a remote computer (e.g., a server) to a requesting computer (e.g., a client) by way of data signals embodied in a carrier wave or other propagation medium via a communication link (e.g., a modem or network connection).
• elements of the disclosed subject matter may also be provided as a computer program product which may include a machine-readable medium having stored thereon instructions which may be used to program a computer (e.g., a processor or other electronic device) to perform a sequence of operations. Alternatively, the operations may be performed by a combination of hardware and software.
• the machine-readable medium may include, but is not limited to, floppy diskettes, optical disks, CD-ROMs, and magneto-optical disks, ROMs, RAMs, EPROMs, EEPROMs, magnet or optical cards, propagation media or other type of media/machine-readable medium suitable for storing electronic instructions.
• elements of the disclosed subject matter may be downloaded as a computer program product, wherein the program may be transferred from a remote computer or electronic device to a requesting process by way of data signals embodied in a carrier wave or other propagation medium via a communication link (e.g., a modem or network connection).
• a communication link e.g., a modem or network connection

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