Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L12/00—Data switching networks
  • H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L65/00—Network arrangements, protocols or services for supporting real-time applications in data packet communication
  • H04L65/40—Support for services or applications
  • H04L65/401—Support for services or applications wherein the services involve a main real-time session and one or more additional parallel real-time or time sensitive sessions, e.g. white board sharing or spawning of a subconference
  • H04L65/4015—Support for services or applications wherein the services involve a main real-time session and one or more additional parallel real-time or time sensitive sessions, e.g. white board sharing or spawning of a subconference where at least one of the additional parallel sessions is real time or time sensitive, e.g. white board sharing, collaboration or spawning of a subconference
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L65/00—Network arrangements, protocols or services for supporting real-time applications in data packet communication
  • H04L65/60—Network streaming of media packets
  • H04L65/65—Network streaming protocols, e.g. real-time transport protocol [RTP] or real-time control protocol [RTCP]
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L65/00—Network arrangements, protocols or services for supporting real-time applications in data packet communication
  • H04L65/60—Network streaming of media packets
  • H04L65/75—Media network packet handling
  • H04L65/764—Media network packet handling at the destination 
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L65/00—Network arrangements, protocols or services for supporting real-time applications in data packet communication
  • H04L65/80—Responding to QoS
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04Q—SELECTING
  • H04Q3/00—Selecting arrangements
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04Q—SELECTING
  • H04Q3/00—Selecting arrangements
  • H04Q3/0016—Arrangements providing connection between exchanges
  • H04Q3/0025—Provisions for signalling
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W80/00—Wireless network protocols or protocol adaptations to wireless operation
  • H04W80/04—Network layer protocols, e.g. mobile IP [Internet Protocol]

Definitions

• IP data networks developed for the Internet provide an opportunity for users to interact utilizing multimedia communications.
• a computing device with the appropriate hardware and software allows a user to send/receive video, audio, instant messages (e.g., text), and the like between other networked computing devices.
• Data transmitted over the IP data network is processed into a sequence of data blocks, called packets that adhere to IP protocols capable of communicating a variety of media types.
• a personal computer such as a desktop or laptop
• users may establish multimedia network sessions in which different media types are communicated concurrently.
• an IP phone implements functionality to digitize analog phone signals, partition the digitized signal into packets, and transmit the packets to another IP networked computing device.
• the audio data may be packetized in accordance with the Voice over Internet Protocol ("VoIP").
• VoIP Voice over Internet Protocol
• media streams may be transmitted between remote users.
• media streams e.g., video and audio
• a user may employ multiple computing devices to participate in a network session.
• a user may employ a system configuration where a desktop computer is closely associated with an IP phone. The user's preferences may dictate that audio data be sent/received using the IP phone while video data is sent/received using the desktop computer.
• existing systems are unable to reliably synchronize media streams that are communicated across multiple computing devices.
• a method for synchronizing incoming audio and video streams. More specifically, the method includes establishing a communication channel between a first computing device that is receiving an incoming audio stream with the second computing device that is receiving an incoming video stream. Once the communication channel is established, the current network conditions that describe attributes of the incoming audio stream are obtained by the first computing device. Then, the delay in the incoming audio stream is calculated. When the delay is known, the method causes the incoming video stream to be delayed to match the delay in the incoming audio stream. As a result, even though multiple devices are being used to participate in the multimedia network session, the rendering of the different media streams is synchronized. DESCRIPTION OF THE DRAWINGS
• FIGURE 1 illustrates a networking environment in which aspects of the present invention may be implemented
• FIGURE 2 illustrates a routine that synchronizes media streams being transmitted across multiple computing devices
• FIGURE 3 illustrates an exemplary exchange of control information that occurs when media streams are synchronized.
• the present invention may be described in the general context of computer- executable instructions, such as program modules, being executed by a computer.
• program modules include routines, programs, applications, widgets, objects, components, data structures, and the like that perform particular tasks or implement particular abstract data types.
• the present invention will typically be practiced in distributed computing environments where tasks are performed by remote processing devices that are linked through a communications network.
• program modules may be located on local and/or remote computer storage media.
• FIGURE 1 and the following discussion is intended to provide a brief, general description of a networking environment 100 in which aspects of the present invention may be implemented.
• the networking environment 100 is comprised of the computers 102-104 that are communicatively connected via the network 101.
• the computers 102-104 include a software system that operates as a session controller 105 to manage the exchange control information in a multimedia network session.
• the computers 102-104 may be desktop computers, laptop computers, mini- and mainframe computers, server computers, hand-held computing devices such as personal digital assistants and tablets, microprocessor-based and/or programmable consumer electronics including media systems, set-top boxes, gaming systems, or any other computing device capable of serving as a session controller.
• the network 101 may be implemented as a local area network (“LAN”), wide area network (“WAN”), cellular network, IEEE 802.11, Bluetooth wireless networks, and the like.
• the network 101 will be the global network commonly known as the Internet or World Wide Web (“WWW”).
• WWW World Wide Web
• the invention may also be used in other interactive environments, such as local or wide area networks or any other data networks that communicate using IP protocols.
• the computer 102 is associated with the IP phone 106 and the WebCam 108.
• the computer 104 is associated with the IP phone 110 and the stand-alone video device 112.
• the stand-alone video device 112 may be any device that is capable of receiving and rendering a sequence of images in real time.
• the stand-alone video device 112 may be a computer that is associated with a Web camera, a television, an entertainment system, a gaming system, etc.
• the WebCam 108 communicates with the computer 102 over a direct communication link.
• any one of the number of protocols may be used to facilitate communication, including but not limited to, Universal Serial Bus (“USB”), Fire Wire (also known as "IEEE 1394" or "lLink”), and the like.
• the IP phone 106 communicates with the computer 102 using computer networking systems developed for local area networks.
• the IP phone 110 and the stand-alone media device 112 may also communicate with the computer 104 using computer networking systems developed for local area networks.
• these systems for communicating between local devices may include Ethernet networking technologies developed in accordance with the IEEE 802.3 standard.
• other local area network technologies such as Wi-Fi systems that adhere to the IEEE standard 802.11 standard may also be utilized.
• Session Initiation Protocol is an exemplary protocol for initiating, modifying, and terminating a network session that involves multimedia streams such as video and audio.
• SIP Session Initiation Protocol
• MGCP Media Gateway Control Protocol
• SOAP Simple Object Access Protocol
• XMPP Extensible Messaging and Presence Protocol
• users employ a plurality of computing devices to send/receive different media streams during a multimedia network session.
• direct communication channels are established between computing devices that are preferred for communicating a particular media stream.
• control information is exchanged that enables the IP phones 106 and 110 to directly communicate audio data over the direct communication channel 114.
• the direct communication channel 116 is established between the computer 102 and the stand-alone video device 112. Once direct communication channels have been established, media streams may be communicated between preferred devices without being routed through a computer that serves as the session controller.
• users have been unable to employ multiple computing devices to participate in a multimedia network session.
• a user may employ a system configuration where the IP phone 106 is used to send/receive audio data while the computer 102 sends/receives video data.
• Another user may employ a system configuration where the IP phone 110 is used to send/receive audio data while the stand-alone video device 112 sends/receives video data.
• the computer 104 merely serves as a session controller managing the exchange of control information.
• aspects of the present invention synchronize media streams when multiple computing devices are being used to participate in a network session. For example, during a multimedia network session, an audio stream may be _ _
• FIGURE 2 a flow diagram illustrative of a synchronization routine 200 will be described.
• the synchronization routine 200 performs processing that synchronizes media stream being transmitted across multiple computing devices.
• processing performed by the synchronization routine 200 extends the functionality of a network architecture so that media streams transmitted on different communication channels are synchronized.
• aspects of the present invention may be implemented in different types of networks, including wide and local area networks that utilize a variety of protocols.
• a multimedia network session may be established between devices and networks that maintain different configurations.
• a user may employ a computer that serves as a session controller to transmit a media stream.
• one or more media-specific devices may be used to transmit a media stream during the same network session.
• the synchronization routine 200 begins at block 202 when a multimedia network session in which media streams are transmitted across multiple devices is established.
• the Session Initiation Protocol (“SIP") is an exemplary protocol for initiating, modifying, and terminating a network session that involves media streams, such as video and audio.
• SIP is utilized to exchange control information between remote devices so that the multimedia network session may be established, at block 202.
• establishing the multimedia network session may be performed using systems outside the scope of the present invention, these systems will not be described in detail here.
• transmission of the media streams between devices associated with remote users is initiated.
• the media streams are transmitted over direct communication channels without being routed through a computer that serves as a session controller.
• data in a media stream may be packetized and transmitted in accordance with standards dictated by the real-time transport protocol ("RTP").
• RTP is one exemplary Internet standard protocol that may be used to transmit real-time data including video and audio.
• a media stream may be may be transmitted using other media transport layer protocols without departing from the scope of the claimed subject matter.
• the network conditions are observed and statistics that describe the network conditions are collected, at block 206.
• network conditions are observed and statistics collected for each of the communication channels being used to transmit a media stream. For example, in the networking environment 100 depicted in FIGURE 1, statistics that describe the transmission of data over each of the direct communication channels 114-116 is collected.
• RTP may be used as the media transport protocol in transmitting various types of media streams.
• the real-time control protocol (“RTCP") may be used to exchange messages and distribute statistics that describe network conditions. These statistics describe a number of different network variables regarding the transmission of data. More specifically, network variables including packet loss rates and jitter that affect the delay in transmitting the media stream are collected. These network conditions may be periodically reported to devices that are sending/receiving a media stream. Typically, this data has been used to adjust the properties of the media stream to more appropriately account for network conditions. However, as described in further detail below, aspects of the present invention use this information to synchronize media streams that are being transmitted across multiple devices.
• a computing device that is sending/receiving an audio stream receives a data packet that describes the current network conditions.
• the synchronization routine 200 is described in the context of synchronizing audio and video streams being transmitted to the IP phone 106 and computer 102, respectively.
• RTCP packets may be periodically transmitted between computing devices that are participating in a multimedia network session.
• RTCP packets report statistics that describe current network conditions every five (5) seconds.
• an RTCP packet may be transmitted over the - -
• the IP phone 106 obtains data that describes the current network conditions.
• other computing devices participating in the multimedia network session may also periodically receive data that describes the network conditions on their respective communication channels.
• the computer 102 may periodically receive RTCP packets that describe the transmission of a video stream on the communication channel 116.
• the expected delay in transmitting the audio stream is calculated.
• processing executed on the IP phone 106 by aspects of the present invention calculates the expected delay in presenting the audio stream to a user. More specifically, data in the RTCP packet received at block 208 that includes the packet loss rate and jitter may be used to calculate the expected delay in the audio stream. In performing this calculation, a numeric value (e.g. two seconds) that represents the expected delay in the audio stream is identified.
• a set of data that includes the expected delay in the audio stream is reported to a computer that serves as a session controller. In one embodiment, processing is performed to "pair" devices that are being employed by a user to participate in a multimedia network session.
• the IP phone 106 and computer 102 may be paired when the multimedia network session is established. Once paired, these devices may freely exchange control information that relates to the multimedia network session.
• the IP phone 106 reports the set of data that includes the expected delay in the audio system to the computer 102, at block 212, using a previously established communication channel. More specifically, the IP phone 106 transmits a SIP-based info message to the computer 102, at block 212, with arguments that report the set of data that includes the expected delay in the audio stream.
• the set of data transmitted at block 212 includes timing information corresponding to the IP phone 106.
• the RTCP packet received by the IP phone 106 contains both relative timing information that is reported as a RTP time and an absolute time that is reported as a NTP ("Network Time Protocol") time.
• RTP time and NTP time corresponding to the IP phone 106 processing may be performed on the computer 102 to identify a "real" time in which packets in _ _
• Identifying a real time in which packets in the audio stream were received provides the computer 102 with information needed to synchronize the video stream with the audio stream.
• the synchronization routine 200 causes the rendering of the video stream to be delayed to match the audio stream.
• a computer that serves as a session controller may also be responsible for transmitting a media stream.
• the IP phone 106 receives an audio stream during a multimedia network session while the paired computer 102 receives a video stream.
• data that may be used to calculate the delay in a video stream is periodically transmitted from the stand-alone video device 112 to the computer 102.
• a set of data that includes the expected delay in the audio stream is reported in an info from the IP phone 106 to the computer 102, at block 212.
• the computer 102 may identify a "real" time in which packets in the audio stream were received by the IP phone 106.
• the "real" time corresponding to the audio stream and the expected delay in both the video and audio streams is known, the extent in which the media streams are "out-of-synch" may be readily identified.
• frames in a video stream are buffered in the memory of the computer 102 so that the delay in rendering the video stream matches the delay in the audio stream. As a result of delaying the video stream in this way, presentation of the audio and video streams is synchronized when presented to the user.
• a media specific computing device may delay the rendering of a media stream.
• the computer 106 is not responsible for sending/receiving a media stream and only serves as a session controller.
• the computer 106 may receive an info message from the IP phone 110 with a set of data that includes the expected delay in the audio stream.
• another SIP-based info message with arguments that report the set of data that includes the expected delay in the audio stream may be transmitted to the stand-alone video device 112.
• processing performed on the stand-alone video device 112 causes frames in a video stream to be buffered in memory to match the delay in the audio stream.
• synchronization routine 200 proceeds to block 216, where it terminates. Conversely, if the multimedia network session has not ended, the synchronization routine 200 proceeds back to block 206, and blocks 206 through block 215 repeat until the multimedia network session is over.
• the synchronization routine 200 described above with reference to FIGURE 2 should be construed as exemplary and not limiting. In this regard, additional or fewer steps may be performed when synchronizing media streams across multiple computing devices. Moreover, steps may be performed in a different order than described. For example, while the synchronization routine 200 described above with reference to FIGURE 2 causes a video stream to be delayed in order to match an audio stream, this is merely exemplary as an audio stream to be delayed to match the video stream. Also, while the examples above are provided in the context of audio and video streams, aspects of the present invention may be implemented to synchronize other types of media streams.
• FIGURE 3 For illustrative purposes, an exemplary exchange of control information between computing devices in the networking environment 100 (FIGURE 1) is depicted in FIGURE 3.
• the exchange of control information allows media streams that are being transmitted across multiple devices to be synchronized.
• a multimedia network session is established so that the IP phones 106 and 110 may directly communicate audio data over a direct communication channel.
• video data is directly transmitted between the computer 102 and the standalone video device 112.
• an RTCP packet is transmitted from the IP phone 110 to the IP phone 106, at event 300.
• an RTCP packet is transmitted from the IP phone 106 to the IP phone 110, at event 302.
• an RTCP packet may be periodically transmitted between devices that are exchanging one or more media streams.
• packet loss rates and jitter reported in these RTCP packets may be used to calculate the expected delay in an incoming media stream.
• processing executed on the IP phone 106 identifies the expected delay in the incoming audio stream. Then, the IP phone 106 transmits a SIP-based info message with arguments that report a set of data that includes the expected delay to the computer 102, at event 304. As described _ _
• processing implemented by aspects of the present invention on the computer 102 may cause the video stream to be buffered. As a result, rendering of the video stream may be delayed to match the audio stream.
• an info message is transmitted to the computer 102 that reports a set of data that includes the estimated delay of the incoming audio stream.
• video and audio streams being transmitted on multiple devices may continually be synchronized during the multimedia network session.
• the IP phone 110 when the IP phone 110 receives the RTCP packet, at event 302, the set of data that includes expected delay in the incoming audio stream is calculated. Then, similar to the description provided above, the IP phone 110 transmits a SIP -based info message with arguments that report the set of data that includes the expected delay in the audio stream to the computer 104, at event 306. Since the computer 104 does not send/receive a media stream, the info message that reports the expected delay in the audio stream is forwarded to the stand-alone media device 112, at event 308. As described previously, processing performed on the stand-alone video device 112 may cause frames in the incoming video stream to be buffered to match the delay in the incoming audio stream. As a result, each of the media streams may be synchronized even though the media streams are being transmitted across different devices.

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• Engineering & Computer Science (AREA)
• Multimedia (AREA)
• Computer Networks & Wireless Communication (AREA)
• Signal Processing (AREA)
• Data Exchanges In Wide-Area Networks (AREA)
• Telephonic Communication Services (AREA)
• Two-Way Televisions, Distribution Of Moving Picture Or The Like (AREA)

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• 2006
  • 2006-12-08 US US11/608,714 patent/US7953118B2/en active Active
• 2007
  • 2007-09-26 EP EP07843265.5A patent/EP2103040B1/en not_active Not-in-force
  • 2007-09-26 ES ES07843265.5T patent/ES2658073T3/es active Active
  • 2007-09-26 KR KR1020097014087A patent/KR101354793B1/ko not_active Expired - Fee Related
  • 2007-09-26 JP JP2009540346A patent/JP5270567B2/ja active Active
  • 2007-09-26 WO PCT/US2007/079596 patent/WO2008070253A1/en not_active Ceased

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