JP2008153800A - Content distribution system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mechanism which does not charge when receiving notice of reception of an unviewable content from a receiver since a transmission side is basically unable to know whether a sent packet has been delivered to an opposite side through UDP (User Datagram Protocol) though UDP is generally used in large-scale stream distribution service such as IP broadcasting in order for distribution efficiency of a content distributing server. <P>SOLUTION: When the content is distributed on a streaming basis using the communication protocol through which whether the sent data packet has been received by the communication partner is unknown, content distribution processing is performed by monitoring the number of loss packets, the occurrence state of a buffer overflow, etc., on a receiver side, and judging that the content is too poor to view and then not charging for the content distribution service when a certain reference value is exceeded. Consequently, it can be guaranteed that the distribution of the stream content which is not suitable to a service user is not charged for. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a content distribution system, a content distribution method, and a content distribution program that perform content stream distribution via a communication network such as the Internet in response to a viewer's request.

  In recent years, video on demand (VOD) services that allow users to enjoy not only normal television broadcasts but also desired titles when they want to watch are spreading. Also, an IP broadcast service is started in which a broadcast station distributes broadcast programs through the Internet instead of broadcast radio waves. In such a VOD service and IP broadcast, the distribution server of the service provider transmits AV media content files such as music and video images one by one from the top in order, and transmits it to the viewer's receiver (client). However, in this case, generally, the reproduction and viewing while receiving without waiting for the entire content file to be delivered to the receiver is called stream delivery or streaming. On the other hand, the term “download” is often used when all content data is received, stored once in a storage device in the receiver, and then reproduced again.

  In the content distribution by streaming, the content that can be viewed by the viewer is limited by the performance of the communication line and the receiver used. When streaming, video content is sent as a data packet over the network by the distribution server, generally reaches the receiver via a device such as a router or switching hub, is taken into the receiver and sent to the playback device. Although converted into a viewable video, the data transfer capacity per second is called a bit rate, and is a value specific to each content file. The larger this value, the higher the quality such as the resolution and smoothness of the moving image, but the use band necessary for receiving data for viewing increases. If the network environment used by the viewer and the available bandwidth of the receiver are larger than the bit rate of the content, the content can be played back without problems, but if the available bandwidth is smaller, the data is received. If the video does not reach the device or the playback process inside the receiver is not in time, the video will be distorted, and if it becomes too severe, viewing will be impossible.

Furthermore, in the distribution of data packets using the network, the data does not generally reach the receiver at the bit rate sent by the server, and is very high in some cases due to the characteristics of devices such as routers and hubs that pass along the way. Data arrival varies, such as receiving at the bit rate and interrupting at certain times. In addition, packets may arrive after being switched.
In particular, in the case of a mobile terminal using wireless communication, the receivable bandwidth varies depending on time and circumstances. In other words, even if the processing capability of the receiver is constant, the number and performance of relaying routers and hubs change, and the surrounding wireless environment also changes from moment to moment. For this reason, content with the same bit rate may or may not be viewed depending on the location and time.

  A receiver usually has a mechanism for storing content data in a buffer to some extent when a data packet is received, and reproducing the data with a time difference so that the user does not know variations in data distribution during reproduction. The larger the amount stored in the buffer, the more it can cope with changes in the bit rate at the time of content reception, but the amount of memory installed in the receiver increases and the cost of the equipment increases, and each viewer's cost increases. Since the amount of memory required varies depending on the network environment, generally a large buffer is not installed. Under these circumstances, it can be said that the content can basically be viewed only by a viewer who can use a band larger than the bit rate of the content.

  Under such circumstances, in order to guarantee the content reproduction to the viewer, there is also a distribution system that takes measures such as preparing a content with a different bit rate for each band for each video title and allowing the viewer to select the content. is there. However, in reality, it is difficult for amateur viewers to select appropriate content according to the bandwidth, and content with a bit rate larger than the actual bandwidth is selected, or conversely, it is much smaller than the actual bandwidth. By selecting bit rate content, it may not be possible to view clear content comfortably.

For this reason, Japanese Patent Application Laid-Open No. 2004-357093 discloses a system for providing a content distribution service by sending special dummy data before actual content distribution, measuring the distribution time, and determining that reproduction is guaranteed. Is disclosed.
Japanese Patent Laid-Open No. 2006-60802 sequentially reports the buffer occupancy rate of the receiver to the distribution server, and the distribution server determines that the use bandwidth is low when the buffer occupancy rate is high, and the streaming bit rate. Is reduced by excluding multiple types or classes of video frames from the content data packet, and then when the buffer occupancy decreases, the excluded type or class video frames are removed from the content data packet. A distribution method is disclosed in which control is performed to increase the bit rate by re-inserting into.

JP 2004-357093 A JP 2006-60802 A

However, a large-scale stream distribution service represented by IP broadcast generally performs streaming using UDP (User Datagram Protocol) in order to increase the distribution efficiency of the content distribution server. UDP basically does not return a response at the protocol level, it keeps sending data packets and is not reliable. In other words, it is not known to the transmitting side whether the transmitted data packet has arrived at the communication partner, and if an error occurs on the receiving side, the packet is simply discarded and no retransmission is performed.
Further, in IP broadcasting or the like, stream distribution is performed by simultaneous distribution to a large number of receivers by multicast communication, that is, one-to-many transmission / reception. In this method, the number of receivers that the content distribution server basically receives, and how much bandwidth can be used for each of the content distribution servers changes for each distribution.

In the one-to-many communication as described above, the bandwidth used by each receiver is measured, or the bit rate of the transmitted content is changed in real time according to the buffer occupancy of the receiver. Band adjustment based on one-to-one transmission and reception is difficult to apply.
From the viewer's side, when the content exceeds the use band of the receiver and the video is distorted, how much to endure viewing depends on the viewing content and viewing conditions. If you just want to know what happened today, and if you distribute a free news program, you may have to play the video to the extent that you can understand the approximate content. In case of, I am worried about a little disturbance of the image. In other words, a service system that performs paid stream distribution that cannot adjust the bit rate of distribution contents for each receiver does not charge for the contents when receiving a notice of unviewable content reception from the receiver. A mechanism is necessary for the integrity of the service.

  In the content distribution system according to the present invention, when the content distribution server performs the stream distribution, a means for determining whether or not the quality of the reproduced video can be enjoyed from the content data packet reception status received by the receiver. When the determination means determines that the content cannot be withstood, the viewer is warned that the bit rate of the content is out of the usable bandwidth of the receiver, and the stream content being received is charged for In some cases, a stream service invalid notice is sent to the content distribution server. The server that has received the invalid notice does not perform billing processing for the viewer of the receiver.

  Specifically, the receiver according to the present invention, when the data reception interruption time due to reception buffer overflow exceeds a certain threshold, and when the number of lost packets discarded due to an error exceeds a certain threshold, Since the viewing is impossible, that is, the viewer is not viewing the content, the streaming service is determined to be invalid.

  When the content distribution system of the present invention performs content stream distribution using a communication protocol in which it is not known whether or not the transmitted data packet has arrived at the communication partner, the number of lost packets and the occurrence of buffer overflow are performed on the receiver side. When a certain reference value is exceeded, it is possible to guarantee that inappropriate content will not be paid for viewers by providing a mechanism that does not charge the content distribution service.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows an example of a content distribution system of the present invention. Video content is streamed from the content distribution server 2 to the network-compatible television 3 as a receiver via the network 1.
Network 1 is a communication network that uses any of a variety of conventional Internet protocols and is implemented in any of a variety of conventional network physical layers (including optical, wired, or wireless networks). Alternatively, a plurality of local area networks (LAN), a part of a wide area network (WAN), or the like. In this example, it is assumed that the Internet is general-purpose. Note that the network 1 also includes communication control devices such as routers and hubs for accurately sending data packets from the transmission source to the transmission destination.

  The content distribution server 2 is a server system operated by a service provider that provides a service for streaming video media content to a receiver in response to a request from a viewer. Typically, a server for such a content distribution service provides a content management function for accumulating and managing content, a streaming management function for streaming content selected by a user request, service promotion, and content navigation. Portal server function that provides a user interface for users to use services through receivers, customer management functions that manage user registration processing and service usage history for each user, users pay services Billing / settlement management function that performs payment processing when used, license management function that assigns a key to decrypt encrypted content, IP broadcast management function that distributes content to multiple receivers at once by multicast , Content It has a such as the download function to download rather than streaming.

  Note that, from the service provision form, not all the functions described above are provided to the servers of these service providers, and there may be various functions other than the functions described above. In some cases, the server is physically configured by a single server, and in some cases, a service is provided by a plurality of servers divided for various functions.

  The receiver is a client device that receives content via a network and reproduces it for a viewer. In this example, it is assumed that the receiver is a network compatible digital television. FIG. 2 shows a functional configuration of the network compatible television.

  The network-compatible television of this embodiment includes an IP communication port for transmitting and receiving IP (Internet Protocol) data packets in addition to an antenna and digital tuner for receiving broadcast radio waves, and includes TCP (Transmission Control Protocol), UDP (User Various communication protocols such as Datagram Protocol (DHCP), Dynamic Host Configuration Protocol (DHCP), domain name server (DNS), HyperText Transfer Protocol (HTTP), Real-time Transport Protocol (RTP), Real Time Streaming Protocol (RTSP), and browsers Application can be connected to the public line (Internet) outside the home via a router or the like via the IP communication port, and the content distribution server 2 can be accessed to use various content streaming services. .

  In the content distribution system of the present embodiment, a service use procedure such as selection of content to be distributed using the HTTP protocol is performed between the content distribution server and the receiver, and the receiver is based on information obtained by the procedure. Assume that a stream reception request is made using the RTSP protocol, and the stream is received from the server using the RTP protocol. Of course, the protocol used for the service is not limited to the above. This network-compatible television converts the data packet of the content received using the RTP protocol so that it can be decoded in the same manner as the broadcast wave, and then sends it to the decoder. As a result, stream content can be reproduced and viewed in the same way as broadcasting.

  Next, the streaming operation of the content distribution system will be described with reference to FIG. 3 and FIG. FIG. 3 is a flowchart illustrating an operation in which the network-compatible television 3 accesses the content distribution server 2 to receive and reproduce the content distributed by streaming, and FIG. 4 is a flowchart illustrating an operation of the content distribution server 2 in performing the streaming distribution service. It is.

  First, according to the user's instruction, the network compatible TV accesses the portal site provided by the content distribution server using an HTTP browser. In this embodiment, it is assumed that the user interface of the server and the receiving organization is provided by an HTTP server and a browser. Also, usually for paid services, it is usually impossible to use the service unless you have registered as a member to register information about users and receivers to be used. When the receiver first establishes a connection to the server, device authentication processing is performed to determine whether or not the receiver and the server are connected to the correct partner (step 1000, step 2000, 2001). However, in this example, it is assumed that the member registration has been completed and the device authentication is correctly processed (step 2002).

  When the network compatible TV connects to the portal site of the server, the user can select the content he / she wants to view from the content menu of various free / paid streaming services presented on the portal site screen on the TV browser (step 1002, 2003). When the user selects content, the content distribution server checks whether the selected content is distributed for a fee or free (steps 2003 and 2004). If it is paid content, user authentication and license processing are performed (step 2005), the content data packet is encrypted and distributed, and billing is settled after the distribution ends. User authentication is a process for preventing unauthorized access such as impersonation by confirming whether or not the user is a correct user by, for example, causing a registered user to input a password registered in advance.

  In addition, the license process is a process for enabling only the purchaser who agrees to pay to view paid content by giving a key for decrypting the content to be encrypted only to the receiver of the distribution destination. is there.

  There are various forms of billing mechanisms for content, for example, a certain amount is paid each time the content is streamed once, or the first time is free and charged from the second streaming, or a certain amount You can stream as many times as you like. Accordingly, the billing / settlement process also varies depending on the past service usage status of the user who uses the billing / settlement process. In other words, for example, content that can be streamed any number of times when a certain fee is paid does not charge a user who has already made a payment, and only a user who views the content for the first time makes a payment request. The customer management function of the content distribution server stores and manages service use / payment information for each user, and this information is stored and updated each time the user uses the service.

  When the network compatible TV receives the content decryption key and is ready to receive and play the distribution content, it sends a stream start request to the content distribution server, and the content distribution server starts transmitting the streaming data packet. Starts data packet reception (steps 1004, 2006). At this time, in the network-compatible television, the effective reproduction flag indicating normal reception of the stream is initialized to the set state (step 1004).

  While receiving a streaming data packet (step 1005), the network-compatible TV discards the reception processing interruption time due to overflow of the reception buffer (step 1006), the number of data packets that have been correctly received and processed, and the reproduction processing cannot be correctly performed. The number of lost packets is counted (steps 1008 and 1012). The correctly received data packet is sent to the decoder after the decryption process using the distributed decryption key, and the video is reproduced and displayed one screen at a time (step 1009).

  If the overflow of the reception buffer occurs, the process proceeds to step 1013, where the accumulation is calculated by using the duration of the overflow state as the reception interruption time, and when the accumulated value becomes larger than the set threshold value, It is determined that the rate exceeds the available bandwidth of the network-compatible TV, and viewing is not possible. In step 1014, information indicating the above performance shortage is displayed on the TV screen, and if the successful playback flag is set ( In step 1015), the flag is cleared and the content distribution server is notified that the content cannot be reproduced and viewed (step 1016). In this example, the threshold value for the determination in step 1013 is set to ¼ or more of the accumulated time during which the continuous duration time in the overflow state can be received.

  Also, if the bit rate of the content exceeds the processing performance of the relaying network device, or if the network communication status is poor (especially likely when using wireless), the data packet captured in the reception buffer may be corrupted. The order may be skipped because there are data packets that do not reach the reception buffer. When such an error packet is received, the process proceeds to step 1012, and the number of lost packets that have not reached the reception buffer or have been broken and discarded is totaled. Since the RTP protocol used for the stream in this example is such that each packet is given a serial number in the order of transmission, the number of lost packets can be calculated in advance from the number of missing numbers. If the number of lost packets exceeds the set threshold, the processing from steps 1015 to 1017 is performed as in the case of the overflow reception interruption. In the case of this example, the number of lost packets is set to ½ or more of the number of packets that should be received as a threshold for determination in step 1012.

  The threshold may be set by the server sending it to the receiver every time content is distributed. In this case, when the content distribution server assigns a decryption key to the receiver by license processing before the stream starts, the threshold data is sent to the receiver together, and the received receiver sets and uses it.

Alternatively, a measurement count value such as the total number of lost packets and the total reception interruption time may be sent to the content distribution server, a reference (threshold value) is provided on the distribution server side, and invalidity determination may be performed based on the value. Also, either the reception interruption time or the lost packet is not monitored, but either one may be used.
When the content has been sent to the end or the user has intentionally instructed stop (steps 1010 and 2007), the content distribution server stops data packet transmission (step 2008), and the network-compatible television stops reception processing. (Step 1011).

  After the content distribution processing is completed, the content distribution server checks whether or not a service invalidity notification has been received from the distribution destination receiver (step 2009), and billing / settlement management is performed for the distribution destination user who has not transmitted the service invalidity notification. The fee collection procedure is performed by the function, and at the same time, the service usage history information of the user is updated (step 2010). For the receiver that has sent the service invalidity notification, it is assumed that the content is not viewed, and neither the charge listening nor the service usage history is updated.

  One content streaming is completed as described above. If the user wants to further view the content, he / she returns to the portal to select the content (steps 1017 and 2011), and disconnects the access to the server when the streaming ends (steps 1018 and 2012).

  As described above, according to the present invention, when a content stream is distributed using a communication protocol in which it is not known whether or not the transmitted data packet has reached the communication partner, the number of lost packets and the occurrence of buffer overflow occur on the receiver side. The state is monitored, and when a certain reference value is exceeded, it is ensured that inappropriate content is not paid to the viewer by paying a fee for the content distribution service.

It is a block diagram which shows an example of embodiment of a content delivery system. It is a figure which shows the function structure of a network corresponding television. It is a flowchart explaining the streaming operation | movement of a content delivery system. It is a flowchart which shows operation | movement of the content delivery server at the time of performing a streaming delivery service.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Network 2 Content delivery server 3 Receiver 11 Antenna tuner 12 Descrambler 13 Demultiplexer 14 Video audio decoder 15 Media recording control part 16 Hard disk 17 Digital video disk 18 Display screen 19 Speaker 20 CPU
21 Remote control interface unit 22 IP (Internet protocol) communication port 23 Random access memory 24 Read only memory 25 Graphic audio engine 26 Video display control unit 27 Audio output control unit 28 Memory card 30 Remote control 101 Portal site management function 102 Customer management function 103 Accounting Payment management function 104 License processing function 105 Content management function 106 Stream management function 107 IP broadcast management function 108 Download management function

Claims (4)

A content distribution server that distributes the content specified by the viewer from the stored video content via the communication network, and the data packet of the stream distributed by the content distribution server are received and reproduced as a video that can be viewed by the viewer In a content distribution system consisting of receivers,
The content distribution server comprises paid content distribution service means for charging a viewer for content distribution;
The receiver monitors the reception state of the data packet of the content transmitted by the content distribution server and records the numerical value, and the distribution is performed by comparing a preset threshold value with the numerical value recorded by the defective recording unit. Service determining means for determining whether or not the received content can be viewed, and notification means for transmitting service invalidity notification information to the content distribution server when the service determining means determines that the content cannot be viewed,
When the content distribution server receives service invalidity notification information, the content distribution server does not charge the content receiver for the corresponding receiver.   2. The content distribution system according to claim 1, wherein the reception failure recording means records the cumulative number of lost packets as a reception state of content data packets.   2. The content distribution system according to claim 1, wherein the reception failure recording means records the accumulated time of reception interruption numerically as the reception state of the content data packet.   2. The content distribution system according to claim 1, wherein the threshold value of the service determination unit is acquired and set from the content distribution server before starting the content distribution.

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