JP4247888B2 - Video distribution system and video distribution method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a video distribution system and a video distribution method for distributing video from a video distribution server to a viewer terminal using a network.
[0002]
[Prior art]
There are roughly two methods for distributing video to a listener using a network. One is a method of transferring video data to a viewer terminal by downloading from a video distribution server on the network, and reproducing the video on the viewer terminal after the transfer is completed. Another method is a streaming technique of playing back video data while downloading it from a video distribution server on the network. In the case of video distribution, the latter technique is now widely recognized, and many video distribution software such as Windows Media (registered trademark), Real (registered trademark), QuickTime (registered trademark), etc. adopt this technology. .
[0003]
When streaming video to a listener through a network, use a network transmission band sufficient to deliver high-quality video when the network between the video distribution system and the viewer terminal is congested. Video data (packets) is lost. As a result, the encoded video cannot be correctly decoded, and the reproduced video is distorted or frozen. For this reason, the quality of the distribution video is degraded. In order to reduce this quality degradation, the video distribution system using the software prepares encoded video of multi-stage quality in advance, and the video with the optimal encoding speed according to the available network transmission band. And the like are distributed.
[0004]
Specifically, the viewer terminal has already received information on the amount of data (packet loss) that has not been correctly received from the video distribution system, information on temporal fluctuation of data arrival (delay fluctuation), or the viewer terminal. Information on the data amount (buffering amount) of the video that has arrived before playback is returned to the video distribution system. In the video distribution system, the degree of congestion of the network between the video distribution system and the viewer terminal is estimated from these pieces of information, and when it is determined that the network is congested, the video distribution system transmits the video data transmission bandwidth to the viewer terminal. Is reduced by one step.
[0005]
As a result, the necessary network transmission bandwidth is reduced, and although video quality degradation is accompanied by a reduction in coding speed, video distortion, freeze, sound interruption, etc. due to data loss (packet loss), etc. It is possible to avoid a serious quality deterioration phenomenon. From such an idea, a streaming media server has been proposed in which an appropriate connection speed parameter suitable for the actual communication environment can be automatically set in a streaming reception application for each client (see, for example, Patent Document 1). ).
[0006]
On the other hand, in recent years, for the purpose of quality assurance of continuous media communication such as audio / video using a network, a mechanism for realizing bandwidth guarantee, delay time guarantee and the like has become available in the network. Although it is conceivable to use this mechanism to completely guarantee the use band for all viewers, the network construction cost increases. As an alternative, a method of setting a minimum guaranteed bandwidth for a certain viewer is considered effective. Specifically, the DiffservAF class standardized by IETF is one implementation method for guaranteeing the minimum bandwidth used by the user in each router of the network.
[0007]
By combining the dynamic video coding rate control mechanism of the video distribution system as described above and the minimum bandwidth guarantee mechanism of the network, video distribution with minimum video quality can be ensured.
[0008]
[Patent Document 1]
JP 2002-94603 A (page 3, FIG. 1)
[0009]
[Problems to be solved by the invention]
However, the minimum bandwidth guarantee using the Diffserv technique does not operate in cooperation with all routers between the video distribution server and the viewer terminal, and is exchanged and transferred independently for each router, so that the network is congested. There is a problem that the video connection that is affected in this case varies stochastically.
[0010]
Specifically, for example, a connection is considered in which high-quality encoded video is normally distributed in a band of 2 Mbit / s, and medium-quality encoded video is distributed in a band of 1 Mbit / s when the network is congested. Assume that a bandwidth of 20 Mbit / s is prepared for the video connection group, and the minimum guaranteed bandwidth for each connection is set to 1 Mbit / s. In this example, video distribution can be performed while maintaining a high quality state up to 10 connections, but from the 11th connection, 9 connections are divided by 2 Mbit / s and 2 connections are divided by 2 Mbit / s to obtain 1 Mbit / s. s band is used. Since it is rare for all connections to start and end at the same time, for example, if only the 11th connection starts and ends randomly, the bandwidth used decreases to 1 Mbit / s in the other 10 connections ( Connections (affected by congestion) are stochastically random.
[0011]
Here, when the video encoding speed fluctuates with time, the video quality perceived by the user is as described in Reference 1, “July 2002, IEICE Communication Quality Study Group CQ2002-71“ Changes in Bit Rate in Video Distribution Services. "Subjective quality assessment of influence""and reference 2," 2003 IEICE General Conference SB-7-1 "Subjective Quality Estimation Model of Video Distribution Service Under QoS Control""and the like. In this case, when the use band is lowered, the impression that the impression received from the quality in the low band has a strong influence on the overall overall quality, and the result is lower than the quality of the average band. In addition, it has been proved that even when the occupancy rate of the time distributed in the low band becomes large, the quality when it does not change in the low band is not lowered.
[0012]
In consideration of this quality evaluation characteristic, in the above example, when the eleventh connection is randomly generated and the connection whose use band is reduced to 1 Mbit / s is randomly determined among the other 10 connections, However, there is a problem that the quality is close to that when video is distributed in a low band.
[0013]
The present invention has been made in view of the above-described problems, and an object of the present invention is to provide video distribution that enables a user to experience high video quality when the network is congested. To provide a system and a video distribution method.
[0014]
[Means for Solving the Problems]
In order to achieve the object, a video distribution system according to the invention of claim 1 is a video distribution system for distributing video content from a video distribution server to a viewer terminal via a network including a packet switch, The packet switch records the maximum bandwidth used in the past in the video connection for each viewer terminal, and the priority of the video information packet distributed based on the bandwidth usage information recorded in the maximum bandwidth recording section A packet priority determination / distribution unit that distributes video information packets to packet transmission buffers having different priorities based on the determined priority information, and each packet transmission buffer based on the priority information. A packet extraction unit that extracts video information packets from the network, and video information packets extracted by the packet extraction unit. Characterized in that it comprises a transmitter which transmits to the viewer terminal side for each image connection.
[0015]
A video distribution system according to a second aspect of the present invention is a video distribution system for distributing video content from a video distribution server to a viewer terminal via a network including a packet switch, and at least the packet switch and the video distribution A video information packet priority adding device is provided between the servers, and the video information packet priority adding device records a maximum used bandwidth recording unit in a video connection for each viewer terminal, and a maximum used bandwidth recording unit. A packet priority determination unit for determining the priority of the video information packet distributed based on the used bandwidth information recorded in the packet, and information on each priority determined by the packet priority determination unit is attached to the packet, and the video And a transmission unit that transmits the information packet to the viewer terminal.
[0016]
According to a third aspect of the present invention, there is provided a video distribution method for distributing video content from a video distribution server to a viewer terminal via a network including a packet switch. The maximum used bandwidth recording step for recording the past maximum used bandwidth in the connection, and the priority of the video information packet distributed based on the recorded used bandwidth information is determined, and based on the determined priority information A packet priority determination / distribution step for distributing video information packets to packet transmission buffers having different priorities, a packet extraction step for extracting video information packets from each packet transmission buffer based on the priority information, and the extracted video A transmission step of transmitting an information packet to the viewer terminal for each video connection; And wherein the Mukoto.
[0017]
According to a fourth aspect of the present invention, there is provided a video distribution method for distributing video content from a video distribution server to a viewer terminal via a network including a packet switch, and at least the packet switch and the video distribution. A packet for determining the priority of a video information packet distributed based on the recorded used bandwidth information, and a maximum used bandwidth recording unit that records the past maximum used bandwidth in a video connection for each viewer terminal between servers. A priority determination step, and a transmission step of assigning the determined priority information to the packet and transmitting the packet to the viewer terminal as a video information packet.
[0018]
In the video distribution method and the video distribution apparatus according to the present invention as described above, video connections whose used bandwidth has been reduced in the past due to network congestion or the like are recorded in a list, and when the network is congested again, the used bandwidth is reduced. Since video connections can be determined based on the list, it is possible to distribute video while maintaining the minimum quality of video affected by congestion while leaving many video connections that are not affected by congestion. It becomes possible. In the example described above, if the 11th connection occurs randomly, and the connection whose bandwidth is reduced to 1 Mbit / s is fixed among the other 10 connections, 9 connections will display high quality video. Since two connections can deliver medium quality video, it is possible to maintain high quality when viewed over the entire 11 connections.
[0019]
Japanese Patent Laid-Open No. 2000-253021 eliminates call loss and connection delay when setting a new call by previously registering the system configuration information of the number of connected calls and the minimum guaranteed bandwidth to the bandwidth control device. At the same time, there has been proposed a method for realizing a guarantee of communication quality that requires real-time performance by performing a minimum bandwidth guarantee. However, it does not take into account the effects of communications that require real-time performance from network congestion. Japanese Patent Laid-Open No. 2003-18209 proposes a method for realizing quality-assured video distribution, but is a system that presupposes securing a bandwidth in advance, and is different from the present invention.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0021]
(Embodiment 1)
FIG. 1 is a system configuration diagram showing a video distribution system according to Embodiment 1 of the present invention.
[0022]
As shown in FIG. 1, the viewer terminals 11 to 13 transfer to a single packet switch 31 in the network 30 via a user accommodating packet switch 20 that transfers a plurality of viewer data mixedly on the same communication line. It is connected. A video distribution server 40 is connected to another packet switch 32 in the network 30. Accordingly, the viewer terminals 11 to 13 request video content from the video distribution server 40 via the network 30 that enables quality control including the user-accommodating packet switch 20 and the packet switches 31 and 32, Can watch.
[0023]
FIG. 2 is a block diagram showing a detailed configuration of the packet switch 31. The packet switch 31 includes a packet transmission interface 310, packet reception interfaces 311a to 311c, a memory buffer 312, a packet priority determination / allocation unit 313, a maximum used bandwidth recording unit 314, a high priority buffer 315, and a medium priority buffer 316. , A low priority buffer 317 and a packet extraction unit 318.
[0024]
The packet reception interfaces 311a to 311c receive a plurality of video information packets transmitted from the video distribution server 40 via the network 30, and the memory buffer 312 records each received packet in the order of reception. Is. The maximum used bandwidth recording unit 314 records the past maximum used bandwidth for each video connection, and according to the maximum used bandwidth information, the packet priority determination / distribution unit 313 stores the video information packet in the memory buffer 312. Determine the priority.
[0025]
The packet priority determination / distribution unit 313 functions to distribute each video information packet to the high priority buffer 315 or the medium priority buffer 316 based on the determined priority. The low priority buffer 317 is applied to packets other than the video connection handled in the present invention. The high priority buffer 315, the medium priority buffer 316, and the low priority buffer 317 constitute a packet transmission buffer.
[0026]
The packet extraction unit 318 functions to extract each packet from each of the buffers 315 to 317 and send it to each viewer terminal 11 to 13 via the packet transmission interface 310 and the user accommodating exchange 20. In FIG. 2, the number of packet reception interfaces 311 a to 311 c or the number of priority level buffers 315 to 317 is shown as three, but it can be configured with an arbitrary number of two or more. Further, FIG. 2 shows a configuration relating only to the direction in which the video information packet flows to the viewer terminal (the direction from the packet switch 32 to the user accommodating packet switch 20), and the reverse configuration (similar to the existing packet switching method). Is omitted.
[0027]
Next, the operation of the video distribution system according to this embodiment will be described.
[0028]
When many viewers request video viewing and receive video distribution from the video distribution server 40, when the network between the user-accommodated packet switch 20 and the packet switch 31 is congested, the video connection is usually not conscious. Thus, the video information packet is discarded in the packet switch 31. On the other hand, in the present invention, when the packet receiving interfaces 311a to 311c as receiving units receive video information packets from the video distribution server 40, they are temporarily recorded in the memory buffer 312 in the order of received time.
[0029]
Next, the packet priority determination unit 313 determines the priority of the priority information packet of the received video information packet, and assigns each video information packet to the high priority buffer 315 or the medium priority buffer 316 according to this priority.
[0030]
The priority of the video information packet is determined from information of the maximum used bandwidth recording unit 314 in which the past maximum used bandwidth is recorded for each video connection. From the start of distribution of the received video connection to the present, it is determined that the maximum bandwidth (the state of being distributed at a high video encoding rate without being affected by network congestion) is maintained and transmitted. If so, it is distributed to the high priority buffer 315.
[0031]
In addition, the maximum bandwidth may not be maintained and the bandwidth used may have decreased from the time when the received video connection was started until the present time. (Due to the influence of network congestion, etc. If there is a status, the medium priority buffer 316 is assigned. The use band within a certain time after the video connection is established is set as the maximum use band, the use band of the video connection flowing through the memory buffer 312 is monitored, and the information of the maximum use band recording unit 314 is updated.
[0032]
Here, whether or not the received data is a video connection can be identified by header information of a packet transmitted and received in the network 30 that enables quality control. Each video connection can be further specified using an IP address or a communication port number described in the header of the video information packet. If the used bandwidth is not within a certain period of time, the same IP address and communication port number are regarded as different video connections.
[0033]
The packet extraction unit 318 extracts packets based on the priority of each of the buffers 315 to 317 using an algorithm such as WFQ (Weighted Fair Queuing) or WRR (Weighted Round Robin), for example, and a packet transmission interface as a transmission unit The video information packet is transmitted to the viewer terminals 11 to 13 via 310. Among the buffers 315 to 317, for example, the high priority buffer 315 can be treated as a complete bandwidth guarantee, the medium priority buffer 316 can be treated as a minimum area guarantee, and the low priority buffer 317 can be treated as a best effort.
[0034]
According to Embodiment 1 above, the bandwidth used is monitored for each video connection, the bandwidth used is monitored for each video connection received when network congestion occurs, and the video affected when network congestion occurs By biasing the connections, it is possible to solve the subject of the present invention and keep the quality of the entire video connection high.
[0035]
(Embodiment 2)
In the first embodiment, the principle of the present invention is applied to a video information packet handled by the packet switch 31. However, in the second embodiment, the video information packet transmitted from the video distribution server 40 is applied to the video information packet. Apply the principles of the invention.
[0036]
FIG. 3 is a system configuration diagram showing a video distribution system according to the second embodiment.
[0037]
As shown in FIG. 3, the viewer terminals 11 to 13 transfer to a single packet switch 31 in the network 30 via a user accommodating packet switch 20 that transfers a plurality of viewer data mixedly on the same communication line. It is connected. Further, a video distribution server 40 is connected to another packet switch 32 in the network 30 via a video information packet priority adding device 50. Accordingly, the viewer terminals 11 to 13 transmit video to the video distribution server 40 via the network 30 including the user accommodating packet switch 20 and the packet switches 31 and 32 that enable quality control and the video information packet priority adding device 50. You can request content and watch it.
[0038]
FIG. 4 is a block diagram showing a detailed configuration of the video information packet priority adding device 50.
[0039]
The video information packet priority adding device 50 includes a packet transmission interface 501, a packet reception interface 502, a packet priority determination unit 503, and a maximum used bandwidth recording unit 504. The packet reception interface 502 receives a plurality of video information packets transmitted from the video distribution server 40. The maximum used bandwidth recording unit 504 records the past maximum used bandwidth for each video connection. The packet priority determination unit 503 determines the priority of the video information packet according to the maximum usable bandwidth information.
[0040]
The maximum used bandwidth recording unit 503 functions to give priority information based on the determined priority in the header of the video information packet. The packet transmission interface 501 functions to transmit video information packets with priority information to the viewer terminals 11 to 13 through the packet switch 32, the network 30, the packet switch 31, and the user accommodating packet switch 20. . In FIG. 4, the direction in which the video information packet flows to the viewer terminals 11 to 13 (only the direction from the video distribution server 40 to the packet switch 32 is shown, and the reverse configuration (similar to the existing packet switching method) is shown. It is omitted.
[0041]
Next, the operation of the video distribution system according to the second embodiment will be described.
[0042]
In the second embodiment, the bandwidth of the distribution video is controlled by detecting network congestion between the viewer terminals 11 to 13 connected to the video distribution server 40 and the video distribution server 40. For this reason, it is possible to monitor the amount of transmission data other than where the video information packet priority adding device 50 is installed in FIG. 3, and the installation location is not limited. In the second embodiment, when the video information packet is received by the packet reception interface 502, the priority of the video information packet received by the packet priority determination unit 503 is determined, and the priority information is converted into the video information according to the determined priority. It is added in the packet header.
[0043]
Specifically, the priority information is recorded in the TOS (Type Of Services) field of the IP packet. The packet priority is determined based on information of the maximum used bandwidth recording unit 504 in which the past maximum used bandwidth is recorded for each video connection. When it is determined that the received video connection has been transmitted with the maximum bandwidth maintained from the start of distribution until the present, it is determined as high priority. Further, when the received bandwidth is reduced because the maximum bandwidth cannot be maintained from when the received video connection is started to the present, the medium priority is determined as described above. Further, the use band of the video connection is monitored and the information of the maximum use band recording unit 504 is updated.
[0044]
As in the first embodiment, each video connection is specified using an IP address or a communication port number described in the header of the video information packet. Furthermore, when the transmission data amount does not exist within a certain time, the same IP address and communication port number are regarded as different video connections. Data packets other than video connections are processed as low priority packets.
[0045]
According to the second embodiment, since the video information packet transmitted by giving priority to each video connection is controlled based on the information given in the network 30 that enables quality control, It is possible to maintain high video quality that is affected when network congestion occurs.
[0046]
【The invention's effect】
As described above, according to the present invention, when video is distributed to viewers using a network, when the network is congested in the past, the video connection whose bandwidth is reduced is grasped, and the network is congested again. By controlling the video connection to reduce the bandwidth used, video connections that are not affected by network congestion can be distributed with high quality. Also, video connections affected by network congestion can be delivered with medium quality. Therefore, if such distribution control is not performed, all video connections are affected little by little due to network congestion, and the quality perceived by the user is greatly affected by the worst video quality. Overall, medium-quality delivery will dominate. According to the present invention, it is possible to maintain a high distribution video quality in the entire video connection experienced by the viewer without increasing the network construction cost.
[Brief description of the drawings]
FIG. 1 is a system configuration diagram showing a video distribution system according to a first embodiment of the present invention. FIG. 2 is a block diagram showing a packet switch in FIG. 1. FIG. 3 is a video distribution system according to a second embodiment of the present invention. FIG. 4 is a block diagram showing a video information packet priority adding apparatus in FIG. 3;
11, 12, 13: Viewer terminal, 20: User accommodating packet switch, 30: Network, 31, 32: Packet switch, 310: Packet transmission interface (transmitting unit), 311a, 311b, 311c: Packet reception interface, 312: Memory buffer, 313: Packet priority determination / allocation unit, 314: Maximum used bandwidth recording unit, 315: High priority buffer, 316: Medium priority buffer, 317: Low priority buffer, 318: Packet extraction unit, 40 : Video distribution server, 50: Video information packet priority adding device, 501: Packet transmission interface, 502: Packet reception interface, 503: Packet priority determination unit, 504: Maximum used bandwidth recording unit.

Claims (4)

A video distribution system for distributing video content from a video distribution server to a viewer terminal via a network including a packet switch,
The packet switch is
A maximum usable bandwidth recording unit that records the past maximum usable bandwidth to the video connection units for each of the viewer's terminal,
The priority of the delivered video information packets based on the maximum usable bandwidth recording unit used bandwidth information recorded in the case that maintain the maximum bandwidth from the distribution start to now determines that high priority, distribution start If the maximum bandwidth has not been maintained from the current time to the present and the bandwidth used has decreased, it is determined as medium priority, and high priority video information packets are assigned high priority based on this determined priority information. A packet priority determination / distribution unit that distributes video information packets of medium priority to a medium priority packet transmission buffer;
A packet extraction unit that extracts a video information packet from the high-priority packet transmission buffer or the medium-priority packet transmission buffer based on the priority information;
A transmission unit that transmits the image information packet extracted by the packet extracting unit to the viewer's terminal for each video connection,
A video distribution system comprising: A video distribution system for distributing video content from a video distribution server to a viewer terminal via a network including a packet switch,
Provided video information packet priority application device to at least the packet switching device and between said video distribution server,
The video information packet priority adding device comprises:
A maximum usable bandwidth recording unit that records the past maximum usable bandwidth to the video connection units for each of the viewer's terminal,
The priority of the delivered video information packets based on the maximum usable bandwidth recording unit used bandwidth information recorded in the case that maintain the maximum bandwidth from the distribution start to now determines that high priority, distribution start A packet priority determination unit that determines medium priority when there is a decrease in the use bandwidth without being able to maintain the maximum bandwidth from to the present,
The grant information for each priority which is determined by the packet priority decision unit into the packet, a transmission unit for transmitting to the viewer terminal as a video information packet,
A video distribution system comprising: A video distribution method for distributing video content from a video distribution server to a viewer terminal via a network including a packet switch,
A maximum usable bandwidth recording step of recording historical maximum usable bandwidth to the video connection units for each of the viewer's terminal,
The priority of the video information packet distributed based on the recorded used bandwidth information is determined to be high priority when the maximum bandwidth is maintained from the start of distribution until the present, and between the start of distribution and the present When the maximum bandwidth cannot be maintained and the used bandwidth has decreased, it is determined as medium priority, and based on the determined priority information, high priority video information packets are distributed to the high priority packet transmission buffer. A packet priority determination / distribution step for distributing the medium priority video information packet to the medium priority packet transmission buffer;
A packet extracting step for extracting a video information packet from the high priority packet transmission buffer or the medium priority packet transmission buffer based on the priority information;
A transmission step of transmitting the retrieved video information packets to the viewer terminal for each video connection,
A video distribution method comprising: A video distribution method for distributing video content from a video distribution server to a viewer terminal via a network including a packet switch,
In at least the packet switching device and between said video distribution server, and the maximum usable bandwidth recording step of recording the maximum usable bandwidth of past video connection units for each of the viewer's terminal,
The priority of the video information packet distributed based on the recorded used bandwidth information is determined to be high priority when the maximum bandwidth is maintained from the start of distribution until the present, and between the start of distribution and the present A packet priority determination step for determining a medium priority when the maximum bandwidth cannot be maintained and the used bandwidth has decreased;
Grant information for each priority determined in the packet, a transmission step of transmitting to the viewer terminal as a video information packet,
A video distribution method comprising:

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