JP4993310B2 - Method for identifying quality event of media stream, terminal, communication node device, and program - Google Patents

Description

  The present invention relates to a technique for distributing a media stream from a media distribution server, and relates to a method, a terminal, a communication node device, and a program for specifying a quality event used for controlling the media stream. In particular, it is based on a technique for distributing a hierarchically encoded media stream to a terminal by hierarchically controlling the communication node apparatus.

  In recent years, regarding an access network for a terminal to connect to an IP (Internet Protocol) network, a data transfer speed has been increased regardless of a mobile network or a fixed network. With the rapid spread of such access networks, the construction of a large-scale media distribution service using “NGN (New Generation Network)” as a core network is being studied. By using NGN, a high-quality and high-security media distribution service is expected in line with the diversification of media types and distribution forms (business models).

  The media distribution service is a service that a terminal possessed by a user plays while receiving a media stream from a media distribution server. A media stream is audio or video content data that is continuously distributed in real time. Conventionally, a terminal that receives and plays back a media stream has to be equipped with a high-performance processor and a large-capacity memory.

  On the other hand, there is a technique in which a media distribution server transmits a hierarchically encoded media stream so that the media stream can be reproduced according to the processing capability and memory capacity of the terminal. Hierarchical coding is a technique for dividing a media stream into a plurality of hierarchies and obtaining different decoded data in stages. The first layer encodes basic resolution media data, and the next layer encodes higher resolution media data to implement these multi-layer encodings (for example, based on the relationship between profiles and levels in MPEG2). Encoding). For example, hierarchical encoding is performed according to media types and various quality measures such as audio / video, audible frequency band, resolution, color tone, and the like.

  When NGN is used for the media distribution service, the IP packet transfer state of the network between the transmission device and the reception device is always measured. When quality degradation (for example, audio interruption or image disturbance) occurs during reception of a media stream, the media stream transfer resource or transfer rate in the IP network is controlled. This prevents IP packet quality degradation.

  As a first conventional technique, there is a technique in which a media distribution server accumulates media streams for a plurality of different transfer rates, and a terminal selects the transfer rate (see, for example, Patent Document 1).

  As a second conventional technique, there is a technique in which a terminal or a network system controls a transfer rate in accordance with a media access type (MAC (Media Access Control) layer type) in an access network (see, for example, Patent Document 2). .

  As a third conventional technique, there is a technique in which a terminal transmits a quality degradation state of received media data to a media distribution server, and the media distribution server transmits the media data by controlling an encoding rate or a transmission rate. (For example, refer to Patent Document 3). According to this technology, the transfer rate of an IP packet to which media data should be distributed is estimated based on the size of the IP packet to be transmitted, the loss rate of the packet, and the round trip delay time between the terminal and the media distribution server. And control.

  As a fourth conventional technique, there is a technique for controlling increase / decrease in the number of layers of hierarchical coding in accordance with the quality degradation state measured by a terminal (see, for example, Patent Document 4). According to this technique, the terminal itself confirms the degree of quality degradation, and acquires resources of the transfer band in order from the terminal that started receiving the media data.

JP 2004-135017 A JP 2000-295276 A JP 2003-298777 A Xue Li, Sanjoy Paul, Mostafa H. Ammar, "Multi-session Rate Control for Layered Video Multicast," in Proc. SPIE Multimedia Computing and Networking, vol. 3654, San Jose, CA, Jan. 1999, pp. 175-189 .

  According to the first prior art, the transfer rate is selected only by the determination of the terminal itself regardless of the congestion state of the entire network. For this reason, there is a possibility that significant quality degradation occurs in the entire network. Further, since each terminal can independently select the I transfer rate, there is a possibility that the congestion of the network will be increased over a long period of time.

  According to the second conventional technique, when one terminal selectively uses a plurality of access networks, it is necessary to provide a control scheme for each access network. Also, due to application layer control such as packet loss compensation, the control result based on layers below the MAC (Media Access Control) layer may not match the quality of the IP application service.

  According to the third prior art, there is a possibility that an increase in the load on the media distribution server and an increase in network congestion may occur due to an increase in traffic of quality degradation state information transmitted from the terminal to the media distribution server.

  According to the fourth conventional technique, since the resources of the transfer band are acquired in order from the terminal that started receiving the media data, the fairness between the terminals cannot be maintained. Further, since the terminal executes the increase / decrease control of the number of hierarchies (particularly, it takes time to reduce the number of hierarchies), the followability of the control with respect to the congestion of the entire network is deteriorated.

  Therefore, the present invention immediately identifies the quality event of the terminal for the control when the hierarchical control is executed by the communication node device provided between the media distribution server and the terminal for the hierarchically encoded media stream. It is an object to provide a method, a terminal, a communication node device, and a program that can be used.

According to the present invention, a media distribution server that transmits a hierarchically encoded media stream, a communication node device that receives the media stream from the media distribution server and transmits the media stream by multicast, and a terminal that receives the media stream A method for identifying a media stream quality event for a system comprising:
The terminal measures the quality event in the media stream received from the communication node device,
A first step in which a first terminal transmits its first quality event by multicast;
The second terminal that has received the first quality event transmits the second quality event by multicast only when its second quality event is degraded as compared with the first quality event. A second step;
The communication node apparatus has a third step of controlling the number of layers of media streams to be transmitted to all terminals based on a quality event finally received from one or more terminals.

  According to another embodiment of the method of the present invention, the terminal has a timer unit that generates a trigger of a predetermined period, and the first step or the second step is executed when the trigger occurs. It is also preferable.

  According to another embodiment of the method of the present invention, the media stream is transmitted using RTP (Real-time Transport Protocol), and the quality event includes RTP header information and RTCP (RTP Control Protocol) information. It is also preferable that it is measured based on the above and transmitted using RTCP.

  According to another embodiment of the method of the present invention, the quality event is also preferably based on one specific layer of media stream in the audio media.

According to the present invention, a terminal is connected to a communication node device that receives a hierarchically encoded media stream from a media distribution server, and receives a media stream from the communication node device,
Quality event measuring means for measuring a quality event in the media stream received from the communication node device;
Timer means for generating a trigger of a predetermined period;
When a trigger occurs, if a first quality event has already been received from another terminal and its second quality event has deteriorated compared to the first quality event, or Quality event determination means for determining a case where a quality event has not yet been received from another terminal;
If the determination is true, a multicast transmission means for multicasting the second quality event is provided.

According to another embodiment of the terminal of the present invention,
The media stream is transmitted using RTP,
The quality event is also preferably measured based on RTP header information and RTCP information and transmitted using RTCP.

According to another embodiment of the terminal of the present invention,
It is also preferable that the quality event measuring means measures a quality event based on one specific hierarchical media stream in the audio media.

According to the present invention, a communication node device that transmits a media stream to the terminal described above,
Control event generation means for generating a control event based on a quality event finally received from one or more terminals;
Media stream control means for controlling the number of layers of media streams to be transmitted to all terminals based on the control event.

According to the present invention, a program is connected to a communication node device that receives a hierarchically encoded media stream from a media distribution server, and causes a computer mounted on a terminal that receives the media stream from the communication node device to function. ,
Quality event measuring means for measuring a quality event in the media stream received from the communication node device;
Timer means for generating a trigger of a predetermined period;
When a trigger occurs, if a first quality event has already been received from another terminal and its second quality event has deteriorated compared to the first quality event, or Quality event determination means for determining a case where a quality event has not yet been received from another terminal;
When the determination is true, the computer is caused to function as multicast transmission means for transmitting the second quality event by multicast.

According to the present invention, there is provided a program for causing a computer installed in a communication node device that transmits a media stream to the terminal described above to function.
Control event generation means for generating a control event based on a quality event finally received from one or more terminals;
The computer is caused to function as media stream control means for controlling the number of layers of media streams to be transmitted to all terminals based on the control event.

  According to the method, the terminal, the communication node device, and the program of the present invention, when hierarchical control is performed by a communication node device provided between a media distribution server and a terminal, a hierarchically encoded media stream is controlled. Terminal quality events can be immediately identified.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a system configuration diagram according to the present invention.

  According to the system of FIG. 1, the media distribution server 3 transmits the hierarchically encoded media stream to the communication node device 2. The media stream is transmitted using RTP.

  The IP network corresponding to the multicast is configured by a plurality of communication node devices 2 arranged in a tree structure. These communication node devices 2 are usually communication facilities operated by a communication carrier. The media stream is transmitted from an upper layer communication node device to a lower layer communication node device (hierarchical multicast).

  The terminal 1 is connected to the communication node device 2 in the lowest layer via the access network. Examples of the access network include a mobile phone network, a WiMAX network, and a wired broadband network.

  The communication node device 2 controls the number of media stream layers and transmits it to a plurality of terminals 1 and / or communication node devices under its control. The communication node device 2 needs to know the “quality event” in the terminal 1 in order to control the number of layers. According to the present invention, the communication node device 2 can immediately collect and identify “quality events” that are elements for controlling the number of layers of media streams.

  The “quality event” indicating the communication quality of the media stream in the terminal 1 is, for example, jitter. The event means “event”, but may simply mean “information”.

  FIG. 2 is a functional configuration diagram of a terminal, a communication node device, and a media distribution server in the present invention.

  The media distribution server 3 includes a media content accumulation unit 30 that accumulates hierarchically encoded media content, a packet transmission / reception unit 31, a multicast processing unit 32, and an RTP processing unit 33. The packet transmission / reception unit 31 processes a communication protocol below the transport layer, and specifically includes a transport protocol processing unit (UDP / TCP), an IP processing unit, and a network connection interface unit. These functional components (excluding the network connection interface in the packet transmission / reception unit 31) are realized by executing a media distribution program that causes a computer mounted on the server to function.

  The RTP processing unit 33 configures the hierarchically encoded media stream output from the media content storage unit 30 into RTP packets. The media stream of the RTP packet is output to the multicast processing unit 32.

  The multicast processing unit 32 multicasts RTP packets to one or more communication node devices and terminals. Multicast transmission is performed based on the multicast group identifier. Note that non-multicast packets are transmitted by unicast.

  In the packet transmitting / receiving unit 31, the media stream output from the multicast processing unit 32 is configured into a UDP packet by the transport protocol processing unit. Further, the IP processing unit configures the IP packet. Then, the IP packet is transmitted from the network connection interface unit. The network connection interface unit is a physical layer unit that connects to a wireless or wired access network.

  The communication node device 2 includes a packet transmission / reception unit 201 (transport protocol processing unit, IP processing unit, network connection interface unit), multicast processing unit 202, RTCP processing unit 213, control event generation unit 214, media stream control Part 205. These functional components (except for the network connection interface unit of the packet transmission / reception unit 201) can be realized by executing a program that causes a computer installed in the communication node device to function.

  The packet transmitting / receiving unit 201 and the multicast processing unit 202 are the same as those of the media distribution server 3 described above. Here, the multicast processing unit 202 controls the multicast transmission according to the number of layers output from the media stream control unit 205. Further, the RTCP processing unit 213 transmits / receives the quality event transmitted from the terminal 1 under its control by RTCP. The received quality event is notified to the control event generation unit 214.

  Based on the quality event finally received from one or more terminals 1, the control event generating unit 214 generates a control event for controlling the number of layers of media streams to be transmitted to all the terminals. The generated control event is notified to the media stream control unit 205. Conversely, the control event may be notified from the media stream control unit 205 to the control event generation unit 214. A control event is generated for each multicast group identifier and service identifier in the subordinate terminal 1.

Control events are based on quality events,
(1) RTP packet transmission interval in media stream,
(2) Packet loss compensation strength and / or compensation algorithm in the packet loss compensation unit,
(3) Transfer rate in encoding unit (4) Number of media frames loaded in UDP or TCP packet in transport packet transmitting / receiving unit,
(5) Any one of the number of simultaneously connected streams for the same content, or a combination thereof.

  The media stream control unit 205 controls the number of media streams to be transmitted to all terminals based on the control event. Specifically, it is opening / closing control of the transfer port number of the media stream.

  The terminal 1 includes a media output interface unit 10, a packet transmission / reception unit 11 (transport protocol processing unit, IP processing unit, network connection interface unit), an RTP / RTCP processing unit 13, a multicast processing unit 12, and a hierarchical decoding unit. 14, a media stream playback unit 15, a quality event measurement unit 16, a service control processing unit 17, a quality event determination unit 18, and a timer unit 19. These functional components (except for the media output interface unit 10 and the network connection interface unit of the packet transmission / reception unit 11) are realized by executing a program that causes a computer installed in the terminal to function.

  The packet transmitting / receiving unit 11 and the multicast processing unit 12 are the same as those of the media distribution server 3 described above. The RTP / RTCP processing unit 13 receives the quality event transmitted from the communication node device 2 by RTCP, and outputs the quality event to the quality event determination unit 18. Further, the RTP / RTCP processing unit 13 receives the media stream received from the communication node device 2 by RTP, and outputs the media stream to the hierarchical decoding unit 14. Note that the RTP / RTCP processing unit 13 confirms synchronization between RTP and RTCP.

  The hierarchical decoding unit 14 decodes the hierarchically encoded media data and generates an integrated media stream. The generated media stream is notified to the media stream playback unit 15.

  The media stream playback unit 15 outputs the media stream to the media output interface unit 10 in response to an instruction from the service control processing unit 17. The media output interface unit 10 is, for example, a display and a speaker. As a result, the media stream can be reproduced while being received.

  The quality event measurement unit 16 measures a quality event in the media stream received from the communication node device 2. Specifically, for example, jitter (delay time) and packet loss of the packet in the RTP / RTCP processing unit 13 are measured. The quality event measurement unit 16 measures a quality event based on one specific hierarchical media stream in the audio media. The measured quality event is output to the quality event determination unit 18.

  The timer unit 19 generates a trigger with a predetermined period. Even if the predetermined cycles in the plurality of terminals 1 are the same, since the trigger generation time (start-up time) is different, all terminals do not generate triggers at the same time.

  The quality event determination unit 18 has already received the first quality event from another terminal when the trigger is generated, and the second quality event of the quality event determination unit 18 is deteriorated as compared with the first quality event. Or a case where a quality event has not yet been received from another terminal. If this determination is true, the second quality event is notified to the RTP / RTCP processing unit 13 and the service control processing unit 17.

  The RTP / RTCP processing unit 13 configures the second quality event with RTCP. The RTCP packet is transmitted by multicast by the multicast processing unit 12.

  The service control processing unit 17 receives the second quality event from the quality event determination unit 18. Then, the service control processing unit 17 controls the media stream playback unit 15 based on the finally received quality event. Specifically, control such as packet loss compensation processing or playback speed control processing in the media stream playback unit 15 is executed. Also, control such as adjustment of reproduction volume or adjustment of the number of display screens in the media output interface unit 10 is executed.

  FIG. 3 is another system configuration diagram in the present invention.

  According to FIG. 2, the IP packet transfer function (packet transmission / reception unit 201, multicast processing unit 202, RTCP processing unit 213) and the media stream control function (control event generation unit 214, media stream control unit 205) have one. It is integrally mounted in the communication node device. However, as shown in FIG. 3, the IP packet transfer apparatus (IP packet transfer function) 20 and the media stream control server (media stream control function) 21 can be divided into functions. Thus, an existing multicast router can be used as an IP packet transfer device. That is, when the media stream control server 21 transmits a media control event to the IP packet transfer device 20 that has received the media stream from the media distribution server 3, the IP packet transfer device 20 Perform hierarchical control. Then, the IP packet transfer apparatus 20 transmits a media stream based on the control to the terminal 1.

  FIG. 4 is a transmission sequence diagram of quality events in the present invention.

  According to FIG. 4, five terminals A to E are connected to one communication node device 2. Each terminal measures a quality event in the media stream received from the communication node device 2. Each terminal has a timer unit that generates a trigger with a predetermined period. According to FIG. 4, triggers are generated in the order of terminal A-> terminal C-> terminal E-> terminal D-> terminal B. And

(T1) First, the trigger of terminal A occurred. At this time, terminal A has not yet received a quality event from another terminal. Therefore, terminal A transmits the first quality event (jitter = 100 ms) of the media stream received by itself by multicast. This quality event is transmitted to the terminals B to E via the communication node device 2. As a result, all terminals under the communication node device 2 know the existence of a quality event terminal with jitter = 100 ms.

(T2) The trigger of terminal C occurred. At this time, terminal C has already received the first quality event from terminal A. Terminal C determines that its second quality event (jitter = 120 ms) has deteriorated compared to the first quality event (jitter = 100 ms). In this case, the terminal C transmits the second quality event (jitter = 120 ms) of the media stream received by itself by multicast. This quality event is transmitted to the terminals A, B, D and E via the communication node device 2. As a result, all the terminals under the communication node device 2 know the existence of a quality event terminal with jitter = 120 ms.

(T3) The trigger of the terminal E has occurred. At this time, the terminal E has already received the first quality event from the terminal A, and has further received the second quality event from the terminal C. Terminal E determines that its third quality event (jitter = 110 ms) is better compared to the second quality event (jitter = 120 ms). In this case, the terminal E does not transmit a quality event.

(T4) The trigger of terminal D occurred. At this time, the terminal D has already received the first quality event from the terminal A, and has further received the second quality event from the terminal C. Terminal D determines that its fourth quality event (jitter = 100 ms) is better than the most recent second quality event (jitter = 120 ms). In this case, the terminal D does not transmit a quality event.

(T5) The terminal B trigger occurred. At this time, the terminal B has already received the first quality event from the terminal A, and has further received the second quality event from the terminal C. Terminal B determines that its fifth quality event (jitter = 80 ms) is good compared to the latest second quality event (jitter = 120 ms). In this case, the terminal B does not transmit a quality event.

  When at least the time up to the trigger T5 has elapsed, the communication node device 2 and all the terminals under it can know that the worst quality event is jitter = 120 ms. The communication node device 2 can control and distribute the media stream according to jitter = 120 ms. For example, as is apparent from FIG. 1, the plurality of terminals connected to the lowermost communication node device usually have the same access network. Therefore, there is no significant difference in quality events. In this case, the communication node device 2 can control and distribute the media stream according to the worst quality event in the same access network.

  On the other hand, quality events are greatly different for a plurality of terminals connected to different access networks. In such a case, when the communication node device 2 controls the media stream according to the worst quality event, the service of the entire system is extremely deteriorated.

  As another embodiment, the communication node device in the upper layer can be used for controlling the media stream transmitted to the communication node device in the lower layer. For example, the media distribution server transmits a seven-layer media stream to an upper-layer communication node device closer to the media distribution server, and the upper-layer communication node device communicates with the media distribution server in two communication layers lower than itself. It is also possible to transmit a 5-layer media stream to the node device. The first lower-layer communication node device transmits a three-layer media stream to the lowest-layer communication node device, and the second lower-layer communication node device has the lowest-layer communication node device. A five-layer media stream can also be transmitted.

  FIG. 4 shows a sequence between the communication node device 2 in the lowest layer and a plurality of terminals 1 under its control. However, the quality event transmitted from the terminal 1 may be transmitted from the lowest layer to the communication node device 2 in the higher layer. This can control the transfer range by setting the packet filter of the IP packet transfer function (IP packet transfer device) of the communication node device 2. By being transmitted to the higher-layer communication node device 2, the media stream is controlled by the worst quality event received by the higher-layer communication node device 2.

  As described above in detail, according to the method, the terminal, the communication node device, and the program of the present invention, the hierarchically encoded media stream is hierarchically controlled by the communication node device provided between the media distribution server and the terminal. , The terminal quality event for that control can be immediately identified. Thereby, according to the communication quality of the terminal (for example, according to the access network), hierarchical control of the media stream becomes possible, and the quality of the media distribution service of the entire system is improved. Further, even when the terminal is connected to a different access network, a media stream corresponding to the communication quality of the terminal can be distributed without any control by the media distribution server itself. Further, according to the present invention, the quality event packet is not transmitted to the media distribution server, and the worst quality event is specified between the communication node device and the terminal in an extremely small sequence. There is little influence of load.

  In the various embodiments of the present invention described above, various changes, modifications, and omissions in the scope of the technical idea and the viewpoint of the present invention can be easily made by those skilled in the art. The above description is merely an example, and is not intended to be restrictive. The invention is limited only as defined in the following claims and the equivalents thereto.

It is a system configuration diagram in the present invention. It is a functional block diagram of the terminal in this invention, a communication node apparatus, and a media delivery server. It is another system block diagram in this invention. It is a transmission sequence diagram of a quality event in the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Terminal 10 Media output interface part 11 Packet transmission / reception part 12 Multicast process part 13 RTP / RTCP process part 14 Hierarchical decoding part 15 Media stream reproduction | regeneration part 16 Quality event measurement part 17 Service control process part 18 Quality event determination part 2 Communication node apparatus 20 IP packet transfer device 21 Media stream control server 201, 211 Packet transmission / reception unit 202 Multicast processing unit 213 RTCP processing unit 214 Control event generation unit 205 Media stream control unit 3 Media distribution server 30 Media content storage unit 31 Packet transmission / reception unit 32 Multicast processing unit 33 RTP processor

Claims (10)

A media distribution server that transmits a hierarchically encoded media stream, a communication node device that receives the media stream from the media distribution server and transmits the media stream by multicast, and a terminal that receives the media stream A method for identifying media stream quality events for a system, comprising:
The terminal measures a quality event in the media stream received from the communication node device;
A first step in which a first terminal transmits its first quality event by multicast;
The second terminal that has received the first quality event transmits the second quality event by multicast only when its second quality event is degraded as compared with the first quality event. A second step;
The communication node device has a third step of controlling the number of layers of the media stream to be transmitted to all the terminals based on a quality event finally received from one or more terminals. how to.   The method according to claim 1, wherein the terminal includes a timer unit that generates a trigger of a predetermined period, and the first step or the second step is executed when the trigger is generated. . The media stream is transmitted using RTP (Real-time Transport Protocol),
The method according to claim 1 or 2, wherein the quality event is measured based on RTP header information and RTCP (RTP Control Protocol) information, and is transmitted using the RTCP.   The method according to any one of claims 1 to 3, wherein the quality event is based on a media stream of one specific layer in audio media. A terminal that is connected to a communication node device that receives a hierarchically encoded media stream from the media distribution server, and that receives the media stream from the communication node device;
Quality event measuring means for measuring a quality event in the media stream received from the communication node device;
Timer means for generating a trigger of a predetermined period;
When the trigger has occurred, if a first quality event has already been received from another terminal and its second quality event is degraded compared to the first quality event, or , Quality event determination means for determining a case where a quality event has not yet been received from another terminal,
A terminal having multicast transmission means for transmitting the second quality event by multicast when the determination is true. The media stream is transmitted using RTP,
The terminal according to claim 5, wherein the quality event is measured based on RTP header information and RTCP information, and is transmitted using the RTCP.   The terminal according to claim 5 or 6, wherein the quality event measurement unit measures a quality event based on a media stream of one specific layer in audio media. A communication node device that transmits the media stream to a terminal according to any one of claims 5 to 7,
Control event generation means for generating a control event based on the quality event finally received from the one or more terminals;
Media node control means for controlling the number of layers of the media stream to be transmitted to all the terminals based on the control event. A program connected to a communication node device that receives a hierarchically encoded media stream from the media distribution server, and causing a computer mounted on a terminal that receives the media stream from the communication node device to function.
Quality event measuring means for measuring a quality event in the media stream received from the communication node device;
Timer means for generating a trigger of a predetermined period;
When the trigger has occurred, if a first quality event has already been received from another terminal and its second quality event is degraded compared to the first quality event, or , Quality event determination means for determining a case where a quality event has not yet been received from another terminal,
When the determination is true, a program for a terminal that causes a computer to function as a multicast transmission unit that transmits a second quality event by multicast. A program that causes a computer mounted on a communication node device that transmits the media stream to function as a terminal according to any one of claims 5 to 7,
Control event generation means for generating a control event based on the quality event finally received from the one or more terminals;
A program for a communication node device, which causes a computer to function as media stream control means for controlling the number of layers of the media stream to be transmitted to all the terminals based on the control event.

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