JP2009206843A - System and program for distributing medium stream to mobile terminal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a system and the like for performing appropriate distribution control of a medium stream based on communication quality of the medium stream even when a mobile terminal is subjected to handover. <P>SOLUTION: The mobile terminal has: a quality event generation means for generating a quality event representing the communication quality of the medium stream; a handover event generation means for generating a handover event representing transition of a network when the handover is detected; and a transmission means for transmitting the quality event and the handover event to a communication state management server. The communication state management server has: a stream control event generation means for generating a stream control event based on the quality event and the handover event; and a transmission means for transmitting the stream control event to the medium distribution server. The medium distribution server has a stream distribution control means for controlling distribution of the medium stream based on the stream control event. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a system and program for delivering a media stream to a mobile terminal.

  There is a communication service in which a terminal possessed by a user reproduces 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, in order to play a media stream while receiving it, the terminal has to be equipped with a high-performance processor and a large-capacity memory. Therefore, the terminal is often limited to a fixed terminal connected to a wired broadband network.

  On the other hand, in recent years, even in a mobile terminal, higher performance of a processor, larger capacity of a memory, and further broadbandization of a wireless link have been realized. For this reason, an environment has been provided in which a mobile terminal can reproduce a media stream while receiving it.

JP 2008-005394 A

  When a fixed terminal connected to a wired broadband network receives a media stream from a media distribution server, the communication quality (for example, jitter) of the packet is substantially constant. On the other hand, when a mobile terminal connected to a wireless link network receives a media stream from a media distribution server, the communication quality of the packet often varies. In particular, when a mobile terminal executes a handover that switches access networks due to movement, the communication quality varies greatly. Thus, even after the communication quality greatly fluctuates, the media distribution server does not change the distribution control of the media stream at all. That is, the media stream distribution control before the handover and the media stream distribution control after the handover are the same.

  When handover is performed from a broadband network to a narrowband network, the media stream overflows. Conversely, when a handover is performed from a narrowband network to a wideband network, the media stream causes buffer empty. These situations lead to deterioration of communication quality. As an invention filed by the same applicant, there is a technique for avoiding buffer empty of the receiving terminal at the time of handover (see, for example, Patent Document 1).

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a system and a program capable of performing appropriate media stream delivery control based on the communication quality of media stream packets even when a mobile terminal is handed over. To do.

According to the present invention, there is provided a system including a mobile terminal that receives a media stream, a media distribution server that distributes the media stream to the mobile terminal via a network, and a communication status management server that is connected to the network.
The mobile terminal includes a quality event generation unit that generates a quality event indicating the communication quality of the media stream, a handover event generation unit that generates a handover event indicating a network transition when a handover is detected, and the quality event and the handover. A transmission means for transmitting the event to the communication status management server;
The communication status management server includes stream control event generation means for generating a stream control event based on the quality event and the handover event, and transmission means for transmitting the stream control event to the media distribution server.
The media distribution server includes a stream distribution control unit that controls distribution of a media stream based on a stream control event.

According to the present invention, a mobile terminal that receives a media stream, a media distribution server that distributes the media stream to the mobile terminal via a network, a communication status management server that is connected to the network, and a mobile that is connected to the network and moves A system having a handover management device for monitoring a handover of a terminal,
The mobile terminal has quality event generation means for generating a quality event representing the communication quality of the media stream, and transmission means for transmitting the quality event to the communication status management server,
The handover management apparatus includes a handover event generation unit that generates a handover event indicating network transition when a handover of a mobile terminal is detected, and a transmission unit that transmits the handover event to the communication status management server,
The communication status management server includes stream control event generation means for generating a stream control event based on the quality event and the handover event, and transmission means for transmitting the stream control event to the media distribution server.
The media distribution server includes a stream distribution control unit that controls distribution of a media stream based on a stream control event.

  According to another embodiment of the system of the present invention, it is also preferable that the communication status management server inquires and collects quality events from the mobile terminal at a predetermined cycle.

According to the present invention, a system having a mobile terminal that receives a media stream and a media distribution server that distributes the media stream to the mobile terminal via a network,
The mobile terminal includes a quality event generation unit that generates a quality event indicating the communication quality of the media stream, a handover event generation unit that generates a handover event indicating a network transition when a handover is detected, and the quality event and the handover. Transmission means for transmitting the event to the media distribution server,
The media distribution server includes stream control event generation means for generating a stream control event based on the quality event and the handover event, and stream distribution control means for controlling distribution of the media stream based on the stream control event. Features.

According to the present invention, a mobile terminal that receives a media stream, a media distribution server that distributes the media stream to the mobile terminal via a network, and a handover management apparatus that is connected to the network and monitors handover of the mobile terminal A system comprising:
The mobile terminal has quality event generation means for generating a quality event based on the media stream being received, and transmission means for transmitting the quality event to the media distribution server,
The handover management apparatus has a handover event generation means for generating a handover event indicating network transition when a handover of a mobile terminal is detected, and a transmission means for transmitting the handover event to the media distribution server server,
The media distribution server includes stream control event generation means for generating a stream control event based on the quality event and the handover event, and stream distribution control means for controlling distribution of the media stream based on the stream control event. Features.

According to another embodiment of the system of the present invention,
The media stream is transmitted using RTP (Real-time Transport Protocol), the quality event and the handover event are transmitted using RTCP (RTP Control Protocol),
A quality event is a jitter standard deviation value,
The handover event is a movement event from the first network to the second network,
Stream control events are based on quality events and handover 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 the encoding unit,
(4) The number of media frames loaded in a UDP (User Datagram Protocol) or TCP (Transmission Control Protocol) packet in the transport packet transmission / reception unit;
(5) Number of simultaneously connected streams for the same content,
(6) Any one of GOP (Group of Picture) sizes in the encoding unit or a combination thereof is also preferable.

According to the present invention, in a mobile terminal that receives a media stream,
Quality event generation means for generating a quality event representing the communication quality of the media stream;
Handover event generating means for generating a handover event representing network transition when a handover is detected;
Transmission means for transmitting a quality event and a handover event.

According to the present invention, there is provided a media distribution server that distributes a media stream to the above mobile terminal via a network,
Receiving means for receiving a quality event and a handover event;
Stream control event generation means for generating a stream control event based on the quality event and the handover event;
And stream delivery control means for controlling delivery of the media stream based on the stream control event.

According to the present invention, there is provided a communication status management server for communicating a network with the mobile terminal described above,
Receiving means for receiving a quality event and a handover event;
Stream control event generation means for generating a stream control event based on the quality event and the handover event;
And a transmission means for transmitting the stream control event to a media distribution server that distributes the media stream.

According to the present invention, there is provided a media distribution server that is connected to the above-described communication status management server via a network and distributes a media stream to the mobile terminal according to claim 7 via the network,
Receiving means for receiving a stream control event;
And stream delivery control means for controlling delivery of the media stream based on the stream control event.

According to the present invention, in a program for causing a computer installed in a mobile terminal that receives a media stream to function,
Quality event generation means for generating a quality event representing the communication quality of the media stream;
Handover event generating means for generating a handover event representing network transition when a handover is detected;
A computer is made to function as a transmission means for transmitting a quality event and a handover event.

  According to the system and program of the present invention, even when a mobile terminal is handed over, appropriate media stream distribution control can be performed based on the communication quality of media stream packets. Thereby, it is possible to improve the service quality in the delivery of the media stream to the mobile terminal.

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

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

  1 includes a mobile terminal 1 that receives a media stream using RTP, a media distribution server 2 that distributes the media stream to the mobile terminal 1 via a network, and a communication status management server 3 that is connected to the network. And have. The mobile terminal 1 is connected to an IP (Internet Protocol) network 5 via an access network 6. Examples of the access network include a mobile phone network, a WiMAX network, and a wired broadband network. The communication interface of the mobile terminal 1 has a function of performing handover between access networks.

  According to FIG. 1, the mobile terminal 1 generates a “quality event” representing the communication quality of the media stream. The quality event is, for example, a jitter standard deviation value. In addition, when a handover is detected, the mobile terminal 1 generates a “handover event” indicating network transition. The handover event is, for example, a movement event from the first network to the second network. These quality events and handover events are transmitted to the communication status management server 3. The event means “event”, but may simply mean “information”.

  The communication status management server 3 generates a stream control event based on the quality event and the handover event. The generated stream control event is transmitted to the media distribution server 2. Examples of the stream control event include (1) RTP packet transmission interval, (2) packet loss compensation strength and / or compensation algorithm in the packet loss compensation unit, (3) transfer rate in the encoding unit, and (4) transport packet transmission / reception. One of the number of media frames loaded in the UDP or TCP packet in the unit, (5) the number of simultaneously connected streams for the same content, and (6) the GOP (Group of Picture) size in the encoding unit, or a combination thereof. .

  The media distribution server 2 controls the distribution of the media stream to the terminal 1 based on the stream control event received from the communication status management server 3.

  FIG. 2 is a system configuration diagram in which a handover management apparatus is further provided in the system of FIG.

  The handover management device 4 is a part of communication equipment operated by a mobile communication service provider. According to the system of FIG. 2, the mobile terminal 1 transmits only the quality event to the communication status management server 3. On the other hand, when the handover of the mobile terminal 1 is detected, the handover management device 4 generates a handover event indicating network transition and transmits the handover event to the communication status management server 3.

  FIG. 3 is a second system configuration diagram according to the present invention.

  The system of FIG. 3 includes only a mobile terminal 1 that receives a media stream using RTP and a media distribution server 2 that distributes the media stream to the mobile terminal 1 via a network. The system of FIG. 3 does not include the communication status management server 3 as compared with the system of FIG. The media distribution server 2 includes the function of the communication status management server 3 in FIG. The mobile terminal 1 transmits a quality event and a handover event to the media distribution server 2.

  The media distribution server 2 generates a stream control event based on the quality event and the handover event, and controls the distribution of the media stream based on the stream control event.

  FIG. 4 is a system configuration diagram in which a handover management apparatus is further provided in the system of FIG.

  According to the system of FIG. 4, the mobile terminal 1 transmits only the quality event to the media distribution server 2. On the other hand, when the handover of the mobile terminal 1 is detected, the handover management device 4 generates a handover event indicating network transition and transmits the handover event to the media distribution server 2.

  FIG. 5 is a functional configuration diagram of the mobile terminal in the present invention.

  According to FIG. 5, the mobile terminal 1 includes a packet transmission / reception unit 101, an RTP / RTCP processing unit 102, a media stream reproduction unit 103, a media output interface unit 104, a quality information measurement unit 105, and a quality information management unit. 106, service control processing unit 107, quality event generation unit 108, and handover event generation unit 109. These functional components (except for the network connection interface unit and the media output interface unit) can be realized by executing a program that causes a computer installed in the mobile terminal to function.

  According to FIG. 5, the packet transmitting / receiving unit 101 processes a communication protocol below the transport layer. Specifically, a transport protocol processing unit (UDP / TCP), an IP processing unit, and a network connection interface unit are included. The network connection interface unit is a physical layer unit that connects to the access network 6 by wireless or wired. The IP processing unit transmits and receives IP packets. The transport protocol processing unit transmits and receives UDP / TCP packets. The media stream received from the media distribution server 2 is a UDP packet, and the quality event and the handover event transmitted to the communication status management server 3 (or the media distribution server 2) are TCP packets.

  The RTP / RTCP processing unit 102 receives a media stream from the media distribution server 2 via the packet transmission / reception unit 101. The media stream received from the media distribution server 2 is an RTP packet, and the quality event and the handover event transmitted to the communication status management server 3 (or the media distribution server 2) are RTCP packets. The RTP / RTCP processing unit 102 outputs the media stream received by RTP to the media stream reproduction unit 103. In the RTP / RTCP processing unit 102, the RTCP packet is confirmed to be synchronized with the received RTP packet.

  The media stream playback unit 103 outputs the media stream to the media output interface unit 104 in response to an instruction from the service control processing unit 107. The media output interface unit 104 is, for example, a display and a speaker. As a result, the media stream can be reproduced while being received.

  The quality information measuring unit 105 measures the quality information of the packet in the RTP / RTCP processing unit. The quality information is, for example, jitter. The measured quality information is output to the quality information management unit 106. The quality information management unit 106 accumulates quality information. The service control processing unit 107 refers to the quality information stored in the quality information management unit 106 and instructs the media stream playback unit 103 to perform playback control. For example, media decoding processing, packet loss compensation processing, playback speed control processing, and the like. The service control processing unit 107 also controls the media output interface unit 104 to adjust the playback volume and the display screen number.

  The quality event generation unit 108 generates a quality event representing the communication quality of the received media stream. Here, the generated quality event is transmitted to the communication status management server 3 according to FIGS. 1 and 2 described above, and is transmitted to the media distribution server 2 according to FIGS. 3 and 4 described above. When transmitting to the communication status management server 3, the generated quality event is output to the packet transmission / reception unit 101 (or RTP / RTCP processing unit 102 when transmitting by RTCP packet). The packet transmitting / receiving unit 101 transmits the quality event to the communication status management server 3. On the other hand, when transmitting to the media distribution server 2, the generated quality event is output to the RTP / RTCP processing unit 102. The RTP / RTCP processing unit 102 configures the quality event into an RTCP packet, and transmits it to the media distribution server 2 through the packet transmission / reception unit 101.

  The handover event generation unit 109 generates a handover event indicating a network transition when the packet transmission / reception unit 101 (particularly the network connection interface unit) detects a handover. Here, the generated handover event is also transmitted to the communication status management server 3 according to FIGS. 1 and 2 described above, and is transmitted to the media distribution server 2 according to FIGS. 3 and 4 described above. When transmitting to the communication status management server 3, the generated handover event is output to the packet transmitting / receiving unit 101 (or RTP / RTCP processing unit 102 when transmitting by RTCP packet). The packet transmitting / receiving unit 101 transmits the handover event to the communication status management server 3. On the other hand, when transmitting to the media distribution server 2, the generated handover event is output to the RTP / RTCP processing unit 102. The RTP / RTCP processing unit 102 configures the handover event into an RTCP packet, and transmits it to the media distribution server 2 through the packet transmission / reception unit 101.

  FIG. 6 is a functional configuration diagram of the communication status management server and the media distribution server in the present invention.

  According to FIG. 6, the communication status management server 3 includes a packet transmitting / receiving unit 301, an RTCP processing unit 302, a quality event processing unit 303, a handover event processing unit 304, an information management unit 305, and a quality event collection schedule management. A unit 306 and a stream control event generation unit 307. These functional components (excluding the network connection interface unit) can be realized by executing a program that causes a computer mounted on the server to function.

  The RTCP processing unit 302 is required when receiving the quality event and the handover event configured in the RTCP packet (broken line). The RTCP processing unit 302 outputs the quality event received from the mobile terminal 1 to the quality event processing unit 303, and outputs the handover event received from the mobile terminal 1 or the handover management device 4 to the handover event processing unit 304. Note that the RTCP processing unit 302 is not required when receiving a quality event and a handover event that are not configured in the RTCP packet.

  The quality event processing unit 303 associates the media distribution server for the quality event (corresponding to the IP address, port number, and service identifier) and outputs the associated information to the information management unit 305. The handover event processing unit 304 associates the media distribution server with respect to the handover event and outputs it to the information management unit 305. The information management unit 305 stores a quality event and a handover event in association with each media distribution server.

  The quality event collection schedule management unit 306 operates to inquire the mobile terminal 1 about quality events at a predetermined cycle. Thereby, a quality event can be received from the mobile terminal 1 in a predetermined cycle.

  The stream control event generation unit 307 refers to the information stored in the information management unit 305 and generates a stream control event. The generated stream control event is output to the RTCP processing unit 302 and transmitted to the media distribution server 2 through the packet transmitting / receiving unit 301.

  According to FIG. 3, the media distribution server 2 includes a packet transmitting / receiving unit 201, an RTP / RTCP processing unit 202, a media content storage unit 203, an encoding unit 204, a packet loss compensation control unit 205, and a stream distribution control. Part 206. These functional components (excluding the network connection interface unit) can be realized by executing a program that causes a computer mounted on the server to function.

  The media content storage unit 203 stores the content of the media stream to be distributed to the mobile terminal. The media content is output to the encoding unit 204.

  The encoding unit 204 changes the encoding rate or the encoding algorithm in response to an instruction from the stream distribution control unit 206. The encoding unit 204 encodes the media content and outputs the media stream to the packet loss compensation control unit 205.

  The packet loss compensation control unit 205 changes the strength of packet loss compensation (the number of simultaneous loss packets to be compensated) or the loss compensation algorithm in accordance with an instruction from the stream distribution control unit 206. Here, the “loss compensation algorithm” is a process that uses information on the transmitting side and the receiving side that complements the loss interval by adding information other than the media information necessary to detect and complement the loss at the receiving side terminal. Means the algorithm. The media stream that has been subjected to the packet loss compensation is output to the RTP / RTCP processing unit 202.

  The RTP / RTCP processing unit 202 changes the RTP header configuration and the packet transmission interval in accordance with an instruction from the stream distribution control unit 206. The RTP / RTCP processing unit 202 transmits the media stream configured in the RTP packet to the mobile terminal 1 through the packet transmission / reception unit 201.

  The media distribution server 2 receives the stream control event received from the communication status management server 3 and included in the RTCP packet or included in the packet having a configuration other than the RTCP packet. The stream delivery control unit 206 receives the stream control event from the RTP / RTCP processing unit 202. When the stream distribution control unit 206 receives a stream control event included in a packet having a configuration other than the RTCP packet, it is received directly from the transport protocol processing unit of the packet transmitting / receiving unit 201 instead of from the RTP / RTCP processing unit 202. To do. The stream distribution control unit 206 controls the encoding unit 204, the packet loss compensation control unit 205, the RTP / RTCP processing unit 202, and the packet transmission / reception unit 201 according to the stream control event.

  Note that the media distribution server 2 preferably includes the function of the communication status management server 3 as an event generation unit. In this case, it is not necessary to provide the communication status management server 3 separately. This is based on the embodiment of FIGS.

  Here, an example in which a stream control event is generated based on a quality event and a handover event will be specifically described.

[1] Based on the handover event, a stream control event for controlling the transmission interval of RTP packets in the media stream is generated. When shifting from a high transmission rate network to a low transmission rate network, control is performed to increase the transmission interval. Conversely, when shifting from a low transmission rate network to a high transmission rate, the transmission interval is controlled to be small. As a result, the RTP / RTCP processing unit 202 of the media distribution server 2 is controlled.

Table 1 below is an example of changing the transmission interval of RTP packets in the RTP / RTCP processing unit. Of course, two or more set values may be the same value.

[2] A stream control event for controlling the packet loss compensation strength and / or compensation algorithm is generated based on the quality event and the handover event. When shifting from a network with a high transmission rate to a network with a low transmission rate, control is performed so as to select an algorithm with a large loss strength or high loss tolerance. Conversely, when shifting from a low transmission rate network to a high transmission rate network, control is performed to select an algorithm with low loss strength or low loss tolerance. As a result, the packet loss compensation control unit 205 of the media distribution server 2 is controlled.

Table 2 below is an example of changing the loss compensation strength and algorithm in the packet loss compensation control unit 205. Of course, two or more set values may be the same value.

[3] A stream control event for controlling the transfer rate in the encoding unit is generated based on the quality event and the handover event. When the network shifts from a high transmission rate network to a low transmission rate network and the jitter standard deviation information is large, control is performed so as to select an encoding algorithm with a small transfer rate or a smaller transfer rate. Conversely, when the network shifts from a low transmission rate network to a high transmission rate network and the jitter standard deviation information is small, control is performed so as to select an encoding algorithm with a higher transfer rate or a higher transfer rate. . As a result, the encoding unit 204 of the media distribution server 2 is controlled.

Table 3 below is an example of changing the transfer rate and algorithm in the encoding unit 204. Of course, two or more set values may be the same value.

[4] Based on the quality event and the handover event, a stream control event for controlling the number of media frames loaded in the UDP or TCP packet in the transport protocol processing unit of the packet transmitting / receiving unit is generated. When the network shifts from a high transmission rate network to a low transmission rate network and the jitter standard deviation information is large, control is performed to increase the number of loaded media frames. Conversely, when the network shifts from a low transmission rate network to a high transmission rate network and the jitter standard deviation information is small, control is performed to increase the number of loaded media frames. As a result, the packet transmission / reception unit 201 of the media distribution server 2 is controlled.

Table 4 below is an example in which the number of frames in the packet transmitting / receiving unit 201 is changed. Of course, two or more set values may be the same value.

[5] A stream control event for controlling the number of simultaneously connected streams for the same content is generated based on the quality event and the handover event. When the network shifts from a high transmission rate network to a low transmission rate network and the jitter standard deviation information is large, control is performed to reduce the number of streams. On the other hand, when the network shifts from a low transmission rate network to a high transmission rate network and the jitter standard deviation information is small, control is performed to increase the number of streams. As a result, the packet transmission / reception unit 201 of the media distribution server 2 is controlled.

Table 5 below is an example in which the number of streams in the packet transmitting / receiving unit 201 is changed. Of course, two or more set values may be the same value.

[6] A stream control event for controlling a GOP (Group of Picture) size in the encoding unit is generated based on the quality event and the handover event. When the network shifts from a high transmission rate network to a low transmission rate network and the jitter standard deviation information is large, the GOP size is controlled to be small / large. On the other hand, when the network shifts from a low transmission rate network to a high transmission rate network and the jitter standard deviation information is small, control is performed to increase / decrease the GOP size. As a result, the encoding unit 204 of the media distribution server 2 is controlled.

Table 6 below is an example of changing the GOP size in the encoding unit 204. Of course, two or more set values may be the same value.

  As described above in detail, according to the system and program of the present invention, even when the mobile terminal is handed over, appropriate media stream delivery control is performed based on the communication quality of the media stream packet. be able to. Thereby, it is possible to improve the service quality in the delivery of the media stream to the mobile terminal.

  In addition, according to the present invention, there is an effect of eliminating or reducing the interruption of the media stream even in the case of handover between different access networks. In particular, when a mobile terminal transmits a handover event, it is not necessary to provide a handover management device, and it is only necessary to install a communication status management server.

  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 1st system block diagram in this invention. FIG. 2 is a system configuration diagram further including a handover management apparatus in the system of FIG. 1. It is a 2nd system block diagram in this invention. FIG. 4 is a system configuration diagram further including a handover management device in the system of FIG. 3. It is a function block diagram of the mobile terminal in this invention. It is a function block diagram of the communication condition management server and media delivery server in this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mobile terminal 101 Packet transmission / reception part 102 RTP / RTCP processing part 103 Media stream reproduction part 104 Media output interface part 105 Quality information measurement part 106 Quality information management part 107 Service control processing part 108 Quality event generation part 109 Handover event generation part 2 Media Distribution server 201 Packet transmission / reception unit 202 RTP / RTCP processing unit 203 Media content storage unit 204 Encoding unit 205 Packet loss compensation control unit 206 Stream distribution control unit 3 Communication status management server 301 Packet transmission / reception unit 302 RTCP processing unit 303 Quality event processing unit 304 Handover event processing unit 305 Information management unit 306 Quality event collection schedule management unit 307 Stream control event generation unit 4 handover Management device 5 IP network 6 access network

Claims (11)

A system comprising a mobile terminal that receives a media stream, a media distribution server that distributes the media stream to the mobile terminal via a network, and a communication status management server connected to the network,
The mobile terminal includes a quality event generation unit that generates a quality event indicating communication quality of the media stream, a handover event generation unit that generates a handover event indicating a network transition when a handover is detected, and the quality Transmitting means for transmitting the event and the handover event to the communication status management server,
The communication status management server has stream control event generation means for generating a stream control event based on the quality event and the handover event, and transmission means for transmitting the stream control event to the media distribution server,
The system according to claim 1, wherein the media distribution server includes a stream distribution control unit that controls distribution of the media stream based on the stream control event. A mobile terminal that receives the media stream; a media distribution server that distributes the media stream to the mobile terminal via the network; a communication status management server that is connected to the network; and a handover of the mobile terminal that is connected to the network A system having a handover management device for monitoring
The mobile terminal has quality event generation means for generating a quality event indicating communication quality of the media stream, and transmission means for transmitting the quality event to the communication status management server.
A handover event generating means for generating a handover event indicating a network transition when the handover of the mobile terminal is detected; and a transmitting means for transmitting the handover event to the communication status management server. Have
The communication status management server has stream control event generation means for generating a stream control event based on the quality event and the handover event, and transmission means for transmitting the stream control event to the media distribution server,
The system according to claim 1, wherein the media distribution server includes a stream distribution control unit that controls distribution of the media stream based on the stream control event.   The system according to claim 1 or 2, wherein the communication status management server inquires and collects the quality event from the mobile terminal at a predetermined cycle. A system having a mobile terminal that receives a media stream and a media distribution server that distributes the media stream to the mobile terminal via a network,
The mobile terminal includes a quality event generation unit that generates a quality event indicating communication quality of the media stream, a handover event generation unit that generates a handover event indicating a network transition when a handover is detected, and the quality Transmitting means for transmitting an event and the handover event to the media distribution server,
The media distribution server includes stream control event generation means for generating a stream control event based on the quality event and the handover event, and stream distribution control means for controlling distribution of the media stream based on the stream control event. The system characterized by having. A system comprising: a mobile terminal that receives a media stream; a media distribution server that distributes the media stream to the mobile terminal via a network; and a handover management device that is connected to the network and monitors handover of the mobile terminal. And
The mobile terminal has quality event generation means for generating a quality event based on the media stream being received, and transmission means for transmitting the quality event to the media distribution server,
When the handover of the mobile terminal is detected, the handover management apparatus generates a handover event that represents a network transition, and a transmission unit that transmits the handover event to the media distribution server server Have
The media distribution server includes stream control event generation means for generating a stream control event based on the quality event and the handover event, and stream distribution control means for controlling distribution of the media stream based on the stream control event. The system characterized by having. The media stream is transmitted using RTP (Real-time Transport Protocol), and the quality event and the handover event are transmitted using RTCP (RTP Control Protocol),
The quality event is a jitter standard deviation value;
The handover event is a movement event from the first network to the second network;
The stream control event is based on the quality event and the handover event,
(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 the encoding unit,
(4) The number of media frames stacked in a UDP (User Datagram Protocol) or TCP (Transmission Control Protocol) packet in the transport packet transmission / reception unit;
(5) Number of simultaneously connected streams for the same content,
(6) The system according to any one of claims 1 to 5, which is any one of GOP (Group of Picture) sizes in the encoding unit or a combination thereof. In a mobile terminal that receives a media stream,
Quality event generation means for generating a quality event representing the communication quality of the media stream;
Handover event generating means for generating a handover event representing network transition when a handover is detected;
A mobile terminal comprising: transmission means for transmitting the quality event and the handover event. A media delivery server for delivering the media stream to a mobile terminal according to claim 7 via a network,
Receiving means for receiving the quality event and the handover event;
Stream control event generating means for generating a stream control event based on the quality event and the handover event;
A media distribution server comprising: stream distribution control means for controlling distribution of the media stream based on the stream control event. A communication status management server for communicating between the mobile terminal according to claim 7 and a network,
Receiving means for receiving the quality event and the handover event;
Stream control event generating means for generating a stream control event based on the quality event and the handover event;
A communication status management server, comprising: transmission means for transmitting the stream control event to a media distribution server that distributes the media stream. A media distribution server connected to the communication status management server according to claim 9 via a network and distributing the media stream to the mobile terminal according to claim 7 via the network,
Receiving means for receiving the stream control event;
A media distribution server comprising: stream distribution control means for controlling distribution of the media stream based on the stream control event. In a program for causing a computer mounted on a mobile terminal that receives a media stream to function,
Quality event generation means for generating a quality event representing the communication quality of the media stream;
Handover event generating means for generating a handover event representing network transition when a handover is detected;
A program for a mobile terminal, which causes a computer to function as transmission means for transmitting the quality event and the handover event.

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