System and apparatus for streaming data communication, and streaming data distribution method

The present invention relates to a streaming data communication system, a streaming data communication device, and a streaming data distribution method.

Conventionally, streaming broadcasting by IP multicast has been realized by using public broadband networks such as ADSL and FTTH (for example, Patent Document 1). However, on the user side where a set-top box (hereinafter referred to as "STB (Set Top Box)") is installed, the performance of this STB is not necessarily the same as that of the network environment (modem, router, hub, etc.), so packet loss. There is a situation in which the image is distorted due to the above.

As a countermeasure against such a problem, RTCP (RTP control protocol) exists as a protocol for adjusting the bit rate (transfer rate). This RTCP dynamically adjusts the send bit rate of the server during streaming playback by exchanging packet drop statistics between the server and the STB.

It is also possible to adjust the bit rate in advance and change the bit rate of IP multicast streaming.<patcit num="1"><text>Japanese Unexamined Patent Publication No. 2001-69483</text></patcit>

<p> However, the method using RTCP as described above has a problem that image distortion cannot be prevented in advance because the transmission bit rate is dynamically adjusted after packet discarding. Further, when the bit rate is dynamically changed, the image quality is lowered or improved in the middle, which causes a problem in terms of homogenizing the image quality with respect to the channel. Furthermore, not only does the same problem occur with STBs that are already being received, but in the case of STBs that cannot respond to dynamic bit rate changes (variable bit rate), image distortion and images cannot be displayed, etc. Problems may occur.</p><p> It is also conceivable to pre-adjust the bit rate for each STB and distribute it by unicast instead of multicast. However, it is practically impossible to deal with each STB individually in consideration of the network environment, and the method using unicast has a one-to-one relationship between the distribution server and the receiving terminal device. Due to the distribution of the data, the traffic on the network becomes large and the distribution speed decreases.</p><p> The present invention has been made in view of such problems, and is a streaming data communication system, a streaming data communication device, and a streaming data communication device capable of delivering streaming data at a bit rate suitable for STB on a network by using a multicast method. The purpose is to provide a streaming data distribution method.</p>

<p> INDUSTRIAL APPLICABILITY In a streaming data communication system including a server for distributing streaming data and a streaming data communication device for reproducing streaming data, the server is a bit for detecting an appropriate bit rate of the streaming data communication device. A test data packet with a different rate is sent and streaming data is delivered at the bit rate requested according to the test data packet, and the streaming data communication device has an appropriate bit according to the packet loss detected from the test data packet. It determines the rate and requests the distribution of streaming data at the bit rate.</p>

<p> According to the streaming data communication system, the streaming data communication device, and the streaming data distribution method according to the present invention, streaming data can be distributed at a bit rate suitable for STB on the network by using the multicast method.</p>

The streaming data communication system according to the first aspect of the present invention is a streaming data communication system including a server for distributing streaming data and a streaming data communication device for reproducing the streaming data. A test data packet in which the bit rate is changed to detect an appropriate bit rate of the streaming data communication device is sent, the streaming data is delivered at a bit rate requested according to the test data packet, and the streaming data communication is performed. The apparatus adopts a configuration in which an appropriate bit rate is determined according to the packet loss detected from the test data packet and distribution of streaming data at the bit rate is requested.

According to this configuration, an appropriate bit rate is determined according to the packet loss detected from the test data packet, and distribution of streaming data at the bit rate is required. Therefore, the appropriate bit in the streaming data communication device from the server. Streaming data can be delivered according to the rate.

A second aspect of the present invention is the streaming data communication system according to the first aspect, wherein the streaming data communication device is determined according to the channel number of the streaming data for which distribution is requested and the network environment to which the device main body is connected. The server notifies the initial band to be generated, and adopts a configuration in which the server determines and distributes the bit rate of the streaming data according to the initial band and the communication band currently allottable.

According to this configuration, the bit rate of the streaming data is determined according to the initial band determined according to the network environment and the communication band currently allottable in the server, so that the bit rate of the streaming data is determined according to the network environment of the streaming data communication device. Streaming data can be delivered according to an appropriate bit rate.

A third aspect of the present invention is that in the streaming data communication system according to the second aspect, when the initial band is lower than the currently allottable communication band, the server uses the appropriate communication band of the streaming data communication device. A configuration is adopted in which a certain final band is determined and streaming data is distributed according to the final band.

According to this configuration, when the initial band is lower than the currently allottable communication band, the final band, which is the appropriate communication band of the streaming data communication device, is determined, so that the more appropriate bit rate in the streaming data communication device is determined. Streaming data can be delivered according to the above.

A fourth aspect of the present invention is the streaming data communication system according to the second or third aspect, in which the server distributes with the channel number when the initial band exceeds the currently allottable communication band. A configuration is adopted in which the bit rate of the streaming data is determined and distributed according to the maximum band and the currently allottable communication band.

According to this configuration, when the initial band exceeds the currently allottable communication band, streaming is performed according to the maximum band delivered by the previously notified channel number and the currently allottable communication band on the server. Since the bit rate of the data is determined, the streaming data that has already been distributed can be effectively utilized to distribute the streaming data.

A fifth aspect of the present invention is the streaming data communication system according to the fourth aspect, in which, when the maximum band is lower than the currently allottable communication band, the server streams data according to the currently allottable communication band. Adopt a configuration to deliver.

According to this configuration, when the maximum band is lower than the currently allottable communication band, streaming data is delivered according to the currently allottable communication band, so that the currently allottable communication band is fully utilized. Streaming data can be delivered.

A sixth aspect of the present invention is that in the streaming data communication system according to the fourth or fifth aspect, when the maximum band exceeds the currently allottable communication band, the server streams data according to the maximum band. Adopt a configuration to deliver.

According to this configuration, when the maximum bandwidth exceeds the currently allottable communication bandwidth, streaming data is distributed according to the maximum bandwidth, so the streaming data of the maximum bandwidth already distributed can be effectively utilized. Streaming data can be delivered.

The streaming data communication device according to the seventh aspect of the present invention is a streaming data communication device that reproduces the distributed streaming data, and is a bit rate for detecting an appropriate bit rate from the server that distributes the streaming data. A receiving means for receiving the test data packet, a detecting means for detecting the packet loss of the test data packet, and a detecting means for detecting the packet loss, and determining an appropriate bit rate according to the detection result of the packet loss, and streaming data at the bit rate. A configuration including a control means for requesting distribution and a reproduction means for reproducing the streaming data distributed in response to the request of the control means is adopted.

According to this configuration, an appropriate bit rate is determined according to the detection result of packet loss of the test data packet, distribution of streaming data at the bit rate is requested, and the delivered streaming data is reproduced in response to the request. Therefore, the streaming data can be reproduced according to an appropriate bit rate in the streaming data communication device.

An eighth aspect of the present invention notifies the streaming data communication device according to the seventh aspect of the channel number of the streaming data for which distribution is requested and the initial band determined according to the network environment to which the device main body is connected. The reproduction means further includes a notification unit, and the reproduction means adopts a configuration in which the server reproduces streaming data at a bit rate determined according to the initial band and the communication band currently allottable.

According to this configuration, the bit rate of streaming data is determined according to the initial band determined according to the network environment and the communication band currently allottable in the server, so that it depends on the network environment of the streaming data communication device. Streaming data can be played according to an appropriate bit rate.

The server device according to the ninth aspect of the present invention is a server device that delivers streaming data to the streaming data communication device, and is for detecting an appropriate bit rate of the streaming data communication device prior to the streaming data. A configuration is adopted in which a transmission means for transmitting a test data packet having a different bit rate and a distribution means for distributing the streaming data at a bit rate requested by the streaming data communication device according to the test data packet are provided. ..

According to this configuration, an appropriate bit rate is determined according to the packet loss detected from the test data packet, and distribution of streaming data at the bit rate is required. Therefore, the appropriate bit rate in the streaming data communication device is obtained. Streaming data can be delivered accordingly.

The tenth aspect of the present invention is determined in the server device according to the ninth aspect according to the channel number of the streaming data requested to be delivered from the streaming data communication device and the network environment to which the device main body is connected. A configuration is further provided in which a receiving means for receiving the initial band and a control means for determining the bit rate of the streaming data according to the initial band and the currently allottable communication band are provided.

According to this configuration, the bit rate of the streaming data is determined according to the initial band determined according to the network environment and the communication band currently allottable in the server, so that the bit rate of the streaming data is determined according to the network environment of the streaming data communication device. Streaming data can be delivered according to an appropriate bit rate.

An eleventh aspect of the present invention is the server device according to the tenth aspect, wherein the control means is an appropriate communication band of the streaming data communication device when the initial band is lower than the currently allottable communication band. A configuration is adopted in which the final band is determined and the streaming data is distributed to the distribution means according to the final band.

According to this configuration, when the initial band is lower than the currently allottable communication band, the final band, which is the appropriate communication band of the streaming data communication device, is determined, so that the more appropriate bit rate in the streaming data communication device is determined. Streaming data can be delivered according to the above.

A twelfth aspect of the present invention is the server device according to the tenth or eleventh aspect, wherein when the initial band exceeds the currently allottable communication band, the control means delivers the maximum with the channel number. A configuration is adopted in which the bit rate of the streaming data is determined according to the band and the currently allottable communication band and distributed to the distribution means.

According to this configuration, when the initial band exceeds the currently allottable communication band, streaming is performed according to the maximum band delivered by the previously notified channel number and the currently allottable communication band on the server. Since the bit rate of the data is determined, the streaming data that has already been distributed can be effectively utilized to distribute the streaming data.

According to a thirteenth aspect of the present invention, in the server device according to the twelfth aspect, when the maximum band is lower than the currently allottable communication band, the control means transmits streaming data according to the currently allottable communication band. A configuration is adopted in which the distribution means is used for distribution.

According to this configuration, when the maximum band is lower than the currently allottable communication band, streaming data is delivered according to the currently allottable communication band, so that the currently allottable communication band is fully utilized. Streaming data can be delivered.

A fourteenth aspect of the present invention is the server device according to the twelfth or thirteenth aspect, in which the control means transmits streaming data according to the maximum band when the maximum band exceeds the currently allottable communication band. A configuration is adopted in which the distribution means is used for distribution.

According to this configuration, when the maximum bandwidth exceeds the currently allottable communication bandwidth, streaming data is distributed according to the maximum bandwidth, so the streaming data of the maximum bandwidth already distributed can be effectively utilized. Streaming data can be delivered.

The streaming data distribution method according to the fifteenth aspect of the present invention is a streaming data distribution method for a streaming data communication device that reproduces the distributed streaming data, and is appropriate for the streaming data communication device prior to the streaming data. A test data packet with a different bit rate for detecting the bit rate is sent, and an appropriate bit rate is determined according to the packet loss detected from the test data packet by the streaming data communication device, and the bit rate is used. It requests the delivery of streaming data and delivers the streaming data at the requested bit rate.

The 16th aspect of the present invention is determined in the streaming data distribution method according to the 15th aspect according to the channel number of the streaming data requested to be distributed from the streaming data communication device and the network environment to which the device main body is connected. The initial band is notified, and the bit rate of the streaming data is determined and distributed according to the initial band and the currently allottable communication band.

In the 17th aspect of the present invention, in the streaming data distribution method according to the 16th aspect, when the initial band is lower than the currently allottable communication band, the final band which is an appropriate communication band of the streaming data communication device is set. It is determined and the streaming data is distributed according to the final band.

An eighteenth aspect of the present invention is the maximum band distributed by the channel number and the present when the initial band exceeds the currently allottable communication band in the streaming data distribution method according to the sixteenth or seventeenth aspect. The bit rate of the streaming data is determined and distributed according to the allottable communication band.

A nineteenth aspect of the present invention is the streaming data distribution method according to the eighteenth aspect, in which, when the maximum band is lower than the currently allottable communication band, the streaming data is distributed according to the currently allottable communication band. Is.

A twentieth aspect of the present invention is the streaming data distribution method according to the eighteenth or nineteenth aspect, in which, when the maximum band exceeds the currently allottable communication band, the streaming data is distributed according to the maximum band. Is.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram showing a network configuration to which a streaming data communication system according to an embodiment of the present invention is applied.

As shown in FIG. 1, the network to which the streaming data communication system according to the present embodiment is applied receives the broadcasting server 101 that distributes the streaming data and the streaming data distributed from the broadcasting server 101 via the Internet. It is composed of a set top box (hereinafter referred to as "STB (Set Top Box)") 102 to 106 as a plurality of streaming data communication devices. Each STB 102 to 106 has a display 107 to display on which streaming data is displayed. 111 is connected.

The broadcast server 101 includes a TV tuner 112. The TV tuner 112 converts analog data received from satellite broadcasting or the like into digital data such as MPEG. The broadcasting server 101 distributes the converted digital data as streaming data to STB 102 to 106 via the Internet.

FIG. 2 is a block diagram showing a network environment around STB 102 to 106 in the streaming data communication system according to the present embodiment. Of the network environments around STB102 to 106, the network environment around STB102 will be described as a representative, and the other network environments around STB103 to 106 will be omitted.

As shown in FIG. 2, in the network environment around STB102, ADSL or FTTH (hereinafter referred to as ADSL or the like) 201 is connected to the router / hub 203 via the modem 202. The router / hub 203 is connected to the STB 102 and the personal computer (hereinafter referred to as PC) 204 connected to the display 107. In ADSL, etc. 201, the bandwidth is usually guaranteed in advance, but since modems 202 and routers / hubs 203 are used by various manufacturers depending on the user, the bandwidth used by STB102 is limited depending on only ADSL, etc. 201. It is difficult to determine.

FIG. 3 is a block diagram showing the configurations of STBs 102 to 106 in the streaming data communication system according to the present embodiment. Since STB102 to 106 have the same configuration, the configuration of STB102 will be described, and the configurations of other STB103 to 106 will be omitted.

As shown in FIG. 3, the STB102 includes a CPU 301, a memory 302, an infrared interface (I / F) 303, a storage device 304, a TV interface (I / F) 305, and a network interface (I / F) 306.

The CPU 301 controls the operation of the entire device. The memory 302 stores a program executed by the CPU 301 when controlling the entire device and data necessary for the control. The infrared I / F 303 accepts operation input from the remote controller. Streaming data received from the broadcast server 101 is stored in the storage device 304. The TVI / F305 connects the connected display and the main body of the device via an interface. The network I / F 306 connects the Internet and the main body of the device via an interface.

FIG. 4 is a functional block diagram of the CPU 301 included in the STB102 in the streaming data communication system according to the present embodiment.

As shown in FIG. 4, the CPU 301 includes a streaming processing unit 401, a TV playback unit 402, a communication quality measuring unit 403, and a remote control processing unit 404.

The streaming processing unit 401 receives the streaming data input via the network I / F 306. The received streaming data is passed to the TV playback unit 402 and the communication quality measurement unit 403. The TV playback unit 402 converts the digital data obtained from the streaming processing unit 401 into analog data, and reproduces the analog data on the display via the TVI / F 305.

The communication quality measuring unit 403 measures the communication quality of the streaming data obtained from the streaming data processing unit 401. Specifically, as will be described later, the loss of received packets is checked. The remote control processing unit 404 processes the operation input received via the infrared I / F 303 and notifies the communication quality measuring unit 403.

FIG. 5 is a block diagram showing a configuration of a broadcasting server 101 in the streaming data communication system according to the present embodiment.

As shown in FIG. 5, the broadcasting server 101 includes a bit rate conversion unit 501, a packet transmission unit 502, and an STB communication unit 503.

The bit rate conversion unit 501 converts the bit rate of digital data such as MPEG converted by the TV tuner 112. The bit rate converted by the bit rate conversion unit 501 follows the bit rate determined by the STB communication unit 503 with the STB as the distribution destination.

The packet transmission unit 502 transmits the packet of the bit rate converted by the bit rate conversion unit 501 to the STB which is the delivery destination via the Internet. The STB communication unit 503 communicates a data packet necessary for determining the bit rate to be converted by the bit rate conversion unit 501 with the STB which is the delivery destination. The bit rate determined by the STB communication unit 503 is notified to the bit rate conversion unit 501.

Hereinafter, the operation in the present streaming data communication system having the above configuration will be described. First, the STB activation process in the streaming data communication system according to the present embodiment will be described.

FIG. 6 is a sequence diagram for explaining the STB activation process in the streaming data communication system according to the present embodiment. Here, the operation when STB102 is started will be described.

As shown in FIG. 6, when the STB102 is started, the STB102 notifies the broadcasting server 101 of the communication band of its own network environment recognized in advance. For example, STB102 notifies the communication band guaranteed by 201 such as ADSL. The communication band notified here is only used as an upper limit when determining the optimum communication band (hereinafter referred to as "final band") in the current network environment that is actually used, so it is a rough value. I do not care.

Upon receiving the notification of this communication band, the broadcasting server 101 changes the bit rate up to this communication band to determine the optimum bit rate for STB102 (hereinafter referred to as "test packet") communication. To start. Specifically, first, the STB102 is notified of the rate information for transmitting the test packet and the port used for the transmission.

Here, the rate information for transmitting the test packet will be described. FIG. 7 is a diagram showing an example of rate information. The rate information is information for notifying the unit of the bit rate of the test packet. FIG. 7 shows a case of notifying that transmission is performed in 1 Mbps units from 2 Mbps to 8 Mbps.

FIG. 8 is a sequence diagram for explaining a process in which the STB 102 receives a test packet from the broadcasting server 101 in the streaming data communication system according to the present embodiment.

When receiving a test packet from the broadcast server 101, the STB102 first connects to the port specified by the broadcast server 101 according to TCP (Transmission Control Protocol) (hereinafter referred to as "TCP connection"), and then RTSP (Real Time). Send "DESCRIBE" specified in Streaming Protocol).

This "DESCRIBE" includes a URL corresponding to an identifier (hereinafter referred to as "test ID") for identifying the reception of the test packet. On the other hand, the broadcasting server 101 sends "SDP" defined in RTSP to STB102. This "SDP" contains the URL for SETUP.

Upon receiving "SDP" from the broadcast server 101, STB102 analyzes the "SDP" and sends out "SETUP" specified in RTSP. In response, the broadcast server 101 sends the RTP address / port to the STB102. Upon receiving this response, STB102 sends out "PLAY" specified in RTSP. In response to this, the broadcast server 101 sends out "rtptime".

When "rtptime" is sent, the broadcast server 101 sends an RTP stream to STB102 as shown in FIG. This RTP stream is sent according to the bit rate unit shown in the above rate information. That is, since the 1 Mbps unit is specified in the above rate information, an RTP stream of 2 Mbps, 3 Mbps ... 8 Mbps is sent to the STB102.

Here, the packets constituting the RTP streaming sent from the broadcasting server 101 will be described with reference to FIG. The RTP packet sent from the broadcast server 101 includes an ether header, an IP header, a UDP header, an RTP header, and test data, as shown in FIG. The RTP header contains a 1-bit mark bit and sequence number according to RFC1889.

The mark bit is changed when the bit rate in the rate information is incremented. In the above example, the mark bit is transmitted at "0" at 2 Mbps, and the mark bit is changed at "1" when the bit rate is changed from 2 Mbps to 3 Mbps. Also, when changing the bit rate from 3 Mbps to 4 Mbps, the mark bit is changed to "0" and transmitted. The STB102 side detects that the communication band of the test packet has been switched by detecting the value of this mark bit. The content of the test data is not particularly limited, and any data may be used.

This will be described with reference to the example of FIG. The broadcast server 101 first sends a 2 Mbps RTP stream to the STB 102. Then, after a lapse of a certain period of time from the transmission of the RTP stream, the bit rate is increased by 1 Mbps based on the rate information, and the 3 Mbps RTP stream is transmitted. At this time, the broadcasting server 101 changes the mark bit of the RTP header from "0" to "1".

The STB102 detects that the mark bit of the RTP header has been changed and detects that the communication band has been switched. At the same time, packet loss (packet loss) is checked by detecting the continuity of the sequence number in the RTP header.

Such processing is repeated up to the 8 Mbps RTP stream indicated in the rate information. Then, when the RTP stream of 8 Mbps is completed, the communication band immediately before the packet loss occurs is registered as the initial band on the user side. Here, the initial band means a communication band that is predetermined in the startup process in order to determine the final band of STB102. Then disconnect according to TCP. For example, if packet loss occurs in an RTP stream of 5 Mbps, 4 Mbps will be registered as the initial band.

Hereinafter, the operation when the streaming data is delivered in response to the request of the STB in which the initial band is registered will be described with reference to FIG. FIG. 11 is a flow chart for explaining an operation in which streaming data is distributed in response to a request from the STB in the streaming data communication system according to the present embodiment.

As shown in FIG. 11, when the STB requests the distribution of streaming data, the channel number desired to be distributed from the STB and the initial band registered in the STB are transmitted to the broadcasting server 101. Broadcast server 101 accepts this channel number and initial band (ST1101).

When the channel number and the initial band are accepted, the broadcasting server 101 determines whether the communication band currently allocated by the broadcasting server 101 has a free space equal to or larger than the initial band (ST1102). The free communication band is determined by comparing the sum of the bit rate set in the channel table shown in FIG. 12 and the initial band transmitted from the STB with the communication band of the broadcasting server 101. This channel table is managed by the broadcasting server 101.

As shown in FIG. 12, the channel table records the type, bit rate, multicast address / port, latest date and time of use, and number of accesses corresponding to the channel number corresponding to the content provided by the broadcast server 101. There is. The bit rate at each channel number is set in the channel table according to the request from the STB. In the latest usage date and time, the date and time when the entry was last used is recorded. In the number of accesses, the number of STBs currently using the entry is recorded.

When the communication band currently allocated by the broadcasting server 101 has a free space equal to or larger than the initial band, the broadcasting server 101 determines the final band of the STB requesting the distribution of the streaming data (ST1103). The process of determining the final band will be described later.

Once the final band has been determined, the STB sends the final band, and the broadcast server 101 accepts this (ST1104). Then, a stream of the final band is generated (ST1105), and the generated stream sends a packet to the STB (ST1106). The communication band (bit rate) of the generated stream is newly set in the channel table.

On the other hand, if there is no free space equal to or greater than the initial band in the communication band currently allocated by the broadcasting server 101, the broadcasting server 101 has the maximum channel number (hereinafter referred to as "designated channel number") specified from the channel table. Get the bandwidth (bit rate) (ST1107). Assuming that the designated channel number is "100" in FIG. 12, the maximum bandwidth is "8 Mbps". Then, it is determined whether or not there is a free space equal to or more than the maximum band in the communication band currently allocated by the broadcasting server 101 (ST1108).

If the communication band currently available to the broadcast server 101 has more than the maximum bandwidth, a stream of the communication band that can be allocated is generated (ST1109), and the generated stream sends a packet to the STB. (ST1110). The communication band (bit rate) of the generated stream is set in the channel table.

On the other hand, if there is no free space above the maximum bandwidth in the communication bandwidth currently allocated by the broadcast server 101, the stream with the communication bandwidth (bit rate) closest to the specified initial bandwidth is selected (ST1111). , Send packets to STB with the selected stream (ST1112).

Here, a specific example will be described according to the communication band that can be currently allocated by the broadcasting server 101. As a specific example, when there is a free space above the initial band in the communication band currently allocated by the broadcasting server 101 (Fig. 13), and when there is no free space above the initial band in the communication band currently allocated by the broadcasting server 101. (FIGS. 18 and 21) will be described. In particular, when there is no free space above the initial band, the communication band currently allocated by the broadcast server 101 does not have a free space above the maximum band of the specified channel number (Fig. 18), and the broadcast server 101 can currently allocate it. The case where the communication band has a free space equal to or larger than the maximum band of the specified channel number (Fig. 21) will be described.

FIG. 13 is a diagram showing an example of a case where the communication band currently allocated by the broadcasting server 101 has a free space equal to or larger than the initial band. In FIG. 13, it is assumed that the broadcasting server 101 has a communication band of 12 Mbps. In addition, it is assumed that STB102 and STB103 are currently receiving streaming data distribution, and STB104 newly requests distribution of streaming data. It is assumed that the final band of STB102 is 2.2 Mbps and the final band of STB103 is 1.5 Mbps. That is, the broadcasting server 101 has a free space of 8.3 Mbps as a communication band that can be currently allocated. Further, it is assumed that the initial band of STB104 is 5 Mbps and the final band is 5.9 Mbps.

14 to 17 are sequence diagrams in the case of distributing streaming data when the communication band currently allocated by the broadcasting server 101 has a free space equal to or larger than the initial band. Hereinafter, a specific example shown in FIG. 13 will be used for description.

As shown in FIG. 14, when requesting the distribution of streaming data, the STB 104 notifies the broadcasting server 101 of the channel number and the initial band. In the example shown in FIG. 13, STB104 notifies 5 Mbps as the initial band.

Upon receiving this notification, the broadcasting server 101 determines whether or not the communication band that can be currently allocated has a free space equal to or larger than the initial band, as described above. In the example shown in FIG. 13, since there is a 8.3 Mbps free space as the communication band that can be currently allocated, it is determined that there is a free space equal to or higher than the initial band (5 Mbps) of the STB104.

Subsequently, the broadcasting server 101 determines the communication band that can be finally allocated from the free communication band. That is, the operation shifts to the operation of determining the final band of STB104. At that time, the broadcasting server 101 first notifies the STB 104 of the rate information for transmitting the test packet and the port used for the transmission.

The rate information shows the unit of the bit rate of the test packet as when determining the initial band, but unlike the case of the initial band that notifies that it is transmitted in 1 Mbps units, it can be transmitted in 100 Kbps units. You will be notified. The unit of the bit rate of the test packet in the rate information can be arbitrarily changed.

Upon receiving this rate information and port number, STB104 makes a TCP connection to the port specified by the broadcasting server 101 as shown in Fig. 15, and sends "DESCRIBE" specified in RTSP (Real Time Streaming Protocol). Send out. This "DESCRIBE" contains the URL corresponding to the test ID. On the other hand, the broadcasting server 1010 sends "SDP" defined in RTSP to STB104. This "SDP" contains the URL for SETUP.

Upon receiving "SDP" from the broadcast server 101, STB104 analyzes the "SDP" and sends out "SETUP" specified in RTSP. In response, the broadcast server 101 sends the RTP address / port to the STB104. Upon receiving this response, STB104 sends out "PLAY" specified in RTSP. In response to this, the broadcast server 101 sends out "rtptime".

When "rtptime" is sent, the broadcast server 101 sends an RTP stream to STB104 as shown in FIG. This RTP stream is sent according to the unit shown in the rate information described above. That is, since the 100Kbps unit is specified in the above rate information, an RTP stream of initial band + 100Kbps, initial band + 200Kbps ... initial band + 1000Kbps is sent to STB104.

The mark bit of the RTP packet is changed when the bit rate in the rate information is advanced, as in the case of the initial band, and the STB104 side indicates that the communication band of the test packet was switched by detecting the value of this mark bit. Detect with. At the same time, packet loss is checked by detecting the continuity of the sequence number in the RTP header. Then, the communication band immediately before the packet loss occurs is registered as the final band on the user side. Finally, disconnect according to TCP. In the example shown in FIG. 13, packet loss occurs in the initial band of 5 Mbps + 1000 Kbps, and 5.9 Mbps is registered as the final band of STB104.

When the final band is registered, STB104 notifies the broadcasting server 101 of this as shown in FIG. Upon receiving the final band, the broadcast server 101 generates a multicast stream of the final band of the specified channel number and sends the RTP packet to the IP router. Then add an entry to the channel table and increment the number of accesses.

After that, the broadcasting server 101 notifies the STB104 of the multicast address / port of the designated channel number. Upon receiving this notification, STB104 sends a JOIN packet specified in the IGMP (Internet Gateway Multicast Protocol) protocol to the IP router. In this JOIN packet, the multicast address to which the streaming data that the STB wants to deliver is sent is specified.

When the IP router receives this JOIN packet, it opens the gate corresponding to the specified multicast address. As a result, the STB104 can receive the RTP packet delivered from the broadcasting server 101 at the multicast address.

The STB104 receives and reproduces this RTP packet. Then, when the desired reproduction is completed, the LEAVE packet defined in the IGMP protocol is sent. Upon receiving this LEAVE packet, the IP router closes the gate corresponding to the destination multicast address. This makes it impossible for the STB to receive RTP packets.

Finally, STB104 notifies the broadcasting server 101 of the end of reception. Upon receiving the reception end, the broadcast server 101 decrements the number of accesses of the designated channel number in the channel table and ends the process.

As described above, according to the streaming data communication system according to the present embodiment, the STB notifies the channel number of the streaming data requesting distribution and the initial band determined according to the network environment to which the device main body is connected. The broadcasting server 101 determines and distributes the bit rate of the streaming data according to the initial band and the communication band that can be currently allocated. That is, since the bit rate of the streaming data is determined according to the initial band determined according to the network environment and the communication band currently allottable in the broadcasting server 101, the appropriate bit rate according to the STB network environment. Streaming data can be delivered according to the above.

In particular, according to the streaming data communication system according to the present embodiment, when the communication band currently allocated by the broadcasting server 101 has a free space equal to or larger than the initial band, the final band of the STB 104 is determined and the final band is determined. Generates a multicast stream and distributes streaming data. That is, since the final band, which is the appropriate communication band of the STB104, is determined, the streaming data can be distributed according to the more appropriate bit rate of the STB104.

FIG. 18 is a diagram showing an example in the case where the communication band currently allocated by the broadcasting server 101 has no free space equal to or larger than the initial band. In particular, FIG. 18 is a diagram showing an example in the case where the communication band currently allocated by the broadcasting server 101 does not have a free space equal to or greater than the maximum band of the designated channel number.

Note that FIG. 18 differs from the example shown in FIG. 13 in that the final bands of STB 102 and 103 are 6 Mbps and 4 Mbps, respectively, and the initial band of STB 104 is 8 Mbps. That is, the broadcasting server 101 has a free space of 2 Mbps as a communication band that can be currently allocated. It is assumed that STB102 and STB103 are receiving streaming data of the same channel number as the designated channel number by STB104, and no other bit rate is set in this designated channel number.

19 and 20 are sequence diagrams in the case of distributing streaming data when there is no free space equal to or more than the initial band in the communication band currently allocated by the broadcasting server 101. Hereinafter, a specific example shown in FIG. 18 will be described.

As shown in FIG. 19, when requesting the distribution of streaming data, the STB 104 notifies the broadcasting server 101 of the channel number and the initial band. In the example shown in FIG. 18, STB104 notifies 8 Mbps as the initial band.

Upon receiving this notification, the broadcasting server 101 determines whether or not the communication band that can be currently allocated has a free space equal to or larger than the initial band, as described above. In the example shown in FIG. 18, since there is only 2 Mbps available as the communication band that can be currently allocated, it is determined that there is no free space above the initial band (8 Mbps) of STB104.

Next, the broadcasting server 101 determines whether or not the communication band that can be currently allocated has a free space equal to or larger than the maximum band of the channel number designated by STB104. In the example shown in FIG. 18, it is assumed that the maximum bandwidth of the channel number specified by STB104 is 6 Mbps. Therefore, the broadcasting server 101 determines whether or not there is a free space of 6 Mbps or more in the communication band that can be currently allocated. Here, since there is only 2 Mbps available as the communication band that can be currently allocated, it is determined that there is no free space above the maximum band (6 Mbps) of the channel number specified by STB104.

In this case, the broadcast server 101 acquires the entry of the closest communication band below the initial band (8 Mbps) of the STB 104. Here, the 6 Mbps received by STB102 is the closest. Therefore, the broadcast server 101 acquires an entry of 6 Mbps. At the same time, it increments the number of accesses to this entry in the channel table.

Subsequently, the broadcasting server 101 notifies the STB104 of the multicast address / port of the designated channel number as shown in FIG. Upon receiving this notification, the STB104 sends a JOIN packet specified in the IGMP protocol to the IP router. In this JOIN packet, the multicast address to which the streaming data that the STB wants to deliver is sent is specified.

Upon receiving this JOIN packet, the IP router opens the gate corresponding to the specified multicast address. As a result, the STB104 can receive the RTP packet delivered from the broadcasting server 101 at the multicast address.

The STB104 receives and reproduces this RTP packet. When the playback is completed, the LEAVE packet specified in the IGMP protocol is sent. Upon receiving this LEAVE packet, the IP router closes the gate corresponding to the destination multicast address. This makes it impossible for the STB to receive RTP packets.

Finally, STB104 notifies the broadcasting server 101 of the end of reception. Upon receiving the reception end, the broadcast server 101 decrements the number of accesses of the designated channel number in the channel table and ends the process.

As described above, according to the streaming data communication system according to the present embodiment, when the initial band exceeds the communication band that can be currently allocated, the maximum band distributed by the designated channel number and the current allocation in the broadcasting server 101 Since the bit rate of the streaming data is determined according to the available communication band, the streaming data can be distributed by effectively utilizing the already distributed streaming data.

In particular, according to the streaming data communication system according to the present embodiment, there is no space above the initial band in the communication band currently allocated by the broadcasting server 101, and there is space above the maximum band of the designated channel number. If not, the currently set communication band (bit rate) that is closest to the initial band is selected and the streaming data is distributed using the multicast stream. Therefore, the streaming data can be distributed by effectively utilizing the streaming data of the maximum band that has already been distributed.

FIG. 21 is a diagram showing an example in the case where the communication band currently allocated by the broadcasting server 101 has no free space equal to or larger than the initial band. In particular, FIG. 21 is a diagram showing an example in the case where the communication band currently allocated by the broadcasting server 101 has a free space equal to or larger than the maximum band of the designated channel number.

Note that FIG. 21 differs from the example shown in FIG. 13 in that the final bands of STB 102 and 103 are 4 Mbps and 3 Mbps, respectively, and the initial band of STB 104 is 6 Mbps. That is, the broadcasting server 101 has a free space of 5 Mbps as a communication band that can be currently allocated. It is assumed that STB102 and STB103 are receiving streaming data of the same channel number as the designated channel number by STB104, and no other bit rate is set in this designated channel number.

Figure 22 and Figure 23 is a sequence diagram of a case where the broadcast server 101 delivers the streaming data when there is no initial bandwidth more free the communication bandwidth to be allotted. Hereinafter, a specific example shown in FIG. 21 will be described.

As shown in FIG. 22, when requesting the distribution of streaming data, the STB 104 notifies the broadcasting server 101 of the channel number and the initial band. In the example shown in FIG. 21, STB104 notifies 6 Mbps as the initial band.

Upon receiving this notification, the broadcasting server 101 determines whether or not the communication band that can be currently allocated has a free space equal to or larger than the initial band, as described above. In the example shown in FIG. 21, since there is only 5 Mbps available as the communication band that can be currently allocated, it is determined that there is no free space above the initial band (6 Mbps) of STB104.

Next, the broadcasting server 101 determines whether or not the communication band that can be currently allocated has a free space equal to or larger than the maximum band of the channel number designated by STB104. In the example shown in FIG. 21, it is assumed that the maximum bandwidth of the channel number specified by STB104 is 4 Mbps. Therefore, the broadcasting server 101 determines whether or not there is a free space of 4 Mbps or more in the communication band that can be currently allocated. Here, since there is a free space of 5 Mbps as the communication band that can be currently allocated, it is determined that there is a free space of 5 Mbps or more of the maximum band (4 Mbps) of the channel number specified by STB104.

If it is determined that there is more free space than the maximum bandwidth (4 Mbps) of the specified channel number by STB104, the broadcast server 101 sets the multicast stream of the specified channel number at the bit rate (5 Mbps) of the free band as shown in FIG. Generate and send RTP packets to the IP router. Then add an entry to the channel table and increment the number of accesses.

After that, the broadcasting server 101 notifies the STB104 of the multicast address / port of the designated channel number. Upon receiving this notification, the STB104 sends a JOIN packet specified in the IGMP protocol to the IP router. In this JOIN packet, the multicast address to which the streaming data that the STB wants to deliver is sent is specified.

Upon receiving this JOIN packet, the IP router opens the gate corresponding to the specified multicast address. As a result, the STB104 can receive the RTP packet delivered from the broadcasting server 101 at the multicast address.

The STB104 receives and reproduces this RTP packet. Then, when the desired reproduction is completed, the LEAVE packet defined in the IGMP protocol is sent. Upon receiving this LEAVE packet, the IP router closes the gate corresponding to the destination multicast address. This makes it impossible for the STB to receive RTP packets.

Finally, STB104 notifies the broadcasting server 101 of the end of reception. Upon receiving the reception end, the broadcast server 101 decrements the number of accesses of the designated channel number in the channel table and ends the process.

As described above, according to the streaming data communication system according to the present embodiment, there is no free space equal to or more than the initial band in the communication band currently allocated by the broadcasting server 101, and the free space is equal to or larger than the maximum band of the designated channel number. If there is, a multicast stream with the bit rate of the free bandwidth is generated and the streaming data is distributed. Therefore, the streaming data can be distributed by making maximum use of the communication band that can be currently allocated.

As described above, according to the streaming data communication system according to the present embodiment, when the communication band currently allocated by the broadcasting server 101 has a free space equal to or larger than the initial band, a multicast stream of the final band of STB104 is generated. And deliver streaming data. If there is no free space above the initial band in the communication band that can be currently allocated by the broadcast server 101, and there is no free space above the maximum band of the specified channel number, the currently set communication band ( Of the bit rates), the one closest to the initial band is selected and the streaming data is distributed using the multicast stream. Furthermore, if there is no free space above the initial band in the communication band that can be currently allocated by the broadcast server 101, and there is free space above the maximum band of the specified channel number, a multicast stream with the bit rate of that free band And distribute the streaming data. Therefore, it is possible to distribute the streaming data by using the communication band of the broadcasting server 101 more efficiently while supporting the network environment of the STB to which the streaming data is distributed.

In particular, according to the streaming data communication system according to the present embodiment, in STB, an appropriate bit rate is determined according to the packet loss detected from the test packet, and the distribution of the streaming data at the bit rate is delivered by the broadcasting server 101. Therefore, streaming data can be distributed from the broadcasting server 101 according to an appropriate bit rate in the STB.

As described above, in the streaming data communication system according to the present embodiment, streaming is performed by more efficiently using the communication band of the broadcasting server 101 while supporting the network environment of the STB to which the streaming data is distributed. Deliver data. That is, a multicast stream having a bit rate corresponding to the network environment of the STB to which the streaming data is delivered is generated and the streaming data is delivered.

However, when the network environment of the STB to which the streaming data is delivered changes, it is not preferable to continue delivering the multicast stream at the bit rate according to the network environment before the change. Therefore, in the streaming data communication system according to the present embodiment, entries that have not been accessed for a certain period of time on the channel table are automatically deleted.

FIG. 24 is a flow chart for explaining an operation of automatically deleting an entry that has not been accessed for a certain period of time on the channel table in the streaming data communication system according to the present embodiment.

As shown in FIG. 24, the broadcasting server 101 monitors the passage of a certain period of time (ST2401). Then, after a certain period of time has passed, the channel table is searched (ST2402) to determine whether there is an entry whose access count is "0" (ST2403).

Here, if there is an entry whose access count is "0", it is determined whether a certain time has passed since the last access time of the entry (ST2404). The elapse of a certain time from the last access time is determined by comparing the latest usage date and time on the channel table with the current time.

If a certain amount of time has passed since the last access time of the entry, the broadcasting server 101 deletes the entry (ST2405). Then, the generation of the multicast stream at the bit rate of the entry is stopped (ST2406). As a result, the distribution of the multicast stream at the bit rate of the entry is stopped.

Then, the broadcast server 101 determines whether or not the deletion process has been completed for all the entries (ST2407). If it is completed for all entries, the process is terminated, if it is not completed, the process is returned to ST2402, and the process after ST2402 is repeated again.

If there is no entry with the number of accesses "0" in ST2403, or if a certain time has not passed since the last access time of the entry with the number of accesses "0" in ST2404, the broadcasting server 101 processes. To ST2407, and determine whether the deletion process has been completed for all entries.

As described above, according to the streaming data communication system according to the present embodiment, entries that have not been accessed for a certain period of time on the channel table are automatically deleted. Therefore, the generation of the multicast stream at the bit rate (communication band) of the entry is stopped. Therefore, it is possible to allocate the communication band to another STB. As a result, the communication band can be newly allocated to the STB that requires the communication band, so that the communication band of the broadcasting server 101 can be used more efficiently while supporting the network environment of the STB to which the streaming data is distributed. ..

The present invention can also be practiced using common commercial digital computers and microprocessors programmed according to the techniques described in the embodiments described above, as will be apparent to those skilled in the art. Also, as will be apparent to those skilled in the art, the present invention includes computer programs created by those skilled in the art based on the techniques described in the above embodiments.

Also included in the scope of the invention are computer program products that are storage media containing instructions that can be used to program a computer that implements the invention. The storage medium is a floppy (R) disk, an optical disk, a disk such as a CDROM or a magnetic disk, ROM, RAM, EPROM, EEPROM, a magnetic optical card, a memory card, a DVD, or the like, but is not particularly limited thereto. Absent.

According to the streaming data communication system, the streaming data communication device, and the streaming data distribution method according to the present invention, the communication band of the broadcasting server is obtained by distributing the streaming data at a bit rate suitable for STB on the network by using the multicast method. It is useful in that it can be used efficiently.

<figref num="1">The figure which shows the structure of the network to which the streaming data communication system which concerns on one Embodiment of this invention is applied.</figref><figref num="2">A block diagram showing a network environment around an STB in a streaming data communication system according to the above embodiment.</figref><figref num="3">A block diagram showing a configuration of an STB in a streaming data communication system according to the above embodiment.</figref><figref num="4">Functional block diagram of the CPU included in the STB in the streaming data communication system according to the above embodiment.</figref><figref num="5">A block diagram showing a configuration of a broadcasting server in a streaming data communication system according to the above embodiment.</figref><figref num="6">A sequence diagram for explaining the STB activation process in the streaming data communication system according to the above embodiment.</figref><figref num="7">The figure which shows an example of the rate information transmitted from the broadcasting server in the streaming data communication system which concerns on the said Embodiment.</figref><figref num="8">A sequence diagram for explaining a process in which the STB receives a test packet from a broadcasting server in the streaming data communication system according to the above embodiment.</figref><figref num="9">A sequence diagram for explaining a process in which the STB receives a test packet from a broadcasting server in the streaming data communication system according to the above embodiment.</figref><figref num="10">The figure which shows the packet which constitutes RTP streaming sent from the broadcasting server in the streaming data communication system which concerns on the said Embodiment.</figref><figref num="11">A flow chart for explaining an operation in which streaming data is distributed in response to a request from an STB in a streaming data communication system according to the above embodiment.</figref><figref num="12">The figure which shows an example of the channel table which a broadcasting server registers in the streaming data communication system which concerns on the said Embodiment.</figref><figref num="13">In the streaming data communication system according to the above embodiment, a diagram showing an example in which the communication band currently allocated by the broadcasting server has a free space equal to or larger than the initial band.</figref><figref num="14">In the streaming data communication system according to the above embodiment, a sequence diagram in the case of distributing streaming data when there is a free space equal to or larger than the initial band in the communication band currently allocated by the broadcasting server.</figref><figref num="15">In the streaming data communication system according to the above embodiment, a sequence diagram in the case of distributing streaming data when there is a free space equal to or larger than the initial band in the communication band currently allocated by the broadcasting server.</figref><figref num="16">In the streaming data communication system according to the above embodiment, a sequence diagram in the case of distributing streaming data when there is a free space equal to or larger than the initial band in the communication band currently allocated by the broadcasting server.</figref><figref num="17">In the streaming data communication system according to the above embodiment, a sequence diagram in the case of distributing streaming data when there is a free space equal to or larger than the initial band in the communication band currently allocated by the broadcasting server.</figref><figref num="18">In the streaming data communication system according to the above embodiment, the figure which shows an example of the case where there is no free space more than an initial band in the communication band which can be currently allocated by a broadcasting server.</figref><figref num="19">In the streaming data communication system according to the above embodiment, a sequence diagram in the case of distributing streaming data when there is no free space equal to or more than the initial band in the communication band currently allocated by the broadcasting server.</figref><figref num="20">In the streaming data communication system according to the above embodiment, a sequence diagram in the case of distributing streaming data when there is no free space equal to or more than the initial band in the communication band currently allocated by the broadcasting server.</figref><figref num="21">In the streaming data communication system according to the above embodiment, the figure which shows an example of the case where there is no free space more than an initial band in the communication band which can be currently allocated by a broadcasting server.</figref><figref num="22">In the streaming data communication system according to the above embodiment, a sequence diagram in the case of distributing streaming data when there is no free space equal to or more than the initial band in the communication band currently allocated by the broadcasting server.</figref><figref num="23">In the streaming data communication system according to the above embodiment, a sequence diagram in the case of distributing streaming data when there is no free space equal to or more than the initial band in the communication band currently allocated by the broadcasting server.</figref><figref num="24">In the streaming data communication system according to the above embodiment, a flow chart for explaining an operation of automatically deleting an entry that has not been accessed for a certain period of time on the channel table.</figref>

Code description

101 Broadcast server 102 ~ 106 STB (set-top box) 107 ~ 111 Display 112 TV tuner 202 Modem 203 Router / hub 301 CPU 302 Memory 304 Storage device 401 Streaming processing unit 402 TV playback unit 403 Communication quality measurement unit 404 Remote control processing unit 501 Bit rate conversion unit 502 Packet transmission unit 503 STB communication unit