JP2010118836A - Method and apparatus for retransmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce loads on a network in the retransmission of a TS (Transport Stream) to which a variable rate is applied. <P>SOLUTION: TS packets to which a variable transfer rate is applied are inputted, a data broadcasting TS which is a series of TS packets of data broadcasting is extracted from the inputted TS packets, the extracted data broadcasting TS is reconstructed to the data of a carrousel form, and rate information indicating the variation of the transfer rate is cyclically detected from the extracted data broadcasting TS. A setting rate for which the variation indicated by the rate information is flattened is obtained for each detection, and the TS packets are formed from the reconstructed data and transmitted by an output rate based on the setting rate. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a technique for retransmitting a digital broadcast TS (Transport Stream).

  Transfer rates used for transmitting digital broadcast waves are roughly classified into CBR (Constant Bit Rate) that is fixedly set and variable VBR (Variable Bit Rate). By using the latter VBR, it is possible to express various kinds of distribution data and to effectively use the transmission band.

  One of the terrestrial digital broadcasting services is a so-called IP retransmission service. This is a service in which a TS obtained by demodulating a broadcast wave received from a broadcasting station or the like is redistributed by multicast communication on an IP network. Since there is a limit to the bandwidth that can be used in the IP network, it is desired to suppress the load on the IP network during retransmission.

A technique that takes into consideration the network load in IP retransmission is described in, for example, Patent Document 1 described later. The retransmission apparatus described in the document removes an unnecessary NULL packet from the received TS, obtains a prescribed bit rate corresponding to the communication parameter of the TS from a rate table compliant with ISDB-T, and uses the bit rate. The TS is retransmitted. Here, the load on the IP network is reduced by removing unnecessary NULL packets.
JP 2007-214946 A

  By the way, when the variable rate (VBR) is applied to the transfer rate of the TS, the use band may reach the upper limit of the line depending on the TS. In the technique of Patent Document 1, the original transfer rate is fixed (CBR), and the same rate is applied as it is to retransmission. Therefore, when the variable rate is applied to the technique of the same document, the relatively high transfer rate as described above is also applied to the retransmission as it is, which causes a problem that it is difficult to reduce the load on the IP network.

  An object of the present invention is to provide a technique for reducing a load on a network in retransmission of a TS to which a variable rate is applied.

  The retransmission method according to the present invention inputs a TS packet to which a variable transfer rate is applied, extracts a data broadcast TS, which is a series of TS packets of a data broadcast, from the input TS packet, and extracts the extracted data broadcast The TS is reconstructed into carousel format data, rate information representing a change in transfer rate is sequentially detected from the extracted data broadcast TS, and the change represented by the rate information is flattened each time the rate information is detected. In this method, a set rate is obtained, a TS packet is formed from the reconstructed data, and the formed TS packet is transmitted at an output rate based on the set rate.

  The retransmission apparatus according to the present invention includes means for inputting a TS packet to which a variable transfer rate is applied, means for extracting a data broadcast TS which is a series of TS packets of data broadcast from the input TS packet, Means for reconstructing the extracted data broadcast TS into carousel format data, and rate information representing fluctuations in transfer rate from the extracted data broadcast TS are sequentially detected, and each time the rate information is detected, the rate information represents Means for obtaining a set rate obtained by flattening fluctuations, and means for forming a TS packet from the reconstructed data and transmitting the formed TS packet at an output rate based on the set rate.

  According to the present invention, it is possible to reduce a load on a network in retransmission of a TS to which a variable rate is applied.

  FIG. 1 shows the configuration of an embodiment of the present invention. The retransmission apparatus 100 retransmits a variable rate (VBR) TS packet input from a TS-IRD (TS Integrated Receiver / Decoder) 200, which is a digital broadcast wave receiver, to the IP network 300 by IP multicast communication. Device. In the configuration shown in the figure, the retransmission apparatus 100 and the TS-IRD 200 are separate apparatuses, but a combination of both may be used as the retransmission apparatus (100).

  The TS-IRD 200 demodulates digital broadcast waves received from a broadcasting station or the like, converts them into a series of TS packets, and sequentially inputs them to the retransmission apparatus 100.

  As shown in FIG. 1, the retransmission apparatus 100 includes a distributor 10, an SI (Service Information) analysis circuit 11, a TS filtering circuit 12, a carousel construction circuit 13, an event message processing circuit 14, a rate detection circuit 15, and TS packetization. A circuit 16 is provided.

  The distributor 10 distributes TS packets from the TS-IRD 200 to the SI analysis circuit 11 and the TS filtering circuit 12.

  The SI analysis circuit 11 has a TS packet PSI (Program Specific Information) monitoring function and a stream monitoring function, and detects whether or not a PID (Packet Identifier) used in data broadcasting is included in the TS packet. . As a result, when the PID of the data broadcast is detected, the information is notified to the TS filtering circuit 12.

  The TS filtering circuit 12 extracts the data broadcast TS, which is a data broadcast TS packet, from the TS packet input by the distributor 10 using the PID information notified about the data broadcast. Then, the extracted data broadcast TS is supplied to each of the carousel construction circuit 13, the event message processing circuit 14, and the rate detection circuit 15.

  The carousel construction circuit 13 reconstructs the data broadcast TS into carousel format data and supplies it to the TS packetization circuit 16.

  The event message processing circuit 14 detects the presence or absence of an event message in the data broadcast TS. If there is an event message, it is extracted from the data broadcast TS, synchronized with PCR (Program Clock Reference), and supplied to the TS packetizing circuit 16.

  The rate detection circuit 15 sequentially detects rate information indicating fluctuations in the transfer rate of the data broadcast TS using time stamp information such as PCR. Then, every time the rate information is detected, a set rate described later is obtained and supplied to the TS packetizing circuit 16 sequentially.

  The TS packetizing circuit 16 forms a TS packet from the data supplied by the carousel construction circuit 13 and the event message processing circuit 14, and transmits it to the IP network 300 at an output rate based on the set rate from the rate detection circuit 15. To do.

  The operation of the retransmission apparatus 100 will be described with reference to the flowchart shown in FIG. The distributor 10 inputs the TS packet from the TS-IRD 200 to the SI analysis circuit 11 and the TS filtering circuit 12 (step S1). The SI analysis circuit 11 confirms the PID of each TS packet and supplies the PID information corresponding to the data broadcast to the TS filtering circuit 12 (step S2).

  The TS filtering circuit 12 extracts the data broadcast TS from the TS packet by filtering using the PID information from the SI analysis circuit 11, and sends it to the carousel construction circuit 13, the event message processing circuit 14, and the rate detection circuit 15, respectively. Supply (step S3).

  The carousel construction circuit 13 reconstructs the data broadcast TS from the TS filtering circuit 12 into carousel format data, and supplies it to the TS packetizing circuit 16 (step S4). The event message processing circuit 14 checks whether or not there is an event message in the data broadcast TS (step S5), and if there is an event message, extracts it from the data broadcast TS (step S6). Then, the extracted message is supplied to the TS packetizing circuit 16 through PCR synchronization.

  On the other hand, the rate detection circuit 15 periodically detects the above-described rate information indicating a change in the transfer rate of the data broadcast TS (step S7). As a result, the variable rate (VBR) situation can be detected almost in real time. The rate detection circuit 15 obtains a set rate to be supplied to the TS packetizing circuit 16 by flattening the variation represented by the rate information every time the rate information is detected (step S8).

  Here, the rate information and the set rate will be specifically described. FIG. 3 schematically shows TS packet rate information using waveforms. The illustrated [1] represents the total transfer rate of the TS packets input to the TS filtering circuit 12. The TS packet at the stage [1] includes TS packets other than data broadcast such as video in addition to the data broadcast TS. Thereafter, the data filtering TS among the above TS packets is supplied to the rate detection circuit 15 by the TS filtering circuit 12.

  [2] in FIG. 3 represents the rate information detected from the data broadcast TS by the rate detection circuit 15. In the illustrated example, the rate information is detected at a period P (period: p1, p2,...). The rate detection circuit 15 of the present embodiment detects a change that gradually decreases after the increase in each period, and obtains a set rate by flattening the detected change.

  Specifically, for example, in the period p1 of [2], the rate gradually decreases at the time t1 to t2, but at the subsequent times t2 to t3, a ridge-like variation is observed in which the rate gradually decreases after the increase. In such a case, the fluctuation at the time t1 to t2 that is only gradually decreased is left as it is, and the fluctuation at the subsequent time t2 to t3 is flattened by the minimum value of the period p1, that is, here by the value at time t2. As a result, as shown in FIG. 3 [3], the set rate for the period p1 is obtained by gradually decreasing at times t1 to t2 and then fixing the value at time t2 until time t3.

  The rate detection circuit 15 sequentially supplies the set rate obtained as described above to the TS packetizing circuit 16. The TS packetizing circuit 16 converts the data from the carousel construction circuit 13 and the event message processing circuit 14 into a TS packet at an output rate based on the supplied set rate, and sends it to the IP network 300 (FIG. 2: step S9). At this time, the data from the event message processing circuit 14 is preferentially transmitted.

  According to the present embodiment, since the ridge-like fluctuation that gradually decreases after the gradual increase in the transfer rate of the data broadcasting TS is flattened, a relatively high rate corresponding to the peak of the bulge can be kept low. Thereby, the load on the IP network 300 at the time of retransmission can be reduced. Also, the retransmission output rate is not a CBR to which a fixed value is always applied, but a pseudo fixed rate that reflects the original variable rate (VBR), so that the service quality of the VBR is prevented from being impaired. You can also.

  Note that the flattening process when obtaining the set rate is not limited to the above-described form, and for example, the minimum value or the average value of the periods may be used as the set rate. In this case, the series of set rate waveforms does not include a curve as shown in [3] in FIG. 3, but is a rectangular wave whose value is switched for each period according to the original VBR.

  In addition, as a retransmission output rate, the set rate from the rate detection circuit 15 may be applied as it is, or may be applied within a preset range. For example, an upper limit value of the output rate is set in the TS packetizing circuit 16, and if the set rate from the rate detection circuit 15 includes a value exceeding the upper limit, the rate is replaced with the upper limit rate. Thereby, the load on the IP network 300 is further reduced.

  The present invention is not limited to the IP retransmission as in the above-described embodiment, but can be applied to a use of retransmitting a digital broadcast wave to a network other than the IP network (300).

It is a block diagram which shows the structure of embodiment of this invention. It is a flowchart which shows the operation | movement procedure of embodiment of this invention. It is explanatory drawing regarding the rate information in embodiment of this invention.

Explanation of symbols

100 retransmitter
200 TS-IRD
300 IP network
10 Distributor
11 SI analysis circuit
12 TS filtering circuit
13 Carousel construction circuit
14 Event message processing circuit
15 Rate detection circuit
16 TS packetization circuit

Claims (8)

Input TS (Transport Stream) packet with variable transfer rate applied,
A data broadcast TS that is a series of TS packets of data broadcast is extracted from the input TS packet,
Reconstructing the extracted data broadcast TS into carousel format data,
Sequentially detecting rate information representing fluctuations in transfer rate from the extracted data broadcast TS;
Each time the rate information is detected, a set rate obtained by flattening the variation represented by the rate information is obtained.
A retransmission method, wherein a TS packet is formed from the reconstructed data, and the formed TS packet is transmitted at an output rate based on the set rate.   2. The retransmission method according to claim 1, wherein when the set rate is obtained, a change in the target rate information that gradually decreases after the transfer rate gradually increases is flattened with a minimum value of the rate information.   2. The retransmission method according to claim 1, wherein when the set rate is obtained, a minimum value or an average value of target rate information is set as the set rate.   Further, the presence or absence of an event message in the extracted data broadcast TS is detected, and when there is the event message, a TS packet including the event message is formed and transmitted preferentially. The retransmission method according to any one of the preceding claims. Means for inputting a TS (Transport Stream) packet to which a variable transfer rate is applied;
Means for extracting a data broadcast TS, which is a series of TS packets of data broadcast, from the input TS packet;
Means for reconstructing the extracted data broadcast TS into carousel format data;
Means for sequentially detecting rate information representing a change in transfer rate from the extracted data broadcast TS, and obtaining a set rate obtained by flattening the variation represented by the rate information for each detection of the rate information;
And a means for forming a TS packet from the reconstructed data and transmitting the formed TS packet at an output rate based on the set rate.   6. The retransmission apparatus according to claim 5, wherein the means for obtaining the set rate flattens fluctuations of the target rate information that gradually decrease after the transfer rate gradually increases with the minimum value of the rate information.   6. The retransmission apparatus according to claim 5, wherein the means for obtaining the set rate uses the minimum value or average value of the target rate information as the set rate. Furthermore, it detects the presence or absence of an event message in the extracted data broadcast TS, and if there is the event message, comprises means for extracting it from the data broadcast TS,
8. The retransmission apparatus according to claim 5, wherein the means for transmitting the TS packet forms a TS packet including the extracted event message and preferentially transmits the TS packet. 9.

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