JP4435061B2 - Digital broadcast signal transmission device - Google Patents

Description

  The present invention relates to a digital broadcast signal transmission apparatus that multiplexes and transmits a plurality of TS (Transport Stream) packets by MPEG2 (Moving Picture Experts Group 2), for example.

  In recent years, digital broadcasting has been started in terrestrial broadcasting systems. In such digital broadcasting, the video and audio TS packets used in the program are multiplexed and transmitted by MPEG2, the TS packet is demodulated on the receiving side, and the combined reproduction is performed at an appropriate timing. Can be viewed. The MPEG2 TS includes a PCR (Program Clock Reference) indicating system time information.

By the way, a multiplexing order is determined in advance for each TS packet, and each TS packet is multiplexed according to this multiplexing order (for example, Patent Document 1). In this case, the PCR packet in which the interval at which the TS packet is multiplexed is defined is multiplexed with the highest priority.
JP2003-69634A.

  However, in the above method, when the transmission rate is low, even if a higher priority is assigned to the PCR packet, it may not be transmitted with priority over other TS packets. In particular, when a PCR is added to a TS packet, the quality of the TS packet may be degraded. In this case, the multiplexing unit may not be able to determine the PCR packet.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a digital broadcast signal transmitting apparatus capable of reliably transmitting a packet assigned with the highest priority in preference to other packets even when the transmission rate is low.

In order to achieve the above object, the present invention is configured as follows.
In a digital broadcast signal transmitting apparatus that multiplexes a plurality of packets at a predetermined transmission rate and transmits a digital broadcast signal including at least one priority packet indicating the highest priority among the plurality of packets. A buffer for storing each of the packets, a multiplexing unit for selectively multiplexing the outputs of the plurality of buffers based on the transmission rate, and transmitting them as digital broadcast signals, and a plurality of buffers for each predetermined time Based on the identification result of the packet identification unit, the determination unit for determining whether there is a priority packet based on the identification result of the packet identification unit, and the determination result of the determination unit The priority flag indicating the priority packet is written to the buffer in which the priority packet is stored, and the priority packet is written to the multiplexing unit. In which bets has an output from the buffer to be stored as a control unit for sending in preference over other buffer output.

  According to this configuration, at the time of low-rate transmission, the packet identification unit identifies the contents of the packets stored in each buffer without depending on the multiplexing unit only for multiplexing processing according to the transmission order, and priority is given to the contents of these packets. When there is a packet, the control unit writes the priority flag to the buffer in which the priority packet is stored, and when the priority flag is set by reading the packet from this buffer, the multiplexing unit changes the priority flag packet. Thus, it is possible to send a packet with priority over the packet, so that the multiplexing process according to the transmission order can be efficiently performed in cooperation between the multiplexing unit and the control unit.

  Therefore, even when the transmission rate is low, priority packets can be reliably transmitted with priority over other packets, and the internal residence time can be shortened.

  As described above in detail, according to the present invention, even when the transmission rate is low, a digital broadcast signal transmission device capable of reliably transmitting a packet assigned the highest priority in preference to other packets is provided. Can do.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a block diagram showing the configuration of an embodiment of a digital broadcast signal transmitting apparatus according to the present invention. In FIG. 1, MPEG2 TS packets are supplied to the 1-system input, 2-system input, and 3-system input. The 1-system input TS packet is temporarily stored in the buffer 11 and then supplied to the multiplexing unit 12. Similarly, the 2-system input TS packet and the 3-system input TS packet are respectively stored in the buffers 13 and 14 and then supplied to the multiplexing unit 12.

  The multiplexing unit 12 is multiplexed and controlled by the control unit 15, and selectively multiplexes the outputs of the buffers 11, 13, and 14 and sends them as TSs.

  By the way, in this embodiment, the control unit 15 is provided with a packet identification unit 151, a determination unit 152, and a multiplex control unit 153. The packet identification unit 151 identifies the contents of the TS packets stored in the buffers 11, 13, and 14 for each predetermined monitoring time.

The determination unit 152 determines whether there is a PCR packet as a high priority packet based on the identification result by the packet identification unit 151.
The multiplex control unit 153 writes the PCR packet flag indicating the PCR packet to the buffer 11 in which the PCR packet is stored based on the determination result of the determination unit 152, and the buffer in which the PCR packet is stored in the multiplex unit 12 11 is preferentially sent over the outputs of the other buffers 13 and 14.

Next, the processing operation of the above configuration will be described below. FIG. 2 shows the states of the buffers 11, 13, and 14 for each monitoring time, and FIG. 3 is a flowchart showing the multiplex control processing procedure of the control unit 15.
In FIG. 2, 1-1, 1-2, 1-3 are outputs of the buffer 11, 2-1, 2-2, 2-3 are outputs of the buffer 13, 3-1, 3-2, 3-3 are The output of the buffer 14, P, indicates that it is a PCR packet flag.

  Here, the 1-system input TS packets are sequentially held in the buffer 11, the 2-system input TS packets are sequentially held in the buffer 13, and the 3-system input TS packets are sequentially held in the buffer 14. The TS packets held in the buffers 11, 13 and 14 are identified by the packet identification unit 151.

  Then, the control part 15 transfers to step ST3b from step ST3a, and judges whether there exists a PCR packet here. If there is a PCR packet, the control unit 15 moves from step ST3b to step ST3c, writes a PCR packet flag in the corresponding buffer 11 here, and reads the PCR packet from the buffer 11 to the multiplexing unit 12. Supply.

  In step ST3b, when there is no PCR packet, the control unit 15 determines whether there is a TS packet other than the PCR packet (step ST3d). Here, when there is a TS packet, the control unit 15 reads out the TS packet in the order of the buffers 11, 13, and 14 and supplies the TS packet to the multiplexing unit 12 (step ST3e).

  On the other hand, when there is no TS packet, the control unit 15 outputs a NULL packet (invalid packet) from the buffers 11, 13, and 14 (step ST3f).

  In this way, the multiplexing unit 12 multiplexes and sends TS packets in the order of 1-1 → 2-1 → 3-1 by checking the PCR packet flag during the first monitoring time. At the next monitoring time, TS packets are multiplexed and transmitted in the order of 2-2 → 3-2 → 1-2, and at the next monitoring time, TS packets are ordered in the order of 3-3 → 1-3 → 2-3. Are multiplexed and sent.

  As described above, in the above-described embodiment, at the time of low-rate transmission, the multiplexing processing according to the transmission order is stored in each of the buffers 11, 13, and 14 by the packet identification unit 151 in the control unit 15 without depending on only the multiplexing unit 12. The contents of the received TS packets are identified, and when there is a PCR packet from the contents of these TS packets, the multiplexing control unit 153 writes a PCR packet flag into the buffer 11 in which the PCR packet is stored, and the PCR 11 When the packet is read and the PCR packet flag is set, the multiplexing unit 12 confirms the PCR packet flag, and thereby, the PCR packet is transmitted with priority over other TS packets.

  Therefore, since the multiplexing unit 12 and the control unit 15 can efficiently execute multiplexing processing according to the transmission order, even when the transmission rate is low, the PCR packet is given priority over other TS packets. It can be reliably delivered and the internal residence time can be shortened.

  In the above-described embodiment, an example in which a PCR packet is preferentially transmitted has been described. However, a priority packet having a higher priority than other TS packets may be transmitted in addition to this PCR packet.

  In the above-described embodiment, the case of three input systems has been described. However, the present invention can be similarly implemented even when there are a larger number of systems.

  In addition to the above, when handling a digital broadcast signal defined by other than the MPEG2 encoding method, the packet determination control procedure by the control unit, and the like can be variously modified and implemented without departing from the gist of the present invention.

The block diagram which shows the structure of one Embodiment of the digital broadcast signal transmission apparatus concerning this invention. The figure shown in order to demonstrate the state of each buffer for every monitoring time in the same embodiment. The flowchart which shows the multiple control processing procedure of the control part in the embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11, 13, 14 ... Buffer, 12 ... Multiplexing part, 15 ... Control part, 151 ... Packet identification part, 152 ... Determination part, 153 ... Multiplexing control part.

Claims (2)

In a digital broadcast signal transmission device that multiplexes a plurality of packets at a predetermined transmission rate and transmits a digital broadcast signal including at least one priority packet indicating the highest priority among the plurality of packets.
A buffer provided for each system, each storing the packet;
A multiplexer that selectively multiplexes the outputs of the plurality of buffers based on the transmission rate and transmits the output as the digital broadcast signal;
A packet identification unit for identifying each of the contents of the packets stored in the plurality of buffers for each predetermined monitoring time;
A determination unit that determines whether or not there is the priority packet based on the identification result of the packet identification unit;
Based on the determination result of the determination unit, the priority flag indicating the priority packet is written to the buffer in which the priority packet is stored, and the output from the buffer in which the priority packet is stored in the multiplexing unit is output to another buffer. The packet is transmitted in priority over the output, and in the monitoring time, it is determined in order whether or not the packet is stored in a plurality of buffers other than the buffer in which the priority flag is written, and the packet is stored. A multiplex control unit for sequentially reading out and transmitting the packets from a plurality of corresponding buffers to the multiplexing unit, and outputting invalid packets from the buffer without the packets. Signal transmission device. When the digital broadcast signal is TS (Transport Stream) defined by MPEG2 (Moving Picture Experts Group 2),
The determination unit determines whether there is a PCR (Program Clock Reference) packet based on the identification result of the packet identification unit,
The multiplex control unit writes a PCR packet flag to the buffer storing the PCR packet based on a determination result of the determination unit, and outputs an output from the buffer storing the PCR packet to the multiplex unit. 2. The digital broadcast signal transmission apparatus according to claim 1, wherein the digital broadcast signal transmission apparatus performs transmission with priority over other buffer outputs.

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