JP5036235B2 - Terrestrial digital broadcast receiver - Google Patents

Description

  The present invention relates to a terrestrial digital broadcast receiving apparatus.

A receiving device that receives terrestrial digital broadcasting includes an OFDM demodulator, includes a tuner that demodulates a transport stream (TS) from received radio waves, separates a packet (elementary stream) from the transport stream, and Video and audio are output by decoding. Conventionally, in a mobile receiver, in particular, a technique has been proposed in which a packet in which an uncorrectable error has occurred is acquired from a server by communication in order to cope with deterioration of reception conditions (Patent Document 1). reference).
JP 2005-294923 A

  However, as described above, in the technology for acquiring the lost packet from the server, it is expected that many broadcast receiving apparatuses access the server all at once, and if the server is heavily loaded, the lost packet cannot be transmitted. Can occur.

  In view of the above circumstances, an object of the present invention is to provide a digital terrestrial broadcast receiving apparatus that can acquire the same packet as that packet without using a server even if a packet loss occurs in demodulation of received radio waves. To do.

  In order to solve the above problems, a terrestrial digital broadcast receiving apparatus of the present invention receives a terrestrial digital broadcast wave and outputs a transport stream, a demultiplexer that separates packets from the transport stream, and a demultiplexer A decoder that decodes the received packet, a communication unit that performs communication with another broadcast receiving device to perform data transmission and reception, and when the packet is lost in the transport stream, Means for requesting the other broadcast receiving apparatus to transmit the same packet and, when the same packet is acquired from the other broadcast receiving apparatus, supplying the same packet to the decoder; (Hereinafter referred to as the first configuration in this section).

  With the above configuration, when a packet loss occurs, the same packet can be acquired from another broadcast receiving device, so even if a packet loss occurs, it is the same as the packet regardless of the server. Packets can be acquired.

  The first configuration may further include storage means for previously registering destination information for communicating with the other broadcast receiving apparatus. In such a configuration, the communication may be automatically executed at the same time as the start of broadcast reception or when a predetermined condition occurs in the destination registered in advance. In such a configuration, the predetermined condition may be that the degree of error correction of the transport stream exceeds a predetermined reference value. In such a configuration, the communication with the other broadcast receiving apparatus may be stopped when the error correction level of the transport stream is equal to or less than a predetermined reference value. In such a configuration, when the degree of error correction of the transport stream exceeds a predetermined reference value during the stop, the communication with the other broadcast receiving apparatus may be automatically resumed.

  In the digital terrestrial broadcast receiving apparatus having these configurations, the importance level of the lost packet may be determined, and the missing packet having a low importance level may be excluded from the request target to the other broadcast receiving apparatus.

  The terrestrial digital broadcast receiver according to the present invention includes a tuner that receives a terrestrial digital broadcast wave and outputs a transport stream, a demultiplexer that separates packets from the transport stream, and a decoder that decodes the separated packets. And communication means for performing data transmission / reception with another broadcast receiving device, and when receiving a packet transmission request from the other broadcast receiving device, the same packet as the requested packet is received. Means for acquiring from the transport stream and transmitting the same packet to the other broadcast receiving apparatus using the communication means (hereinafter referred to as a second configuration in this section). .

  In the second configuration, when the communication unit establishes a communication path with the other broadcast receiving device, the communication unit may transmit a message indicating that it has a packet transmission function. In the digital terrestrial broadcast receiving apparatus having these configurations, the importance of a packet that has received a transmission request may be determined, and a missing packet having a low importance may be excluded from transmission targets to the other broadcast receiving apparatus. In the second configuration or a configuration subordinate thereto, a plurality of the tuners may be provided, and a tuner other than that used for receiving the broadcast may be used for packet transmission to the other broadcast receiving device.

  According to the present invention, even if a packet loss occurs in demodulating received radio waves, the same packet as that packet can be acquired without depending on the server.

  A terrestrial digital broadcast receiving apparatus according to an embodiment of the present invention will be described below with reference to FIGS. For convenience of explanation, FIG. 1 shows a mobile phone 30 with a TV function that requests a missing packet, and FIG. 2 shows a mobile phone 31 with a TV function that receives the packet request and transmits the packet. However, it is preferable that one mobile phone with a TV function has both a packet request function and a request packet transmission function. In FIGS. 1 and 2, common elements are denoted by the same reference numerals.

  The antenna 1 receives a digital broadcast signal transmitted from a terrestrial broadcast station. The terrestrial digital tuner 2 takes out a signal of a specific frequency from the high frequency digital modulation signal including the video / audio data. Further, the tuner 2 includes an OFDM (Orthogonal Frequency Multiplexing) demodulation circuit, a deinterleave circuit, an error correction circuit, and the like, thereby demodulating the selected digital modulation signal and outputting a transport stream (TS). A case where the error correction circuit cannot correct a packet is hereinafter referred to as a reception error or a packet loss.

  The TS buffer 25 temporarily holds a transport stream for a certain time output from the tuner 2. The TS buffer 25 of the mobile phone 31 with a TV function that receives a packet request and transmits the packet stores a TS packet, an offset value from a PCR (program clock reference), and a PCR value.

  The DEMUX (demultiplexer) 9 converts the transport stream output from the tuner 2 into MPEG2 (Moving Picture Experts Group 2) or H.264. H.264 video stream, audio stream, data broadcast data, and PSI / SI (Program Specific Information / Service Information).

  The decoder 3 includes a video decoder that decodes a video stream, an audio decoder that decodes an audio stream, and the like. Video data output from the video decoder is output to the video processing unit 4, and audio data output from the audio decoder is output to the audio processing unit 5. The data broadcast data (BML file) is processed by the data broadcast processing unit (BML engine) 6. PSI / SI is supplied to the microcomputer 13. The mobile phone 30 with a TV function that requests a missing packet is provided with a reception TS buffer 26 that temporarily holds packets transmitted from the mobile phone 31 with a TV function. The mobile phone 30 with the TV function extracts the same packet as the missing packet from the reception TS buffer 26 and decodes it.

  The video processing unit 4 receives the video data output from the decoder 3 and performs D / A conversion or the like to generate a video signal. The video processing unit 4 has an OSD (on-screen display function), and is based on character information or image information output from the microcomputer 13 or based on character information or image information output from the data broadcast processing unit 6. A video is superimposed on the video data. The audio processing unit 5 receives the audio data output from the decoder 3 and generates right (R) sound data and left (L) sound data.

  The driver 7 that has received the video signal drives a display (for example, a liquid crystal display panel) 11. The audio data is converted into an analog signal through the D / A conversion amplifier 8 and input to the speaker 12 or headphones (not shown).

  The memory (RAM, EEPROM, flash memory, ROM, etc.) 14 stores various programs and data. When the mobile phone 30 with the TV function 31 is turned on, the microcomputer 13 expands the program and data stored in the ROM into the RAM and executes the program on the RAM. This program includes a driver and a protocol stack for controlling the USB interface 20 and the LAN interface 18.

  When a key of the operation unit 15 is operated, a signal indicating a command corresponding to the key is supplied to the microcomputer 13. A USB memory 21 can be attached to the USB interface 20. The USB memory 21 can store received video / audio data, for example. The mobile phone unit 16 includes a microphone 16a and a speaker 16b, and executes mobile phone communication processing. By attaching a LAN card 19 to the LAN interface 18, wireless LAN communication can be performed. In this embodiment, the transmission request for the lost packet and the reception of the transmitted packet are performed using the wireless LAN.

  In the mobile phone 30 with the TV function, the missing packet specifying unit 10 provides the microcomputer 13 with specific information for specifying the packet when there is a packet causing a reception error in the transport stream output from the tuner 2. . The microcomputer 13 instructs the LAN card 19 to transmit the specific information to the mobile phone 31 with a TV function. Details thereof will be described later.

  In the mobile phone 31 with the TV function, the microcomputer 13 that has received the specific information via the LAN card 19 provides the specific information to the request packet extracting unit 17. The request packet extracting unit 17 extracts the requested packet from the TS buffer 25. The microcomputer 13 instructs the LAN card 19 to transmit the extracted request packet to the mobile phone 30 with a TV function. Details thereof will be described later.

[Processing when requesting a packet with a reception error]
(1) The microcomputer 13 of the mobile phone 30 with a TV function activates the terrestrial digital tuner 2 when, for example, a TV button of the operation unit 15 is pressed by the user. The microcomputer 13 of the mobile phone with TV function 30 acquires the network ID of the transport stream acquired by the terrestrial digital tuner 2, and receives a tuner start command and receives it from the mobile phone with TV function 31 via the LAN card 19. The network ID indicating the broadcast to be transmitted is transmitted. The microcomputer 13 of the mobile phone 30 with TV function may instruct the mobile phone 31 with TV function to start the tuner when the error correction frequency of the terrestrial digital tuner 2 becomes higher than a predetermined threshold. .

(2) The terrestrial digital tuner 2 includes a transport error indicator that indicates that a TS packet (hereinafter simply referred to as a packet) in the transport stream (TS) has a reception error (packet missing). It has been. The missing packet specifying unit 10 monitors the transport error indicator, and when there is no reception error, passes the packet to the demultiplexer 9. On the other hand, if there is a reception error in the packet, information specifying the packet in which the reception error has occurred is generated and passed to the microcomputer 13.

(3) The packet specifying information is information indicating, for example, the number of packets from a packet including a PCR (program clock reference) immediately before that in which a reception error has occurred. Specific parameters include a PCR value and an offset value (number of packets). The PCR is recommended to be retransmitted within 233 ms, and the value always changes, so that the packet can be easily identified. In this case, the missing packet specifying unit 10 includes a PCR determination unit and a counter. The packet specifying information can be a packet PID and a continuity index, and both of them can be used. In addition, when frequent reception errors occur, if an acquisition request is made for each packet, the load on the microcomputer 13 or the like increases, so that a certain amount of time may be requested at once. FIG. 4 shows a description example when requesting packet specific information for a fixed time.

[Processing on request side]
(4) The microcomputer 13 of the mobile phone 31 with a TV function acquires the packet specifying information via the LAN card 19 and supplies the packet specifying information to the request packet extracting unit 17. The request packet extraction unit 17 extracts a requested packet from the TS buffer 25. As described above, the TS buffer 25 of the mobile phone 31 with a TV function that receives a packet request and transmits the packet stores a TS packet, an offset value from a PCR (program clock reference), and a PCR value. . The request packet extracting unit 17 extracts a requested packet from the TS buffer 25 based on the packet specifying information (PCR value and offset value). The microcomputer 13 passes the extracted packet to the LAN card 19. A request packet is transmitted to the mobile phone 30 with a TV function by the LAN card 19.

[Process after receiving request packet]
(5) The request packet received by the LAN card 19 of the mobile phone 30 with TV function from the LAN card 19 of the mobile phone 31 with TV function is stored in the reception TS buffer 26. Here, there is a delay due to the communication processing described above until the request packet is acquired. Therefore, in the mobile phone 30 with the TV function, it is difficult for the decoder 3 to acquire the video / audio packet and the microcomputer 13 to acquire the PSI / SI packet through the demultiplexer 9. Therefore, the acquired request packet is stored in the reception TS buffer 26. For a plurality of request packets stored in the reception TS buffer 26, it is determined which packet is a requested packet at which time using the packet specifying information (PCR value and offset value) described above. It is not possible. Since the decoder 3 and the microcomputer 13 that require a missing packet can grasp the PID and continuity index of the missing packet, the decoder 3 and the microcomputer 13 correspond to the PID and continuity index of these missing packets. A packet having a PID and a continuity index may be extracted from the reception TS buffer 26.

  FIG. 3 is a flowchart showing an example of the lost packet acquisition process in the mobile phone 30 with the TV function. The mobile phone 30 with a TV function acquires a packet from the transport stream output from its own tuner 2 (step S1). Then, it is determined whether a reception error has occurred (step S2). If no reception error has occurred, the acquired packet is adopted for output (step S3), and the adopted packet is output to the decoder 3 (step S4). When a reception error occurs, the mobile phone 31 with a TV function is requested to transmit the same packet as the lost packet (step S5). When the same packet can be acquired from the mobile phone 31 with TV function, the same packet acquired from the mobile phone 31 with TV function is used for output instead of the packet with the loss (step S7). , To the decoder 3 (step S4). If the same packet cannot be obtained from the mobile phone 31 with the TV function, a NULL packet is adopted for output instead of the packet (step S8) and passed to the decoder 3 (step S4).

  As described above, the mobile phone 30 with the TV function can acquire the missing packet from the mobile phone 31 with the TV function. Hereinafter, the mobile phone 30 with the TV function and the mobile phone 31 with the TV function are between the mobile phone 30 with the TV function. The communication will be described in further detail.

  When a mobile phone communication network or the above-described wireless LAN is used for communication, communication is performed using the TCP / IP protocol, so that the IP address of the communication partner is required. By registering the IP address in the mobile phones 30 and 31 in advance, communication using the TCP / IP protocol becomes possible. In the case of a mobile phone, if the mobile phone operator is preparing a procedure for acquiring an IP address from a telephone number or mail address, the IP address can be acquired from the telephone number or mail address registered in the address book. . In push-to-talk, when using SIP (session initiation protocol) that is used when calling a partner with an IP phone and a terminal a selects a telephone number of the terminal b in the address book and makes a call, the terminal a Can log in to the control server via the SIP server and call terminal b. Therefore, it is possible for the mobile phones 30 and 31 to communicate using such SIP.

  When performing near field communication such as infrared or bluetooth, the communication partner can be detected according to the installed protocol. When it is necessary to confirm whether or not the receiver as the communication partner has the TS packet transmission function after the communication path is established, it is necessary to perform processing for confirming whether or not the TS packet transmission function is present.

  In the above example, the mobile phone 30 with TV function sends a broadcast reception activation command and a network ID to the mobile phone 31 with TV function. At this time, the mobile phone 31 with TV function can watch TV. It can be done. In this case, the mobile phone with TV function 31 determines whether the network ID in the currently received broadcast matches the network ID requested from the mobile phone with TV function 30. When the network IDs match, the mobile phone with TV function 31 transmits to the mobile phone with TV function 30 that the TS packet transmission function can be executed. For example, when a Japanese game of the Soccer World Cup is broadcast, it is considered that many people watch the broadcast, and the network IDs coincide with a high probability (the probability of watching the same broadcast is high). it is conceivable that.

  When the network IDs do not match, the mobile phone with TV function 31 transmits to the mobile phone with TV function 30 that the TS packet transmission function cannot be executed. Of course, the mobile phone 31 with a TV function uses the OSD function to display on the display 11 that a TS packet transmission request has been received and the network ID (a specific broadcasting station name may be displayed), and the TS 11 You may make it confirm with a user whether it may respond to the request | requirement of packet transmission. When the user performs an operation indicating that the TS packet transmission request may be answered, and after notification that the TS packet transmission function cannot be executed (after communication is completed), the TV function is provided. The mobile phone 31 may become a caller side and notify the mobile phone 30 with a TV function that the TS packet transmission function can be executed.

  If the protocol is capable of one-to-many communication such as bluetooth, the TS packet transmission function can be confirmed and a packet transmission request can be sent to two or more receiving devices. In this case, transmission is performed all at once, but responses to requests are accepted individually.

  Due to restrictions on communication speed and processing speed, packets may not be transmitted for all packet transmission requests. In addition, even the side that made the packet transmission request may not be able to process all the received packets. In view of such circumstances, it may be considered to process packets with priorities (importance).

  For example, in the MPEG system, if a reference frame called an I frame is lost, the video is disturbed until the I frame is received again, so if the missing packet is a packet constituting the I frame, Priority is given to processing. In addition, the voice packet is also a packet having a relatively high priority because if the packet is lost, the voice is disturbed. Packets other than the I frame have the next rank after the voice packet or a priority higher than the voice packet. Also, since data broadcasts transmitted by PSI / SI or carousel method are retransmitted after a certain time, the influence is small even if the transmission request is not responded, and therefore the priority is low. Since a NULL packet does not contain necessary information, there is no need to acquire it even if it is lost.

  For example, it is assumed that the upper limit is that a packet request (processing) for 10 packets is performed within a certain time under the current communication speed or processing speed, but 12 packets are lost within a certain time. In the case where two excess packets are not requested among the 12 packets, no request is made for two packets having a low priority based on the priority.

  Similarly, even if there is a request for 12 packets on the mobile phone 31 with a TV function, two packets with lower priority may not be transmitted based on the priority.

  The microcomputer 13 of the mobile phone 30 with a TV function receives information indicating the error correction frequency from the terrestrial digital tuner 2, and when it is determined that the error correction frequency is low (below a predetermined threshold) based on this information, the microcomputer 13 has the TV function. Communication with the mobile phone 31 may be terminated. In transport stream transmission, a Reed-Solomon code is added to each packet, and the 16-byte code is added to a 188-byte main packet, so one packet is transmitted in 204 bytes. . If the error is within 8 bytes of 204 bytes, it can be corrected. Packets that can be corrected are not error packets (missing packets). In addition, the microcomputer 13 of the mobile phone 30 with a TV function may resume the communication that has been stopped when the error correction frequency of the terrestrial digital tuner 2 becomes higher than a predetermined threshold.

  The stop and restart of the communication are not limited to being determined by the value of the error correction frequency. For example, even if the value of the error correction frequency is less than the predetermined threshold, the communication may be resumed when the rate of increase in the error correction frequency exceeds a predetermined slope (reference). Further, instead of stopping and restarting the communication with a single threshold value, hysteresis may be given to the stop and restart of the communication by setting two threshold values. Further, the processing described above is not based on the error correction frequency (the number of bytes in which an error has occurred in one packet), but the ratio of packets in which an error has occurred (for example, how many packets in 10 packets cause an error). It is good also as performing. The degree of error correction includes the above-described ratio, the above-described error correction frequency, and the rate of increase (change).

  In order for the mobile phone with TV function 30 and the mobile phone with TV function 31 to acquire the same transport stream, it is only necessary to receive broadcast waves of the same frequency. However, it is possible to acquire the same packet even if the frequencies received by both are different. In terrestrial digital broadcasting, a relay station may transmit the same transport stream at a frequency different from that of the main broadcast station in order to expand the broadcast area. In the terrestrial distribution system descriptor of NIT (network information table), which is additional information of terrestrial digital broadcasting, all the frequencies used by the transmission equipment for transmitting the transport stream are described. Using the NIT, for example, the mobile phone 31 with a TV function can receive a broadcast having a frequency different from the reception frequency of the mobile phone 30 with a TV function.

  A plurality of destinations for performing communication for packet acquisition described above are registered in advance, and when the first destination cannot be executed, the second destination is selected, and this second destination is selected. When the destination cannot be executed, a process of selecting a third destination may be performed.

  A mobile phone with a TV function may include a plurality of terrestrial digital tuners. One tuner may be used for viewing his / her own TV, and the other tuner may be used for responding to a packet acquisition request. By providing a plurality of tuners as described above, it is possible to respond to TS packet transmission requests at almost any time. Therefore, if the configuration includes a plurality of tuners, it is possible to realize a mode in which the remaining tuners of the two specific terminals are mutually used. Even if their favorite programs are completely different, no problem will occur.

  In the above-described example, a mobile phone with a TV function is shown. However, the digital terrestrial broadcast receiving apparatus according to the present invention can be applied as an in-vehicle type or a fixed installation type receiving apparatus.

It is the block diagram which showed the mobile telephone with a TV function (packet request | requirement side) of embodiment of this invention. It is the block diagram which showed the mobile telephone with a TV function (packet transmission side) of embodiment of this invention. It is the flowchart which showed the processing content of embodiment of this invention. It is explanatory drawing which showed the packet specific information (packet request information) of embodiment of this invention. It is explanatory drawing which showed the reception content with respect to the said packet specific information of embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Antenna 2 Tuner 3 Decoder 10 Missing packet specification part 13 Microcomputer 17 Request packet extraction part 25 TS buffer 26 Reception TS buffer 30, 31 Mobile phone with TV function

Claims (11)

Communication between a tuner that receives a terrestrial digital broadcast wave and outputs a transport stream, a demultiplexer that separates packets from the transport stream, a decoder that decodes the separated packets, and another broadcast receiving apparatus And the communication means for sending a command for receiving the received terrestrial digital broadcast wave to the other broadcast receiving apparatus, and the packet is lost in the transport stream. The same packet is transmitted to the decoder when the same broadcast request is transmitted to the other broadcast receiving device and the same packet is obtained from the other broadcast receiving device. And a digital terrestrial broadcast receiving apparatus. 2. The terrestrial digital broadcast receiving apparatus according to claim 1, further comprising storage means for previously registering destination information for communicating with the other broadcast receiving apparatus. . 3. The terrestrial digital broadcast receiving apparatus according to claim 2, wherein the communication is automatically executed at the same time as the start of broadcast reception or when a predetermined condition occurs in the destination registered in advance. A terrestrial digital broadcast receiving device. 4. The terrestrial digital broadcast receiving apparatus according to claim 3, wherein the predetermined condition is when an error correction degree of the transport stream exceeds a predetermined reference value. 5. The terrestrial digital broadcast receiving apparatus according to claim 4, wherein the communication with the other broadcast receiving apparatus is stopped when a degree of error correction of the transport stream becomes a predetermined reference value or less. A terrestrial digital broadcast receiver. 6. The terrestrial digital broadcast receiving apparatus according to claim 5, wherein the communication with the other broadcast receiving apparatus is automatically performed when an error correction level of the transport stream exceeds a predetermined reference value during the stop. A terrestrial digital broadcast receiver characterized in that it is restarted. 7. The terrestrial digital broadcast receiving apparatus according to claim 1, wherein the importance level of the missing packet is determined, and a missing packet having a low importance level is requested from a request target to the other broadcast receiving apparatus. A terrestrial digital broadcast receiver characterized by being removed. Communication between a tuner that receives a terrestrial digital broadcast wave and outputs a transport stream, a demultiplexer that separates packets from the transport stream, a decoder that decodes the separated packets, and another broadcast receiving apparatus A communication means for performing data transmission and reception, and when receiving a terrestrial digital broadcast wave reception command from the other broadcast receiving device, the tuner receives the commanded terrestrial digital broadcast wave, and the other broadcast When a packet transmission request is received from a receiving device, the same packet as the requested packet is acquired from the transport stream, and the same packet is transmitted to the other broadcast receiving device using the communication means. And a digital terrestrial broadcast receiving apparatus. 9. The terrestrial digital broadcast receiving apparatus according to claim 8, wherein the communication means transmits a message indicating that it has a packet transmission function when a communication path is established with the other broadcast receiving apparatus. Broadcast receiving device. 10. The terrestrial digital broadcast receiving apparatus according to claim 8 or 9, wherein the importance of a packet for which a transmission request has been received is determined, and missing packets having a low importance are excluded from transmission targets to the other broadcast receiving apparatus. A terrestrial digital broadcast receiver characterized by the above. 11. The terrestrial digital broadcast receiving apparatus according to claim 8, wherein a plurality of the tuners are provided, and tuners other than those used for receiving broadcasts of itself are transmitted to the other broadcast receiving apparatuses. A terrestrial digital broadcast receiver characterized by being used for the purpose.

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