JP4413099B2 - Digital broadcast receiver - Google Patents

Description

  The present invention relates to a digital broadcast receiving apparatus that receives a digital broadcast.

  Digital radio broadcasting and digital television broadcasting have been started as new broadcasting media replacing analog broadcasting. On the other hand, the digital broadcast receiving device that receives these digital broadcasts performs error correction processing when demodulating the received signal even if the radio wave condition of the broadcast wave deteriorates due to fading or a decrease in radio wave intensity. It is possible to reproduce and provide high-quality video and audio to the user.

  However, as a feature of digital broadcasting, if the radio wave condition deteriorates while the digital broadcast receiver is receiving broadcast waves, it is possible to suppress the deterioration of the quality of video and audio until the limit of error correction capability is reached. However, when the limit of the error correction capability is exceeded, there is a problem that a so-called cliff effect phenomenon occurs in which the quality of video, audio and the like deteriorates rapidly.

  Therefore, in order to avoid the influence of such a cliff effect and prevent quality deterioration of video and audio, a broadcast receiving device disclosed in Japanese Patent Laid-Open No. 2001-217735 has been proposed.

  This broadcast receiving apparatus is a simultaneous broadcast receiving apparatus that receives a simulcast broadcast in which a digital broadcast signal and an analog broadcast signal comprising the same program are frequency-division-multiplexed, and a bit error rate ( BER (Bit Error Rate) is monitored, and when the bit error rate reaches a predetermined limit point, it is switched to an analog broadcast signal to receive it so as to prevent a sudden deterioration in the quality of video and audio. Yes. In other words, when switching to analog broadcast signals, the quality of video and audio will be lower than when receiving digital broadcast signals under good reception conditions, but the influence of the cliff effect can be avoided. It is possible to continuously receive broadcast programs.

Japanese Patent No. 2001-217735

  However, in the conventional broadcast receiving apparatus, when it is detected that the bit error rate has reached a predetermined limit point, it is not possible to perform a rapid reception switching from a digital broadcast signal to an analog broadcast signal, There is a problem that distortion and noise are mixed when switching to an analog broadcast signal.

  The conventional broadcast receiving apparatus is limited to a case where a broadcast program based on digital broadcasting and a broadcast program based on analog broadcast are simultaneously transmitted after being frequency-division multiplexed, as in simulcast television broadcasting. There is a problem that it is not possible to switch reception between programs.

  The present invention has been made in view of such conventional problems. For example, when the reception state is deteriorated, by switching reception between programs by digital broadcasting, the program is continued with good quality. It is an object of the present invention to provide a digital broadcast receiving apparatus and a receiving method thereof that can be reproduced.

  It is another object of the present invention to provide a digital broadcast receiving apparatus and a receiving method thereof capable of performing quick reception switching.

According to the first aspect of the present invention, high bit rate program data and low bit rate program data having the same contents and different bit rates are each divided into a plurality of packet data, and stream data is time-division multiplexed. A digital broadcast receiving apparatus for receiving a broadcast wave transmitted as described above, wherein the stream data is demodulated on the basis of a receiving means for receiving the broadcast wave and a reception signal output from the receiving means. A demodulating means for restoring a port stream (hereinafter referred to as TS) and attaching error packet mark data to a transport stream packet (hereinafter referred to as TSP) having an error when demodulating, and the demodulated TS as the bit rate Information in packetized elementary streams (hereinafter referred to as PES) for different programs While away, the error packet mark data detect and outputs the PES while subjected the error packet mark data in PES, outputs a first error data for identifying the PES associated with the error packet mark data Information separating means for decoding the PES related to the information-separated audio or video in synchronism between the programs having different bit rates, detecting the error packet mark data, and attaching the error packet mark Decoder means for outputting second error data for identifying the PES relating to the audio or video to which the error packet mark data is attached immediately before decoding the PES relating to the audio or video being received, The data decoded by the decoder means When the first error data related to the PES of the high bit rate program is output from the information separating means, the PES having an error is specified based on the first error data, As the second error data related to the identified PES is output from the decoder means, the data obtained by decoding the PES having the error is switched to the data obtained by decoding the PES of the low bit rate program. Error discriminating means for controlling the output means so as to output.

According to the sixth aspect of the present invention, stream data obtained by dividing high-bit-rate program data and low-bit-rate program data having the same contents and different bit rates into a plurality of packet data and time-division multiplexed. A receiving method in a digital broadcast receiving apparatus that receives a broadcast wave transmitted in the above-described manner, wherein the stream data is demodulated based on a reception step of receiving the broadcast wave and a reception signal received in the reception step The demodulating step of restoring the TS and attaching error packet mark data to the TSP having an error at the time of demodulation, separating the demodulated TS into PES for each program having a different bit rate, and the error packet mark data detect and outputs the PES while subjected the error packet mark data in PES, An information separation step for outputting first error data for identifying PES associated with the error packet mark data, and decoding the PES relating to the information-separated audio or video in synchronization between the programs having different bit rates At the same time, the error packet mark data is detected, and the PES related to the audio or video with the error packet mark data is identified immediately before decoding the PES related to the audio or video with the error packet mark. The second error data for outputting the data, the output step for outputting the data decoded by the decoder step of the program selected for reception, and the PES of the high bit rate program by the information separation step When the first error data is output, PES having an error is identified based on the first error data, and the second error data related to the identified PES is output by the decoder process, and the PES having the error is decoded, And an error determination step for controlling the output step so that the PES of the low bit rate program is switched to the decoded data for output.

  A digital broadcast receiving apparatus according to an embodiment of the present invention will be described with reference to FIG. FIG. 1A is a block diagram showing the configuration of the digital broadcast receiving apparatus of this embodiment.

  In FIG. 2A, a digital broadcast receiving apparatus 1 is a receiving apparatus that receives terrestrial digital broadcasts, and includes a receiving unit 2 to which an antenna ANT that receives incoming radio waves is connected, a demodulation and error correction unit 3, An information separation unit 4, a decoder unit 5, an output unit 6, and an error determination unit 7 are included.

  Here, before describing the individual configuration of the digital broadcast receiving apparatus 1, terrestrial digital broadcast transmitted from the broadcast station side will be outlined with reference to FIGS.

  In digital terrestrial broadcasting, an MPEG-2 TS (which enables multiple transmissions of multichannel programs (contents) such as video, audio, and data encoded (encoded) in MPEG-2 as a single stream. Transport Stream) is used, and an OFDM (Orthogonal Frequency Division Multiplexing) scheme is adopted as a transmission path coding scheme for transmitting MPEG-2 TS.

  First, MPEG-2 TS (hereinafter referred to as “transport stream”) will be described with reference to FIG.

  The transport stream (TS) is composed of a plurality of fixed-length (188 bytes) packet data called transport stream packets (TSP).

  Each transport stream packet (TSP) includes a fixed-length TS header (Transuport Stream header), followed by a variable-length adaptation field (Adaptation field) and a TS payload (Transuport Stream payload). The payload is configured by a PES packet (Packetized Elementary Stream packet) including a PES header (Packetized Elementary Stream header) followed by a PES payload (Packetized Elementary Stream payload).

  Then, clock data called a program clock reference (PCR) for synchronizing the basic clock between the broadcasting station side and the receiving apparatus side is transmitted in the adaptation field, and MPEG-2 Video as a video encoding system is transmitted. Packetized elementary streams (PES: Elementary Streams) such as video encoded with MPEG-2 and audio encoded with MPEG-2 AAC (Advanced Audio Coding) as an audio encoding method. It is divided into packet data called “Packetized Elementary Stream” and transmitted in the PES payload.

  Further, the PES header includes an identifier (Stream ID) for identifying a packetized elementary stream (PES) transmitted in the PES payload, a packet size, time information for performing synchronous playback on the receiving device side, Other control information is described and transmitted. In the TS header, an identifier (PID) for identifying the type of the transport stream packet (TSP) and various flags are described and transmitted.

  Furthermore, since the transport stream can multiplex-transmit multi-channel content, it is composed of descriptors for representing the relationship between each channel and a packetized elementary stream (PES) such as video and audio. Table information is specified.

  This table information is called Program Specification Information (PSI), and a total of four types such as a Program Association Table (PAT) and a Program Map Table (PMT) are defined. , A unit called a section is arranged and transmitted in a TS payload in a transport stream packet (TSP).

  An identifier (PID) for identifying the program map table (PMT) is described in the program association table (PAT), and the configuration of each channel and the video corresponding to each channel are described in the program map table (PMT). When an identifier (PID) or the like for identifying a stream such as an audio stream is described and transmitted from the broadcasting station side to the receiving device side, the receiving device side stores in a program association table (PAT) and a program map table (PMT). By referring to the contents of the above described identifier and the like, for example, a transport stream packet (TSP) related to a channel selected and designated by the user is extracted, and video reproduction or Music can be played.

  Next, a transmission path coding system in terrestrial digital broadcasting will be described with reference to a system diagram schematically shown in FIG.

When transmitting a digital broadcast, the broadcasting station side creates the above-described transport stream (TS) and then adds an error correction code (Reed-Solomon code) to each transport stream packet (TSP). And mapping to a frame of a predetermined number of slots, forming a super frame in units of the predetermined number of frames, then performing byte interleaving for each slot position, and performing inner code encoding by a convolutional code, Digital modulation is performed using a modulation method selected from DQPSK, QPSK, 16QAM, and 64QAM.

  Here, for example, when a program having the same content is transmitted in a layered manner at a high bit rate and a low bit rate, as shown in FIG. The above-described byte interleaving, inner code encoding, and digital modulation are performed in parallel.

  Next, in the case of hierarchical transmission, since the bit rate of each layer processed in parallel is different, the digitally modulated modulated signal is subjected to rate conversion in symbol units, and layer synthesis is performed. In order to improve error tolerance for a path, etc., time interleaving and frequency interleaving are performed, and further, IFFT (inverse Fourier transform) is performed to generate an OFDM modulated wave, and further, a guard interval is added and orthogonal modulation is performed. A wave (digital broadcast wave) is generated and transmitted from the transmitting antenna.

  Then, the receiving device side receives the digital broadcast wave and generates a demodulated signal by performing the reverse processing shown in FIG. 3, that is, orthogonal demodulation, FFT processing, digital demodulation, etc., and inner code decoding the demodulated signal. By performing processing such as decoding, deinterleaving and outer code decoding, the transport stream (MPEG-2 TS) is restored, and the packetized elementary stream (PES) is further decoded to broadcast video and audio. The content sent from the station can be played back.

With reference to FIG. 1A again, each configuration of the receiving device 1 of the present embodiment will be described.
The receiving unit 2 frequency-converts the high-frequency signal output from the antenna ANT that receives the incoming radio wave by tuned reception based on the local transmission frequency corresponding to the broadcast station selected by the user, and converts the frequency converted signal to A / D-converted into a frequency converted signal (hereinafter referred to as “received signal”) Dif composed of a digital data string capable of digital signal processing and output.

  The demodulation and error correction unit 3 performs a process for restoring the transport stream Dts by demodulating the reception signal Dif.

  That is, the demodulation and error correction unit 3 generates a demodulated signal by performing Fourier transform and performing frequency deinterleaving and time deinterleaving after performing synchronization based on the guard interval included in the received signal Dif, Further, the demodulated signal is subjected to error correction (inner code decoding) processing by Viterbi decoding, byte deinterleaving, and then error correction (outer code decoding) processing by Reed-Solomon decoding. Restore the stream Dts.

  Further, the demodulation and error correction unit 3 detects a bit error rate (BER) in units of transport stream packets (TSP) in the error correction process by the above inner code decoding and outer code decoding processes. When the detected bit error rate BER is a bad result exceeding a predetermined threshold value, an error packet mark data ER indicating an error packet is attached to the transport stream packet (TSP), and the information separation unit Output to 4 side.

  The information demultiplexing unit 4 demultiplexes the transport stream Dts to demultiplex into packetized elementary streams (PES) for each content such as video and audio, and outputs them to the decoder unit 5.

  Further, the information separation unit 4 detects the presence or absence of error packet mark data ER at the time of demultiplexing. When the error packet mark data ER is detected, the error packet mark data ER is output to the decoder unit 5 while being attached to the packetized elementary stream (PES), and related to the error packet mark data ER. First error data ER <b> 1 for identifying a packetized elementary stream (PES) is output to the error determination unit 7.

  The decoder unit 5 decodes the packetized elementary stream (PES) supplied from the information separation unit 4 for each content, and outputs the decoded signal back to a digital signal such as video or audio transmitted on the broadcast station side.

  In addition, the decoder unit 5 is a high-bit rate music program (for example, a 5.1 channel high-quality music program) and a low bit rate music program (for example, fading, etc.) 2), the packetized elementary stream Dpa related to the high bit rate music program is sent from the information separator 4 as shown in FIG. A packetized elementary stream Dpb related to a low bit rate music program is supplied.

  As described above, when the packetized elementary streams Dpa and Dpb of programs having the same contents but different bit rates are supplied, the decoder unit 5 decodes the packetized elementary streams Dpa to obtain high quality. A digital signal Db that enables mobile reception resistant to fading or the like is generated and output by decoding a packetized elementary stream Dpb and generating a digital signal Da that enables music playback and the like.

  Further, the decoder unit 5 detects the presence / absence of the error packet mark data ER immediately before starting the decoding process for each of the packetized elementary streams Dpa and Dpb. When the error packet mark data ER is detected, the second error data ER2 for identifying the packetized elementary stream Dpa or Dpb to which the error packet mark data ER is attached is output to the error determination unit 7.

  The output unit 6 is formed of an analog switch or the like. As described above, when the broadcast selected by the user or the like is a music program having the same content at a high bit rate and a low bit rate, the error determination unit 7 The switching operation is performed to give priority to the output of the digital signal Da on the high bit rate side in accordance with the instruction of the switching control signal CNT. Further, when an instruction is given by the switching control signal CNT from the error discriminating unit 7 to output the low bit rate side digital signal Db while outputting the high bit rate side digital signal Da, the output unit 6 performs a switching operation and outputs a digital signal Db.

  As described above, when the broadcast selected by the user or the like is a high-bit-rate and low-bit-rate music program having the same content, the error discriminating unit 7 outputs the packetized elementary stream Dpa on the high-bit-rate side. It monitors one by one whether the related first and second error data ER1 and ER2 are supplied from the information separation unit 4 and the decoder unit 5. In a period in which the first and second error data ER1 and ER2 are not supplied, the output unit 6 is switched and controlled by the switching control signal CNT, thereby outputting the digital signal Da on the high bit rate side.

  On the other hand, when the first and second error data ER1 and ER2 related to the packetized elementary stream Dpa on the high bit rate side are supplied, the error determination unit 7 is supplied first from the information separation unit 4. Based on one error data ER1, a packetized elementary stream Dpa having an error is specified, and then when the second error data ER2 related to the packetized elementary stream Dpa is supplied from the decoder unit 5, By switching and controlling the output unit 6 using the switching control signal CNT, the low bit rate digital signal Db is output.

  That is, since the decoder unit 5 inputs the respective packetized elementary streams Dpa and Dpb from the information separating unit 4 and starts decoding processing, a time delay is caused by performing so-called buffering or the like. The error discriminating unit 7 specifies the packetized elementary stream Dpa having an error in advance based on the first error data ER1, and the second error immediately before the packetized elementary stream Dpa is decoded. When the data ER2 is supplied, the digital signal Db generated by decoding the packetized elementary stream Dpb is output by switching the output unit 6 quickly.

  When the first and second error data ER1 and ER2 relating to the packetized elementary stream Dpa on the high bit rate side are not supplied, the error determination unit 7 switches the output unit 6 again to control the high bit rate. The output is switched to the output of the rate side digital signal Da.

  As described above, according to the digital broadcast receiving apparatus of the present embodiment, when receiving music programs having the same contents with different bit rates, the high bit rate programs are given priority to so-called reception and reproduction. When it detects that there is an error in the packetized elementary stream Dpa making up the bit rate program, it switches to the packetized elementary stream Dpb making up the low bit rate program and automatically receives and plays back. By performing the above, the music program or the like can be continuously received and reproduced without causing significant quality deterioration.

  That is, as illustrated in FIGS. 1B and 1C, among the packetized elementary streams Dpa (j−1) to Dpa (j + 6)... On the high bit rate side, Dpa (j + 1) And Dpa (j + 5) has an error, and no error has occurred in the low bit rate side packetized elementary streams Dpb (k-1) to Dpb (k + 6). When the output unit 6 performs a switching operation under the control of the determination unit 7, as illustrated in FIG. 1D, the packetized elementary streams Dpa (j + 1) and Dpa (j + 5) having errors are illustrated. ) Instead of the digital signals Db (k + 1) and Dpb (k + 5) decoded based on the low bit rate side packetized elementary streams Dpb (k + 1) and Dpb (k + 5) Is output as the output signal Dout.

  Therefore, by supplying the output signal Dout to the speaker through D / A conversion or the like, it is possible to continuously reproduce the music program having the same contents without causing a significant deterioration in quality and provide it to the user or the like. It is.

  Further, before the decoder unit 5 decodes the packetized elementary stream Dpa on the high bit rate side having an error, the error discriminating unit 7 determines the packetized elementary stream Dpa based on the first error data ER1. And the output unit 6 is switched according to the supply of the second error data ER2 immediately before the packetized elementary stream Dpa is decoded, so that the switching control can be performed very quickly. it can. For this reason, it is possible to prevent the occurrence of a problem such as outputting a digital signal having an error decoded based on the packetized elementary stream Dpa having an error. It can be played continuously.

  Furthermore, since it is possible to perform switching in units of packetized elementary streams, for example, it is possible to prevent the occurrence of problems such as lack of playback sound during reception and playback of music programs, etc. Music with good quality can be played continuously.

  Furthermore, the packetized elementary stream on the high bit rate side is preferentially received and played back, and if an error occurs, the packetized elementary stream on the low bit rate side is switched to be received and played. The effect of the cliff effect can be avoided even when switching between digital broadcast programs.

  Next, more specific examples according to the above-described embodiment will be described with reference to FIGS. 4 and 5. FIG. 4 is a block diagram showing the configuration of the digital broadcast receiving apparatus of this embodiment, and the same or corresponding parts as those in FIG.

  4, the digital broadcast receiving apparatus 1 includes a front end unit 2 corresponding to the receiving unit 2 illustrated in FIG. 1A, a demodulation and error correction unit 3, and a demultiplexer (DEMUX as an information separation unit 4). : MPEG-2 Demultiplexer), an AAC decoder 5 as a decoder unit 5, an output unit 6 formed by an analog switch or the like, an error discriminating unit 7, and a video decoder unit 8.

  The front end unit 2 generates a frequency conversion signal by tuned reception of a high-frequency signal output from the antenna ANT based on a local transmission frequency corresponding to a broadcast station selected and received by the user, and further converts the frequency conversion signal into a digital signal. A / D converted to a received signal Dif comprising a digital data string that can be signal-processed and output.

  The demodulation and error correction unit 3 performs a process for restoring the transport stream Dts by demodulating the reception signal Dif.

  That is, the demodulation and error correction unit 3 generates a demodulated signal by performing Fourier transform and performing frequency deinterleaving and time deinterleaving after performing synchronization based on the guard interval included in the received signal Dif, Further, the demodulated signal is subjected to error correction (inner code decoding) processing by Viterbi decoding, byte deinterleaving, and then error correction (outer code decoding) processing by Reed-Solomon decoding. Restore the stream Dts.

  Further, the demodulation and error correction unit 3 detects a bit error rate (BER) in units of transport stream packets (TSP) in error correction processing by inner code decoding and outer code decoding processing, and detects the detected bit error rate. When a bad result (BER) exceeds a predetermined threshold value, error packet mark data ER is attached to the PES header of the PES packet of the transport stream packet (TSP), and the result is output to the information separation unit 4 side. .

  The information separation unit 4 demultiplexes the transport stream Dts, separates it into packetized elementary streams (PES) for each content such as video and audio, and outputs them to the decoder unit 5 and the video decoder unit 8. . That is, as shown in the figure, the packetized elementary streams Dpa and Dpb related to audio are output to the AAC decoder 5, and the packetized elementary stream DV related to video is output to the video decoder unit 8.

  Further, the information separation unit 4 detects the presence or absence of error packet mark data ER during demultiplexing. When the error packet mark data ER is detected, the information separation unit 4 converts the error packet mark data ER into a PES header (in other words, a packet. The first error for identifying the packetized elementary stream (PES) associated with the error packet mark data ER while being output to the decoder unit 5 while being attached to the (tethered elementary stream (PES)) Data ER1 is output to the error discriminating unit 7.

  The AAC decoder 5 is sent from the broadcast station side by decoding a packetized elementary stream (PES) such as music encoded by the MPEG-2 AAC encoding method supplied from the information separation unit 4. The original digital signal is generated and output.

  Further, the AAC decoder 5 simultaneously broadcasts the channel selected by the user or the like as a high bit rate music program and a low bit rate music program, and the packetized elementary data related to the high bit rate music program from the information separator 4. When the stream Dpa and the packetized elementary stream Dpb related to the low bit rate music program are supplied, the audio decoder unit 5a for decoding the packetized elementary stream Dpa and the packetized elementary stream Dpb are decoded. The digital signal Da, Db is output from the audio decoder units 5a, 5b by performing the function of the audio decoder unit 5b.

  Furthermore, immediately before starting the decoding process for the packetized elementary stream Dpa, the audio decoder unit 5a detects the presence / absence of the error packet mark data ER, and if the error packet mark data ER is detected, the error packet mark data ER Is output the second error data ER2a for identifying the packetized elementary stream Dpa, and the audio decoder unit 5b similarly immediately before starting the decoding process for the packetized elementary stream Dpb, When the presence or absence of error packet mark data ER is detected, and error packet mark data ER is detected, second error data ER2b for identifying the packetized elementary stream Dpb to which the error packet mark data ER is attached is output. To do.

  The output unit 6 is formed of an analog switch or the like, and when the broadcast selected by the user or the like is a music program having the same content at a high bit rate and a low bit rate, a switching control signal CNT from the error determination unit 7 In accordance with this instruction, the switching operation is performed so as to preferentially output the digital signal Da on the high bit rate side. Further, when an instruction is given by the switching control signal CNT from the error discriminating unit 7 to output the low bit rate side digital signal Db while outputting the high bit rate side digital signal Da, the output unit 6 performs a switching operation and outputs a digital signal Db.

  When the broadcast selected by the user or the like is a high-bit-rate and low-bit-rate music program having the same content, the error discriminating unit 7 is associated with the high-bit-rate packetized elementary streams Dpa and Dpb. Whether the 1 error data ER1 and the second error data ER2a and ER2b are supplied from the information separation unit 4 and the audio decoder units 5a and 5b is monitored one by one.

  Then, during a period in which the first error data ER1 and the second error data ER2a related to the packetized elementary stream Dpa on the high bit rate side are not supplied, the output unit 6 is switched by the switching control signal CNT, and thus the high The digital signal Da on the bit rate side is output.

  Further, when the first error data ER1 and the second error data ER2b related to the packetized elementary stream Dpb on the low bit rate side are supplied, the output unit 6 is switched by the switching control signal CNT. Then, the digital signal Da on the high bit rate side is output.

  Meanwhile, the first error data ER1 and the second error data ER2a related to the packetized elementary stream Dpa on the high bit rate side are supplied, and the first error data ER2a related to the low bit rate side packetized elementary stream Dpb are supplied. When the 1 error data ER1 is not supplied, the error determination unit 7 specifies the packetized elementary stream Dpa having an error based on the first error data ER1 previously supplied from the information separation unit 4, and Next, when the second error data ER2a related to the packetized elementary stream Dpa is supplied from the audio decoder unit 5a, the output unit 6 is controlled to be switched by the switching control signal CNT, so that the digital signal Db on the low bit rate side is obtained. Is output.

  Next, the operation of the digital broadcast receiving apparatus 1 having such a configuration will be described with reference to the flowchart shown in FIG. The operation when receiving a music program or the like having the same content broadcast at a high bit rate and a low bit rate will be described.

  First, when a broadcast program is selected by a user or the like, in step ST1, the front end unit 2, the demodulation and error correction unit 3, the information separation unit 4, the ACC decoder 5, the output unit 6, and the error determination unit 7 perform reception operations. Start. Then, the information separation unit 4 outputs the high bit rate side packetized elementary stream Dpa output from the demodulation and error correction unit 3 to the audio decoder unit 5a and the low bit rate side packetized elementary stream Dpb to the audio. Separately output to the decoder unit 5b and further output the digital signals Da and Db decoded by the audio decoder units 5a and 5b, respectively, and while the packetized elementary stream Dpa has no error, the error determination unit 7 Under the control, the output unit 6 outputs the digital signal Da on the high bit rate side.

  In step ST2, the error determination unit 7 monitors whether or not the first error data ER1 is output from the information separation unit 4, and if the first error data ER1 is not output, the processing from step ST1 is performed. If it is output repeatedly, the process proceeds to step ST3.

  In step ST3, the error discriminating unit 7 specifies the packetized elementary stream Dpa or Dpb having an error based on the first error data ER1.

  Next, in step ST4, the error discriminating unit 7 determines whether or not the second error data ER2a or ER2b has been output from the audio decoder units 5a and 5b, and if output, outputs the second error data ER2a or ER2b to step ST5. The process proceeds to step ST6.

  In step ST6, the error determination unit 7 performs a first determination process. That is, the first error data ER1 and the second error data ER2a related to the high bit rate side packetized elementary stream Dpa are input, and the low bit rate side packetized elementary stream Dpb is input. It is determined whether or not two conditions that the related first error data ER1 is not input are satisfied.

If these two conditions are satisfied, the process proceeds to step ST7, and the output unit 6 is controlled to switch, thereby outputting the digital signal Db on the low bit rate side.

  On the other hand, in the first determination process in step ST6, if the above two conditions are not satisfied, the process proceeds to step ST8, and the error determination unit 7 performs the second determination process.

  That is, in step ST8, the error discriminating unit 7 inputs the first error data ER1 and the second error data ER2a, ER2b related to the packetized elementary streams Dpa, Dpb on the high bit rate and low bit rate sides. Judgment is made. If these conditions are satisfied, the process proceeds to step ST9, and the output unit 6 is controlled to be switched, thereby continuously outputting the digital signal Da on the high bit trade side. In step ST8, if these conditions are not satisfied, the processing is continued from step ST1 while the high-bit trade side digital signal Da is continued.

That is, in steps ST8 and ST9, it is confirmed that there is an error in both packetized elementary streams Dpa and Dpb. If there is an error in the packetized elementary stream Dpb, it is unavoidable to improve the reception quality even if the digital signal Db is switched and output, so the digital signal Da on the high bit rate side is not desired. It is designed to output continuously.

  When the process of step ST7 or ST9 is completed, the process returns to step ST1, and the output unit 6 is switched to output the digital signal Da on the high bit rate side under the control of the error determination unit 7, and the reception operation is continued.

  Note that steps ST8 and ST9 described above are processes that are performed in a confirming manner, and may be omitted. If it is determined in step ST6 that the condition is not satisfied, the process returns directly to step ST1 to perform the process. You may continue.

  As described above, according to the digital broadcast receiving apparatus of the present embodiment, when receiving music programs having the same contents with different bit rates, priority is given to high bit rate programs, so-called reception playback is performed. When it detects that there is an error in the packetized elementary stream Dpa making up the bit rate program, it switches to the packetized elementary stream Dpb making up the low bit rate program and automatically receives and plays back. By performing the above, the music program or the like can be continuously received and reproduced without causing significant quality deterioration.

  Further, before the ACC decoder 5 decodes the packetized elementary stream Dpa on the high bit rate side having an error, the error discriminating unit 7 determines the packetized elementary stream Dpa based on the first error data ER1. And the output unit 6 is switched according to the supply of the second error data ER2 immediately before the packetized elementary stream Dpa is decoded, so that the switching control can be performed very quickly. it can. For this reason, it is possible to prevent the occurrence of a problem such as outputting a digital signal having an error decoded based on the packetized elementary stream Dpa having an error. It can be played continuously.

  Furthermore, since it is possible to perform switching in units of packetized elementary streams, for example, it is possible to prevent the occurrence of problems such as lack of playback sound during reception and playback of music programs, etc. Music with good quality can be played continuously.

  Furthermore, the packetized elementary stream on the high bit rate side is preferentially received and played back, and if an error occurs, the packetized elementary stream on the low bit rate side is switched to be received and played. The effect of the cliff effect can be avoided even when switching between digital broadcast programs.

  In the above description, the case where the so-called reception quality is improved by performing a switching operation for a music program or the like has been described. However, the reception quality can also be improved by performing the switching operation for a video program. It is.

It is a figure for demonstrating the structure and operation | movement of a digital broadcast receiver which concerns on embodiment of this invention. Diagram for explaining transport stream Diagram for explaining the OFDM system It is a block diagram showing the structure of the more concrete Example of a digital broadcast receiver. 5 is a flowchart for explaining the operation of the digital broadcast receiving apparatus shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Digital broadcast receiver 2 ... Reception part 3 ... Demodulation and error correction part 4 ... Information separation part 5 ... Decoder part 6 ... Output part 7 ... Error discrimination part

Claims (6)

The broadcast data transmitted as time-division multiplexed stream data is divided into a plurality of packet data, respectively, for high bit rate program data and low bit rate program data having the same contents but different bit rates. A digital broadcast receiving device for receiving,
Receiving means for receiving the broadcast wave;
Based on the received signal output from the receiving means, the stream data is demodulated to restore a transport stream (hereinafter referred to as TS), and a transport stream packet (hereinafter referred to as TSP) having an error when demodulated. ) Demodulation means for attaching error packet mark data to
The demodulated TS is separated into packetized elementary streams (hereinafter referred to as PES) for the programs having different bit rates, the error packet mark data is detected, and the error packet mark data is attached to the PES. information separating means for the as outputs the PES, and outputs the first error data for identifying the PES associated with the error packet mark data,
The information-separated PES relating to the audio or video is decoded in synchronism between the programs having different bit rates, the error packet mark data is detected, and the PES relating to the audio or video to which the error packet mark is attached Decoder means for outputting second error data for identifying a PES related to the audio or video to which the error packet mark data is attached immediately before decoding
Output means for outputting data decoded by the decoder means of the program selected for reception;
When the first error data related to the PES of the high bit rate program is output from the information separating means, the PES having an error is specified based on the first error data, and the PES is related to the specified PES. As the second error data is output from the decoder means, the output is performed such that the data obtained by decoding the PES having the error is switched to the data obtained by decoding the PES of the low bit rate program. Error discriminating means for controlling the means;
A digital broadcast receiving apparatus comprising: The demodulating unit attaches the error packet mark data to a TSP in which an error is detected by performing Reed-Solomon code processing for each TSP;
The digital broadcast receiving apparatus according to claim 1. The error determination means outputs the high bit rate when the first error data and the second error data related to the PES of both the high bit rate program and the low bit rate program are output. Controlling the output means so that the PES of the program outputs the decoded data;
The digital broadcast receiver according to claim 1 or 2. The packet data and stream data are MPEG-2 system packets and transport streams;
The digital broadcast receiver according to any one of claims 1 to 3. The decoder means is an MPEG-2 AAC decoder;
The digital broadcast receiver according to any one of claims 1 to 4. The broadcast data transmitted as time-division multiplexed stream data is divided into a plurality of packet data, respectively, for high bit rate program data and low bit rate program data having the same contents but different bit rates. A receiving method in a receiving digital broadcast receiving device, comprising:
Receiving the broadcast wave; and
A demodulating step of demodulating the stream data based on the received signal received in the receiving step to restore the TS and attaching error packet mark data to a TSP having an error when demodulating;
The demodulated TS is separated into PES for each program having a different bit rate, the error packet mark data is detected, the PES is output while the error packet mark data is attached to the PES, and the error packet is output. An information separation step of outputting first error data for identifying the PES associated with the mark data;
The information-separated PES relating to the audio or video is decoded in synchronism between the programs having different bit rates, the error packet mark data is detected, and the PES relating to the audio or video to which the error packet mark is attached A decoder step of outputting second error data for identifying a PES related to the audio or video to which the error packet mark data is attached immediately before decoding
An output step of outputting the data decoded by the decoder step of the program selected for reception;
When the first error data related to the PES of the high bit rate program is output by the information separation step, the PES having an error is identified based on the first error data, and the PES associated with the identified PES is identified. As the second error data is output by the decoder process, the output is performed such that the data obtained by decoding the PES having the error is switched to the data obtained by decoding the PES of the low bit rate program. An error discrimination process for controlling the process;
A receiving method comprising:

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