JP4867591B2 - Receiving device, decoding device, and program - Google Patents

Description

  The present invention relates to a receiving device, a decoding device, and a program, and more particularly, to a receiving device, a decoding device, and a program suitable for receiving a three-segment digital audio broadcast.

  Terrestrial broadcasting such as television and radio is shifting from conventional analog broadcasting to digital broadcasting. Although the conventional terrestrial analog television broadcasting stops due to such digitalization of broadcasting, the implementation of terrestrial digital audio broadcasting (digital radio) using a frequency band that becomes blank due to this is planned.

Terrestrial digital audio broadcasting includes three-segment broadcasting (so-called three-segment broadcasting) that uses a band corresponding to three segments adjacent to each other within one channel band, and such a three-segment broadcasting receiver is being put into practical use. There is (for example, Patent Document 1).
JP 2003-78839 A

  In 3 segment broadcasting of digital terrestrial radio, audio is broadcast in one segment (A layer) arranged in the center of the three segments, and moving images etc. using two segments (B layer) arranged on both sides of the A layer Additional information can be broadcast. In such a case, since the bit rate of data to be transmitted is different between audio and moving images, a modulation method suitable for each is applied. As one operation method, a phase modulation method such as QPSK (Quadrature Phase Shift Keying) is used for the A layer for transmitting audio data, and 16 QAM (Quadrature Amplitude Modulation) is used for the B layer for transmitting moving image data. : 16-value quadrature amplitude modulation) or the like is used.

  In this case, QPSK, which is a modulation method of audio data, is suitable for reception by a mobile body because the bit rate is relatively low, and it is easy to maintain a good reception state even when moving or away from a radio wave source. However, since 16QAM used for modulation of moving image data has a higher bit rate than QPSK and is susceptible to fading, reception quality may be lower than QPSK when moving or away from a radio wave source.

  This is because 16QAM, which has a higher bit rate, has a higher required CN ratio (Carrier to Noise Ratio) than QPSK, and the signal level (reception limit) that can guarantee a certain level of error correction is also 16QAM. This is because is higher than QPSK. As a result, in the case of 3-segment broadcasting, for example, if the signal level decreases as the distance from the radio wave source increases, even if error correction of layer A modulated by QPSK is possible, error of layer B modulated by 16QAM is possible. A situation in which correction becomes difficult or a situation in which layer A can be received but layer B cannot be received occurs.

  Here, in 3 segment broadcasting of digital radio, one content may be composed of the audio of the A layer and the moving image of the B layer. In this case, there is a problem that if the reception quality of any layer is lowered, the entire content cannot be reproduced properly. In other words, when one content is composed of the audio of the A layer and the moving image of the B layer, it is necessary to synchronize the audio and the moving image at the time of reproduction. However, error correction and reception of the B layer cannot be performed, and the moving image packet If it is continuously lost, there is a case where data serving as a reference for synchronization may not exist, and synchronization with audio may not be achieved. Also, even if the reception status of the B layer is improved, normal moving picture data will suddenly appear. Therefore, when the synchronization with the audio is taken, there occurs a situation in which the audio becomes discontinuous, and the listener (viewer) has to do so. May be uncomfortable. That is, when a content including a moving image is broadcast by 3-segment broadcasting of digital radio, there is a disadvantage that the reproduction of the content becomes unstable depending on the reception situation.

  Even in such a case, since the processing operation for the B layer is always performed, useless power is consumed. That is, in order to synchronize the sound and the moving image, it is necessary to buffer at least several frames of data. However, if the buffer operation of data that cannot be error-corrected is continued, a large amount of power is consumed. Such a state where the power consumption is high in spite of the deterioration of the reproduction quality is not preferable, and improvement of such inconvenience is desired.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a receiving device, a decoding device, and a program that can stabilize reproduction and reduce power consumption.

In order to achieve the above object, a receiving apparatus according to the first aspect of the present invention provides:
When receiving the three-segment broadcast of the terrestrial digital audio broadcast, the demodulated packet data is converted into the A-layer packet data including the audio data and the B-layer packet data including the moving image data constituting the 3-segment broadcast. A hierarchy separating means for separating;
Synchronous output means for synchronizing and outputting the A layer packet data and the B layer packet data separated by the layer separation means;
A layer decoding means for performing a decoding operation of audio data included in the A layer packet data output from the synchronous output means ;
B layer decoding means for decoding moving image data included in the B layer packet data output from the synchronous output means ;
Discrimination means for discriminating whether or not stable reproduction of moving image data included in the B layer can be obtained based on an error level in the packet data of the B layer;
If the stable reproduction of the moving image data included by Ri before Symbol B hierarchy said determining means is determined to not be obtained, the B-layer by stopping the input of the B-layer packet data to the synchronous output means When it is determined that stable reproduction of the moving image data included in the B layer is obtained, the decoding of the B layer is performed by inputting the B layer packet data to the synchronization output unit. Control means for controlling to execute the operation;
Lost packet counting means for counting, as lost packets, the B layer data packets whose input to the synchronous output means has been stopped while the decoding operation for the B layer is stopped by the control means;
Equipped with a,
The synchronization output means performs synchronization when resuming the decoding operation for the B layer based on the count by the lost packet counting means.
And wherein a call.

In the above receiver,
The control unit stops the decoding operation of the B layer when the state in which stable reproduction of the moving image data included in the B layer is not obtained continues for a predetermined period based on the determination result of the determination unit, It is desirable to execute the decoding operation of the B layer when a state where stable reproduction of moving image data included in the layer continues for a predetermined period.

The receiving device is
It is desirable to further include message output means for outputting a message indicating that reproduction is stopped while the decoding operation for the B layer is stopped by the control means.

In order to achieve the above object, a decoding device according to the second aspect of the present invention provides:
A decoding device for decoding demodulated digital broadcast reception data,
Separating means for separating the received data for each modulation method after demodulation of the received data multiplexed by different modulation methods;
Synchronous output means for synchronizing and outputting each separated data;
A plurality of decoding means each for decoding data to be decoded included in the output received data;
An error level detection means for detecting an error level of the separated received data;
A determination unit that compares the error level detected by the error level detection unit with a predetermined reference value to determine whether or not stable reproduction of the data can be obtained;
When the determination means determines that stable reproduction of the data cannot be obtained , the data decoding operation is stopped by stopping the input of the data to the synchronous output means, and the stable reproduction of the data is performed. Control means for controlling to execute the decoding operation of the data by inputting the data to the synchronous output means when it is determined that the data is obtained;
Lost packet counting means for counting, as a lost packet, a packet of data targeted by the decoding operation that has been stopped to be input to the synchronous output means while the decoding operation is stopped by the control means;
Equipped with a,
The synchronization output means performs synchronization when resuming the stopped decoding operation based on the number of lost packets counted by the lost packet counting means.
And wherein a call.

In the decoding device,
The control unit stops the decoding operation of the data when the state where the stable reproduction of the data cannot be obtained continues for a predetermined period based on the determination result of the determination unit, and the state where the stable reproduction of the data is obtained It is desirable to execute the data decoding operation when the data continues for a predetermined period.

In order to achieve the above object, a program according to the third aspect of the present invention is:
To a computer that decodes the demodulated digital broadcast reception data,
A function of separating the received data for each modulation method after demodulating the received data multiplexed by different modulation methods;
A function of synchronizing and outputting each separated data;
A function of decoding data to be decoded included in the output received data,
A function of detecting an error level of the separated received data;
A function of comparing the detected error level with a predetermined reference value to determine whether or not stable reproduction of the data can be obtained;
As a result of the determination, when it is determined that stable reproduction of the data cannot be obtained , the data decoding operation is stopped by stopping the input of the data to the output function, and the data is stably reproduced. When it is determined that the data is obtained , a function for controlling the data to be decrypted by inputting the data to the function to be output ;
A function of counting packets of data targeted by the stopped decoding operation as lost packets while the decoding operation is stopped;
A function of performing synchronization when restarting the stopped decoding operation based on the counted number of lost packets;
It is characterized by realizing.

  According to the present invention, it is possible to achieve stable reproduction and low power consumption when receiving a terrestrial digital audio broadcast such as a three-segment broadcast.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings. In the present embodiment, for example, a three-segment broadcast of terrestrial digital audio broadcast (terrestrial digital radio) defined in “Technical Reference for Operation of Digital Terrestrial Audio Broadcasting” (ARIB TR-B13) (hereinafter “3-segment broadcasting”). )) Will be described.

  First, an outline of 3 segment broadcasting assumed in the present embodiment will be described. The three-segment broadcasting in the present embodiment is a form of terrestrial digital audio broadcasting that is broadcast in, for example, a VHF (Very High Frequency) band (ultra-high frequency band), and a plurality of frequency bands for one channel (for example, 8 ) Is a broadcast in which data transmission is performed using carriers (carrier waves) of three adjacent segments (for example, three on the high frequency side). In this embodiment, it is assumed that 432 carriers are configured per segment.

  In the present embodiment, it is assumed that sound and image (moving image) are broadcast by 3 segment broadcasting. In this case, one content composed of sound and image is broadcast using a band for three segments. And Here, it is assumed that audio data is transmitted using one segment located at the center of the three adjacent segments, and this one segment is hereinafter referred to as “A layer”. In addition, it is assumed that image (moving image) data is transmitted using two segments located on both sides of the A layer, and these two segments are hereinafter referred to as “B layer”.

  Content data (audio data + image data) transmitted by 3-segment broadcasting is broadcast and encoded by transmission encoding by OFDM (Orthogonal Frequency Division Multiplexing) digital modulation. It is assumed that different modulation schemes are applied to each of the B layers according to the type of data to be transmitted, the bit rate, and the like. In this embodiment, the A layer for transmitting audio data is modulated by QPSK (Quadrature Phase Shift Keying), and the B layer for transmitting image (moving image) data is 16 QAM (Quadrature Amplitude Modulation: 16 values). It is assumed that the signal is modulated by quadrature amplitude modulation. One of the differences between these modulation schemes is the bit rate, and it is assumed that 16QAM has a higher bit rate than QPSK. In addition, audio data transmitted in the A layer is encoded by, for example, MPEG-2 AAC (Advanced Audio Coding), and image (moving image) data transmitted in the B layer is, for example, H.264. It shall be encoded with / AVC (ISO / IEC 14496-10: Advanced Video Coding).

  In other words, in the 3-segment broadcasting according to the present embodiment, a plurality of types of data (carriers) having different modulation schemes are multiplexed on one channel using three segments (one segment A layer and two segments B layer). Thus, one content including sound and image is broadcast by digital audio broadcasting.

  The configuration of the receiving apparatus according to the present embodiment that receives such 3-segment broadcasting will be described with reference to FIG. FIG. 1 is a block diagram illustrating a configuration example of a receiving device 1 according to an embodiment of the present invention. As illustrated, the receiving device 1 according to the present embodiment includes an antenna 10, a preprocessing unit FP, a postprocessing unit BP, an audio output unit 51, a display output unit 52, an input unit 80, and the like.

  The antenna 10 is an antenna that receives broadcast radio waves in a frequency band used in the 3-segment broadcasting according to the present embodiment, and inputs a received signal to the preprocessing unit FP.

  The preprocessing unit FP performs preprocessing such as channel selection and demodulation of received waves, and includes a tuner unit 20, a demodulation unit 30, and the like as shown in FIG.

  The tuner unit 20 is composed of a digital terrestrial audio broadcasting tuner circuit including various filter circuits and the like, and selects a designated channel from a received signal input from the antenna 10. In the present embodiment, when 3 segment broadcasting of digital terrestrial radio is selected, the bandwidth of 3 segments allocated to 3 segment broadcasting is extracted from the selected channel by the operation of the tuner unit 20. Shall be.

  The demodulator 30 includes an OFDM demodulator circuit for demodulating the OFDM-modulated received wave, and demodulates the received signal selected by the tuner unit 20. The demodulator 30 demodulates a received signal in which a carrier (carrier wave) that transmits voice, an image, or the like is multiplexed by OFDM modulation, and outputs the demodulated signal to the post-processor BP.

  The demodulator 30 performs error correction on the received signal for each of the A layer and the B layer by performing error correction processing such as Viterbi decoding processing and RS (Read Solomon code) decoding processing, for example. To do.

  Further, the demodulation unit 30 decodes TMCC (Transmission and Multiplexing Configuration Control) information included in the received wave. The TMCC information is control information indicating parameters necessary for demodulation, such as a modulation scheme applied to a broadcast wave, an error correction coding rate, an interleave length, and the like. In the present embodiment, the TMCC information indicates that the digital audio broadcasting (3-segment broadcasting) has a three-segment configuration of A layer (1 segment) and B layer (2 segments), and the modulation method applied to each layer. It is assumed that It is assumed that the decoded TMCC information is notified to the control unit 60 of the post-processing unit BP via the front / rear I / F unit 90.

  The demodulator 30 combines the demodulated received signals of the A layer and the B layer, and outputs the combined signals to the post-processing unit BP as a transport stream (TS) signal. An example of the data structure of the TS signal output here is shown in FIG. The TS data output from the demodulator 30 is a data stream in which demodulated A layer and B layer packets (hereinafter referred to as “TS packets”) are combined, as shown in FIG. It is assumed that the size of the TS packets of the A layer and the B layer is both 204 bytes, and NULL indicating that valid data is not included for data that could not be received is inserted.

  An example of the data structure of the TS packet included in the TS signal is shown in FIG. As shown in the figure, each TS packet is composed of a TS header and a payload portion. In addition to PID (Packet Identifier: packet ID) information added at the time of broadcasting, the TS header includes an error indicator bit (EIB) added by the demodulator 30. This EIB indicates whether or not the TS packet contains an error, and is inserted into the TS packet after the error correction operation in the demodulator 30. In this embodiment, the EIB when an error is included is “1”, and the EIB when no error is included is “0”. Note that the PID added at the time of broadcasting includes information indicating whether each packet is of the A layer or the B layer.

  The post-processing unit BP decodes audio data and image data from the signal demodulated by the pre-processing unit FP, and performs reproduction output. As shown in FIG. 1, the post-processing unit BP includes a decoding processing unit 100, a control unit 60, a storage unit 70, an input I / F (interface) unit 81, and front and rear I / Fs interconnected by a predetermined bus BS. (Interface) unit 90, and the like.

  The decoding processing unit 100 is a decoding device configured by, for example, an arithmetic circuit such as an LSI or a CPU (Central Processing Unit) and various memories, and is output from the demodulating unit 30 of the preprocessing unit FP. The demodulated received signal is decoded and reproduced. In the present embodiment, since the digital radio 3 segment broadcast is received, the audio transmitted in the A layer and the image (moving image) transmitted in the B layer are decoded according to the respective encoding methods. In this case, the decoding processing unit 100 converts the decoded audio data into an analog audio signal, and outputs the analog audio signal to the audio output unit 51 configured by an amplifier, a speaker (earphone), and the like to output a report sound, and for each decoded frame The image data is output to a display output unit 52 composed of, for example, a liquid crystal display device and displayed.

  The control unit 60 includes, for example, an arithmetic device such as a CPU and a main storage device such as a RAM (Random Access Memory). The control unit 60 controls each unit of the receiving device 1 including the post-processing unit BP by executing a program. To do.

  The storage unit 70 is configured by a storage device such as a flash memory or a ROM (Read Only Memory), for example, and stores data necessary for the operation of the receiving device 1, a program executed by the control unit 60, and the like.

  The input I / F unit 81 is, for example, an interface between the input unit 80 including operation buttons and the post-processing unit BP, and performs digital conversion of an input signal so that digital processing can be performed by the control unit 60 or the like.

  The front / rear I / F unit 90 is an interface between the post-processing unit BP and the pre-processing unit FP. In the present embodiment, information transmission between the demodulator 30 of the preprocessing unit FP and the control unit 60 and the storage unit 70 of the post-processing unit BP is performed via the front / rear I / F unit 90, and also at the input unit 80. A channel selection signal indicating the channel selection operation is input to the tuner unit 20 via the front / rear I / F unit 90. In this case, if the tuner unit 20 operates by analog processing, the front / rear I / F unit 90 converts the digital signal into an analog signal and inputs the analog signal to the tuner unit 20.

  Each of the above-described configurations is a configuration necessary for realizing the present invention, and other configurations normally included in a digital broadcast receiver are provided as necessary.

  In the present embodiment, reproduction is stabilized and power consumption is reduced by the operation of the decoding processing unit 100. An example of the configuration and operation of the decoding processing unit 100 for this purpose will be described below as a first embodiment. The configuration of the decoding processing unit 100 according to the present embodiment is shown in FIG. FIG. 3 is a block diagram illustrating a configuration of the decoding processing unit 100 according to the present embodiment.

As illustrated, the decoding processing unit 100 according to the present embodiment includes a layer separation unit 101, an A layer buffer 102A, a B layer buffer 102B, a synchronization processing unit 103, an A layer decoder 104A, a B layer decoder 104B, and a sampling circuit 105 ( 105 _{1 to} 105 ₄ ), an integration circuit 106, a comparator 107, a control circuit 108, a SW circuit 109, a lost packet counting unit 110, and the like.

  The layer separation unit 101 separates the TS signal into layer A packet data and layer B packet data based on the PID indicated by the TS header of the input TS packet. The separated A layer packet data is output to the A layer buffer 102 A, and the B layer packet data is output to the SW circuit 109.

  The A layer buffer 102A is a buffer memory for buffering the A layer audio data in order to synchronize the A layer audio data and the B layer image (moving image) data.

  The B layer buffer 102B is a buffer memory for buffering the B layer moving image data in order to synchronize the A layer audio data and the B layer image (moving image) data. Here, in the case of three-segment broadcasting, the audio data of the A layer is transmitted in a band for one segment, and the moving image data of the B layer is transmitted in a band for two segments. It is assumed that the buffer memory has a larger capacity than the hierarchical buffer 102A. Further, it is assumed that the B layer buffer 102B has a capacity sufficient to buffer moving image data for at least several frames.

  The synchronization processing unit 103 is a synchronization circuit that synchronizes the A layer audio data buffered in the A layer buffer 102A and the B layer moving image data buffered in the B layer buffer 102B. Here, in the case where there is moving image data that cannot be corrected or error data that cannot be corrected for bit errors occurring in the wireless section, or audio data exists, the reproducible B layer moving image data and A layer sound data are synchronized. . That is, the synchronization processing unit 103 controls the timing of reading out the A layer audio data buffered in the A layer buffer 102A and the B layer moving image data buffered in the B layer buffer 102B, so that the B layer moving image data and the A layer Synchronize with audio data. The synchronized A layer audio data and B layer moving image data are output to the A layer decoder 104A and the B layer decoder 104B, respectively. In this embodiment, when there is no buffer data in the B layer buffer 102B, the data is output to the A layer decoder 104A without delaying the A layer data.

  The A-layer decoder 104A performs decoding operation on the A-layer audio data output from the synchronization processing unit 103, converts the decoded audio data into an analog audio signal, and outputs the analog audio signal to the audio output unit 51. The report sound is output. In the present embodiment, for example, a decoding operation based on an encoding standard such as MPEG-2 AAC (Advanced Audio Coding) is performed.

  The B layer decoder 104B performs a decoding operation on the B layer moving image data output from the synchronization processing unit 103 and outputs the decoded image data for each frame to the display output unit 52, thereby displaying and outputting the received moving image. In this embodiment, for example, a decoding operation based on a coding standard such as H.264 / AVC (ISO / IEC 14496-10: Advanced Video Coding) is performed.

The sampling circuit 105 is composed of, for example, _four sampling circuits, sampling circuits 105 _{1 to} 105 ₄ , and an error indicator bit (Error) added by the demodulation unit 30 from the B layer packet data separated by the layer separation unit 101. By sampling and sequentially shifting (Indicator Bit: EIB), EIB of four consecutive packets of demodulated B layer data is acquired. The continuous four packets of EIB are output to the integration circuit 106.

  The integrating circuit 106 averages the EIB of four consecutive packets input from the sampling circuit 105. In this case, the integration circuit 106 adds the four input EIB values to ¼ and then subtracts from 1, thereby calculating the ratio of normal packets (hereinafter referred to as “normal packet rate”). Calculate and output to the comparator 107. That is, the average error level of the demodulated B layer packet data is calculated.

  The comparator 107 compares the normal packet rate (error level) output from the integrating circuit 106 with the reference value of the normal packet rate (error level) input from the control unit 60. Here, for the threshold value to be set, for example, based on the processing performance of the decoding processing unit 100, the lower limit value of the normal packet rate at which stable reproduction of moving images transmitted in the B layer is obtained is used. In this embodiment, as an example, it is assumed that stable reproduction is possible if the normal packet rate is 0.6, and this value is set as a reference value. That is, a value indicating an error level that can guarantee stable reproduction of the B layer data is set as the reference value.

  This reference value is assumed to be dynamically set according to the modulation scheme or encoding scheme obtained from the received TMCC. In this case, for example, setting values corresponding to various conditions are assumed to be stored in the storage unit 70 in advance, and depending on the type of broadcast, modulation scheme, encoding scheme, etc. identified based on TMCC information or the like The control unit 60 acquires the corresponding setting value from the storage unit 70 and notifies the comparator 107 of the setting value.

  The comparator 107 outputs binary information indicating a comparison result between the normal packet rate output from the integrating circuit 106 and the reference value of the normal packet rate input from the control unit 60. In the present embodiment, an H (High (high level)) signal is output when the normal packet rate output from the integrating circuit 106 exceeds the reference value, and an L (Low (low level) signal when the normal packet rate is less than or equal to the reference value. ) A signal shall be output.

  The control circuit 108 is configured by an arithmetic circuit such as an LSI, for example, and determines whether or not to invalidate the decoding process for the B layer based on the comparison result output from the comparator 107. In response, the SW circuit 109 is controlled. Here, the control circuit 108 determines that the decoding operation for the B layer should be stopped when the L signal is continuously output from the comparator 107 a predetermined number of times or more (for example, two times or more). That is, based on the comparison between the average value of the obtained error levels and the reference value, it is determined that the decoding operation for the B layer should be stopped when the state in which stable reproduction of the B layer is not continued for a predetermined period. .

  When it is determined in this way, the control circuit 108 sends a control signal to the SW circuit 109 that switches the B layer data input from the layer separation unit 101 to the SW circuit 109 so as not to pass through the B layer buffer 102B. That is, the SW circuit 109 is controlled so that the decoding operation for the B layer is not performed when the state of a low error-free packet state (state where the error level is low) continues for a predetermined period.

  The SW (switch) circuit 109 is a switch circuit that switches the transmission destination of the B layer data from the layer separation unit 101 to either the B layer buffer 102B or the lost packet counting unit 110. The SW circuit 109 operates under the control of the control circuit 108, and switches to switch the path of the B layer data in accordance with the control signal from the control circuit 108. When the destination of the B layer data is switched to the lost packet counting unit 110 by the operation of the SW circuit 109, the B layer data is not transmitted to the B layer buffer 102B, so only the A layer data is transferred from the synchronization processing unit 103 to the A layer. It is output to the decoder 104A. That is, the supply of B layer data to the decoding process is stopped.

  The lost packet counting unit 110 is a counter circuit that counts B layer packets that are no longer supplied to the decoding process due to the operation of the SW circuit 109 as lost packets. That is, the B layer packets while the decoding process for the B layer is stopped are counted. The count value is output to the synchronization processing unit 103 and used for synchronization when the decoding operation for the B layer is resumed.

  In the present embodiment, each configuration of the decoding processing unit 100 described above is realized by hardware, but all or any of these may be realized by software. That is, the function of the decoding processing unit 100 can be realized by the control unit 60 (CPU) that controls the receiving device 1 executing the program. In this case, a program for realizing the function of the decryption processing unit 100 is stored in the storage unit 70 or the like, and the control unit 60 executes the program to function as the decryption processing unit 100.

  The operation of the decoding processing unit 100 having such a configuration will be described below. Here, the “decoding operation control process” is executed by the decoding processing unit 100 in the flowchart of FIG. 4. This “decoding operation control process” is started when a signal (H / L) indicating a comparison result is input from the comparator 107 to the control circuit 108.

  When the process is started, the control circuit 108 determines whether or not the input signal is an L signal (step S101). Here, when the input signal is an L signal (step S101: Yes), the control circuit 108 determines whether or not the input of the L signal is continuous a predetermined number of times (here, two times or more). That is, it is determined whether or not the state where stable reproduction of the B layer is not obtained, which is determined based on the normal packet rate (error level), continues for a predetermined period (step S102).

  When the input of the L signal is greater than or equal to the predetermined number of times (step S102: Yes), the control circuit 108 sends to the SW circuit 109 a control signal for switching to a path where the B layer data is not output to the decoding process. In this case, since the SW circuit 109 switches so that the B layer data from the layer separation unit 101 is input to the lost packet counting unit 110, the B layer packet data is not sent to the B layer buffer 102B. That is, the supply of the B layer packet data to the decoding process is stopped (step S103).

  In this case, since the layer B packet data separated by the layer separation unit 101 is sequentially input to the lost packet counting unit 110, the lost packet counting unit 110 starts counting using the number of these packets as the number of lost packets. (Step S104).

  In step S103, since the layer B packet data is no longer supplied to the layer B buffer 102B, the synchronization processing unit 103 does not delay the layer A audio data buffered in the layer A buffer 102A at that time. Output to the hierarchical decoder 104A. That is, only the A-layer packet data is supplied to the decoding process.

  Further, when the control circuit 108 sends a control signal to the SW circuit 109, the control circuit 108 notifies the control unit 60 that the decoding operation of the B layer has been stopped. The control unit 60 controls the display output unit 52 according to the notification from the control circuit 108 to display a predetermined message. Here, a message (hereinafter referred to as “playback stop message”) indicating that the output of the B layer (that is, moving image display) is stopped due to a data error is displayed on the display output unit 52 (step S105).

  Thereafter, when the normal packet rate of the B layer is improved and the input from the comparator 107 is an H signal (step S106: Yes), if the H signal is continuously input a predetermined number of times (two times or more). That is, when the state in which stable reproduction of the B layer is obtained, which is determined based on the normal packet rate (error level) of the B layer, continues for a predetermined period (step S107: Yes), the control circuit 108 The control unit 60 is notified to cancel the stop of the decoding operation of the hierarchy. The control unit 60 controls the display output unit 52 in response to the notification from the control circuit 108, and ends the display of the reproduction stop message displayed in step S105 (step S108).

  At the same time, the control circuit 108 controls to execute (restart) the decoding operation of the B layer (step S109). Here, a control signal for switching to a path through which the B layer packet data from the layer separation unit 101 is input to the B layer buffer 102B is sent to the SW circuit 109. When the SW circuit 109 performs a switching operation in accordance with a control signal from the control circuit 108, the B layer packet data from the layer separation unit 101 is sequentially sent to the B layer buffer 102B. In this case, the data is output to the B layer decoder 104B after being synchronized by the synchronization processing unit 103, so that the decoding process for the B layer is executed (resumed).

  Here, since the B layer packet is not input to the lost packet counting unit 110 due to the operation of the SW circuit 109, the lost packet counting unit 110 ends the counting operation and notifies the synchronization processing unit 103 of the count value.

The synchronization processing unit 103 controls the timing of reading out the A layer audio data buffered in the A layer buffer 102A and the B layer moving image data buffered in the B layer buffer 102B, so that the B layer moving image data and the A layer audio data are read. Is synchronized with
At this time, the A layer audio data is synchronized with the B layer moving image data based on the number of lost packets notified from the lost packet counting unit 110 (step S110). Here, the information amount of the image included in the B layer packet is estimated, the information amount of the lost image is obtained from the estimated information amount and the number of lost packets, and based on the obtained information amount of the image, B A layer audio data to be synchronized with the layer moving image data is specified and synchronized.

  When the L signal is further input from the comparator 107 (step S106: No) or when the input is changed from the L signal to the H signal, the H signal is not input more than a predetermined number of times. (Step S107: No) continues the stop state of the decoding operation for the B layer (Step S103). That is, when the normal packet rate is still insufficient for stable reproduction of the B layer, or when the normal packet rate is temporarily recovered but is not sufficient as a whole, the decoding operation for the B layer is stopped. Continue state.

  Further, when the signal input from the comparator 107 at the start of processing is an H signal (step S101: No), or when the input signal changes from the H signal to the L signal, the input of the L signal is more than a predetermined number of times. When it is not continuous (step S102: No), it operates so that decoding of the B layer is performed (step S109). For example, if a route for inputting B layer data from the layer separating unit 101 to the B layer buffer 102B is set as a default in the SW circuit 109, when the H signal is input at the start of processing, the control circuit 108 particularly turns on the SW circuit 109. Even without the control, the decoding operation for the B layer is executed.

  By repeating such an operation until the input from the comparator 107 is stopped (step S111: No), when the state where the normal packet rate of the B layer does not reach the required value continues for a certain time, the B layer The layer B packet data is not input to the buffer 102B, and the decoding operation for layer B is stopped.

  As described above, according to the decoding processing unit 100 according to the present embodiment, when it is determined that stable reproduction cannot be obtained based on the error level of the demodulated B layer data, the decoding operation of the B layer is automatically performed. Stop. As a result, unstable playback that occurs in the past, such as intermittent display of images, does not occur, and decoding is not performed for the B layer that consumes a large amount of power. It is possible to greatly reduce the power consumption during the absence.

  In other words, because the reception limit differs between the A gray level and the B gray level due to the difference in the modulation method, even if the A gray level can be corrected well, error correction may be difficult for the B layer. In addition to eliminating the display defect of error-corrected images being displayed intermittently, it is also possible to eliminate poor sound playback caused by synchronizing the sound with a long delay video, so stable playback Can be done.

  In addition, when a situation where the error correction of the B layer can be satisfactorily performed due to a change in the reception environment, the decoding operation of the B layer is automatically restarted, so that the content is reproduced with the optimum reproduction quality according to the reception state. be able to. In this case, the number of lost packets while the decoding operation of the B layer was stopped is used for synchronization with the audio when decoding is resumed, so that a delay in audio reproduction can be prevented and good reproduction can be achieved. Quality can be obtained.

  In this way, when the decoding operation of the B layer is stopped or restarted, it is a condition that a packet having a certain error level is continued for a predetermined period. For example, the signal level of the received signal changes drastically and the packet error rate also increases. When receiving in an area that fluctuates drastically (so-called fringe area), the reproduction quality is not deteriorated by stopping and restarting the decoding operation in a short cycle.

  In addition, the video playback is stopped by stopping the decoding operation of the B layer. In this case, since the video playback is stopped, the video playback is stopped by the operation of the device. Can be recognized by the user, and the device is not mistaken for a malfunction. Note that the output of the message is not limited to display output, and may be audio output, for example.

  The said embodiment is an example and the application range of this invention is not restricted to this. That is, various applications are possible, and all embodiments are included in the scope of the present invention.

  In the above embodiment, the decoding operation of the B layer is stopped when the normal packet rate for the B layer packet is low. However, any error level that can determine whether or not the stable reproduction of the B layer can be obtained. For example, any standard may be used without being limited to the normal packet rate. For example, a packet error rate (PER) of demodulated packets may be used. Also in this case, the quality of the reproduction quality can be determined based on the packet error by comparing the PER with a predetermined reference value.

  In the above embodiment, the case of receiving a three-segment broadcast of a terrestrial digital audio broadcast is illustrated, but a broadcast received by applying the present invention is a digital broadcast in which data modulated by different modulation schemes is multiplexed. Is not limited to 3 segment broadcasting. That is, in the above embodiment, the processing for the B layer of digital audio broadcasting is controlled. However, what is to be controlled is not limited to this. For example, an error occurs because the required signal level is high. The present invention can be applied to control the decoding of data transmitted by an easy modulation method and the decoding of data encoded by a coding method that requires a large amount of power during processing load and processing. The modulation method and coding method are not limited to those exemplified in the above embodiment.

  In the above embodiment, only the decoding operation of the B layer is stopped. However, the decoding operation of the A layer may be stopped when the decoding operation of the B layer is stopped. In this case, an SW circuit similar to the SW circuit 109 is also provided on the A layer side, and control is performed in the same manner as the control of the B layer, so that the input of the A layer data to the A layer buffer 102A can be stopped. . With such a configuration, for example, in the case of content that cannot be enjoyed only by playing back audio, it is possible to further reduce power consumption by stopping audio playback.

  In the above embodiment, control is performed so that the decoding operation of the B layer is stopped when the output of the L signal from the comparator 107 continues for a predetermined number of times or more. However, the stop condition of the operation to be controlled is not limited to this. Is optional. That is, it is only necessary to control to stop the decoding operation for a packet for which stable reproduction cannot be obtained.

  In the above embodiment, the decoding operation of the B layer is stopped by stopping the input to the buffer necessary for synchronization, but the method of stopping the decoding operation is not limited to this. For example, the composite operation may be stopped by directly controlling the part that actually performs the decoding operation, such as the B-layer decoder 104B.

  The receiving apparatus 1 according to the present invention can be realized by being incorporated into a general-purpose device such as a personal computer or a mobile communication terminal, as well as being configured by a dedicated device. In this case, the post-processing unit BP, the audio output unit 51, the display output unit 52, the input unit 80, and the like described in the above embodiment can be realized by the configuration of the general-purpose device. Moreover, you may provide as a module containing the structure of the antenna 10, the pre-processing part FP, and the post-processing part BP which were shown in the said embodiment.

  Further, the present invention may be applied to a receiving device that can receive a plurality of types of broadcasts. In this case, if the present invention is applied to a decoding device prepared in accordance with a receivable digital broadcast, the reception according to the present invention is possible. An apparatus can be realized. That is, by applying the decoding device according to the present invention to a digital broadcast receiver, the receiving device according to the present invention can be realized and the above-described effects can be obtained.

  The decoding device in this case can be configured by a hardware device, and the decoding device according to the present invention can be realized by a computer (such as a CPU) that controls the device to be applied executing a program. Such a program distribution method is arbitrary. For example, the program can be distributed by being stored in a storage medium such as a CD-ROM or a memory card, or can be distributed via a communication medium such as the Internet. By applying (installing) a distributed program to a target device and causing a computer that controls the device to execute the program, the same configuration and operation as the decoding processing unit 100 can be realized in any device.

It is a block diagram which shows the structure of the receiver concerning embodiment of this invention. It is a figure for demonstrating the data structure of TS signal after a demodulation, (a) shows the example of the data structure of TS signal, (b) shows the example of the data structure of TS packet. It is a block diagram which shows the structure of the decoding process part shown in FIG. It is a flowchart for demonstrating the "decoding operation control process" concerning embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Reception apparatus, 10 ... Antenna, FP ... Pre-processing part, 20 ... Tuner part, 30 ... Demodulation part, BP ... Post-processing part, 100 ... Decoding processing part, 101 ... Hierarchy separation part, 102A ... A hierarchy buffer, 102B ... B hierarchy buffer, 103 ... synchronization processing unit, 104A ... A layer decoder, 104B ... B layer decoder, ₁₀₅ (105 1 to 105 ₄₎ ... sampling circuit, 106 ... integrating circuit, 107 ... comparator, 108 ... control circuit, DESCRIPTION OF SYMBOLS 109 ... SW circuit, 110 ... Lost packet counting part, 51 ... Audio | voice output part, 52 ... Display output part, 60 ... Control part, 70 ... Memory | storage part, 80 ... Input part, 81 ... Input I / F part, 90 ... Around I / F section

Claims (6)

In a receiving apparatus that includes terrestrial digital audio broadcasting
When receiving the three-segment broadcast of the terrestrial digital audio broadcast, the demodulated packet data is converted into the A-layer packet data including the audio data and the B-layer packet data including the moving image data constituting the 3-segment broadcast. A hierarchy separating means for separating;
Synchronous output means for synchronizing and outputting the A layer packet data and the B layer packet data separated by the layer separation means;
A layer decoding means for performing a decoding operation of audio data included in the A layer packet data output from the synchronous output means ;
B layer decoding means for decoding moving image data included in the B layer packet data output from the synchronous output means ;
Discrimination means for discriminating whether or not stable reproduction of moving image data included in the B layer can be obtained based on an error level in the packet data of the B layer;
If the stable reproduction of the moving image data included by Ri before Symbol B hierarchy said determining means is determined to not be obtained, the B-layer by stopping the input of the B-layer packet data to the synchronous output means When it is determined that stable reproduction of the moving image data included in the B layer is obtained, the decoding of the B layer is performed by inputting the B layer packet data to the synchronization output unit. Control means for controlling to execute the operation;
Lost packet counting means for counting, as lost packets, the B layer data packets whose input to the synchronous output means has been stopped while the decoding operation for the B layer is stopped by the control means;
Equipped with a,
The synchronization output means performs synchronization when resuming the decoding operation for the B layer based on the count by the lost packet counting means.
Receiving device comprising a call. The control unit stops the decoding operation of the B layer when the state in which stable reproduction of the moving image data included in the B layer is not obtained continues for a predetermined period based on the determination result of the determination unit, Executing the decoding operation of the B layer when a state in which stable reproduction of moving image data included in the layer is continued for a predetermined period;
The receiving apparatus according to claim 1 . A message output means for outputting a message indicating that playback is stopped while the decoding operation for the B layer is stopped by the control means;
The receiving apparatus according to claim 1 or 2 , wherein A decoding device for decoding demodulated digital broadcast reception data,
Separating means for separating the received data for each modulation method after demodulation of the received data multiplexed by different modulation methods;
Synchronous output means for synchronizing and outputting each separated data;
A plurality of decoding means each for decoding data to be decoded included in the output received data;
An error level detection means for detecting an error level of the separated received data;
A determination unit that compares the error level detected by the error level detection unit with a predetermined reference value to determine whether or not stable reproduction of the data can be obtained;
When the determination means determines that stable reproduction of the data cannot be obtained , the data decoding operation is stopped by stopping the input of the data to the synchronous output means, and the stable reproduction of the data is performed. Control means for controlling to execute the decoding operation of the data by inputting the data to the synchronous output means when it is determined that the data is obtained;
Lost packet counting means for counting, as a lost packet, a packet of data targeted by the decoding operation that has been stopped to be input to the synchronous output means while the decoding operation is stopped by the control means;
Equipped with a,
The synchronization output means performs synchronization when resuming the stopped decoding operation based on the number of lost packets counted by the lost packet counting means.
Decoding apparatus according to claim and this. The control unit stops the decoding operation of the data when the state where the stable reproduction of the data cannot be obtained continues for a predetermined period based on the determination result of the determination unit, and the state where the stable reproduction of the data is obtained When the data continues for a predetermined period, the data is decrypted.
The decoding device according to claim 4 . To a computer that decodes the demodulated digital broadcast reception data,
A function of separating the received data for each modulation method after demodulating the received data multiplexed by different modulation methods;
A function of synchronizing and outputting each separated data;
A function of decoding data to be decoded included in the output received data,
A function of detecting an error level of the separated received data;
A function of comparing the detected error level with a predetermined reference value to determine whether or not stable reproduction of the data can be obtained;
As a result of the determination, when it is determined that stable reproduction of the data cannot be obtained , the data decoding operation is stopped by stopping the input of the data to the output function, and the data is stably reproduced. When it is determined that the data is obtained , a function for controlling the data to be decrypted by inputting the data to the function to be output ;
A function of counting packets of data targeted by the stopped decoding operation as lost packets while the decoding operation is stopped;
A function of performing synchronization when restarting the stopped decoding operation based on the counted number of lost packets;
A program characterized by realizing.

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