JP2011223427A - Digital broadcasting receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transport decoder that avoids a mismatch between PES size information added to a PES header and a PES data size transferred to a decoder which is caused by data transformation in a PES header, without degradation in quality resulting from image and audio noises at the time of data decoding which can be caused when transformation or lack of TS packet data frequently occurs in a conventional system using an transmission channel on which transmission errors are likely to occur, such as a radio link.SOLUTION: When a mismatch between Length information in a PES header and a data size actually transferred to a decode part is detected by an analysis of a TS header and the PES header, a transport decode part rewrites the size information added to the PES header to eliminate the mismatch. When the mismatch continues to occur a certain number of times, for example, in case of MPEG2-AAC, audio information in an ADTS header added to the PES header is rewritten in PES packet units and audio volume is decreased in packet units.

Description

  The present invention relates to a digital broadcast receiving apparatus that processes multiplexed compressed signals such as video and audio, and more particularly to means for processing a transport stream.

2. Description of the Related Art In recent years, in television digital broadcasting, an encoding method compliant with the MPEG2 (Moving Picture Experts Group) standard defined by ISO / IEC13818-1 has been adopted as a method for highly efficient compression encoding of video signals and audio signals. Yes. In the MPEG2 system, on the transmission side, a material such as video / audio is encoded, and the encoded data is converted into a packet called PES (Packetized Elementary Stream). The PES is a variable-length packet composed of a PES header and a PES payload, and the PES header includes information indicating the packet length and the header length, conditional coding information, and the like. In the digital broadcasting standard, a format in which a PES is multiplexed and transmitted is divided into 188-byte fixed-length packets called TS (Transport Stream) and transmitted. 4-byte header information is added to these TS packets, and error information in the packet, a flag indicating the head of the PES, packet identification information (PID: Packet Identification) and information indicating the presence / absence of an adaptation field / payload are added. .
On the receiving side, the header information of the transport stream transmitted from the transmitting side is analyzed, and processing such as discarding is performed on error packets due to data corruption in the transmission path. Thereafter, a program that the user desires to view is identified by PID, and TS packets into which video PES and audio PES are inserted are separated, and video and audio PES packets are decoded by a decoder unit (for example, Patent Document 1).

JP 2001-111610 A

In these series of processes, especially in systems that use transmission lines that are prone to transmission errors, such as wireless lines, TS packet data corruption and omissions occur frequently, resulting in video and audio noise during data decoding that degrades quality. If there is an abnormal sound, particularly a metallic sound, particularly with respect to audio, it causes a significant discomfort.
More specifically, if a mismatch occurs between the Length information in the PES header and the size information that is actually transferred to the decoder due to garbled data in the PES header that occurs in the middle of the transmission path, the quality is reduced during the audio decoding process. Decreases. For example, it may be possible to decode data other than audio when the value of PES Length has changed to a large value.
In addition, when the audio decoding unit searches for the PES header, it may be possible to continue the PES header search repeatedly because the data size cannot be matched with the PES Length.
Therefore, in the present invention, in order to solve the conventional problem, a transport that prevents inconsistency between the size information of the PES added to the PES header due to garbled data of the PES header and the data size of the PES transferred to the decoder A decoder is provided.

In a data processing apparatus for analyzing a transport stream, means for calculating the size of a video or audio payload from the header information of the transport stream;
The analysis means for analyzing the PES packet has means for calculating the size of the PES data added to the header information of the PES, and has means for rewriting the header information of the PES packet by comparing the payload size with the data size of the PES. Is a digital broadcast receiving device.
Further, in the means for rewriting the header information of the PES packet by comparing the payload size and the data size of the PES, if the comparison result does not match and the number of mismatches exceeds a certain threshold, the audio PES The digital broadcast receiving apparatus is characterized in that volume information added to packet header information is rewritten.
Further, a digital broadcast receiving apparatus comprising means for processing a transport stream and data decoding means for decoding output data of the transport stream,
An apparatus for analyzing a PES packet included in the transport stream, and a means for discarding data of the PES packet according to the analysis result of the analyzing means.

According to the present invention, there is no inconsistency between Length information of the PES header and the data size actually transferred to the decoder for the garbled data of the PES header generated in the middle of the transmission path. Can be reduced.

  Also, since the TS header and PES header are analyzed and the header information is rewritten in units of PES packets, it is possible to adjust the audio level etc. in units of PES packets according to garbled data in the transmission path or data loss. It becomes possible.

The block diagram which shows the structure of the digital broadcast receiver concerning one embodiment of this invention Block diagram showing the TS processing unit of FIG. The figure for demonstrating operation | movement of the TS analysis part of FIG. Flowchart for explaining the operation of the TS analysis unit in FIG. Flowchart for explaining the operation of the TS analysis unit in FIG. Flowchart for explaining the operation of the TS analysis unit in FIG. The block diagram which shows the structure of the digital broadcast receiver concerning Embodiment 2 of this invention. Block diagram showing the TS processing section of FIG. Flowchart for explaining the operation of the TS analysis unit in FIG. Flowchart for explaining the operation of the TS analysis unit in FIG.

(Embodiment 1)
Embodiments according to the present invention will be described below with reference to the drawings. FIG. 1 shows Embodiment 1 of a digital broadcast receiving apparatus to which the present invention is applied. The digital broadcast receiving apparatus according to this embodiment includes a tuner / demodulator 101, a TS header analyzer 102, a PID filter 103, a TS processor 104, an APES buffer 105, a VPES buffer 106, and an AUDIO decoder 107. And a video decoding unit 108 and a PES buffer control unit 109.

  Hereinafter, this embodiment will be described along the flow of digital signals. The tuner demodulation unit 101 selects a specific carrier IF from the radio wave received by the antenna, performs a process such as demodulation, and outputs a transport stream TS1.

The TS header analysis unit 102 detects a synchronization byte of the TS header and inputs data in units of 188 bytes. In addition, the TS header analysis unit 102 analyzes TS header information, identifies a Transport Error Indicator, discards an error packet, and outputs TS2.
The PID filter unit 103 performs filtering based on the designated audio and video PID values, performs filtering of an audio transport stream, a video transport stream, and the like, and outputs a transport stream TS3.
TS processing section 104 receives TS3, identifies the first byte of the PES packet from the Payload_unit_start_indicator information included in the header information of TS, analyzes the size of the adaptation field / payload from the information of Adaptation_field_control, and from TS Extract PES and output audio PES signal APES and video PES signal VPES.

  The APES buffer 105 and the VPES buffer 106 are memory buffers that can receive audio and video PES signals APES and VPES and can buffer a certain amount. Since these buffers have a maximum size of 64 Kbytes according to the standard of PES packets, it is desirable to secure a size of 64 Kbytes or more.

The AUDIO decoding unit 107 and the VIDEO decoding unit 108 input an audio PES signal and a video PES signal, perform ES extraction processing, and perform audio and video decoding processing.
The PES buffer control unit 109 communicates with the TS processing unit 104, the AUDIO decoding unit 107, and the VIDEO decoding unit 108, and writes data write addresses (write pointers) and data read addresses (read pointers) of the APES buffer 105 and the VPES buffer 106. ) To control.

Next, signal processing from the TS processing unit 104 to the AUDIO decoding unit 107 will be described in more detail. Although the present embodiment describes an example of audio processing, it may be video processing.
FIG. 2 is a block diagram illustrating in detail the TS processing unit 104, APES buffer unit 105, AUDIO decoding unit 107, and PES buffer control unit 109 of FIG.

  The TS processing unit 104 includes a TS buffer 301 and a TS analysis unit 302. The TS buffer 301 is a memory for data buffering until the TS analysis unit 302 analyzes the TS header and the PES header and extracts the audio payload from the transport stream.

  The TS analysis unit 302 calculates the APES buffer write pointer WP from the payload data size extracted from the TS, and transmits the WP to the PES buffer control unit 109.

The PES buffer control unit 109 transmits the APES buffer write pointer WP received from the TS analysis unit 302 to the AUDIO decoding unit 107.
Upon receiving the APES buffer write pointer, the AUDIO decoding unit 107 updates the APES buffer read pointer RP, captures audio data, and simultaneously transmits the read pointer RP to the PES buffer control unit 109.

  The PES buffer control unit 109 checks the remaining free space of the APES buffer 105 based on the difference between the write pointer WP and the read pointer RP, and controls the write pointer WP. For example, when the APES buffer 105 is used as a ring buffer, the PES buffer control unit 109 calculates the remaining free space of the APES buffer 105 = RP-WP from the write pointer WP and the read pointer RP, and the free remaining amount is constant. When the value is equal to or less than the threshold, it is determined that the APES buffer 105 has overflowed, and updating of the write pointer WP is stopped.

FIG. 3 shows the relationship between the TS packet input to the TS buffer 301 and the write pointer WP of the APES buffer 105. FIG. 3 is a diagram showing a case where two TS packets are input. Since the PES header is included in the first packet, Payload_unit_start_indicator (PUSI) indicates 1, and the second Since this packet is a continuation of PES, PUSI is 0.
In the example of FIG. 3, the PES Length shown in the PES header is 300 bytes, the first TS packet includes a 184-byte payload, and the second packet includes a 116-byte payload. The total size of the payloads of these two packets is 300 bytes. In the example of FIG. 3, one PES packet is composed of two TS packets.

  In this embodiment, when two packets shown in FIG. 3 are input, the TS analyzer 302 updates the write pointer WP of the APES buffer by 184 when the first TS packet is input, and inputs the second packet. The write pointer is updated 116.

Next, contents of data processing of the TS analysis unit 302 according to the present invention will be described. FIG. 4 is a flowchart showing an example of processing for detecting the head of a PES packet in an input audio transport stream.
FIG. 5 shows that there is a mismatch between the PES transfer size (= WP write pointer) that the TS analysis unit 302 analyzed the TS and transferred to the APES buffer, and the PES size information added to the PES header. It is the flowchart which showed the processing example in the case of a case.
First, in step 1 of FIG. 4, TS header information is analyzed to check whether the head of the PES packet is included in TS. In the MPEG2 standard, when the Payload_unit_start_indicator (hereinafter PUSI) flag is 1, it is determined to indicate the head of the PES packet. When the TS analysis unit 302 detects PUSI = 1 in the header information of the TS packet, the TS analysis unit 302 determines that the head of the PES packet is included in the corresponding TS, and proceeds to step 2.

In step 2, it is determined whether the PES header is the head of an audio PES packet. The MPEG2 standard stipulates that an audio PES packet should be included when packet_start_code_prefix == 0x000001 and stream_id == 0xC *. If both of these conditions are met, the audio PES packet is determined to be the start position. Go to step 3.
In step 3, the PES size information is extracted from the PES_packet_length information of the PES header and held. The data size of the PES packet is variable, and it is determined that 2-byte size information is added to the PES header. The maximum size of the PES packet is 64 Kbytes.
When all the above conditions of Step 1 to Step 3 are satisfied, the TS analysis unit 302 starts counting up the total size of the audio PES data output to the APES buffer 105.

The TS analysis unit 302 checks whether or not the head of the next PES packet is included by checking whether or not the head of the PES packet is included according to the processing procedure of Step 1 to Step 3 for all the TS packets that are input. If it is determined that the transfer size of the PES data output to the APES buffer 105 is counted, the transfer size count of the PES data is stopped.
FIG. 5 and FIG. 6 are flowcharts showing an example of processing when a mismatch occurs between the PES transfer size and the PES Length information.
If the PES packet size held in step 3 and the total size of the PES output to the APES buffer 105 do not match, the TS analysis unit 302 actually outputs the PES header information PES_packet_length to the APES buffer on the APES buffer 105. The transfer size of the payload is rewritten (FIG. 5).

Furthermore, if the transfer size to the APES buffer and PES Length information in the PES header continue to be mismatched N times or more, data corruption occurs frequently in the transmission path, and abnormal noise occurs when AUDIO decoding is performed. Then, the audio volume information included in the PES header is rewritten and the audio is muted. For example, in the case of MPEG2-AAC, processing such as rewriting the gain information of AUDIO added to the ADTS header to make the volume zero (FIG. 6) can be considered.
With the configuration as described above, in the digital broadcast receiving apparatus of the present invention, between the PES header data garble that occurred in the middle of the transmission path, the length information of the PES header and the data size actually transferred to the decoder Inconsistency does not occur in the audio signal, so that the deterioration of the audio quality can be reduced.

  Also, since the TS header and PES header are analyzed and the header information is rewritten in units of PES packets, it is possible to adjust the audio level etc. in units of PES packets according to garbled data in the transmission path or data loss. It becomes possible.

(Embodiment 2)
Next, Embodiment 2 of the digital broadcast receiving apparatus to which the present invention is applied is shown in FIG.
FIG. 7 shows the case of the second embodiment with respect to the part of FIG. 2 in the configuration example 1, and all the configurations except the TS analysis unit 402 and the PES buffer control unit 409 are the same as those of the first embodiment. Since it is the same as that, it is omitted. The PES data count method for detecting the PES header and outputting it to APES is the same as in the first embodiment.
Hereinafter, the processing in the second embodiment will be described. The TS analysis unit 402 outputs the APES buffer write pointer WP and the APES buffer boundary pointer BP to the PES buffer control unit 409.
At this time, the TS analysis unit 402 inputs the write pointer WP to the boundary pointer BP when the transfer size of the PES packet reaches the PES Length, and writes the write to the boundary pointer BP when the transfer size does not reach the PES Length. Do not input the pointer WP.
The PES buffer control unit 409 transmits the reception boundary pointer BP from the TS analysis unit 402 to the AUDIO decoding unit 107. Upon receiving the APES buffer boundary pointer, the AUDIO decoding unit 107 performs APES buffer decoding processing, updates the read pointer RP, and notifies the PES buffer control unit.
The PES buffer control unit 409 checks the remaining free space of the APES buffer 105 based on the difference between the write re-pointer WP and the read pointer RP, and controls the update of the boundary pointer BP.

That is, the boundary pointer is a pointer used to discard a PES packet that does not reach the PES Length. In the second embodiment, a TS packet including the head of the next PES is input without reaching the PES Length. In this case, the PES packet being processed is output to the APES buffer. However, since the boundary pointer is not updated, the next PES packet is overwritten and discarded.
FIG. 8 shows the relationship between the TS packet input to the TS buffer 301, the write pointer WP output from the TS analysis unit 104, and the boundary pointer BP input to the TS analysis unit 104. FIG. 8 is a diagram in the case where two TS packets are input as in FIG. 3, the PES Length added to the PES header is 300 bytes, and the first TS packet includes a payload of 184 bytes. The second packet contains a 116-byte payload.

  In this embodiment, when two packets shown in FIG. 8 are input, the TS analysis unit 402 updates the write pointer WP of the APES buffer 184 when the first TS packet is input, and the boundary pointer remains 0. . When the second packet is input, the write pointer is updated by 116, and since the payload size reaches 300 bytes of the PES Length, the write pointer value 300 (= 184 + 116) is input to the boundary pointer.

  Next, FIG. 9 and FIG. 10 show two cases where the PES Length and the payload transfer size do not match. FIG. 9 shows a case where the PES data transferred to the APES buffer is larger than the PES Length, and FIG. 10 shows a case where the PES data transferred to the APES buffer is smaller than the PES Length.

  In this embodiment, when the two packets shown in FIG. 9 are input, the TS analysis unit 402 updates the write pointer WP of the APES buffer by 184 when the first TS packet is input, and the boundary pointer remains 0. . When the second packet is input, the write pointer is updated by 116, and since the payload size reaches 300 bytes of the PES Length, the write pointer value 300 (= 184 + 116) is input to the boundary pointer. Therefore, 4 bytes of PES data are not transferred.

  When the two packets shown in FIG. 10 are input, when the first TS packet is input, the TS analysis unit 302 updates the write pointer WP of the APES buffer by 100 and the boundary pointer remains 0. When the second packet is input, PUSI = 1 and it is determined that the PES packet starts, and the write pointer 100 is reset to zero. Therefore, PES packets that do not reach the PES Length are discarded.

  With the configuration as described above, in the digital broadcast receiving apparatus of the present invention, when a TS packet including the head of the next PES is input without reaching the length of the PES, the PES packet being processed is displayed as an APES buffer. However, because the boundary pointer is not updated, the next PES packet is overwritten and discarded. Since no mismatch occurs between the data sizes transferred to the decoder, it is possible to reduce the deterioration of the audio quality.

  The transport stream processing apparatus according to the present invention can be used in a digital broadcast receiving apparatus that receives a transport stream, a hard disk processing apparatus that records / reproduces a transport stream, a network processing apparatus, and the like.

101 tuner / demodulation unit 102 TS header analysis unit 103 PID filter unit 104 TS processing unit 105 APES buffer 106 VPES buffer 107 AUDIO decode unit 108 VIDEO decode unit 109 PES buffer control unit 301 TS buffer 302 TS analysis unit

Claims (4)

A digital broadcast receiving device comprising a data processing device for analyzing and processing a transport stream, and a data decoding means for decoding output data of the data processing device,
Analyzing means for analyzing the PES packet included in the transport stream;
A digital broadcast receiving apparatus comprising means for rewriting data of a PES packet in accordance with an analysis result of the analysis means. In the data processing device for analyzing the transport stream,
Means for calculating the size of the video or audio payload from the header information of the transport stream;
In the analysis means for analyzing the PES packet, comprising means for extracting the size of the PES data added to the header information of the PES,
2. The digital broadcast receiving apparatus according to claim 1, further comprising means for rewriting header information of a PES packet by comparing the payload size with the data size of the PES. In the means for rewriting the header information of the PES packet by comparing the payload size with the data size of the PES, if the comparison result does not match, and the number of mismatches exceeds a certain threshold, the audio PES packet The digital broadcast receiving apparatus according to claim 2, wherein the volume information added to the header information is rewritten. A digital broadcast receiving apparatus comprising means for processing a transport stream and data decoding means for decoding output data of the transport stream,
Analyzing means for analyzing the PES packet included in the transport stream;
A digital broadcast receiving apparatus comprising means for discarding data of a PES packet according to an analysis result of the analysis means.