JP5700853B2 - Digital data recording / reproducing device - Google Patents

Description

  The present invention relates to a digital data recording / reproducing apparatus that re-encodes an encoded AV (Audio Visual) stream.

(Description of direct recording and re-encoded recording in the recording / reproducing apparatus)
In recent years, digital data recording / reproducing apparatuses that receive and reproduce a stream (AV (Audio Visual) data) according to digital television broadcasting and record the received AV data on a storage medium have become widespread. The storage medium is an HDD (Hard Disk Drive), a BD (Blu-ray Disc), a DVD (Digital Versatile Disc), or the like. Hereinafter, the digital data recording / reproducing apparatus is also simply referred to as a recording / reproducing apparatus.

  When recording AV data received by the recording / reproducing apparatus, there are two types of recording methods if classified according to the handling of the data to be recorded.

  One is a method of recording received data as it is (hereinafter referred to as recording method A). The recording method A has an advantage that recording can always be performed with broadcast quality, but has a disadvantage that the data size cannot be arbitrarily adjusted during recording.

  The other is a method of decoding received data once and then re-encoding and recording the re-encoded stream (hereinafter referred to as recording method B). The recording method B has an advantage that the data size at the time of recording can be adjusted, but has a disadvantage that the quality of video and audio is deteriorated as compared with the time of broadcasting.

  Many consumer recording / reproducing apparatuses are equipped with functions of both recording methods A and B so that the recording methods A and B can be switched according to the purpose of the user.

(Description of dubbing operation)
Further, some recording / reproducing apparatuses have a function of re-encoding and recording data recorded on a storage medium instead of re-encoding received broadcast data.

  For example, AV data may be recorded on a DVD medium in a DVD-Video standard format for playback on a DVD player or the like. The stream format adopted in digital television broadcasting is MPEG-2 TS (Transport Stream), but the stream format adopted in DVD-Video is MPEG-2 PS (Program Stream), and conversion of the stream format is possible. I need it.

  Patent Document 1 discloses a technique (hereinafter referred to as Conventional Technology A) for converting MPEG-TS format data into MPEG-PS format data.

  In addition, since the number of recorded pixels of video data and the compression format (encoding format) of audio data differ between digital television broadcasting and the DVD-Video standard, data conversion by re-encoding is necessary.

  Another reason for the conversion is the data size. By recording at a low bit rate (data size per video unit time), the data size can be reduced, and a longer video can be recorded on a storage medium having a limited storage capacity.

(Explanation of AV synchronization when re-encoding)
When re-encoding is performed, it is necessary to process video data and audio data separately. Therefore, AV separation is performed once, video data and audio data are each decoded, re-encoded, and then multiplexed. In order to prevent the video data and the audio data from deviating when multiplexed, the following processing is performed.

  First, using the synchronization information attached to the stream, AV synchronization at the time of decoding is aligned. Here, AV synchronization is synchronization of video data and audio data. Further, aligning AV synchronization or synchronizing AV synchronization means processing video data and audio data in synchronization. Furthermore, at the timing when the video data and the audio data are synchronized, the decoded video data and the decoded audio data are supplied to the video encoding unit and the audio encoding, respectively.

  The reason why it is necessary to align AV synchronization will be described. When receiving a digital television broadcast, there may be a situation in which one or both of video data and audio data cannot be normally decoded (hereinafter also referred to as an abnormal decoding situation). An abnormal decoding situation occurs, for example, when a part of data is lost due to some kind of failure such as poor reception of radio waves.

  When AV data decoded in a decoding abnormal situation is reproduced without considering synchronization in a recording / reproducing apparatus, a state in which video data and audio data are not synchronized, so-called sound deviation occurs.

  Similarly, if AV data decoded in a decoding abnormality situation is re-encoded and multiplexed without considering synchronization in the recording / reproducing apparatus, an AV stream that is out of synchronization is generated. If AV synchronization information is included in each of the video data and audio data of the stream before decoding, even if the data is missing at the time of decoding, the video data and audio data are synchronized, Playback and re-encoding can be performed.

  In addition to data loss due to a failure, for example, when editing is performed such that AV data is partially divided and combined and then re-encoded, video data and audio data may be misaligned. This is because the unit time constituting the video data is different from the unit time constituting the audio data. However, even in such a case, it is possible to prevent synchronization loss using AV synchronization information.

(Explanation of AV synchronization during playback and re-encoding)
In an MPEG-2 TS or MPEG-2 PS AV stream, PTS (Presentation Time Stamp) as time information is indicated in the headers of a plurality of PES (Packetized Elementary Stream) packets constituting the stream.

  PTS shows the display time (display timing) of each of video data and audio data. By using PTS, even if each video data and audio data is individually decoded, video data and audio data are output to an AV output device (TV or AV amplifier) according to this time information. It is possible to synchronize during playback.

  The system reference time for taking the output timing is referred to as STC (System Time Clock). The STC is a counter whose value is counted up every time a predetermined time elapses.

  In the following, video PTS is also referred to as VPTS. In the following, the audio PTS is also referred to as APTS.

  By controlling the decoding unit so that the video data and the audio data are output at the timing when each of the VPTS and the APTS matches the STC value, the AV synchronization is achieved between the video data and the audio data. It becomes a state.

  Each of the decoded video data and audio data is temporarily stored in a corresponding output buffer, and then transmitted from each buffer by the video output unit and the audio output unit.

  The video output unit and the audio output unit output data in synchronization with a clock supplied from a common clock generation unit. Therefore, at the time of reproduction, the video data and the audio data are synchronized.

  In the case of re-encoding, each of the video data and the audio data sent by the video output unit and the audio output unit is stored in the corresponding encoding unit buffer.

  Each of the video encoding unit and the audio encoding unit sequentially encodes the data supplied to the corresponding encoding unit buffer, and stores the re-encoded stream in the corresponding encoding output buffer.

  The AV multiplexing unit multiplexes the video stream stored in one encoded output buffer and the audio stream stored in the other encoded output buffer to generate an MPEG-2 PS or TS stream. . As described above, since AV synchronization at the time of input to encoding is achieved, a stream generated after re-encoding is also synchronized with AV.

Japanese Patent Laid-Open No. 2003-111023

  However, in the related art A, re-encoding is performed in real time on the stream being reproduced. Therefore, in the case where re-encoding is performed while processing video data and audio data in synchronization using the conventional technique A, the time required for re-encoding is almost the same as the playback time of the stream. That is, the re-encoding speed is fixed.

  Because the re-encoding speed is fixed, for example, when re-encoding needs to be performed at high speed, or when re-encoding needs to be performed at low speed in order to reduce the power consumption of the device, it is flexible. There is a problem that it can not cope with.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to make it possible to change the re-encoding speed of a stream while processing video data and audio data synchronously. A digital data recording / reproducing apparatus having

  In order to solve the above-described problem, a digital data recording / reproducing apparatus according to an aspect of the present invention is configured such that a first video bit stream and audio data generated by encoding video data are encoded. The first AV (Audio Visual) bit stream in which the generated first audio bit stream is multiplexed is processed. The digital data recording / reproducing apparatus has at least two types of operation modes, the first video bitstream includes video synchronization information, the first audio bitstream includes audio synchronization information, and the video Each of the synchronization information and the audio synchronization information is information for processing the video data and the audio data in synchronization.

  The digital data recording / reproducing apparatus includes an AV separation unit that extracts the first video bit stream and the first audio bit stream from the first AV bit stream, and the digital video recording / playback device from the first video bit stream. A video synchronization information extraction unit that extracts video synchronization information, an audio synchronization information extraction unit that extracts the audio synchronization information from the first audio bitstream, and the video data by decoding the first video bitstream A video decoding unit for outputting the video data, an audio decoding unit for acquiring the audio data by decoding the first audio bitstream, and outputting the audio data, Synchronize video data and audio data A clock generation unit that generates an AV synchronization clock for processing; and an AV synchronization control unit that performs control for processing the video data and the audio data in synchronization with each other. The AV synchronization control unit includes: The output timing of the video data by the video decoding unit and the output timing of the audio data by the audio decoding unit are synchronized using the video synchronization information, the audio synchronization information, and the AV synchronization clock. The video decoding unit and the audio decoding unit are controlled.

  The digital data recording / reproducing apparatus further includes a video output unit that outputs the video data in synchronization with a video output clock synchronized with the AV synchronization clock, and an audio output clock synchronized with the AV synchronization clock. An audio output unit that outputs the audio data, a video encoding unit that generates a second video bitstream by encoding the video data output from the video output unit, and an output from the audio output unit An audio encoding unit that generates a second audio bitstream by encoding the audio data, and a second by multiplexing the second video bitstream and the second audio bitstream. Multiplexing to generate AV bitstreams With the door, the clock generating unit further, depending on the type of the operation mode of the digital data recording and reproducing apparatus, changes the speed of the AV synchronization clock.

  That is, the AV synchronization control unit controls the video decoding unit and the audio decoding unit so that the output timing of the video data by the video decoding unit is synchronized with the output timing of the audio data by the audio decoding unit. Control.

  That is, video data and audio data are processed in synchronization.

  The video decoding unit acquires video data by decoding the first video bit stream multiplexed into the first AV bit stream, and the audio decoding unit is multiplexed into the first AV bit stream. Audio data is obtained by decoding the first audio bitstream.

  The video data and audio data are encoded by the video encoding unit and the audio encoding unit, respectively. As a result, a second video bit stream and a second audio bit stream are generated.

  That is, the video decoding unit, the audio decoding unit, the video encoding unit, and the audio encoding unit decode the stream and encode the data obtained by the decoding. That is, re-encoding is performed on the stream.

  The clock generation unit changes the speed of the AV synchronization clock according to an operation mode. The video output unit outputs the video data in synchronization with the video output clock synchronized with the AV synchronization clock. The audio output unit outputs the audio data in synchronization with the audio output clock synchronized with the AV synchronization clock.

  Therefore, the output timing of video data and audio data changes with the change in the speed of the AV synchronization clock. That is, the timing at which the video encoding unit and the audio encoding unit encode the video data and the audio data, respectively, changes. That is, the re-encoding speed of the stream is changed with the change of the speed of the AV synchronization clock.

  As described above, it is possible to change the re-encoding speed of the stream while processing the video data and the audio data in synchronization.

  Preferably, the digital data recording / reproducing apparatus decodes the first AV bitstream as the operation mode and the first AV bitstream, and obtains the first AV bitstream by decoding. A second mode for encoding the received data, and the clock generation unit determines a speed of the AV synchronization clock generated when the operation mode of the digital data recording / reproducing apparatus is the second mode. The speed of the AV synchronization clock generated when the operation mode of the digital data recording / reproducing apparatus is the first mode is made faster.

  Preferably, each of the video synchronization information, the audio synchronization information, and the AV synchronization clock indicates a value used for control by the AV synchronization control unit, and the value indicated by the AV synchronization clock indicates that time has elapsed. The AV synchronization control unit (a) causes the video decoding unit to output the video data at a timing when the value indicated by the video synchronization information matches the value indicated by the AV synchronization clock. And (b) the audio decoder so that the audio decoder outputs the audio data at a timing when the value indicated by the audio synchronization information matches the value indicated by the AV synchronization clock. Control the decoding unit.

  A digital data recording / reproducing apparatus according to another aspect of the present invention provides a first video bit stream generated by encoding video data and a first audio bit generated by encoding audio data. A first AV (Audio Visual) bit stream in which the stream is multiplexed is processed. The first video bitstream includes video synchronization information, the first audio bitstream includes audio synchronization information, and the digital data recording / reproducing device receives the first AV bitstream from the first AV bitstream. An AV separation unit that extracts the video bit stream and the first audio bit stream, a video synchronization information extraction unit that extracts the video synchronization information from the first video bit stream, and the first audio bit stream An audio synchronization information extraction unit for extracting the audio synchronization information from the video data, a video decoding unit for obtaining the video data by decoding the first video bit stream, and outputting the video data; By decoding the audio bitstream of An audio decoding unit for obtaining audio data and outputting the audio data, an AV synchronization control unit for controlling the video data and the audio data to be processed in synchronization, and the video decoding unit decoding An alternative video data generation unit that generates alternative video data that is an alternative to the decoded video data that is video data acquired by the method, and an alternative that is an alternative to the decoded audio data that is the audio data that the audio decoding unit acquires by decoding An alternative audio data generation unit that generates audio data; a video encoding unit that generates a second video bitstream by encoding the decoded video data or the alternative video data; and the decoded audio data or the By encoding alternative audio data An audio encoding unit that generates two audio bitstreams, and an AV multiplexing unit that generates the second AV bitstream by multiplexing the second video bitstream and the second audio bitstream; Is provided.

  Each of the video synchronization information and the audio synchronization information is information for controlling the video encoding unit and the audio encoding unit, and the AV synchronization control unit includes the video synchronization information, the audio synchronization information, And (a) according to the comparison result, the decoded video data and the encoded video data and the timing at which the video encoding unit performs encoding and the timing at which the audio encoding unit performs encoding are synchronized. The video encoding unit is controlled to cause the video encoding unit to encode any of the alternative video data, and (b) either the decoded audio data or the alternative audio data according to the comparison result The audio encoding unit is controlled so that the audio encoding unit encodes the above.

  That is, the AV synchronization control unit compares the video synchronization information with the audio synchronization information, and the timing at which the video encoding unit performs encoding and the timing at which the audio encoding unit performs encoding are synchronized. (A) controlling the video encoding unit to cause the video encoding unit to encode either the decoded video data or the alternative video data according to the comparison result, and (b) In accordance with the comparison result, the audio encoding unit is controlled to cause the audio encoding unit to encode either the decoded audio data or the alternative audio data.

  That is, video data and audio data are processed in synchronization.

  The video encoding unit and the audio encoding unit encode data (for example, video data) obtained by decoding a stream (for example, the first video bit stream). That is, the video decoding unit, the audio decoding unit, the video encoding unit, and the audio encoding unit re-encode the stream.

  Further, according to this aspect, each of the video decoding unit, the audio decoding unit, the video encoding unit, and the audio encoding unit is not controlled in synchronization with the timing of performing the corresponding processing (encoding, decoding, etc.) . That is, each of the video decoding unit, the audio decoding unit, the video encoding unit, and the audio encoding unit can operate asynchronously.

  Therefore, for example, the speed of re-encoding for a stream can be changed by changing the speed of processing performed by each of the video decoding unit, the audio decoding unit, the video encoding unit, and the audio encoding unit. It becomes.

  As described above, the digital data recording / reproducing apparatus has a configuration capable of changing the re-encoding speed of a stream while processing video data and audio data in synchronization.

  Preferably, each of the video synchronization information and the audio synchronization information indicates a value used for control by the AV synchronization control unit, and the AV synchronization control unit includes a value indicated by the video synchronization information and the audio synchronization information. When a value obtained from the value indicated by the information satisfies a predetermined condition, (c) a process for controlling the video encoding unit to cause the video encoding unit to encode the alternative video data; and (d) One of the processes of controlling the audio encoding unit is performed so that the audio encoding unit encodes the alternative audio data.

  Preferably, the predetermined condition is a condition that an absolute value of a difference between a value indicated by the video synchronization information and a value indicated by the audio synchronization information is a predetermined synchronization threshold value or more, and the AV synchronization control unit (E) When the absolute value is equal to or greater than the synchronization threshold value and the value indicated by the video synchronization information is smaller than the value indicated by the audio synchronization information, the alternative video data is encoded in the video encoding unit. (F) if the absolute value is greater than or equal to the synchronization threshold and the value indicated by the audio synchronization information is smaller than the value indicated by the video synchronization information, The audio encoding unit is controlled to cause the unit to encode the alternative audio data.

  In the present invention, all or some of a plurality of components constituting such a digital data recording / reproducing apparatus may be realized as a system LSI (Large Scale Integration).

  In addition, the present invention may be realized as a digital data recording method in which operations of characteristic components included in the digital data recording / reproducing apparatus are steps. Further, the present invention may be realized as a program that causes a computer to execute each step included in such a digital data recording method. Further, the present invention may be realized as a computer-readable recording medium that stores such a program. The program may be distributed via a transmission medium such as the Internet.

  According to the present invention, it is possible to change the re-encoding speed of a stream while processing video data and audio data in synchronization.

FIG. 1 is a block diagram showing a configuration of a digital data recording / reproducing apparatus according to the first embodiment. FIG. 2 is a block diagram showing a configuration of a digital data recording / reproducing apparatus according to the second embodiment. FIG. 3 is a block diagram showing a characteristic first functional configuration of the digital data recording / reproducing apparatus. FIG. 4 is a block diagram showing a characteristic second functional configuration of the digital data recording / reproducing apparatus.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

<First Embodiment>
(Configuration of digital data recording / reproducing device)
FIG. 1 is a block diagram showing a configuration of a digital data recording / reproducing apparatus 1000 according to the first embodiment. For the sake of explanation, FIG. 1 also shows a storage medium 101 that is not included in the digital data recording / reproducing apparatus 1000.

  The digital data recording / reproducing apparatus 1000 has a normal reproduction mode and a re-encoding mode as operation modes. The normal playback mode is an operation mode for performing a process of reproducing (outputting) an encoded stream (data) by decoding (hereinafter also referred to as a normal playback process). That is, the normal reproduction mode is a first mode for reproducing the AV bit stream.

  The re-encoding mode is an operation mode for performing a process of decoding the encoded stream (data) and re-encoding the decoded data (hereinafter referred to as a re-encoding process). That is, the re-encoding mode is a second mode for decoding the AV bit stream and encoding the data obtained by the decoding.

  When the operation mode of the digital data recording / reproducing apparatus 1000 is the normal reproduction mode, normal reproduction processing is performed. When the operation mode of the digital data recording / reproducing apparatus 1000 is the re-encoding mode, re-encoding processing is performed.

  The digital data recording / reproducing apparatus 1000 is an AV reproducing apparatus such as an HDD recorder. The digital data recording / reproducing apparatus 1000 is not limited to the HDD recorder, and may be any apparatus as long as it has a normal reproduction mode and a re-encoding mode.

  Referring to FIG. 1, a digital data recording / reproducing apparatus 1000 includes an AV separation unit 102, an input video bit stream buffer unit 103, an input audio bit stream buffer unit 104, a video decoding unit 105, and a video output data buffer unit. 106, an audio decoding unit 107, an audio output data buffer unit 108, a video output unit 109, a video encoding input buffer unit 110, an audio output unit 111, and an audio encoding input buffer unit 112.

  The digital data recording / reproducing apparatus 1000 further includes a video encoding unit 113, an encoded video bitstream buffer unit 114, an audio encoding unit 115, an encoded audio bitstream buffer unit 116, and an AV multiplexing unit 117. Is provided.

  The storage medium 101 is a BD (Blu-ray Disc), a DVD (Digital Versatile Disc), or the like.

  The storage medium 101 may be an HDD (Hard Disk Drive) or the like. In this case, the storage medium 101 may be included in the digital data recording / reproducing apparatus 1000.

  In the storage medium 101, an AV bit stream AVST1 to be re-encoded is recorded. The AV bit stream AVST1 is an encoded stream. The AV bit stream AVST1 is a stream in which the video bit stream VST1 and the audio bit stream AST1 are multiplexed according to a predetermined encoding format. The predetermined encoding format is, for example, MPEG-2 TS.

  The predetermined encoding format is not limited to MPEG-2 TS, and may be another encoding format. Each of the video bit stream VST1 and the audio bit stream AST1 is an encoded stream.

  The AV bitstream AVST1 is composed of a plurality of PES (Packetized Elementary Stream) packets. The header of the PES packet indicates PTS (Presentation Time Stamp). PTS is synchronization information used for synchronization processing. The PTS is a counter whose value is counted up every time a predetermined time elapses.

  That is, each of the video bit stream VST1 and the audio bit stream AST1 is composed of a plurality of PESs. That is, each of the video bit stream VST1 and the audio bit stream AST1 includes a plurality of PTSs.

  Hereinafter, the PTS included in the video bitstream VST1 is referred to as VPTS (video synchronization information). In the following, the PTS included in the audio bitstream AST1 is referred to as APTS (audio synchronization information).

  In other words, each of VPTS and APTS is a counter whose value is counted up every predetermined time. Each of VPTS (video synchronization information) and APTS (audio synchronization information) is information for processing video data and audio data in synchronization.

  The video bit stream VST1 is a stream generated by encoding the video data VD1 according to a predetermined moving image encoding format. The moving image encoding format is, for example, MPEG2 TS. The video data VD1 is moving image data. That is, the video bit stream VST1 as the first video bit stream includes VPTS (video synchronization information).

  Note that the moving image encoding format is not limited to MPEG2 TS, and may be other encoding formats.

  The audio bit stream AST1 is a stream generated by encoding the audio data AD1 according to a predetermined audio encoding format. The audio encoding format is AAC (Advanced Audio Coding). The audio data AD1 is audio data. That is, the audio bit stream AST1 as the first audio bit stream includes APTS (audio synchronization information).

  Note that the audio encoding format is not limited to AAC, and may be another audio encoding format.

  The video decoding unit 105 decodes the video bitstream VST1 by performing a decoding process corresponding to the moving image encoding format used for encoding the video bitstream VST1. The moving image encoding format is, for example, MPEG2 TS.

  The audio decoding unit 107 decodes the audio bitstream AST1 by performing a decoding process corresponding to the audio encoding format used for encoding the audio bitstream AST1. The speech encoding format is, for example, AAC.

  The video encoding unit 113 encodes the decoded video data using a video encoding format (hereinafter referred to as a video re-encoding format) different from the video encoding format used for encoding the video bitstream VST1. Turn into. The moving image re-encoding format is, for example, MPEG2 PS.

  Note that the moving image re-encoding format is not limited to MPEG2 PS, and may be another encoding format (for example, H.264 / AVC).

  The video encoding unit 113 changes the encoding condition (for example, bit rate) according to the same video encoding format as the video encoding format used for encoding the video bitstream VST1, and performs encoding. Processing may be performed.

  The audio encoding unit 115 encodes the decoded audio data according to an audio encoding format (hereinafter referred to as an audio re-encoding format) different from the audio encoding format used for encoding the audio bitstream AST1. The audio re-encoding format is, for example, MPEG2 PS.

  Note that the audio re-encoding format is not limited to MPEG2 PS, and may be another encoding format (for example, AAC (Advanced Audio Coding)).

  The audio encoding unit 115 changes the encoding condition (for example, bit rate) according to the same audio encoding format used for encoding the audio bitstream AST1, and performs encoding processing. You may go.

  Details of processing performed by each of the video output unit 109 and the audio output unit 111 will be described later. In the normal reproduction process, each of the video output unit 109 and the audio output unit 111 outputs the processed data to a processing unit (not shown). In the normal playback process, a data processing path (hereinafter referred to as a normal playback path) from the AV separation unit 102 to the video output unit 109 and the audio output unit 111 is formed.

  In the re-encoding process, the video output unit 109 and the audio output unit 111 output the processed data to the video encoding input buffer unit 110 and the audio encoding input buffer unit 112, respectively. In the re-encoding process, a data processing path (hereinafter referred to as a re-encoding process path) from the AV separation unit 102 to the AV multiplexing unit 117 is formed.

  The re-encoding processing path includes a normal reproduction path. That is, the normal playback path is shared in the normal playback process and the re-encoding process.

  Input video bit stream buffer unit 103, input audio bit stream buffer unit 104, video output data buffer unit 106, audio output data buffer unit 108, video encoding input buffer unit 110, audio encoding input buffer unit 112, encoded video bits Each of the stream buffer unit 114 and the encoded audio bitstream buffer unit 116 is a buffer for temporarily storing data.

  The processes of the AV separation unit 102 and the AV multiplexing unit 117 will be described later.

  The digital data recording / reproducing apparatus 1000 further includes a video synchronization information extraction unit 118, an audio synchronization information extraction unit 119, an AV synchronization control unit 120, and a clock generation unit 121.

  Processing performed by each of the video synchronization information extraction unit 118, the audio synchronization information extraction unit 119, the AV synchronization control unit 120, and the clock generation unit 121 will be described later.

(Description of AV data path (re-encoding processing path) in re-encoding process)
Next, the flow of re-encoding processing will be described with reference to FIG.

  In the re-encoding process, first, the AV separation unit 102 reads the AV bit stream AVST1 stored in the storage medium 101. The AV separation unit 102 extracts the video bit stream VST1 and the audio bit stream AST1 from the AV bit stream AVST1.

  The AV separation unit 102 stores the video bitstream VST1 in the input video bitstream buffer unit 103 and also stores the audio bitstream AST1 in the input audio bitstream buffer unit 104.

  The video decoding unit 105 acquires the video data VD1 by decoding the video bitstream VST1 stored in the input video bitstream buffer unit 103 according to the control described later by the AV synchronization control unit 120. The video data VD1 is decoded video data.

  The video decoding unit 105 then outputs the video data VD1 and stores the video data VD1 in the video output data buffer unit 106 in accordance with the control described later by the AV synchronization control unit 120.

  In parallel with the processing of the video decoding unit 105, the audio decoding unit 107 decodes the audio bitstream AST1 stored in the input audio bitstream buffer unit 104 according to the control of the AV synchronization control unit 120 described later, thereby Data AD1 is acquired. The audio data AD1 is decoded audio data.

  Then, the audio decoding unit 107 outputs the audio data AD1 and stores the audio data AD1 in the audio output data buffer unit 108 according to control described later by the AV synchronization control unit 120.

  The video output unit 109 reads out and outputs the video data VD1 stored in the video output data buffer unit 106, and stores the video data VD1 in the video encoding input buffer unit 110. That is, the video data VD 1 is transferred from the video output data buffer unit 106 to the video encoding input buffer unit 110 by the video output unit 109.

  The audio output unit 111 reads out and outputs the audio data AD1 stored in the audio output data buffer unit 108, and causes the audio encoding input buffer unit 112 to store the audio data AD1. That is, the audio data AD1 is transferred from the audio output data buffer unit 108 to the audio encoding input buffer unit 112 by the audio output unit 111.

  The video encoding unit 113 generates the video bit stream VST2 by encoding the video data VD1 stored in the video encoding input buffer unit 110. That is, the video encoding unit 113 generates the video bit stream VST2 as the second video bit stream by encoding the video data VD1 output from the video output unit 109.

  That is, the video encoding unit 113 re-encodes the video data VD1 obtained by decoding.

  Then, the video encoding unit 113 stores the video bit stream VST2 in the encoded video bit stream buffer unit 114.

  The audio encoding unit 115 generates an audio bitstream AST2 by encoding the audio data AD1 stored in the audio encoding input buffer unit 112. That is, the audio encoding unit 115 generates the audio bit stream AST2 as the second audio bit stream by encoding the audio data AD1 output from the audio output unit 111.

  That is, the audio encoding unit 115 re-encodes the audio data AD1 obtained by decoding.

  Then, the audio encoding unit 115 stores the audio bitstream AST2 in the encoded audio bitstream buffer unit 116.

  The AV multiplexing unit 117 multiplexes the video bit stream VST2 stored in the encoded video bitstream buffer unit 114 and the audio bitstream AST2 stored in the encoded audio bitstream buffer unit 116. The AV bit stream AVST2 is generated.

  The AV multiplexing unit 117 performs multiplexing according to a format such as MPEG-2, for example. Then, the AV multiplexing unit 117 stores the AV bit stream AVST2 in the storage medium 101.

  Through the above re-encoding process, the video data VD1 and audio data AD1 included in the AV bitstream AVST1 are re-encoded.

(Description of AV synchronization)
In the re-encoding process described above, AV synchronization using synchronization information (PTS) will be described.

  The video synchronization information extraction unit 118 extracts VPTS as video synchronization information from the video bit stream VST 1 stored in the input video bit stream buffer unit 103, and transmits the VPTS to the AV synchronization control unit 120.

  In addition, the audio synchronization information extraction unit 119 extracts APTS as audio synchronization information from the audio bitstream AST1 stored in the input audio bitstream buffer unit 104, and transmits the APTS to the AV synchronization control unit 120.

  The clock generation unit 121 generates an AV synchronization clock AVCK for processing video data and audio data in synchronization, and transmits the AV synchronization clock AVCK to the AV synchronization control unit 120. The AV synchronization clock AVCK is a counter whose value increases every elapse of a predetermined time. That is, the value indicated by the AV synchronization clock AVCK increases with time. The AV synchronization clock AVCK plays a role of STC (System Time Clock) at the time of data reproduction (decoding).

  That is, each of VPTS (video synchronization information), APTS (audio synchronization information), and AV synchronization clock AVCK indicates a value that AV synchronization control section 120 uses for control.

  The AV synchronization control unit 120 performs control for processing the video data VD1 and the audio data AD1 in synchronization. Specifically, the AV synchronization control unit 120 uses the VPTS (video synchronization information), APTS (audio synchronization information), and AV synchronization clock AVCK to output the video data VD1 by the video decoding unit 105 and the audio decoding. The video decoding unit 105 and the audio decoding unit 107 are controlled so that the output timing of the audio data AD1 by the unit 107 is synchronized.

  More specifically, the AV synchronization control unit 120 causes the video decoding unit 105 to output the video data VD1 at a timing when the value indicated by VPTS (video synchronization information) matches the value indicated by the AV synchronization clock AVCK. The video decoding unit 105 is controlled.

  In addition, the AV synchronization control unit 120 performs the audio decoding so that the audio decoding unit 107 outputs the audio data AD1 at the timing when the value indicated by APTS (audio synchronization information) matches the value indicated by the AV synchronization clock AVCK. The unit 107 is controlled.

  For example, when the audio bitstream AST1 is abnormal and the value of APTS is a large value that deviates from the value of the AV synchronization clock AVCK, the value of the AV synchronization clock AVCK increases until it matches the value of APTS. The AV synchronization control unit 120 causes the audio decoding unit 107 to stop the decoding process.

  For example, when the APTS value is a small value that deviates from the value of the AV synchronization clock AVCK, the AV synchronization control unit 120 skips the audio decoding unit 107 without decoding all the audio bitstreams AST1. By controlling the audio decoding unit 107 to (skip), the value of the APTS of the audio bitstream AST1 is increased to the value of the AV synchronization clock AVCK.

  Even when the VPTS value of the video bitstream VST1 is abnormal, the AV decoding control unit 120 performs the same control as the above control performed on the audio decoding unit 107 on the video decoding unit 105.

  When the AV synchronization control unit 120 performs the above-described control, even when the AV bit stream before re-encoding has a defect and cannot normally acquire the PTS, when the normal AV bit stream is input, AV synchronization can be restored.

(Description of AV output unit)
The video output unit 109 and the audio output unit 111 are used in common with the output unit for reproduction. The clock generation unit 121 supplies the same clock generated from the same clock generation source to the video output unit 109 and the audio output unit 111. The clock generation source is, for example, a crystal resonator.

  Hereinafter, a clock supplied from the clock generation unit 121 to the video output unit 109 is referred to as a video clock VCK. In the following, the clock supplied from the clock generation unit 121 to the audio output unit 111 is referred to as an audio clock ACK.

  The clock generation unit 121 generates the AV synchronization clock AVCK, which is a clock synchronized with the video clock VCK and the audio clock ACK. That is, the AV synchronization clock AVCK generated by the clock generation unit 121 is a clock synchronized with the video clock VCK and the audio clock ACK.

  The video output unit 109 reads out and outputs the video data VD1 stored in the video output data buffer unit 106 according to the video clock VCK, and outputs the video data VD1 to the video encoding input buffer unit. 110 is stored.

  The audio output unit 111 reads out and outputs the audio data AD1 stored in the audio output data buffer unit 108 according to the audio clock ACK, and outputs the audio data AD1 to the audio encoding input buffer unit. 112 is stored.

  When the video decoding unit 105 and the audio decoding unit 107 normally perform decoding processing, the video data VD1 and the audio data AD1 are output almost simultaneously. That is, in this case, the video data VD1 and the audio data AD1 are output in synchronization.

  That is, the video output unit 109 outputs the decoded data (video data VD1) and stores the video data VD1 in the video encoding input buffer unit 110 when the decoding process by the video decoding unit 105 is normally performed. Let

  On the other hand, when the decoding process by the video decoding unit 105 is stopped under the control of the AV synchronization control unit 120, the video output unit 109 outputs alternative video data. The alternative video data is, for example, data of the last video frame (latest video frame) before the decoding process is stopped.

  That is, the audio output unit 111 outputs decoded data (audio data AD1) when the decoding process by the audio decoding unit 107 is normally performed, and stores the audio data AD1 in the audio encoding input buffer unit 112. Let

  On the other hand, when the decoding process by the audio output unit 111 is stopped by the control by the AV synchronization control unit 120, the audio output unit 111 outputs alternative audio data. The alternative audio data is, for example, silence data.

  Thereby, data is always output from each of the video output unit 109 and the audio output unit 111. Thus, if the data is being decoded, the AV synchronization state is maintained. Accordingly, each of the video encoding unit 113 and the audio encoding unit 115 can maintain (synchronize) the AV synchronization only by sequentially encoding the supplied data without considering the AV synchronization.

(Description of configuration capable of realizing high-speed re-encoding processing)
In the configuration of the digital data recording / reproducing apparatus 1000 in FIG. 1 described above, in order to perform re-encoding at high speed, data processing in each unit constituting the re-encoding processing path needs to be performed at high speed. These units are an AV separation unit 102, a video decoding unit 105, an audio decoding unit 107, a video output unit 109, an audio output unit 111, a video encoding unit 113, an audio encoding unit 115, and an AV multiplexing unit 117.

  Of the above units, the AV demultiplexing unit 102 and the AV multiplexing unit 117 do not require complicated arithmetic processing as compared with encoding processing and decoding processing, and therefore are excluded from the system bottlenecks. be able to.

  Since the video decoding unit 105 and the video encoding unit 113 require complicated arithmetic processing on video data, the video decoding unit 105 and the video encoding unit 113 are configured by a high-speed arithmetic device or a circuit dedicated to arithmetic operations. Just do.

  In addition, since the audio decoding unit 107 and the audio encoding unit 115 require complicated arithmetic processing on audio data, the audio decoding unit 107 and the audio encoding unit 115 are high-speed arithmetic devices or circuits dedicated to arithmetic operations. What is necessary is just to comprise.

  Accordingly, high-speed re-encoding processing can be performed in accordance with the processing capabilities of the video decoding unit 105, audio decoding unit 107, audio decoding unit 107, and audio encoding unit 115 while maintaining AV synchronization.

  When the re-encoding process is performed, the AV synchronization clock AVCK, the video clock VCK, and the audio clock ACK generated by the clock generation unit 121 are faster than the clocks used in the normal reproduction process (frequency Clock).

  That is, the clock generation unit 121 generates different clocks in each of the normal reproduction process and the re-encoding process. That is, when the process performed by the digital data recording / reproducing apparatus 1000 is switched from the normal reproduction process to the re-encoding process, the clock generated by the clock generation unit 121 is switched to a faster clock.

  In other words, the clock generation unit 121 determines the speed of the AV synchronization clock AVCK generated when the operation mode of the digital data recording / reproducing apparatus 1000 is the re-encoding mode as the second mode. When the operation mode is the normal reproduction mode as the first mode, the speed is higher than the speed of the AV synchronization clock AVCK generated.

  That is, the clock generation unit 121 uses the frequency of the AV synchronization clock AVCK generated when the operation mode of the digital data recording / reproducing apparatus 1000 is the re-encoding mode as the second mode as the operation of the digital data recording / reproducing apparatus 1000. The frequency is higher than the frequency of the AV synchronization clock AVCK generated when the mode is the normal reproduction mode as the first mode.

  Accordingly, in the re-encoding process, each of the video decoding unit 105 and the audio decoding unit 107 can speed up the decoding of the corresponding data faster than the decoding process speed in the normal reproduction process. As a result, in the re-encoding process, each of the video output unit 109 and the audio output unit 111 can increase the speed at which the corresponding data is output as compared with the normal reproduction process. Accordingly, each of the video encoding unit 113 and the audio encoding unit 115 can increase the speed at which the corresponding data is re-encoded.

  Note that the clock generation unit 121 generates the speed of the AV synchronization clock AVCK that is generated when the operation mode of the digital data recording / reproducing apparatus 1000 is the re-encoding mode, when the operation mode is the normal reproduction mode. The speed may be slower than the speed of the AV synchronization clock AVCK. Thereby, the power consumption of the digital data recording / reproducing apparatus 1000 when the re-encoding process is performed can be reduced.

  That is, the clock generation unit 121 changes the speed (frequency) of the AV synchronization clock AVCK according to the type of operation mode of the digital data recording / reproducing apparatus 1000.

  As described above, in the re-encoding process of the present embodiment, each of the video output unit 109 and the audio output unit 111 is operated using a clock faster than the clock used for the normal reproduction process.

  Therefore, the re-encoding speed of the stream can be increased while processing the video data and the audio data in synchronization. That is, it is possible to change the re-encoding speed of a stream while processing video data and audio data in synchronization.

  As described above, in the re-encoding process, the above-described normal reproduction path used for the normal reproduction process is used. That is, the normal playback path is shared in the normal playback process and the re-encoding process.

  Therefore, according to the digital data recording / reproducing apparatus 1000 of the present embodiment, a high-speed re-encoding process can be realized with a slight change in the configuration of the recording / reproducing apparatus shown in the prior art. .

<Second Embodiment>
(Configuration of digital data recording / reproducing device)
FIG. 2 is a block diagram showing a configuration of a digital data recording / reproducing apparatus 1000A according to the second embodiment. 2 also shows a storage medium 101 not included in the digital data recording / reproducing apparatus 1000A for the sake of explanation.

  Compared with the digital data recording / reproducing apparatus 1000 in FIG. 1, the digital data recording / reproducing apparatus 1000A includes a video decoding unit 105, an audio decoding unit 107, a video encoding unit 113, an audio encoding unit 115, and an AV synchronization control unit 120. Instead, a video decoding unit 105A, an audio decoding unit 107A, a video encoding unit 113A, an audio encoding unit 115A, and an AV synchronization control unit 120A, and an alternative video data generation unit 211 and an alternative audio data generation unit 212 are further provided. The difference is that the video output unit 109, the audio output unit 111, and the clock generation unit 121 are not provided.

  Since the configuration of the other digital data recording / reproducing apparatus 1000A is the same as that of the digital data recording / reproducing apparatus 1000, detailed description will not be repeated.

  The video decoding unit 105A is different from the video decoding unit 105 in that it is not controlled from the outside (for example, the AV synchronization control unit 120A). Other functions of the video decoding unit 105A are the same as those of the video decoding unit 105, and thus detailed description will not be repeated. That is, the video decoding unit 105 </ b> A has a function of performing the same decoding process as the video decoding unit 105.

  The audio decoding unit 107A is different from the audio decoding unit 107 in that it is not controlled from the outside (for example, the AV synchronization control unit 120A). Other functions of the audio decoding unit 107A are the same as those of the audio decoding unit 107, and thus detailed description will not be repeated. That is, the audio decoding unit 107A has a function of performing the same decoding process as the audio decoding unit 107.

  The video encoding unit 113A is different from the video encoding unit 113 in that it is controlled by the AV synchronization control unit 120A. Other functions of the video encoding unit 113A are the same as those of the video encoding unit 113, and thus detailed description will not be repeated. That is, the video encoding unit 113A performs the same encoding process as the video encoding unit 113.

  The audio encoding unit 115A is different from the audio encoding unit 115 in that the audio encoding unit 115A is controlled by the AV synchronization control unit 120A. The other functions of the audio encoding unit 115A are the same as those of the audio encoding unit 115, and thus detailed description will not be repeated. That is, the audio encoding unit 115A performs the same encoding process as the audio encoding unit 115.

  The alternative video data generation unit 211 generates alternative video data. The substitute video data is video data that substitutes for the video data VD1. The alternative video data generation unit 211 constantly monitors the state of the video decoding unit 105A, and generates alternative video data that is in the latest state of the video decoding unit 105A each time the state of the video decoding unit 105A changes. .

  For example, when the decoding process by the video decoding unit 105A is stopped, the alternative video data generation unit 211 generates alternative video data indicating the last video frame (latest video frame) before the decoding process is stopped.

  The alternative audio data generation unit 212 generates alternative audio data. The alternative audio data is audio data that substitutes for the audio data AD1. The alternative audio data generation unit 212 constantly monitors the state of the audio decoding unit 107A, and generates alternative audio data that is in the latest state of the audio decoding unit 107A each time the state of the audio decoding unit 107A changes. .

  For example, when the decoding process by the audio decoding unit 107A is stopped, the alternative audio data generation unit 212 generates alternative audio data that is silent data.

  Similar to the digital data recording / reproducing apparatus 1000, the digital data recording / reproducing apparatus 1000A has a normal reproduction mode and a re-encoding mode as operation modes.

  Hereinafter, the operation mode of the digital data recording / reproducing apparatus 1000A is also referred to as an apparatus operation mode.

  When the apparatus operation mode is the normal reproduction mode, the normal reproduction process A is performed. When the apparatus operation mode is the re-encoding mode, the re-encoding process A is performed.

  In the re-encoding process A, in the digital data recording / reproducing apparatus 1000A, a data processing path (hereinafter referred to as a re-encoding process path A) from the AV separation unit 102 to the AV multiplexing unit 117 is formed.

(Description of AV Data Path (Recoding Process Path A) in Recoding Process A)
In the re-encoding process A, the processes performed by each of the AV demultiplexing unit 102 and the AV multiplexing unit 117 are the same as the processes described in the first embodiment, and thus detailed description will not be repeated. A brief description is given below.

  In the re-encoding process A, first, the AV separation unit 102 reads the AV bit stream AVST1 stored in the storage medium 101. The AV separation unit 102 extracts the video bit stream VST1 and the audio bit stream AST1 from the AV bit stream AVST1.

  The AV separation unit 102 stores the video bitstream VST1 in the input video bitstream buffer unit 103 and also stores the audio bitstream AST1 in the input audio bitstream buffer unit 104.

  The video decoding unit 105A acquires the video data VD1 by decoding the video bitstream VST1 stored in the input video bitstream buffer unit 103. That is, the video data VD1 is decoded video data that is video data acquired by the video decoding unit 105A by decoding.

  Then, the video decoding unit 105A outputs the video data VD1 and stores the video data VD1 in the video output data buffer unit 106.

  The audio decoding unit 107A acquires the audio data AD1 by decoding the audio bitstream AST1 stored in the input audio bitstream buffer unit 104 in parallel with the processing of the video decoding unit 105A. That is, the audio data AD1 is decoded audio data that is audio data acquired by the audio decoding unit 107A by decoding.

  Then, the audio decoding unit 107A outputs the audio data AD1, and stores the audio data AD1 in the audio output data buffer unit 108.

  Hereinafter, the timing at which the video decoding unit 105A outputs the video data VD1 acquired by the above-described decoding process is referred to as a video output timing. In the following, the timing at which the audio decoding unit 107A outputs the audio data AD1 acquired by the above-described decoding process is referred to as an audio output timing.

  The video encoding unit 113A generates the video bit stream VST2 by encoding the video data VD1 stored in the video output data buffer unit 106 or the latest alternative video data according to the control described later by the AV synchronization control unit 120A. To do. That is, the video encoding unit 113A performs a process of re-encoding the video data VD1 obtained by decoding or a process of encoding the latest alternative video data.

  Then, the video encoding unit 113A stores the video bit stream VST2 in the encoded video bit stream buffer unit 114.

  The audio encoding unit 115A generates the audio bit stream AST2 by encoding the audio data AD1 stored in the audio output data buffer unit 108 or the latest alternative audio data according to the control described later by the AV synchronization control unit 120A. To do. That is, the audio encoding unit 115A performs a process of re-encoding the audio data AD1 that has been encoded once, or a process of encoding the latest alternative audio data.

  Then, the audio encoding unit 115A stores the audio bitstream AST2 in the encoded audio bitstream buffer unit 116.

  The AV multiplexing unit 117 multiplexes the video bit stream VST2 stored in the encoded video bitstream buffer unit 114 and the audio bitstream AST2 stored in the encoded audio bitstream buffer unit 116. The AV bit stream AVST2 is generated. The AV multiplexing unit 117 performs multiplexing according to a format such as MPEG-2, for example. Then, the AV multiplexing unit 117 stores the AV bit stream AVST2 in the storage medium 101.

  Through the above re-encoding process A, the video data VD1 and audio data AD1 included in the AV bit stream AVST1 are re-encoded.

(Description of AV synchronization)
In the re-encoding process A described above, AV synchronization using synchronization information (PTS) will be described.

  Since the processing performed by each of the video synchronization information extraction unit 118 and the audio synchronization information extraction unit 119 is the same as the processing described in the first embodiment, detailed description thereof will not be repeated. A brief description is given below.

  The video synchronization information extraction unit 118 extracts VPTS as video synchronization information from the video bitstream VST1 stored in the input video bitstream buffer unit 103, and transmits the VPTS to the AV synchronization control unit 120A.

  Also, the audio synchronization information extraction unit 119 extracts APTS as audio synchronization information from the audio bitstream AST1 stored in the input audio bitstream buffer unit 104, and transmits the APTS to the AV synchronization control unit 120A.

  The AV synchronization control unit 120A performs control for processing video data and audio data in synchronization. Specifically, the AV synchronization control unit 120A compares VPTS (video synchronization information) and APTS (audio synchronization information). Then, the AV synchronization control unit 120A sets the video encoding unit 113A and the audio encoding unit 115A so that the timing at which the video encoding unit 113A performs encoding and the timing at which the audio encoding unit 115A performs encoding are synchronized. Control.

  More specifically, the AV synchronization control unit 120A controls the video encoding unit 113A to cause the video encoding unit 113A to encode either decoded video data or alternative video data according to the comparison result. At the same time, according to the comparison result, the audio encoding unit 115A is controlled to cause the audio encoding unit to encode either the decoded audio data or the alternative audio data.

  That is, each of VPTS (video synchronization information) and APTS (audio synchronization information) is information for controlling the video encoding unit 113A and the audio encoding unit 115A. Each of VPTS (video synchronization information) and APTS (audio synchronization information) indicates a value used for control by the AV synchronization control unit 120A.

  When the value indicated by the received VPTS and the value indicated by the received APTS are greatly different from each other, the AV synchronization control unit 120A issues a control command to the video encoding unit 113A or the audio encoding unit 115A.

  Specifically, the AV synchronization control unit 120A compares the received VPTS value with the received APTS value, and the absolute value of the difference between the VPTS value and the APTS value is equal to or greater than a predetermined synchronization threshold value. If the VPTS value is smaller than the APTS value, a video encoding control command is transmitted to the video encoding unit 113A.

  Here, the synchronization threshold is a value for determining whether or not the video data VD1 and the audio data AD1 are processed in synchronization. If the absolute value of the difference between the value of the VPTS and the value of the APTS is equal to or greater than the synchronization threshold, the video data VD1 and the audio data AD1 are not processed in synchronization, that is, the video output described above This is a case where the timing and the audio output timing described above are shifted.

  The video encoding control instruction is an instruction for causing the video encoding unit 113A to encode the latest alternative video data generated by the alternative video data generation unit 211.

  The AV synchronization control unit 120A compares the received VPTS value with the received APTS value, and the absolute value of the difference between the VPTS value and the APTS value is equal to or greater than a predetermined synchronization threshold value. If the APTS value is smaller than the VPTS value, an audio encoding control command is transmitted to the audio encoding unit 115A. The audio encoding control command is a command for causing the audio encoding unit 115A to encode the latest alternative audio data generated by the alternative audio data generation unit 212.

  In the following, the absolute value of the difference between the VPTS value and the APTS value is also referred to as an absolute value for determination.

  That is, if the determination absolute value is equal to or greater than the synchronization threshold value and the value indicated by VPTS (video synchronization information) is smaller than the value indicated by APTS (audio synchronization information), the AV synchronization control unit 120A The video encoding unit 113A is controlled to encode the alternative video data.

  Also, if the determination absolute value is equal to or greater than the synchronization threshold value and the value indicated by APTS (audio synchronization information) is smaller than the value indicated by VPTS (video synchronization information), the AV synchronization control unit 120A determines that the audio encoding unit 115A The audio encoding unit 115A is controlled to encode the alternative audio data.

  That is, if the value obtained from the value indicated by VPTS (video synchronization information) and the value indicated by APTS (audio synchronization information) satisfies a predetermined condition, the AV synchronization control unit 120A causes the video encoding unit 113A to send alternative video data. One of the process for controlling the video encoding unit 113A to encode the audio encoding unit 115A and the process for controlling the audio encoding unit 115A to cause the audio encoding unit 115A to encode the alternative audio data. In this case, the predetermined condition is a condition that an absolute value of a difference between a value indicated by VPTS (video synchronization information) and a value indicated by APTS (audio synchronization information) is equal to or greater than a predetermined synchronization threshold.

  Note that the condition for the AV synchronization control unit 120A to transmit the video encoding control instruction or the audio encoding control instruction is not limited to the above condition (condition using the determination absolute value). For example, the AV synchronization control unit 120A may calculate a ratio between the value of the VPTS and the value of the APTS, and transmit a video encoding control command or an audio encoding control command based on the ratio.

  When receiving the video encoding control command, the video encoding unit 113A generates the video bitstream VST2 by encoding the latest alternative video data generated by the alternative video data generation unit 211.

  Note that the video encoding unit 113A generates the video bitstream VST2 by encoding the video data VD1 stored in the video output data buffer unit 106 when the video encoding control command is not received.

  That is, when the video encoding unit 113A receives a video encoding control command, the video encoding unit 113A switches the video data to be encoded from the video data VD1 to alternative video data.

  When receiving the audio encoding control command, the audio encoding unit 115A generates the video bitstream VST2 by encoding the latest alternative audio data generated by the alternative audio data generation unit 212.

  If the audio encoding unit 115A has not received the audio encoding control command, the audio encoding unit 115A encodes the audio data AD1 stored in the audio output data buffer unit 108 to generate the video bitstream VST2.

  That is, when the audio encoding unit 115A receives the audio encoding control command, the audio encoding unit 115A switches the audio data to be encoded from the audio data AD1 to alternative audio data.

  Here, a specific example will be described. For example, it is assumed that the video bit stream VST1 has a defect, the decoding process by the video decoding unit 105A is stopped, and the video synchronization information extraction unit 118 cannot acquire VPTS as the video synchronization information.

  Further, it is assumed that the audio bit stream AST1 is a normal stream. That is, it is assumed that the audio decoding unit 107A has normally received the audio bitstream AST1. Further, it is assumed that the audio synchronization information extraction unit 119 extracts APTS as audio synchronization information from the audio bitstream AST1 and transmits the APTS to the AV synchronization control unit 120A.

  In this case, the value of VPTS does not change, only the value of APTS increases, and the absolute value of the difference between the value of VPTS and the value of APTS is equal to or greater than a predetermined synchronization threshold. That is, it is assumed that the value of VPTS is smaller than the value of APTS and the value of APTS deviates greatly from the value of VPTS. In this case, the AV synchronization control unit 120A transmits a video encoding control command to the video encoding unit 113A. The video encoding control command is, for example, a control command for complementing encoded data.

  When receiving the video encoding control command, the video encoding unit 113A acquires the latest alternative video data generated by the alternative video data generation unit 211, and encodes the alternative video data. That is, in this case, since the video encoding unit 113A does not target the video data VD1 stored in the video output data buffer unit 106, the video encoding unit 113A does not read the video data VD1 from the video output data buffer unit 106.

  In this case, the alternative video data is, for example, final decoded data at the time when the decoding process by the video decoding unit 105A is stopped. The alternative video data is, for example, data of the last video frame (latest video frame) before the decoding process is stopped.

  Also, for example, it is assumed that the audio bit stream AST1 has a defect, and the decoding process by the audio decoding unit 107A is stopped, so that the audio synchronization information extraction unit 119 cannot acquire APTS as audio synchronization information. .

  Further, it is assumed that the video bit stream VST1 is a normal stream. That is, it is assumed that the video decoding unit 105A has normally received the video bitstream VST1. Further, it is assumed that the video synchronization information extraction unit 118 extracts VPTS as video synchronization information from the video bitstream VST1, and transmits the VPTS to the AV synchronization control unit 120A.

  In this case, the APTS value does not change, only the VPTS value increases, and the absolute value of the difference between the VPTS value and the APTS value is equal to or greater than a predetermined synchronization threshold. That is, it is assumed that the APTS value is smaller than the VPTS value, and the VPTS value deviates greatly from the APTS value. In this case, the AV synchronization control unit 120A transmits an audio encoding control command to the audio encoding unit 115A. The audio encoding control command is, for example, a control command for complementing encoded data.

  When the audio encoding unit 115A receives the audio encoding control command, the audio encoding unit 115A acquires the latest alternative audio data generated by the alternative audio data generation unit 212, and encodes the alternative audio data. That is, in this case, since the audio encoding unit 115A does not target the audio data AD1 stored in the audio output data buffer unit 108, the audio encoding unit 115A does not read the audio data AD1 from the audio output data buffer unit 108. The alternative audio data is, for example, silence data (0 data).

(Description of configuration capable of realizing high-speed re-encoding process A)
In the configuration of the digital data recording / reproducing apparatus 1000A shown in FIG. 2 described above, in order to perform re-encoding at high speed, data processing in each unit constituting the re-encoding processing path A needs to be performed at high speed. These units are an AV separation unit 102, a video decoding unit 105A, an audio decoding unit 107A, a video encoding unit 113A, an audio encoding unit 115A, and an AV multiplexing unit 117.

  Of the above units, the AV demultiplexing unit 102 and the AV multiplexing unit 117 do not require complicated arithmetic processing as compared with encoding processing and decoding processing, and therefore are excluded from the system bottlenecks. be able to.

  Since the video decoding unit 105A and the video encoding unit 113A require complicated arithmetic processing on video data, the video decoding unit 105 and the video encoding unit 113 may be an arithmetic processor, a high-speed arithmetic device, or an arithmetic dedicated unit. What is necessary is just to be comprised with a circuit.

  Further, since the audio decoding unit 107A and the audio encoding unit 115A require complicated arithmetic processing on audio data, the audio decoding unit 107A and the audio encoding unit 115A include an arithmetic processor, a high-speed arithmetic device, or an arithmetic operation. What is necessary is just to comprise by a circuit for exclusive use.

  As described above, in the re-encoding process A of the present embodiment, control is performed so that the video data VD1 and the audio data AD1 are processed in synchronization using VPTS and APTS. That is, in the re-encoding process A of the present embodiment, unlike the re-encoding process of the first embodiment, the process depending on the clock is not performed. That is, each of the video decoding unit 105A, the audio decoding unit 107A, the video encoding unit 113A, and the audio encoding unit 115A can operate asynchronously.

  Therefore, according to digital data recording / reproducing apparatus 1000A according to the present embodiment, the performance of each arithmetic circuit (arithmetic processor) of video decoding unit 105A, video encoding unit 113A, audio decoding unit 107A, and audio encoding unit 115A. It is possible to realize a high-speed re-encoding process A that makes the best use of the above.

  Note that the AV synchronization control unit 120A may change the processing speed of each of the video decoding unit 105A, the video encoding unit 113A, the audio decoding unit 107A, and the audio encoding unit 115A according to the type of device operation mode. .

  Hereinafter, each of the video decoding unit 105A, the video encoding unit 113A, the audio decoding unit 107A, and the audio encoding unit 115A is referred to as a re-encoding related unit.

  Specifically, the AV synchronization control unit 120A, for example, determines the processing speed of each re-encoding related unit when the device operation mode is the re-encoding mode, and each re-encoding when the device operation mode is the normal playback mode. Each re-encoding related unit is controlled so as to be faster than the processing speed of the encoding-related unit.

  Thereby, the speed of the re-encoding process A when the apparatus operation mode is the re-encoding mode can be made faster than the speed of the re-encoding process A when the apparatus operation mode is the re-encoding mode. That is, it is possible to change the re-encoding speed for the stream.

  In addition, the said embodiment is an example for implementing this invention, and a various change is possible unless it deviates from the summary of this invention. For example, regarding the storage medium, a recording medium other than the storage medium in which the AV bit stream before re-encoding is recorded may be used for recording the bit stream after re-encoding. As an example, the AV bit stream recorded on the HDD may be re-encoded, and the AV bit stream obtained by the re-encoding may be recorded on the Blu-ray disc.

  The AV synchronization information is extracted by the video synchronization information extraction unit and the audio synchronization information extraction unit, but a configuration in which the AV separation unit has a function of extracting the AV synchronization information is also possible.

  In addition, the AV bit stream AVST1 to be re-encoded may not be recorded in the storage medium 101, and the AV bit stream AVST1 to be re-encoded may be received by broadcast waves, for example. . Further, the AV bit stream AVST1 to be re-encoded may be, for example, streamed from the Internet.

(Function block diagram)
FIG. 3 is a block diagram showing a characteristic first functional configuration of the digital data recording / reproducing apparatus 2000. The digital data recording / reproducing apparatus 2000 corresponds to the digital data recording / reproducing apparatus 1000 of FIG. That is, FIG. 3 is a block diagram showing main functions related to the present invention among the functions of the digital data recording / reproducing apparatus 1000.

  In the digital data recording / reproducing apparatus 2000, the first video bit stream generated by encoding video data and the first audio bit stream generated by encoding audio data are multiplexed. Process the first AV bitstream.

  The first video bit stream corresponds to the video bit stream VST1. The first audio bitstream corresponds to the audio bitstream AST1. The first AV bit stream corresponds to the AV bit stream AVST1.

  The digital data recording / reproducing apparatus 2000 has at least two types of operation modes. The two types of operation modes are the re-encoding mode and the normal reproduction mode, respectively.

  The first video bitstream includes video synchronization information. The video synchronization information corresponds to VPTS. The first audio bitstream includes audio synchronization information. The audio synchronization information corresponds to APTS. Each of the video synchronization information and the audio synchronization information is information for processing video data and audio data in synchronization.

  Functionally, the digital data recording / reproducing apparatus 2000 includes an AV separation unit 2102, a video synchronization information extraction unit 2118, an audio synchronization information extraction unit 2119, a video decoding unit 2105, an audio decoding unit 2107, and a clock generation unit. 2121 and an AV synchronization control unit 2120.

  The AV separation unit 2102 extracts the first video bit stream and the first audio bit stream from the first AV bit stream. The video synchronization information extraction unit 2118 extracts the video synchronization information from the first video bitstream. The audio synchronization information extraction unit 2119 extracts the audio synchronization information from the first audio bitstream.

  The video decoding unit 2105 is a component for acquiring the video data by decoding the first video bitstream and outputting the video data. The audio decoding unit 2107 is a component for acquiring the audio data by decoding the first audio bitstream and outputting the audio data.

  The clock generation unit 2121 generates an AV synchronization clock for processing the video data and the audio data in synchronization. The AV synchronization clock corresponds to the AV synchronization clock AVCK.

  The AV synchronization control unit 2120 performs control for processing the video data and the audio data in synchronization.

  AV separation section 2102, video synchronization information extraction section 2118, audio synchronization information extraction section 2119, video decoding section 2105, audio decoding section 2107, clock generation section 2121 and AV synchronization control section 2120 are respectively connected to AV separation section 102 and video synchronization section 2120. The information extraction unit 118, the audio synchronization information extraction unit 119, the video decoding unit 105, the audio decoding unit 107, the clock generation unit 121, and the AV synchronization control unit 120 are equivalent to each other.

  Specifically, the AV synchronization control unit 2120 uses the video synchronization information, the audio synchronization information, and the AV synchronization clock to output the video data from the video decoding unit 2105, and the audio decoding unit 2107. The video decoding unit 2105 and the audio decoding unit 2107 are controlled so that the output timing of the audio data is synchronized.

  Functionally, the digital data recording / reproducing apparatus 2000 further includes a video output unit 2109, an audio output unit 2111, a video encoding unit 2113, an audio encoding unit 2115, and an AV multiplexing unit 2117.

  The video output unit 2109 outputs the video data in synchronization with the video output clock synchronized with the AV synchronization clock. The video output clock corresponds to the video clock VCK.

  The audio output unit 2111 outputs the audio data in synchronization with the audio output clock synchronized with the AV synchronization clock. The audio output clock corresponds to the audio clock ACK.

  The video encoding unit 2113 generates the second video bitstream by encoding the video data output from the video output unit 2109. The second video bit stream corresponds to the video bit stream VST2.

  The audio encoding unit 2115 generates a second audio bitstream by encoding the audio data output from the audio output unit 2111. The second audio bitstream corresponds to the audio bitstream AST2.

  The AV multiplexing unit 2117 generates a second AV bit stream by multiplexing the second video bit stream and the second audio bit stream. The second AV bit stream corresponds to the AV bit stream AVST2.

  In addition, the clock generation unit 2121 further changes the speed of the AV synchronization clock according to the type of operation mode of the digital data recording / reproducing apparatus 2000.

  Note that the AV separation unit 2102, the video synchronization information extraction unit 2118, the audio synchronization information extraction unit 2119, the video decoding unit 2105, the audio decoding unit 2107, the clock generation unit 2121, the AV synchronization control unit 2120, the video output unit 2109, and the audio output unit. All or part of the 2111, the video encoding unit 2113, the audio encoding unit 2115, and the AV multiplexing unit 2117 may be configured by hardware such as an LSI (Large Scale Integration).

  FIG. 4 is a block diagram showing a characteristic second functional configuration of the digital data recording / reproducing apparatus 3000. The digital data recording / reproducing apparatus 3000 corresponds to the digital data recording / reproducing apparatus 1000A of FIG. That is, FIG. 4 is a block diagram showing main functions related to the present invention among the functions of the digital data recording / reproducing apparatus 1000A.

  In the digital data recording / reproducing apparatus 3000, a first video bit stream generated by encoding video data and a first audio bit stream generated by encoding audio data are multiplexed. Process the first AV bitstream.

  The first video bit stream corresponds to the video bit stream VST1. The first audio bitstream corresponds to the audio bitstream AST1. The first AV bit stream corresponds to the AV bit stream AVST1.

  The first video bitstream includes video synchronization information. The video synchronization information corresponds to VPTS. The first audio bitstream includes audio synchronization information. The audio synchronization information corresponds to APTS.

  Functionally, the digital data recording / reproducing apparatus 3000 includes an AV separation unit 3102, a video synchronization information extraction unit 3118, an audio synchronization information extraction unit 3119, a video decoding unit 3105A, an audio decoding unit 3107A, and AV synchronization control. Unit 3120A, alternative video data generation unit 3211, alternative audio data generation unit 3212, video encoding unit 3113A, audio encoding unit 3115A, and AV multiplexing unit 3117.

  The AV separation unit 3102 extracts the first video bit stream and the first audio bit stream from the first AV bit stream. The video synchronization information extraction unit 3118 extracts the video synchronization information from the first video bitstream. The audio synchronization information extraction unit 3119 extracts the audio synchronization information from the first audio bitstream.

  The video decoding unit 3105A is a component for acquiring the video data by decoding the first video bitstream and outputting the video data. The audio decoding unit 3107A is a component for acquiring the audio data by decoding the first audio bitstream and outputting the audio data. The AV synchronization control unit 3120A performs control for processing the video data and the audio data in synchronization.

  The alternative video data generation unit 3211 generates alternative video data that is an alternative to the decoded video data that is video data that the video decoding unit 3105A acquires by decoding. The alternative audio data generation unit 3212 generates alternative audio data that substitutes for the decoded audio data that is audio data that the audio decoding unit 3107A acquires by decoding.

  The video encoding unit 3113A generates a second video bitstream by encoding the decoded video data or the alternative video data. The second video bit stream corresponds to the video bit stream VST2.

  The audio encoding unit 3115A generates a second audio bitstream by encoding the decoded audio data or the alternative audio data. The second audio bitstream corresponds to the audio bitstream AST2.

  The AV multiplexing unit 3117 generates a second AV bit stream by multiplexing the second video bit stream and the second audio bit stream. The second AV bit stream corresponds to the AV bit stream AVST2.

  Each of the video synchronization information and the audio synchronization information is information for controlling the video encoding unit 3113A and the audio encoding unit 3115A.

  Specifically, the AV synchronization control unit 3120A compares the video synchronization information with the audio synchronization information, and the timing at which the video encoding unit 3113A performs encoding and the audio encoding unit 3115A perform encoding. In order to synchronize with the timing, (a) the video encoding unit 3113A is configured to cause the video encoding unit 3113A to encode either the decoded video data or the alternative video data according to the comparison result. And (b) controls the audio encoding unit 3115A to cause the audio encoding unit 3115A to encode either the decoded audio data or the alternative audio data according to the comparison result.

  The AV separation unit 3102, the video synchronization information extraction unit 3118, the audio synchronization information extraction unit 3119, the video decoding unit 3105A, the audio decoding unit 3107A, and the AV synchronization control unit 3120A are respectively an AV separation unit 102, a video synchronization information extraction unit 118, This corresponds to the audio synchronization information extraction unit 119, the video decoding unit 105A, the audio decoding unit 107A, and the AV synchronization control unit 120A.

  In addition, the alternative video data generation unit 3211, the alternative audio data generation unit 3212, the video encoding unit 3113A, the audio encoding unit 3115A, and the AV multiplexing unit 3117 respectively include an alternative video data generation unit 211 and an alternative audio data generation unit 212. These correspond to the video encoding unit 113A, the audio encoding unit 115A, and the AV multiplexing unit 117.

  Note that the AV separation unit 3102, the video synchronization information extraction unit 3118, the audio synchronization information extraction unit 3119, the video decoding unit 3105A, the audio decoding unit 3107A, the AV synchronization control unit 3120A, the alternative video data generation unit 3211, and the alternative audio data generation unit 3212. All or part of the video encoding unit 3113A, the audio encoding unit 3115A, and the AV multiplexing unit 3117 may be configured by hardware such as an LSI (Large Scale Integration).

  The digital data recording / reproducing apparatus 1000 or the digital data recording / reproducing apparatus 1000A according to the present invention has been described based on the embodiments. However, the present invention is not limited to these embodiments. Unless it deviates from the meaning of this invention, the form which carried out various deformation | transformation which those skilled in the art can think to this embodiment, or the structure constructed | assembled combining the component in different embodiment is also contained in the scope of the present invention. .

  In addition, all or some of the plurality of components constituting the digital data recording / reproducing apparatus 1000 or the digital data recording / reproducing apparatus 1000A may be configured by hardware. Further, all or a part of the components constituting the digital data recording / reproducing apparatus 1000 or the digital data recording / reproducing apparatus 1000A may be a module of a program executed by a CPU (Central Processing Unit) or the like.

  In addition, all or some of the plurality of components constituting the digital data recording / reproducing apparatus 1000 or the digital data recording / reproducing apparatus 1000A are configured by one system LSI (Large Scale Integration). Also good. The system LSI is an ultra-multifunctional LSI manufactured by integrating a plurality of components on one chip. Specifically, a microprocessor, a ROM (Read Only Memory), a RAM (Random Access Memory), etc. It is a computer system comprised including.

  For example, in FIG. 1, an AV separation unit 102, an input video bitstream buffer unit 103, an input audio bitstream buffer unit 104, a video decoding unit 105, a video output data buffer unit 106, an audio decoding unit 107, and an audio output data buffer unit 108 , Video output unit 109, video encoding input buffer unit 110, audio output unit 111, audio encoding input buffer unit 112, video encoding unit 113, encoded video bitstream buffer unit 114, audio encoding unit 115, encoding The audio bit stream buffer unit 116 and the AV multiplexing unit 117 may be configured by one system LSI.

  Further, the present invention may be realized as a digital data recording method in which the operation of the characteristic components included in the digital data recording / reproducing apparatus 1000 or the digital data recording / reproducing apparatus 1000A is a step. Further, the present invention may be realized as a program that causes a computer to execute each step included in such a digital data recording method. Further, the present invention may be realized as a computer-readable recording medium that stores such a program. The program may be distributed via a transmission medium such as the Internet.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention makes it possible to perform high-speed re-encoding processing in accordance with the processing capability of the AV decoding unit and the AV decoding unit while maintaining AV synchronization, and improve the convenience of the user. It can be used as a recording / reproducing apparatus.

101 Storage medium 102, 2102, 3102 AV separation unit 103 Input video bit stream buffer unit 104 Input audio bit stream buffer unit 105, 105A, 2105, 3105A Video decoding unit 106 Video output data buffer unit 107, 107A, 2107, 3107A Audio decoding Unit 108 audio output data buffer unit 109, 2109 video output unit 110 video encoding input buffer unit 111, 2111 audio output unit 112 audio encoding input buffer unit 113, 113A, 2113, 3113A video encoding unit 114 encoded video bit stream Buffer units 115, 115A, 2115, 3115A Audio encoding unit 116 Encoded audio bitstream buffer units 117, 2117, 3117 AV multiplexing unit 118, 2118, 3118 Video synchronization information extraction unit 119, 2119, 3119 Audio synchronization information extraction unit 120, 120A, 2120, 3120A AV synchronization control unit 121, 2121 Clock generation unit 211, 3211 Alternative video data generation unit 212, 3212 Alternative audio data generation unit 1000, 1000A, 2000, 3000 Digital data recording / reproducing apparatus

Claims (4)

First AV (Audio Visual) in which a first video bit stream generated by encoding video data and a first audio bit stream generated by encoding audio data are multiplexed A digital data recording / reproducing apparatus for processing a bitstream,
The digital data recording / reproducing apparatus has at least two kinds of operation modes,
The first video bitstream includes video synchronization information;
The first audio bitstream includes audio synchronization information;
Each of the video synchronization information and the audio synchronization information is information for processing the video data and the audio data synchronously,
The digital data recording / reproducing apparatus comprises:
An AV separation unit for extracting the first video bit stream and the first audio bit stream from the first AV bit stream;
A video synchronization information extraction unit that extracts the video synchronization information from the first video bitstream;
An audio synchronization information extraction unit that extracts the audio synchronization information from the first audio bitstream;
A video decoding unit for obtaining the video data by decoding the first video bitstream and outputting the video data;
An audio decoding unit for obtaining the audio data by decoding the first audio bitstream and outputting the audio data;
A clock generation unit for generating an AV synchronization clock for processing the video data and the audio data in synchronization;
An AV synchronization control unit for controlling the video data and the audio data to be processed in synchronization;
The AV synchronization control unit uses the video synchronization information, the audio synchronization information, and the AV synchronization clock to output the video data output timing by the video decoding unit and output timing of the audio data by the audio decoding unit. Controlling the video decoding unit and the audio decoding unit so that the
The digital data recording / reproducing apparatus further includes:
A video output unit for outputting the video data in synchronization with a video output clock synchronized with the AV synchronization clock;
An audio output unit for outputting the audio data in synchronization with an audio output clock synchronized with the AV synchronization clock;
A video encoding unit that generates a second video bitstream by encoding the video data output from the video output unit;
An audio encoding unit that generates a second audio bitstream by encoding the audio data output from the audio output unit;
An AV multiplexing unit that generates a second AV bitstream by multiplexing the second video bitstream and the second audio bitstream;
The clock generator further changes the speed of the AV synchronization clock according to the type of operation mode of the digital data recording / reproducing device.
Digital data recording / reproducing device. The digital data recording / reproducing apparatus, as an operation mode, decodes the first mode for reproducing the first AV bit stream and the first AV bit stream, and codes the data obtained by the decoding. Having a second mode to
The clock generation unit determines the speed of the AV synchronization clock generated when the operation mode of the digital data recording / reproducing apparatus is the second mode, and the operation mode of the digital data recording / reproducing apparatus is the first mode. Faster than the speed of the AV synchronization clock generated in some cases,
The digital data recording / reproducing apparatus according to claim 1. Each of the video synchronization information, the audio synchronization information, and the AV synchronization clock indicates a value used for control by the AV synchronization control unit,
The value indicated by the AV synchronization clock increases with time,
The AV synchronization control unit (a) the video decoding unit so that the video decoding unit outputs the video data at a timing when a value indicated by the video synchronization information matches a value indicated by the AV synchronization clock. And (b) controls the audio decoding unit so that the audio decoding unit outputs the audio data at a timing when the value indicated by the audio synchronization information matches the value indicated by the AV synchronization clock. ,
The digital data recording / reproducing apparatus according to claim 1 or 2. First AV (Audio Visual) in which a first video bit stream generated by encoding video data and a first audio bit stream generated by encoding audio data are multiplexed A digital data recording / reproducing apparatus for processing a bitstream,
The first video bitstream includes video synchronization information;
The first audio bitstream includes audio synchronization information;
The digital data recording / reproducing apparatus comprises:
An AV separation unit for extracting the first video bit stream and the first audio bit stream from the first AV bit stream;
A video synchronization information extraction unit that extracts the video synchronization information from the first video bitstream;
An audio synchronization information extraction unit that extracts the audio synchronization information from the first audio bitstream;
A video decoding unit for obtaining the video data by decoding the first video bitstream and outputting the video data;
An audio decoding unit for obtaining the audio data by decoding the first audio bitstream and outputting the audio data;
An AV synchronization control unit that performs control for processing the video data and the audio data in synchronization;
An alternative video data generation unit that generates alternative video data to replace the decoded video data that is video data that the video decoding unit acquires by decoding;
An alternative audio data generation unit that generates alternative audio data to replace the decoded audio data that is audio data acquired by the audio decoding unit by decoding; and
A video encoding unit that generates a second video bitstream by encoding the decoded video data or the alternative video data;
An audio encoding unit that generates a second audio bitstream by encoding the decoded audio data or the alternative audio data;
An AV multiplexing unit that generates a second AV bitstream by multiplexing the second video bitstream and the second audio bitstream;
Each of the video synchronization information and the audio synchronization information is information for controlling the video encoding unit and the audio encoding unit,
The AV synchronization control unit compares the video synchronization information with the audio synchronization information so that the timing at which the video encoding unit performs encoding and the timing at which the audio encoding unit performs encoding are synchronized. (A) controlling the video encoding unit to cause the video encoding unit to encode either the decoded video data or the alternative video data according to the comparison result, and (b) the comparison Depending on the result, the audio encoding unit is controlled to cause the audio encoding unit to encode either the decoded audio data or the alternative audio data,
Each of the video synchronization information and the audio synchronization information indicates a value used for control by the AV synchronization control unit,
When the value obtained from the value indicated by the video synchronization information and the value indicated by the audio synchronization information satisfies a predetermined condition, the AV synchronization control unit encodes the alternative video data to the video encoding unit. Performing a process for controlling the video encoding unit to be encoded, and (d) a process for controlling the audio encoding unit to cause the audio encoding unit to encode the alternative audio data,
The predetermined condition is a condition that an absolute value of a difference between a value indicated by the video synchronization information and a value indicated by the audio synchronization information is equal to or greater than a predetermined synchronization threshold.
The AV synchronization control unit
(E) When the absolute value is greater than or equal to the synchronization threshold and the value indicated by the video synchronization information is smaller than the value indicated by the audio synchronization information, the video encoding unit is caused to encode the alternative video data. Controlling the video encoder;
(F) When the absolute value is equal to or greater than the synchronization threshold and the value indicated by the audio synchronization information is smaller than the value indicated by the video synchronization information, the audio encoding unit is caused to encode the alternative audio data. Controlling the audio encoding unit;
Digital data recording / reproducing device.

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