JP4356046B2 - Encoded data recording / reproducing apparatus and encoded data reproducing apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an encoded data recording / reproducing apparatus for recording / reproducing data obtained by encoding moving images and audio, and an encoded data reproducing apparatus for reproducing encoded data . An object of the present invention is to provide an encoded data recording / reproducing apparatus and an encoded data reproducing apparatus suitable for reproducing a program recorded on a medium while being partially connected.
[0002]
[Prior art]
With recent progress of information processing technology, digital audio / video information is being compressed and recorded on an information recording medium. In particular, recordable disc media to which these compression techniques are applied are considered to become mainstream as digital audio-video recording media in the future due to their good random accessibility.
[0003]
In general, since a moving image has an enormous amount of information with respect to audio, advanced compression techniques are used to effectively use the limited amount of recorded information on a medium. A representative method is not only data compression using correlation within a video frame, which is a unit of video, but also compression using correlation between a plurality of temporally adjacent video frames. As a result of this data compression, it is well known that the amount of data per video frame (image data unit in the first predetermined time unit) of the moving image varies greatly according to the complexity of the video in the frame and the degree of correlation between the video frames. It is as follows. In this way, the state in which the amount of code generated in a certain period varies due to data compression is referred to as “compression encoding at a variable bit rate” or “compression encoding at VBR (Variable Bit Rate)”. On the other hand, for audio, the relative amount of information is small, so compression coding at a fixed bit rate, where the amount of code generated in a certain period is constant, so-called compression coding at CBR (Constant Bit Rate) is adopted. There are many cases. As with moving images, audio is generally divided into audio frames corresponding to a certain output period, and is generally compressed and encoded in units of audio frames (audio data units in a second predetermined time unit).
[0004]
A conventional recording / reproducing apparatus for recording / reproducing encoded data of moving images / sounds on a medium has a configuration shown in FIG. A moving image is compression encoded by the moving image encoding unit 1, and similarly, audio is compression encoded by the audio encoding unit 2. The encoded data generated independently from these becomes a single encoded data string in the multiplexing unit 3 so as to be suitable for recording. In the moving image encoding unit 1, encoding is performed by VBR as described above. However, on the recording medium, the encoded data string is continuously arranged without a gap in order to efficiently use the data capacity. For this purpose, a write buffer 4 is provided, and is configured to store encoded data in the write buffer 4 when the output rate of the multiplexing unit 3 is high, or when writing to the recording medium is waiting for rotation. ing. The output of the write buffer 4 is recorded in a continuous arrangement on the recording medium 6 through an information writing unit 5 composed of an optical head or the like.
[0005]
Now, on the recording medium 6, a small amount and a fixed data amount section called a sector are continuously arranged, and the encoded data of moving image / sound is divided into sectors and recorded. Furthermore, writing / reading to / from a recording medium by a recording / reproducing apparatus is generally performed in units of sectors, and it is not preferable to record different types of data in the same sector from the viewpoint of easy access. Therefore, the encoded data of the moving image and the sound are recorded in different sectors as shown in FIG. FIG. 6 shows an example in which the encoded data for configuring each video frame (each image data unit) is V1 to V4, and the encoded data for configuring each audio frame (each audio data unit) is A0 to A5. It is shown. In the example shown in FIG. 6, the encoded data of each video frame is recorded over three sectors, and the encoded data of each audio frame is recorded in one sector. A video frame V1 which is a unit of one image is constituted by the encoded data of three sectors indicated as V1 in the figure.
[0006]
When the encoded moving image / sound data on the recording medium 6 is reproduced, the reverse processing corresponding to the recording is performed. That is, as shown in FIG. 5, each encoded data is intermittently read out by an information reading unit 7 composed of an optical head or the like, temporarily stored in a read buffer 8, and then supplied to a demultiplexing unit 9. Is done. The demultiplexing unit 9 separates the encoded data of the moving image and the sound, and the decoded data is decoded and output by the moving image decoding unit 10 and the sound decoding unit 11, respectively.
[0007]
FIG. 7 shows the temporal relationship between video frames and audio frames output when the sector row on the recording medium shown in FIG. 6 is read and reproduced. That is, it is a state that the moving image encoded data V1 to V4 and the audio encoded data A0 to A5 shown in FIG. 6 are output. The video frame time period (video frame period) is about 33.4msec for the NTSC system and 40msec for the PAL system, but the definition is clear, but the time period of the audio frame (audio frame period) is adopted. In many cases, the audio frame period does not match the video frame period. Therefore, as shown in FIG. 7, it can be seen that the video frame boundary and the audio frame boundary are in an asynchronous relationship.
[0008]
[Problems to be solved by the invention]
Here, it is assumed that reproduction of a video frame (referred to as video frame V2; the same applies hereinafter) corresponding to the moving image encoded data V2 is skipped by editing. That is, the video frame V1 and the video frame V3 are played back as a continuous frame (the video frame V1 and the video frame V3, which are two image data units that are not temporally continuous, are played back continuously). If you want to). At this time, the object is achieved by skipping the reading of the encoded data V2 instead of actually deleting the encoded data V2 shown in FIG.
[0009]
However, for audio, the purpose is not achieved only by skipping reproduction of audio frame A2 (audio frame corresponding to audio encoded data A2) related to video frame V2 (skip reading audio encoded data A2). . This is because the audio is compressed and encoded in units of audio frames, and furthermore, as shown in FIG. 7, the boundaries of the audio frames do not coincide with the boundaries of the video frames.
[0010]
This will be described in more detail with reference to FIG. In normal reproduction, the audio frame temporally related to the video frame V2 is related not only to the audio frame A2, but also to the audio frames A1 and A3 as shown in FIG. Therefore, when the video frame V1 and the video frame V3 are played back continuously, the playback of the audio frames A1 and A3 is temporally overlapped as shown in FIG. 8 simply by skipping the playback of the audio frame A2. Will occur. Therefore, in order not to cause overlap, reproduction of not only the audio frame A2 but also the audio frame A3 (or the audio frame A1) must be skipped. The reproduction output after such editing is as shown in FIG.
[0011]
After the audio frame A1 shown in FIG. 8, there is a period in which there is no audio of one audio frame period at the maximum, so it is necessary to perform output mute in the player. Furthermore, when the sound pressure level of the recorded sound is high, including before and after this period, there is a high possibility that noise will be output due to a large change in the output level with a simple output mute, and the gain as shown in FIG. It was necessary to perform precise mute with a curve.
[0012]
In the present invention, a program recorded on a recording medium is reproduced while being partially connected (a first image data unit and a second image data unit which are not temporally continuous in the recorded image data). Encoded data recording / reproducing apparatus and encoded data reproducing apparatus capable of preventing the audio from being discontinuous without performing the audio mute processing at the connection point when the image data units of 2 are reproduced continuously) The purpose is to provide.
[0013]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides the following apparatus .
(1) Image data compressed and encoded for each image data unit in a first predetermined time unit, and audio data related to the image data and compressed and encoded for each audio data unit in a second predetermined time unit In an encoded data recording / reproducing apparatus for recording / reproducing recorded audio data on a recording medium,
When the first image data unit and the second image data unit, which are two image data units that are not temporally continuous in the image data recorded on the recording medium, are reproduced in succession, they are reproduced together with the image data. Then, the first audio data unit related to the first image data unit and the second audio data unit related to the second image data unit, which are two audio data units that overlap in time. Audio decoding means for decoding
Audio data processing means for performing non-compressed audio data obtained by the decoding by performing a crossfading process on the overlap portion to obtain one block of uncompressed audio data ;
Recording means for recording the one block of uncompressed audio data on the recording medium;
Coded data recording and reproducing apparatus characterized by comprising a.
(2) Image data compressed and encoded for each image data unit in the first predetermined time unit, and audio data related to the image data and compressed and encoded for each audio data unit in the second predetermined time unit In an encoded data reproducing apparatus for reproducing the recorded audio data from the recording medium,
2. A recording medium on which one block of uncompressed audio data subjected to the crossfading process according to claim 1 is recorded is not temporally continuous in image data recorded on the recording medium. When the first image data unit and the second image data unit which are the two image data units described in the above are reproduced in succession, two audio data units that overlap in time when reproduced together with the image data. there, wherein the first second period corresponding to the voice data units related to audio data unit and the second image data unit associated with the first image data unit, reproduced from the recording medium the encoded data reproducing equipment, characterized by comprising output means for outputting the non-compressed audio data of one block.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
When the encoded data recording / reproducing apparatus of the present invention connects image data units that are not adjacently arranged in a program on a recording medium (two image data units that are not temporally continuous in the image data recorded on the recording medium) When the first image data unit (for example, video frame V1) and the second image data unit (for example, video frame V3) are continuously played back, two audio frames that overlap in time ( The decoding means decodes the first audio data unit (audio frame A1) related to the first image data unit and the second audio data unit (audio frame A3) related to the second image data unit. After the cross-fading process is performed by the audio data processing means on the overlapping part of the two obtained uncompressed audio frame data, Characterized by recording on a recording medium as audio data B0.
[0015]
The encoded data reproduction apparatus of the present invention reproduces a video frame V1 and a video frame V3 continuously when reproducing by connecting image data units that are not adjacently arranged on a medium (program parts that are not adjacently arranged). Before playing back the connected portion, the audio data B0 corresponding to the connected portion described above is read from the recording medium into the memory, and two audio frame periods (audio frames A1 and A3) in which overlap occurs are read. In the period, the audio data B0 stored in the memory is output.
[0016]
Also, in the encoded data recording medium, when a program portion that is not adjacently arranged on the recording medium is connected and played back (when the video frame V1 and the video frame V3 are played back continuously), overlap occurs 2 It is characterized in that uncompressed audio data B0 corresponding to one audio frame period (a period between audio frames A1 and A3) is separately recorded.
[0017]
For example, if one period of a compressed audio frame is 32 msec and the audio overlap is very small, uncompressed audio data for approximately 2 audio frames will be recorded, but this data format is 48 kHz sampling, 16 With bit / sample linear PCM, one block is roughly 12kByte and occupies a small area on the medium.
[0018]
At the connection point (connection point between the video frame V1 and the video frame V3) that conventionally required complicated audio mute processing for playback of the recording medium, the playback device read in advance during the period when the audio is discontinuous. The audio data block B0 is output instead of the output of the audio decoding unit so that the final audio output does not have discontinuities. Furthermore, when the audio data block B0 is created, crossfading processing is performed so that there is no sudden level fluctuation at the connection point.
[0019]
Next, an embodiment of the encoded data recording / reproducing apparatus is shown in FIG. A significant difference from the conventional example of FIG. 5 is that a memory unit 21, an audio data processing unit 22, and an output switching unit 23 are added. Hereinafter, this additional portion will be mainly described.
[0020]
First, on the premise that the program shown in FIG. 6 is recorded on the recording medium 16, a case where reproduction of a video frame V2 (video frame composed of encoded data V2) is skipped by editing at the time of reproduction is considered. . In this case, as shown in FIG. 4, the reproduction of the video frame V2 is skipped, the video frames V1 and V3 are connected and reproduced, and the audio frame A0 (the audio frame constituted by the audio encoded data A0) After the reproduction output is completed, an audio data block B0 described below is output, and then editing is instructed to perform reproduction output from the audio frame A4. Since the period of the audio frame A2 shown in FIG. 7 is included in the period of the video frame V2, it is not output at all after editing, but the audio frames A1 and A3 are used to create the audio data block B0 for connection.
[0021]
In FIG. 1, encoded data A1 and A3 corresponding to audio frames A1 and A3 are sequentially decoded from a recording medium 16 via an information reading unit 17, a reading buffer 8, a demultiplexing unit 9, and an audio decoding unit 11, The compressed audio frame data is stored in the memory unit 21. The contents of the uncompressed audio frame data stored in the memory unit 21 are processed by the audio data processing unit 22 and recorded on the medium 16 through the information writing unit 15 as a connection audio data block B0.
[0022]
As an example of the recording medium 16, FIG. 2 shows a case where a connection audio data block is stored in an area having a small sector address. When there are a plurality of connection points, a plurality of connection audio data blocks B0, B1,... Corresponding to each connection point are stored in this area.
[0023]
As shown in FIG. 3, the processing content of the audio data processing unit 22 is obtained by changing the audio level of a part of two uncompressed audio frame data (data obtained by decoding the audio frames A1 and A3). A so-called cross-fade process is performed while mixing. The cross fade period of the audio data processing unit 22 is set so that the output period of the connection audio block data B0 thus created is the difference between the three audio frame periods A1 to A3 and the one video frame period of V2. Is adjusted.
[0024]
As described above, after the connection audio data block B0 is newly recorded, continuous audio can be output at the connection point (connection point between the video frame V1 and the video frame V3). In FIG. 1, a connection audio data block B 0 is stored in the memory unit 21 through the information reading unit 17 from the recording medium 16 prior to the reproduction of the program including the connection point. At the same time, the output switching unit 23 is set so that the input from the speech decoding unit 11 is supplied to an external output to which a D / A converter or the like is connected.
[0025]
After this, program playback starts. That is, encoded data is sequentially supplied from the medium to the information reading unit 17, the reading buffer 8, the demultiplexing unit 9, the moving image decoding unit 10, and the audio decoding unit 11. When the external output of the audio frame A0 is completed, the output switching unit 23 is set so that the input from the memory unit 21 is output to the outside, and the audio data block B0 for connection stored in advance is output. The Thereafter, the output switching unit 23 is set to output the input from the speech decoding unit 11 again, and outputs the speech data after the speech frame A4 output from the speech decoding unit 11 to the outside. The output state before and after the connection point in this encoded data recording / reproducing apparatus is as shown in FIG.
[0026]
【The invention's effect】
As described above, according to the present invention, when a program recorded on a recording medium is reproduced while being partially connected (the first image data unit that is not temporally continuous in the recorded image data). Audio data blocks are used for continuous playback of the image data unit and the second image data unit), the audio is discontinuous at the connection point without performing audio mute processing. Can be prevented.
In addition, according to the present invention, when the audio data block is created, crossfading processing is performed to prevent a sudden level fluctuation at the connection point, so that no noise is generated at the connection point and good reproduction is achieved. Yes.
Further, the area on the recording medium for recording the audio data block, or the amount of memory for temporarily holding it in the apparatus is very small, and the realization is very high.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an embodiment of an encoded data recording / reproducing apparatus.
FIG. 2 is a diagram showing a data arrangement of an embodiment of an encoded data recording medium.
FIG. 3 is a diagram showing a cross-fade process of an embodiment of the encoded data recording / reproducing apparatus.
FIG. 4 is a diagram showing a reproduction output of one embodiment of an encoded data recording / reproducing apparatus.
FIG. 5 is a diagram illustrating a conventional encoded data recording / reproducing apparatus.
[Fig. 6] Fig. 6 is a diagram showing a conventional arrangement form of encoded data.
FIG. 7 is a diagram illustrating a temporal relationship between video frames and audio frames during reproduction.
FIG. 8 is a diagram showing a reproduction output after performing a conventional editing operation.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Moving image encoding part 2 Audio | voice encoding part 3 Multiplexing part 4 Write buffer 8 Read buffer 9 Demultiplexing part 10 Moving image decoding part 11 Voice decoding part 15 Information writing part 16 Recording medium 17 Information reading part 21 Memory part 22 Voice Data processing unit 23 Output switching unit

Claims (2)

Image data compressed and encoded for each first predetermined time unit of image data, and audio data related to the image data and compressed and encoded for each second predetermined time unit of audio data In an encoded data recording / reproducing apparatus for recording / reproducing data on a recording medium,
When the first image data unit and the second image data unit, which are two image data units that are not temporally continuous in the image data recorded on the recording medium, are reproduced in succession, they are reproduced together with the image data. Then, the first audio data unit related to the first image data unit and the second audio data unit related to the second image data unit, which are two audio data units that overlap in time. Audio decoding means for decoding
Audio data processing means for performing non-compressed audio data obtained by the decoding by performing a crossfading process on the overlap portion to obtain one block of uncompressed audio data ;
Recording means for recording the one block of uncompressed audio data on the recording medium;
Coded data recording and reproducing apparatus characterized by comprising a. Image data compressed and encoded for each first predetermined time unit of image data, and audio data related to the image data and compressed and encoded for each second predetermined time unit of audio data In an encoded data reproduction device for reproducing data from a recording medium,
2. A recording medium on which one block of uncompressed audio data subjected to the crossfading process according to claim 1 is recorded is not temporally continuous in image data recorded on the recording medium. When the first image data unit and the second image data unit which are the two image data units described in the above are reproduced in succession, two audio data units that overlap in time when reproduced together with the image data. there, wherein the first second period corresponding to the voice data units related to audio data unit and the second image data unit associated with the first image data unit, reproduced from the recording medium the An encoded data reproducing apparatus comprising output means for outputting one block of uncompressed audio data.

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