JPH09186974A - Digital signal recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reproduce an audio signal smoothly at double speed reproduction. SOLUTION: Audio data (non-magnification speed) AO, data interleaved into 1/2 (double speed data) A1 and data interleaved into 1/3 (triple speed data) A2 of a frame accompanied with video data are recorded with respect to one frame of the video data (figure A). In the case of the double speed reproduction, the data A1 are selected and in the case of the triple speed reproduction, the data A2 are selected. Or as shown in figure C, three frames of audio data A10, A11, A12 including a concerned frame of video data are recorded. In the case of double speed reproduction, the data are interleaved depending on the multiple speed. The unit of thinning is nearly a length of a phoneme.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital signal recording method for recording digital video signals and digital audio signals on, for example, a randomly accessible recording medium.

[0002]

2. Description of the Related Art Digital video signals and digital audio signals have been recorded on recording media such as MO (magneto-optical recording) disks and hard disks. Unlike magnetic tapes, these recording media can be randomly accessed, and it has been attempted to use them in place of a magnetic tape device (VTR) in a broadcasting station system, for example. Although not limited to the broadcasting station system, in the case of editing or the like, not only the reproduction at the normal speed but also the reproduction at the double speed, the triple speed or the like is possible in order to grasp the recorded content of the recording medium.

[0003]

Conventionally, double speed, 3
When the double speed reproduction such as the double speed is performed, the image data is read out intermittently, and the audio data also becomes intermittent. For example, in double speed reproduction, only one frame of audio data can be read out every two frames. Such audio data becomes fragmentary as a reproduced sound, which causes a problem that the contents cannot be fully heard. Therefore, in the case of a reproduction speed exceeding 1 × speed, there is only a method of muting the audio or connecting the readable audio data as it is, and outputting a discontinuous sound, so that satisfactory audio reproduction cannot be performed.

The above-mentioned problem at the time of the conventional double speed reproduction is caused by the fact that the processing of the audio signal is performed by the same method as the processing of the video signal. That is, since the image data is configured in units of 1 frame (1/30 second), it is possible to determine the image after thinning out even if it is thinned out in frame units, whereas if the audio data is thinned out at similar intervals, Since the unit of thinning is too large, it becomes impossible to distinguish the sound after thinning.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a digital signal recording method capable of reproducing a reproduced voice to such an extent that a reproduced voice can be heard at the time of double speed reproduction in consideration of the above point.

[0006]

According to a first aspect of the present invention, there is provided a digital signal recording method for recording video data and audio data on a recording medium, wherein audio data is preliminarily recorded in correspondence with N-times speed reproduction operation. A digital signal recording method, which comprises a step of thinning out to 1 / N and a step of converting thinned out audio data into recording data together with audio data and video data for non-thinning the same speed. .

According to a second aspect of the present invention, in a digital signal recording method for recording video data and audio data on a recording medium, N frames of audio data are recorded in response to a double speed reproduction operation up to N times speed. A digital signal recording method comprising the steps of associating with video data of each frame, and converting N frames of audio data together with video data into recording data.

For each frame of the video data, not only the data of that frame but also audio data of several frames required at the same speed reproduction are recorded correspondingly. Therefore, at the time of double speed reproduction, even if the video data is thinned out, the audio data for several frames can be reproduced. As a result, the quality of sound during double speed reproduction can be improved.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In one embodiment of the invention,
A randomly accessible recording medium in which video data and audio data accompanying the video data are collectively recorded in frame units, and a recording / reproducing apparatus thereof are used. Further, in the embodiment of the present invention, the speed ratio is set to a relatively low speed and is defined in advance.
For example, reproduction at 2 × speed and 3 × speed is possible.

FIG. 1 shows the relationship between video data and audio data in order to explain the recording method of an embodiment of the present invention. As shown in FIG. 1A, video data is recorded in a unit of one frame, and 1x speed data A0 and 2x speed data A are provided as audio data accompanying the video data V1, V2, V3, ... Of each frame.
First and third speed data A2 are recorded. Each of these audio data is data for one frame. Since the video data has a large amount of data, it is usually compressed. On the other hand, the audio data need not be compressed.

The double speed data A1 is 2 consecutively in time.
The audio data for frames is thinned out to 1/2, and the triple speed data A2 is similarly thinned out to audio data for 3 consecutive frames of 1/3. FIG. 1B shows a method of forming, for example, triple speed data A2. As an example, the audio data is an analog audio signal sampled at 48 kHz. 1 mse of all audio data for 3 frames
For example, resampling is performed at 16 kHz so as to be divided into phonemes of about c. In this case, one phoneme is 1/16
It becomes the length of kHz. Then, two resampling units out of three are thinned out so that one resampling unit is selected from three consecutive resampling units. Three frames of audio data (the amount of data is one frame) obtained by thinning out is used as triple speed data A2. The double speed data A1 is also generated by thinning out the data of two consecutive frames by half.

Phonemes constitute syllables, and include vowels and consonants. Although it is difficult to perform thinning out in a phoneme unit strictly, audio data is resampled so as to be divided by a phoneme of a general length. In short, in one embodiment of the present invention, when the audio data is restored to an analog signal and made continuous, the audio data is thinned out in units of a length that allows the contents to be discriminated to some extent.

FIG. 1C illustrates another embodiment of the recording method according to the present invention. When video data is recorded on a recording medium in units of one frame, not only audio data A10 of the frame but also audio data A11 and A12 up to two frames are attached to the video data V of each frame. Record. These audio data are not thinned out. As shown in FIG. 1C, by recording the audio data, by performing thinning processing corresponding to the double speed ratio at any double speed ratio at a triple speed or less,
Audio data can be played back. For example, one frame is thinned out every three frames, and it is possible to cope with the case of 3/2 times speed.

When the recording medium recorded as described above is reproduced at a double speed, for example, as shown in FIG. 2A, the video data is reproduced by thinning out one frame every two frames. For example, only the video data V1, V3, V5, ... Of the first, third, fifth, ... And odd-numbered frames are reproduced. On the other hand, in the case of recording as shown in FIG. 1A as audio data accompanying this video data, the data shown in FIG. 2B is reproduced. That is, the normal speed data A0, the double speed data A1, and the triple speed data A2 are reproduced. FIG. 2B shows a state in which each double speed data is time-divisionally included within the period of one frame of video data. However, it is not necessary to perform time division, and data at each speed may be reproduced in parallel with the video data. In the double speed reproduction operation, as shown in FIG. 2D,
The double speed data is selected, and by processing the double speed data, audio reproduction whose contents can be determined becomes possible.

On the other hand, in another embodiment in which audio data is recorded as shown in FIG. 1C, when the odd-numbered frame is reproduced, as shown in FIG. 2C, the audio data of that frame is included. Thus, audio data A10, A11, A12 for three frames can be read. Similar to the above, the audio data for three frames does not need to be reproduced in time division. The processing shown in FIG. 2E is performed on the audio data A10, A11, and A12 thus read.

For example, at the time of double speed reproduction, one frame (three frames of audio data if the video data is the first frame) of the reproduced three frames of audio data is discarded. As shown in FIG. 1B, the remaining two frames of audio data are decimated to 1/2 in a phoneme unit as in the embodiment of the present invention, so that the two frames of audio data are included and the data amount is reduced. As a result, double speed data A1 ′ for one frame is formed. By reproducing this double speed data A1 ',
It is possible to reproduce a sound that can be discriminated.

FIG. 3 shows a schematic structure of a recording apparatus for carrying out the recording method of an embodiment of the present invention. Reference numeral 1 is a video data input terminal, and 3 is an audio data input terminal. The video data is supplied to the 3-frame delay element 2, and the video data from the delay element 2 is supplied to the synthesizing circuit 4. The audio data from the input terminal 2 is supplied to the 3-frame delay element 5, the 1/2 thinning circuit 6 and the 1/3 thinning circuit 7, respectively, and the output of the delay element 5 obtains the same-speed data A0.

The 1/2 decimation circuit 6 resamples the audio data at phoneme intervals and decimates one sample every two samples. Therefore, the double speed data A1 is obtained from the circuit 6. The 1/3 decimation circuit 7 resamples the audio data at phoneme intervals and decimates two samples for every three samples. Therefore, the triple speed data A2 is obtained from the circuit 7. These audio data A0, A1, A2 are supplied to the synthesizing circuit 4, and the video data V and the audio data A from the synthesizing circuit 4 are supplied.
0, A1, and A2 are supplied to the recording unit 8.

The recording unit 8 has a recording means such as a semiconductor laser device and a pickup, as well as an electronic circuit such as an encoder for encoding an error correction code and a digital modulation circuit. With respect to the disc-shaped recording medium 9 by the recording unit 8,
Video data and audio data are recorded. The disk-shaped recording medium 9 is, for example, an MO (magneto-optical) disk. Video data is compressed by MPEG2 or the like. The video data supplied to the input terminal 1 may be compressed data, or an encoder for compression processing may be provided in the recording unit 8. When video data is compressed and encoded, the encoding causes a delay. Therefore, the delay amount of the 3-frame delay element 3 may be further reduced, or the delay element may be omitted in some cases.

FIG. 4 shows a schematic structure of the reproducing apparatus. The recording data on the recording medium 9 is read by the reading unit 11. The reading unit 11 includes a pickup for optically reproducing recorded data, and a signal processing circuit such as a demodulation circuit for digital modulation and an error correction circuit. The reproduced video data V from the reading unit 11 is taken out to the output terminal 12. In addition, the audio data A0 from the reading unit 11,
A1 and A2 are supplied to the read data selection circuit 13.
The reproduced audio data from the read data selection circuit 13 is taken out to the output terminal 14.

A control signal indicating the reproduction speed is supplied from the reproduction speed control unit 15 to the read unit 11 and the read data selection circuit 13. In the case of one embodiment of the present invention, double speed reproduction and triple speed reproduction are possible. In the double speed reproduction, the reading unit 11 reproduces the video data at a rate of one frame in two frames, and in the triple speed reproduction, the video data is reproduced at a rate of one frame in three frames. The read data selection circuit 13 outputs the audio data A reproduced in association with one frame of video data.
The audio data corresponding to the instructed double speed ratio is selected from among 0, A1, and A2.

Although not shown, the audio data taken out to the output terminal 14 is D / A converted to
Converted back to analog audio signal. During double speed reproduction or triple speed reproduction, audio data decimated in phoneme units is converted into an analog audio signal. Since the thinning is performed on a phoneme-by-phoneme basis, it is possible to perform audio reproduction that can be discriminated when the reproduced sound is heard.

FIG. 5 shows a schematic structure of a recording apparatus corresponding to another embodiment of the present invention. In another embodiment, three frames of audio data are synchronized, so that the two-frame delay element 22 and the one-frame delay element 2 for that purpose are used.
3 are provided. A 2-frame delay element 21 is provided for video data. In the synthesis circuit 4,
Video data V and audio data A for 3 frames
10, A11 and A12 are combined. Then, it is recorded on the disk-shaped recording medium 9 by the recording unit 8.

Although not shown, the reproducing apparatus of another embodiment of the present invention has the same configuration as that of FIG. However, instead of the read data selection circuit 13, a circuit that performs resampling according to the speed ratio is provided.

The recording medium is not limited to a disk, but a tape (magnetic or optical), a semiconductor memory or the like can be used.

[0026]

According to the present invention, when recording a video signal and an audio signal on a recording medium, audio data of the number of frames required for double speed reproduction is recorded in advance, and the video data is intermittently reproduced from the recording medium. Even if necessary, the required audio data can be reproduced. Therefore, it is possible to smoothly reproduce the sound even at the double speed reproduction. Also, for example, 3 for one frame of video data
By recording the audio data for a frame, it is possible to reproduce the sound smoothly at an arbitrary speed ratio of 3 times or less.

[Brief description of the drawings]

FIG. 1 is a schematic diagram for explaining a recording method according to the present invention.

FIG. 2 is a schematic diagram for explaining a double speed reproduction operation according to the present invention.

FIG. 3 is a block diagram showing a schematic configuration of an example of a recording apparatus used to carry out the present invention.

FIG. 4 is a block diagram showing a schematic configuration of an example of a reproducing apparatus used for implementing the present invention.

FIG. 5 is a block diagram showing a schematic configuration of another example of a recording apparatus used to carry out the present invention.

[Explanation of symbols]

 3, 5 3 frame delay element 6 1/2 thinning circuit 7 1/3 thinning circuit 9 recording medium

Claims (3)

[Claims] 1. A digital signal recording method for recording video data and audio data on a recording medium, the step of thinning out the audio data in advance to 1 / N corresponding to a double speed reproduction operation at N times speed, A method for recording a digital signal, comprising the step of converting the extracted audio data into recording data together with audio data for non-decimated speed and the above-mentioned video data. 2. A digital signal recording method for recording video data and audio data on a recording medium, wherein N frames of the audio data are recorded in a video of each frame corresponding to a double speed reproduction operation up to N times speed. A digital signal recording method comprising the steps of associating with data, and converting the N frames of audio data into recording data together with the video data. 3. The digital signal recording method according to claim 1, wherein the audio data is thinned out in units of approximately phonemes.