JPS63268383A - Voice signal recording system - Google Patents

Abstract

PURPOSE:To prevent a reproducing voice from being lost even when one of plural disks becomes impossible to be reproduced, by dividing and recording each of tone color signals of plural channels on each of plural recording media, and recording after multiplexing it on each of the video signals of the plural channels reproduced simultaneously. CONSTITUTION:A time divisional multiplexing circuit 10 performs timedivisional multiplex on each of the four channel signals Y1-Y3 and C, and each of the channel signals A1-A4 cf four-leveled voice signal. Each of the channel signals Y1-Y3 and C outputted from the timedivisional multiplex circuit 10 is supplied to a D/A conversion circuit 15, and is converted to an analog signal, and is recorded on four sheets of video disks respectively. In such a way, it is possible to obtain the reproducing voice even when one of four recording media reproduced simultaneously becomes impossible to be reproduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for multiplexing and recording an audio signal onto a video signal.

1. As a conventional audio signal recording method, each of the audio signals of multiple channels is digitized and then time-division multiplexed to form a single code sequence, and a recording signal is generated according to this code sequence. The method of recording is well known.

On the other hand, as a method for recording wideband video signals such as high-definition television signals onto recording media such as conventional video discs, the video signal is divided into multiple channels and each is recorded on a different recording medium. A method has been proposed in which a plurality of recording media on which each recording medium is simultaneously reproduced.

If an audio signal is multiplexed and recorded using a conventional audio signal recording method on a recording signal obtained using such a video signal recording method, the audio signals of multiple channels are processed at once, so changes such as an increase in the number of channels can be easily accommodated. If, for some reason, it becomes impossible to play back one of the multiple recording media on which audio signals are multiplexed, the played sound will disappear. There was a problem.

Therefore, an object of the present invention is to provide an audio system in which the number of channels can be easily changed and reproduced sound can be obtained even if reproduction of one of a plurality of recording media that is simultaneously reproduced becomes impossible. The purpose of the present invention is to provide a signal recording method.

In the audio signal recording method according to the present invention, each of the audio signals of N (N is a natural number of 2 or more) channels is divided into each of M (M is a natural number of 2 or more) recording media, and is recorded and simultaneously played back. It is characterized in that it is multiplexed and recorded on each of the N channel video signals of the M channel video signals.

Support-U Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

A high-quality television RGB signal input from a video tape recorder, etc. is converted into a luminance signal Y by a matrix circuit 1.
and converted into two color signals C1 and C2. Color signal CL
The signal format of C2 is, for example, a color difference signal R-Y, B-Y, Cw (wideband color signal), or Cn (narrowband color signal). The required transmission frequency band is approximately 20MHz for the luminance signal Y.
, the color signals C1 and C2 are approximately 7MH2.

The luminance signal Y11 signal CL C2 is band-limited, for example, by a low-pass filter provided in the matrix circuit 1, and then is supplied to the AD conversion circuit 2. The AD conversion circuit 2 receives 4 signals output from a pulse generation circuit (not shown).
Two sampling pulses of 8.6 MH2 and 16.2 MHz are provided. In the AD conversion circuit 2, the luminance signal Y is converted into a digital signal corresponding to a sample value obtained by sampling using a 48.6MH2 sampling pulse, and the color signals C1 and C2 are converted into a digital signal corresponding to a sample value obtained by sampling with a 48.6MH2 sampling pulse.
It is converted into a digital signal according to the sample value obtained by sampling using the H2 sampling pulse. The color signal CLC2 digitized by the AD conversion circuit 2 is supplied to the line sequential encoding circuit 3 and converted into a line sequential color signal C (hereinafter simply referred to as color signal C). Since the horizontal scanning frequency is 33.75kHz, the total number of samples within one horizontal scanning period is 48.6MHz/33.75kHz-1440 for the luminance signal Y, and 16.6MHz for the color signal C. -2MHz/33.75kHz-48
However, the number of effective video signal samples excluding the blanking period is 1260 and 420, respectively, assuming the horizontal effective scanning rate is 0.875.

The digitized luminance signal Y and color signal C are supplied to a sub-Nyquist sampling encode circuit 4.

The sub-Nyquist sampling encode circuit 4 is configured to perform subsampling using, for example, a field offset subsampling method that causes relatively little deterioration in image quality.

Half subsampling is performed by this sub-Nyquist sampling encoder circuit 4, and the above-mentioned effective video sample numbers for the luminance signal Y and chrominance signal C are reduced to 630 and 210, respectively, and the sampling frequency is 24.3MH2. and 8. It becomes IMH2. Note that sampling patterns of the field offset subsampling method adopted in the sub-Nyquist sampling encode circuit 4 are shown in FIGS. 2 and 3. FIG. 2 shows a sampling pattern for the luminance signal Y, and FIG. 3 shows a sampling pattern for the color signal C.

In addition, in these figures 2 and 3, the 0 mark is the first
Sample points that are transmitted in the field are indicated, e marks indicate sample points that are transmitted in the second field, and X marks indicate sample points that are not transmitted.

The luminance signal @Y that has passed through the sub-Nyquist sampling encode circuit 4 is supplied to a line unit division circuit 5. In the line unit division circuit 5, the effective video sample of the luminance signal Y is divided into three channels Yl, Y2, and Y3 as shown in FIG. 4 by time division in units of one horizontal scanning (line) period. Ru. As a result, the samples of the luminance signal Y on one screen per frame by interlaced scanning are uniformly distributed and transmitted by each channel signal of Y1, Y2, and Y3 as shown in FIG. In the same figure, O marks indicate sample points transmitted by channel signal Y1, ◎ marks indicate sample points transmitted by channel signal Y2, and ・marks indicate samples transmitted by channel signal Y3. points are shown.

This line unit division circuit 5 makes it possible to reduce the influence of differences in recording and reproduction characteristics between channels on reproduced image quality.

Channel signal Y output from line unit division circuit 5
1, Y2, and Y3 are supplied to the sample unit division circuit 6. In the sample unit dividing circuit 6, 1 of the luminance signal Y
The 630 samples of effective video signals within the horizontal scanning period are divided into three within three consecutive horizontal scanning periods of any one of Yl, Y2, and Y3 channel signals, and the time axis is expanded three times before being transmitted. . As a result, on each channel signal, the number of effective samples within one horizontal scanning period is 630/3-
210. The sampling frequency is 24.3MHz/3-
8.1 MHz, and both have the same value as the color signal C.

Line number of luminance signal Y within one frame period and Yl, Y
The correspondence between the line numbers of the channel signals 2 and Y3 is as shown in FIG.

The arrangement of 630 effective video signal samples (y to y) of the luminance signal Y within three consecutive horizontal scanning periods of each channel signal Yl, Y2, Y3 is shown in FIG.

If a dropout occurs during playback by the sample unit division circuit 6, samples with high correlation that should be adjacent to the missing video signal sample on the luminance signal Y are played back during another horizontal scanning period of the same channel signal. Therefore, effective dropout correction can be performed by replacement or interpolation processing using this. Dropouts longer than three horizontal scan periods cannot be corrected.

However, the frequency of this occurrence is extremely small, and almost complete dropout correction is usually possible.

Through the above signal processing, the high-definition television video signal is divided into four channel signals of the same format: Y1, Y2, Y3, and C. FIG. 8 shows the structure of one frame of the channel signal.

These four channel signals Y1, Y2 . Y3 and C are supplied to a synchronization signal generation/addition circuit 7, where a common format horizontal synchronization signal and frame synchronization signal are generated and added. The horizontal synchronization signal is formed by adding a synchronization waveform to a horizontal blanking period corresponding to a '30 sample transmission period, and the frame synchronization signal is formed by adding a synchronization waveform to one horizontal scanning period during the vertical blanking period.

Four channel signals MY1 and Y2 with synchronization signals added
, Y3, and C are supplied to the screen number identification signal addition circuit 8, and the common screen number identification signal is added to other horizontal scanning periods except for the period in which the frame synchronization signal of the vertical blanking period is added.

The screen number identification signal is a signal obtained by level-modulating a screen frame number identification code generated from the time code output of a video tape recorder using a pie-phase method or the like, and is used for screen synchronization control of four channels in a playback system.

4 channel signals Y with screen number identification signal added
1, Y2, Y3, and C are supplied to a level reference signal adding circuit 9, and a level reference signal for monitoring the DC level and amplitude of each channel signal during reproduction is added. This level reference signal has a waveform capable of providing at least two video signal levels.

The four channel signals Y1, Y2, Y3, and C to which this level reference signal is added are supplied to the time division multiplexing circuit 10.

On the other hand, □A/
Each channel signal A1, A2, A3, and A4 of the D-converted four-channel digital audio signal is supplied to an error detection and correction encoding circuit 11, and processing such as adding an error detection and correction code to each channel signal is performed. The four channel signals A1 to A that have passed through this error detection and correction encoding circuit 11
4 is supplied to a four-value encoding circuit 12, where it is divided into two bits each and converted into a four-value encoding circuit. This four-valued code is treated as a Gray code, so that even if an error occurs in an adjacent level during level identification, the number of bit errors will be 1 bit. That is, as described later, 00.01
．． 11.10 2-bit codes are sequentially associated with each of four different levels.

The four channel signals A1 to A4 encoded with four levels are:
The signal is supplied to a time axis compression circuit 13 and subjected to time axis compression. The compression rate is 1 frame (112
5 lines), the number of lines is set to 84. Note that the time axis compressor 13 does not necessarily need to be placed after the four-value encoding circuit 12, but may be placed before it.

The four channel signals A1 to A4 subjected to time axis compression by the time axis compression circuit 13 are supplied to a four-level circuit 14. The four-level circuit 14 has four-valued numbers 0O101,
11 and 10 correspond to level 0, level 1, level 2, and level 3, respectively. That is, as shown in FIG. 9, one sample value of a video signal is represented by, for example, an 8-bit level (256 levels);
The audio signal uses only 70% of the range of the video signal. For example, the audio signal is 38 times the video signal.
Level (level 0), 98 level (level 1), 158
It is adapted to correspond to either level (level 2) or 218 level (level 3). Increase the audio signal level range (closer to 100%)
and overshoot due to the influence of brienfasis,
Undershoot occurs, the frequency band is occupied more than necessary, and distortion is likely to occur. On the other hand, if it is made smaller, the data S/N deteriorates, and the influence of noise on the four-level discrimination increases. Therefore, it is preferable to use a range of around 70% as in the embodiment.

The time division multiplexing circuit 10 receives four channel signals Y1 to Y3 of the video signal output from the level reference signal adding circuit 9.
and C and each of the four-level audio signal channel signals @A1 to A4 are time-division multiplexed. In other words, the audio signal is applied to each of the 3rd to 44th lines in the vertical retrace period of the first field of the video signal and the 565th to 606th lines of the second field, a total of 84 lines, as shown in FIG. It is inserted into the audio data section formed as shown in FIG. The frequency of the sampling clock of the video signal is 8.1 MH2, and the number of clocks per line is 240. In each line into which an audio signal is inserted, a horizontal synchronization signal exists in the first 30 clock periods. 208 that exists apart from this horizontal synchronization signal interval by a guard interval of one clock.
The period corresponding to one clock is the audio data period, and the period corresponding to one clock following the audio data period is the guard period.

Channel signal Y1 output from time division multiplexing circuit 10
~Y3 and C are each supplied to the DA transition circuit 15,
converted to an analog signal. Later, each of the channel signals Y1 to Y3 and C is converted into an FM signal and supplied as a recording signal to an E10 modulator (not shown) or the like.
recorded on each of the four video discs.

Here, in the error detection and correction encoding circuit 11, if one block is formed of 32 bytes, an audio data block is recorded on each line during the vertical retrace period as shown in FIG. 6 in one field period
This means that seven blocks of audio data can be recorded. The data transmission capacity in this case is 67 [blocks/field] x 32E bytes] x 8 [bits] x 2 [fields] x 30 [frames/5l = 1.029.120
[bps]. Note that the audio signal is applied to each of the 3rd to 46th lines in the vertical retrace period of the first field of the video signal and the 565th to 608th lines of the second field, a total of 88 lines, as shown in FIG. If you insert it into the entire formed audio data section,
Data transmission capacity is 208 [clock] x 2 [bit/
lines] x 44 [lines/field] x 2 [fields] x 30 [frames/s] - 1,098,240 [b
ps].

On the other hand, the transmission capacity required to transmit 14 channels of high-quality PCM audio data with an audio signal band of 20 KHz and 16-bit linear M-coding is a sampling frequency of 44.
If it is 1KHz, (44°1xlO')x16=
705,600 [bps], and even if redundancy due to error correction encoding and transmission of additional data are taken into consideration, sufficient recording is possible with the above-mentioned transmission capacity.

FIG. 12 is a block diagram showing a part of a reproducing apparatus for reproducing information recorded on a video disc by the recording apparatus as described above. In the figure, four channel signals Y1, Y2,
Each of Y3 and C is read by each of the players 21-24.

Since the signal format of each channel' signal and the recording format on the disk are the same, the players 21 to 24 may have the same specifications. Also, the signal band and disk rotation speed are the same as in the conventional system. , the basic specifications of conventional players can be used as they are.

Each of the channel signals Y1 to Y3 and C output from each of the players 21 to 24 is supplied to a synchronization detection circuit 25. In the synchronization detection circuit 25, a horizontal synchronization signal and a frame synchronization signal are separated from each channel signal, and the signals are obtained by comparing the frequency and phase of the separated horizontal synchronization signal and frame synchronization signal with a reference synchronization signal common to each channel. By feeding back the time-base error signal to the time-base servo circuits of the players 21 to 24, it is possible to reproduce each channel signal in a synchronized manner.

The screen number identification signal added to the vertical blanking period of each of the channel signals Y1 to Y3 and C is read by the screen number reading circuit 26 and compared with the reference screen number. The obtained error signal is fed back to the slider servo circuit, tracking servo circuit, and spindle servo circuit of each of the players 21 to 24, and by controlling the signal playback position on the disk, screen-synchronized playback of each channel is performed. .

Each of the channel signals Y1 to Y3 and C is AD converted by the AD conversion circuit 27 at a sampling frequency of 8.1 MH2. The output of this AD conversion circuit 27 is supplied to a phase synchronization detection correction circuit 28. Phase synchronization detection correction circuit 2
8 performs accurate synchronization detection and time axis correction of each channel signal using a horizontal synchronization signal, and also feeds back a sampling phase error signal to the AD conversion circuit 27 to control the sampling clock phase. video signal samples can be obtained.

Channel signal Y1~ passed through phase synchronization detection correction circuit 28
Each of Y3 and C is supplied to a time division separation circuit 29, and the audio signals multiplexed on each channel signal are time division separated.

The four channel signals A1 to A4 of the audio signal are supplied to a four-level identification circuit 30, which of the four levels described above is identified, and converted into a four-valued symbol.

Four channel signals A1 to A4 converted to four-valued symbols
The time axis is expanded by the time axis expansion circuit 31, and then the 4
The signal is supplied to the 1ia decoding circuit 32, where it is converted from a four-value symbol to a normal binary symbol. Each of the four channel signals A1 to A4 that has passed through the four-value decoding circuit 32 is supplied to an error correction circuit 33 where processing such as error detection and correction is performed, and then supplied to an audio decoder (not shown) or the like. be done.

On the other hand, each of the channel signals Y1 to Y3 and C of the video signal is supplied to a signal level detection and correction circuit 35. The signal level detection/correction circuit 35 performs precise detection and correction of the DC level and amplitude of the signal using the level reference signal added to the vertical blanking period of each channel signal.

Each of the channel signals Y1 to Y3 that has passed through the signal level detection correction circuit 35 is supplied to a sample unit synthesis circuit 36, and 630 luminance signal samples during three horizontal scanning periods of each of the channel signals Y1, Y2, and Y3 are Luminance signal Y
are restored to the correct order during one horizontal scanning period. At this time, when a dropout is detected in the players 21 to 23, a dropout detection signal is used to perform dropout correction using the method described above, that is, dropout correction using valid video samples within three consecutive horizontal scanning periods. .

Channel signal Y1~ passed through sample unit synthesis circuit 36
Each of Y3 is supplied to the line unit synthesis circuit 37.

The line-by-line synthesis circuit 37 has three lines based on the correspondence shown in FIG.
By performing time axis compression of one minute and time division synthesis,
Video signal samples of the luminance signal Y are restored. The video signal samples of the luminance signal Y and the chrominance signal C are supplied to the sub-Nyquist sampling decoding circuit 38, and by interpolating the same number of samples that have not been transmitted, Y is sampled at 48.6 MHz, and C is sampled at 16.2 MHz. Original video signal samples according to frequency are reproduced.

Furthermore, the color signal C is separated into color signals C1 and C2 by a color signal II sequentially deflated circuit 9. Furthermore, the signal sample values of the lines that are not transmitted are determined by interpolation, and the original video signal samples of the color signals C1 and C02 are reproduced.

The luminance signal Y11 signals C1 and C2 are supplied to the DA conversion circuit 40, and the luminance signal Y has a frequency of 48.6 MHz.

The color signals C+ and 02 are each subjected to DA conversion at a sampling frequency of 16.2MHz, and then sent to the matrix circuit 4.
1 is converted into a high-definition television RGB signal and sent to a monitor or the like.

11.1 And as detailed above, the audio signal recording method according to the present invention divides each of the audio signals of a plurality of channels into each of a plurality of recording media and records them, and simultaneously reproduces each of the video signals of a plurality of channels. Since each channel signal is multiplexed and recorded, each channel signal becomes independent and does not influence each other, and the number of channels can be easily changed.

Further, even if one of the plurality of disks to be played simultaneously becomes unplayable, the channel signals recorded on the other disks can be played back, so the reproduced sound will not disappear. Another advantage is that during a playback test, the playback sound can be previewed even with just one disc.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIGS. 2 and 3 are diagrams showing sampling patterns of subsampling performed in the apparatus shown in FIG. 1, and FIG. 4 is a block diagram showing an embodiment of the present invention. FIG. 5 is a diagram showing a method of channel division of a luminance signal performed in the device of FIG. 1, and FIG. 6 is a diagram showing a method of sample transmission performed in the device of FIG.
A diagram showing the correspondence between the line numbers of the luminance signal Y and the line numbers of channel signals Y1 to Y3 in the apparatus shown in FIG. 1, and FIG. FIG. 8 is a diagram showing the structure of one frame of the channel signal in the device of FIG.
9 is a diagram showing the level of the audio signal in the device shown in FIG. 1, FIGS. 10 and 11 are diagrams showing the multiplexing format of the audio signal in the device shown in FIG. 1 is a block diagram illustrating an apparatus for reproducing signals recorded by the illustrated apparatus; FIG.

Claims (2)

[Claims] (1) An audio signal recording method for recording N (N is a natural number of 2 or more) channels of audio signals on a recording medium, wherein each of the N channels of audio signals is recorded in M (M is a natural number of N or more) channels. An audio signal recording method characterized in that video signals of N channels of video signals of M channels which are divided and recorded on each recording medium and reproduced simultaneously are multiplexed and recorded. (2) Each of the N-channel audio signals is a quaternary signal having an instantaneous level corresponding to each code of a quaternary code series obtained by dividing the code series formed by PCM into two bits each. An audio signal recording method according to claim 1, characterized in that: