JPS62114163A - Pcm signal recording and reproducing device for sound signal - Google Patents

Abstract

PURPOSE:To record and reproduce simultaneously a sound signal and a video signal even when the sampling frequency of sound and a field frequency are asynchronized by controlling the master clock of a sound processing circuit. CONSTITUTION:An oscillation circuit 22 uses a control signal 50 outputted from a video circuit 44 to generate a clock synchronously with a field frequency. The clock controls a block shown in broken lines 7 in the timing generated by a timing generation circuit 21. Thus, the relation of synchronization is provided to the field period in the processing of the sound signal and the sound signal and the video signal are recorded and reproduced at the same time even when the sampling frequency and the field frequency are asynchronized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an apparatus for recording and reproducing encoded audio signals on a magnetic tape together with a video signal or alone using a rotating magnetic head type scanner, and particularly for a PCM This is suitable for matching the sampling frequency of the audio signal to the rotational frequency of the scanner.

[Conventional technology]

PCM to improve the quality of the audio signal accompanying the video
A method has been introduced. Here, 8vmVidao
, the audio PCM method is adopted, but the audio PCM method is adopted.
The sampling frequency of the CM signal is twice the horizontal synchronization signal repetition frequency.

On the other hand, in the MUSE method, which is one of the transmission methods for high-definition television, the sampling frequency of the audio PCM signal is 52kHz and 48kHz, so if you try to record data sampled at the same sampling frequency field by field, ,1
The number of data per field becomes a fraction, which causes inconvenience. As a way to resolve this inconvenience, NHK Giken Monthly Report 2
7-7 pp. 282, a packet transmission system having a leap field for absorbing the remainder is used.

In addition, for video discs, PCs with the same format as compact discs and a sampling frequency of 44.1 kHz are used.
M voice is being recorded.

However, when attempting to record PCM audio on a device such as a video tape recorder that records or transmits signals temporally discontinuously, the following problems arise. First, if the sampling frequency of the audio signal cannot be divided by the field frequency of the video signal, the above-mentioned problems occur in encoding. For this reason, there is a solution such as the above-mentioned MUSE method, but in this case, the field frequency fr of the video signal, the rotation frequency fn of the head scanner that rotates in synchronization with this, and the sampling frequency fs of the audio signal It is necessary to establish a synchronization relationship between them, and this is a condition that limits the range of application of the system.

Furthermore, as a device for recording and reproducing only audio signals in PCM on a rotary head type VTR, there is a PCY encoder/decoder for consumer use (19sx, 9th enactment) of the Japan Electronics Machinery Industry Association technical standard CPZ-105. Based on this technical standard, for example, as a recording/reproducing device,
At the 69 Convenge Corps May 1, 1981
2nd - 15th Los Angeles N.E.N.I.S.
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Seas (Digitgl Audio / Vid-
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Using Csbztam Made LSI'g
1 and 14 of IC#s).

In the same paper, for example, in the case of NTSC, the field frequency fr and the sampling frequency ft are divided from the same master clock, and there is a relationship between them of ftt - 755f, so the number of samples in one field (6t) is constant at 735. It is said that

In addition, in the same paper, the sampled PCM signal was recorded and
A block diagram of the device configuration for playback is shown in FIG. 1 of the same paper. In the figure, the address of RAM as interleaving memory is controlled by an address control circuit.
There is. However, 3.

This example is based on the premise that the field frequency fr and the sampling frequency fs have a certain relationship, and no consideration is given to the case where fr and fs are uncorrelated.

[Problem that the invention seeks to solve]

In the above conventional technology, the sampling frequency of the audio signal is not an internationally generalized sampling frequency and the number of quantization bits is small, and there is no synchronization relationship between the audio signal sampling frequency and the field frequency. For example, when trying to record audio using a video signal from a camera and a direct digital signal from a CN (compact disc), certain things are required, such as differences in the sampling frequency or differences between the sampling frequency and the field frequency. It has been extremely difficult to record both at the same time due to the lack of synchronization between the two.

SUMMARY OF THE INVENTION An object of the present invention is to realize a video tape recorder capable of recording and reproducing long audio signals together with video signals in which the sampling frequency is correlated with the field frequency.

4. [Means for solving the problem] The above object is achieved by controlling the master clock of the audio signal processing circuit so that there is a constant relationship between the sampling frequency and the field frequency.

[Effect]

In the recording system, the input sampled signal is written into a single memory, subjected to a predetermined encoding process, and then subjected to interleaving processing to form a signal to be sequentially read out from the memory and recorded on a tape. The write period, input sampling signal period, and read period to the memory depend on the field period of the video signal.

Here, when the pchr audio signal is output in bursts, a memory is required to expand the time axis of the pchr audio signal during the field period and record it on the tape.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 is a block diagram of a rotating head type PCM signal recording and reproducing apparatus.

During recording, an H 2-channel/channel analog signal is input from the input terminal 1. The input signal is amplified to a predetermined level by an amplifier circuit 2, band-limited by a filter 3, and then sampled by a sample hold circuit 4. The sampled input signal is sequentially inputted to an A/converter 6 by a switching circuit 5 and converted into a PCM signal. The PCM signal converted by the 4-shift converter 6 is
It is written into the RAM 15 through the pass line 14. Then, the address of the RAM 15 is controlled by the address generation circuits 17 to 19 and the address switching circuit 16, and the arrangement of the PCM signal and the addition of the correction code are performed according to a predetermined format. Note that the addition of the error correction code is performed using the error correction circuit 20.

After the PCM signals are arranged and the error correction code is added, each data is read out from the memory RAM 15 in block units and modulated by the modulation circuit 23. Then, a control signal such as a synchronization signal is added by the control signal generation circuit 24 and the switching circuit 25 and output from the output terminal 34 in a burst manner.

The recording signal output from the output terminal 34 is converted by a data conversion circuit 36 and sent to the RAM through a pass line 38.
59. Then, the address of the RAM 59 is controlled by the address generation circuits 55 and 53 and the address switching circuit 34. Each data is stored in block RAM
59, and the parallel-to-serial conversion circuit 40 inputs the pass line 3.
It is taken in through 8. A control signal such as a synchronization signal is added to the parallel-to-serial converted audio signal by a control circuit 41 and a switching circuit 42, and then modulated by a modulation circuit 43. The audio signal modulated by the modulation circuit 43 is amplified to a predetermined level by the recording amplifier 26 and recorded on the surface or deep layer of the magnetic tape 33 by the cylinder head 32. There is a switching circuit 31 for switching between recording and reproduction.

Here, the oscillation circuit 22 synchronizes with the video signal using the control signal section 50 output from the video circuit 44, and generates a lock. Further, the timing circuit 21 is a circuit that generates timing for controlling the portion 7 indicated by the dotted line by the oscillation circuit 22. On the other hand, the timing circuit 54 is a circuit that generates a timing signal controlled by the control signal section 45 output from the video signal.

During reproduction, the switching circuit 31 is switched to the reproduction side, and the PCM audio signal reproduced by the cylinder head 32 is input to the reproduction amplifier 30 where it is amplified and waveform equalized. After the data is converted into a digital signal by the demodulation circuit, the surface difference conversion circuit 52 reproduces the data, and the synchronization detection circuit 51 detects a synchronization signal. The synchronization signal detected by the synchronization detection circuit 51 is used as a reference for data reproduction. The data demodulated by the surface difference conversion circuit 52 is recorded in the SRAM 39. Address generation circuits 55 and 53 and address switching circuit 3
Control 4. Each data is stored in the RAM 59 in blocks.
The data is read out in a burst manner and is input to the data conversion circuit 37 through the pass line 38. The data conversion circuit 37 again adds a control signal such as a synchronization signal, outputs a PCM audio signal and a control signal necessary for generation, and inputs it to the input terminal 35. A data synchronization circuit 29 extracts a clock synchronized with the data from the signal inputted from the input terminal 35. Then, the demodulation circuit 27 demodulates the data and the synchronization detection circuit 28 detects the synchronization signal. The detected synchronization signal is used as a reference for data reproduction.

The data demodulated by the demodulation circuit 27 is stored in RAM1.
5, the data is rearranged and error correction is performed by the error correction circuit 20. The PCM signals rearranged in chronological order are sequentially converted into analog signals by the Roux converter 12 through the pass line 14, and resampled by the sample and hold circuit 11 for each channel.

Analog signals resampled in each channel are output from an output terminal 8 through a filter 10 and an amplifier circuit 9.

The video signal is inputted from the input terminal 47 during recording, is amplified to a predetermined level by the video circuit 44, and is sent to the cylinder head 3.
2, it is recorded on the magnetic tape 33 together with the PCM audio signal or alone.

Furthermore, the skeleton image circuit 44 is connected to the synchronization signal detection head 4 of the VTR.
The rotation of the cylinder is controlled based on the signal obtained from step 6.

During reproduction, the video signal reproduced by the cylinder head 32 is outputted from the output terminal 48 after processing such as separation of the amplified PCM audio signal from the reproduction signal in the video circuit 44 . Further, the video circuit 44 controls the rotation of the cylinder based on a signal obtained from a synchronization signal detection head 46 of the VTR.

A portion 7 indicated by a dotted line in FIG. 1 has the same configuration as a conventional DAT for recording two-channel PCM signals. In the present invention, by adding a portion 13 indicated by a two-dot broken line to this, the PCM signal outputted in a burst manner is expanded in the time axis so that it can be recorded on the surface or deep layer of the VTR. During playback, the reverse operation is performed.

Note that the field period of the R-DAT is synchronized with the field period of the VTR, so that the recording capacity per field is made the same.

Next, the specific time relationship when recording a PCM audio signal on a VTR using the R-DAT system will be explained.

Sampling frequency 48 kHz, number of quantization pits 1
R- for recording and reproducing 6-bit 2-channel signals
1) The structure of the PCM data of the AT system is shown in FIGS. 2 and 5. Figure 2 shows the data for the +azimuth track, and Figure 5 shows the data for the -azimuth track.
is one symbol (-8 bits) of data, 61 is a first error correction code, and 62 is a second error correction code. In the rotating head type DAT, one word of two channels records a 16-pit PCM signal by dividing it into 8-bit symbols. A 32-symbol f1 block is constructed, and 128 blocks of data are recorded on one track. Furthermore, data is distributed so that even if a large burst error occurs, the error can be corrected.

・11 ・ In other words, the even-numbered data of the L channel is recorded in the first half of the +azimuth track, the odd-numbered data is recorded in the second half of the first azimuth track, and the even-numbered data of the R channel is recorded in the first half of the first azimuth track. , odd-numbered data is recorded in the latter half of the +azimuth track. Note that in R-DAT, since the cylinder rotation speed is 200 rpm, 5760 symbols of data are recorded in 2 tracks.

FIG. 4 shows a recording pattern on a magnetic tape.

On the magnetic tape 33, +azimuth tracks 33-1 and -azimuth tracks 33-2 are alternately recorded.

In this way, the rotating head system ryr (R-nAr)
In this example, two channels of PCM signals are recorded on the 5B, 776° portion of a magnetic tape wrapped at 90° around a cylinder, but in this example, the R-DAT cylinder rotation speed is synchronized with the VTR cylinder rotation speed. The master clock is changed so that the PCM audio signal in an area of approximately 5B, 776° is time-extended to an area of 180° and recorded. During playback, the opposite operation is performed and a control signal such as an audio signal identification signal is added."1: R-DA
Control the T system.

This operation will be explained in detail using FIG.

When the cylinder rotation of the R-DAT is synchronized with a VTR of 525/60 (NTSC), the time interval of one frame is approximately 146aSllIF. Therefore, the sampling frequency is approximately 45.1568 kHz. Figure 5 (,)
The Oa indicated by is approximately 5.448 mg in terms of time in the data output region of R-DAT. θb is approximately L468511# in one frame time. When recording, θα of (α) in the same figure
The PCM audio signals output during the period are stored in the time axis compression/expansion RAM 59 shown in FIG. 1 in the time relationship shown in FIG. 5(b). Next, the audio signal stored in a burst manner is time-extended to the time θb of one frame as shown in FIG. Recorded deep within.

During playback, the magnetic tape 18 is
The PCM audio signal reproduced together with the video signal or alone from the 0° region is stored in the time axis compression/expansion RAM. Next, one frame of audio data is added with a control signal necessary for reproducing the audio signal identification signal, etc., as shown in Fig. 5 (h).
The time axis is compressed and output in bursts. This audio signal output in bursts is reproduced by R-1) AT to obtain an audio signal. As another example, as shown in FIG.
1-(θC+θd) and can be recorded as a postamble and preamble area. For example, when performing NRZ-1 modulation of a PCM audio signal, single (or xi, q
By setting h ), after NRZ -7ffi tone, it becomes 1
It becomes an ampoule signal of 01010...

As another example, synchronizing the R-DAT field frequency with a 62s 15G (pit) VTR,
It is conceivable to record/reproduce on the surface or deep layer of a magnetic tape together with a video signal or alone.

As another example, V of 625150 (PAL)
It is conceivable to synchronize the field frequency of the R-DAT with the TR and record and reproduce the PCM audio signal to which the ampoule signal has been added together with the video signal or alone on the surface or deep layer of the magnetic tape.

Next, the oscillation circuit 22 will be explained with reference to a more specific embodiment shown in FIG.

A phase comparison circuit 58 compares the phases of the output signal 57 of the timing pulse generation circuit 210 and the head switching signal 50 with the waveform shaping circuit 61, and outputs the phase comparison output from the low frequency F
A master clock pulse 56 synchronized with the video system is generated by generating an F wave in a wave circuit 59 and controlling the oscillation frequency of a variable oscillation circuit 60 using the output of the F wave. The pulse 56 is frequency-divided by a frequency dividing circuit 55 to a predetermined division ratio.

For example, in the case of the 525/6o system, the repetition frequency of the head switching signal 50 is approximately 29.97 Hz, and the frequency of the master clock pulse 56 is approximately 24.576 MHz multiplied by 6 in the case of R-DAT. 22.096
Controlled by MHz.

In this case, the frequency dividing ratio of the frequency dividing circuit 55 is 1/7!17280. Similarly, for example, in the case of 62515o method・1
5. The repetition frequency of the head switching signal 50 is 25 Hz, and the frequency of the pulse 500 is controlled to 18.432 JfNz.

〔Effect of the invention〕

According to the present invention, a rotating magnetic head type scanner performs PCM
When recording an audio signal together with a video signal, there is a synchronization relationship between the rotation frequency of the head scanner and the sampling frequency of the PCM audio signal, so any video signal and PC
M audio signals can be combined and recorded simultaneously.

[Brief explanation of drawings]

Figure 1 is a circuit configuration diagram of an embodiment of the present invention, Figures 2 and 3 are
The figure shows the structure of the recorded data of R-DAT. FIG. 4 shows the recording pattern on the magnetic tape. FIG. 5 shows the operation of FIG. 1. FIG. 6 shows a specific example of the oscillation circuit 22. FIG. 1......Input terminal 2...
・・・・・・・・・Amplification circuit 3・・・・・・・・・・・・
Filter 4...Sample/hold circuit 5
.........Switching circuit 6...
......A/n telescope, 16°7...Rotating head fJDAT system 8...Output terminal 9.・
・・・・・・・・・Amplification circuit 10・River・・・・Filter

Claims (1)

[Claims] 1. In a device that records and plays PCM audio signals, PCM
A memory for sequentially storing audio signals, a write address control circuit for storing the PCM audio signal at a predetermined address of the memory, and controlling an address for reading the PCM audio signal etc. stored in the memory. and an oscillation circuit for synchronizing a system clock of a recording/reproducing device for the PCM audio signal with a field synchronization signal at the time of writing or a field synchronization signal at the time of reading. PCM signal recording and reproducing device.