JPH0648583B2 - Digital data magnetic recording method and apparatus - Google Patents

Description

TECHNICAL FIELD The present invention relates to a digital data magnetic recording method and apparatus for recording digital data using a helical scan system VTR.

[Prior Art] Conventionally, as a digital data magnetic recording method capable of recording and reproducing multi-channel digital data using a VTR, a technical standard CPZ-10 of the Japan Electronic Machinery Manufacturers Association (abbreviated as EIAJ) is used.
There are 5 consumer encoders and decoders. This technical standard is a consumer-use PCM that converts two-channel audio signals with a frequency band of 20 kHz or less into PCM and converts them into signals that comply with the standard television signals of the 60-field 525-line system, or the 50-field 625-line system. It is specified for encoders and decoders. The sampling frequency of the signal is However, in the case of an NTSC color television signal in a VTR without external synchronization, the field frequency is 59.94 Hz, so the sampling frequency is 44.056 kHz.
Therefore, although the sampling frequency is 735 times the field frequency, which is an integer ratio, the external input digital audio signal sampled at 44.1 kHz cannot be recorded as it is. The field frequency is 5 for PAL system television signals.
The sampling frequency may be 0 Hz and 44.1 kHz. Linearly quantize the A and B channel signals into 14 bits at the above sampling frequency,
The error correction words P and Q are composed of 14 bits. Then, as shown in FIG. 3, three blocks of A and B, error correction words P and Q, and error detection word (CRC) constitute one block. In the case of 60-field 525-line system, one block of data is arranged in one horizontal sync signal section along with a data sync signal and a white reference signal as shown in FIG. 4, and as shown in FIG. 245 data blocks and 294 data blocks are arranged in the case of 50 field 625 line system. Therefore, the number of samples in one field is 735 in the case of the 60 field 525 line system and 882 in the case of the 50 field 625 line system. In addition, the number of audio samples corresponding to the digital video signals to be recorded on one inclined track of the magnetic tape by the head rotating at the digital video signal frequency is organized into the standard number N of groups, and the audio samples of each group are organized. There is a method of changing the number from Nn to N + n to maintain the synchronization of the audio signal and the rotation frequency. For example, an audio signal from a digital audio recording / reproducing apparatus having a plurality of sampling frequencies such as DAT is recorded. In this case, if the value of n is kept constant, the sampling frequency is 32 kHz, which is a predetermined frequency deviation allowable range ±.
Even if it can follow 0.03%, ± 0.02 at a sampling frequency of 48 kHz
You can only follow%.

[Problems to be Solved by the Invention] In the conventional digital data magnetic recording method, the sampling frequency is an integral multiple of the field frequency, and the data arrangement was easy. Since 48 kHz and 32 kHz are used and are not an integral multiple of the field frequency, and therefore the number of samples is not an integer, data allocation was difficult. Furthermore, when a plurality of digital audio signals are to be input, when the sampling frequency of the digital audio signals changes, the allowable range of deviation from the video signal frequency also changes, making it difficult to follow the input digital audio signals. there were.

The present invention has been made in order to solve the above problems, and the number of samples in a period corresponding to a unit video signal is an integer, data arrangement can be easily realized, and the sampling frequency of an audio signal and video An object of the present invention is to provide a digital data recording method and apparatus capable of keeping a frequency deviation allowable range between signal frequencies constant without depending on a sampling frequency of an audio signal.

[Means for Solving the Problems] In the digital data magnetic recording method and apparatus according to the present invention, the number of samples in a period corresponding to a unit video signal is changed according to a change in a sampling frequency of an audio signal or a unit video signal frequency,
The sampling frequency ratio and the sample number ratio are made to be the same as an integer ratio.

[Operation] In the digital data magnetic recording method and apparatus according to the present invention, the number of samples in the period corresponding to a unit video signal is always an integer, and the sampling frequency ratio and the number of samples ratio are integer ratios. The use of the capacity in the unit video signal can be changed by an integer ratio according to the frequency and the unit video signal frequency, and the data arrangement is easy. Furthermore, the frequency deviation allowable range of the reference clock between the video signal and the digital audio signal can be made constant without depending on a plurality of sampling frequencies,
It is possible to easily follow an input digital audio signal having a plurality of sampling frequencies.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings. First
The figure is a track pattern configuration diagram of a VTR. One video track is a video section for one field, and this section is a digital audio signal recording portion for one field. FIG. 2 is a data block layout diagram of the digital audio signal on the memory. The section corresponding to one field has the maximum length. become. Field frequency f _v is NTSC 60 × 1000/1001
Consider two cases where the sampling frequencies are f _s1 = 48 kHz and f _s2 = 32 kHz. Let N ₁ and N ₂ be the number of samples per channel in each field. Becomes Here, if the ratio of N ₁ and N ₂ coincides with the sampling frequency ratio and becomes an integer ratio, data arrangement becomes easy. Further, the frequency deviation allowable range of the reference clock between the video signal and the digital audio signal can be made constant without depending on the sampling frequencies of 48 kHz and 32 kHz. Further, at each sampling frequency, if the ratios of the field having a large number of samples and the field having a small number of samples are matched, the data arrangement can be further simplified. So for example α1, α2, β
If you choose 1, β2, Becomes

804/536 = 798/532 = 48/32 = 3/2, and the sampling frequency is
When f _s1 = 48 kHz, there are 8 field data blocks with 804 samples, 7 with 798 blocks, and the sampling frequency is f _s2 = 32 kH
When z, there are 8 field data blocks with 536 samples,
The block of 532 becomes 7. It should be noted that the capacity per field data block is 804, which is the maximum value, and dummy data is inserted in field data blocks where the net data number is less than this. If the sampling frequency is 48 kHz, the number of samples is 798 to 804, and if the sampling frequency is 32 kHz, the number of samples is 532 to 536, both are -0.35% to + 0.3996%. Change the sampling frequency. Can also keep the frequency deviation allowable range constant. Further, since the field frequency f _v is 50 Hz in PAL / SECAM, N ₁ and N ₂ corresponding to the sampling frequencies f _s1 = 48 kHz and f _s2 = 32 kHz are N ₁ = 960 ± 6 and N _{2 respectively.} = 640 ± 4, 966/644 = 954/636 = 48/32 = 3/2
Becomes

[Effects of the Invention] As described above, according to the present invention, the number of samples per period corresponding to a unit video signal is an integer, and the sampling frequency ratio and the sample number ratio are made to coincide with each other by an integer ratio. Accordingly, a part of the capacity can be used in an integer ratio, and data arrangement is easy. Further, the frequency tolerance of the reference clock between the video signal and the digital audio signal can be kept constant without depending on the sampling frequency of the audio signal, and the digital audio signal having a plurality of input sampling frequencies can be You can easily follow.

[Brief description of drawings]

FIG. 1 is a block pattern configuration diagram on a tape of a digital data magnetic recording method according to an embodiment of the present invention, FIG. 2 is a data block layout diagram on a memory, and FIG. 3 is a block data configuration diagram showing a conventional example, FIG. 4 is a data waveform diagram in one field, and FIG. 5 is a configuration diagram of a data portion in one field. N is the number of samples, and α and β are natural numbers. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (2)

[Claims] 1. A number of samples to be recorded in a period corresponding to a unit video signal, From Up to the sampling frequencies f _s1 , f _s2 , ..., f _si ..., f
n of _sk , ... f _sn (a natural number _satisfying 1 ≦ i ≦ n, 1 ≦ k ≦ n)
When there are types, the maximum number of samples according to the above n types of sampling frequencies
N _{1 (max)} , N _{2 (max)} … N _{i (max)} ,… N _{k (max)} ,… N _{n (max)} (Α1, α2 ..., αi ..., αk ..., αn: natural number), or the minimum number of samples N _{1 (min)} , N _{2 (min)} ... N _{i (min)} , corresponding to the above n kinds of sampling frequencies. … N _{k (min)} ,… N _{n (min)}
To (Β1, β2 ..., βi ..., βk ..., βn: Natural numbers), the data is arranged on the tape as a digital data magnetic recording method. 2. A digital data magnetic recording apparatus for carrying out a digital data magnetic recording method, comprising: a storage means for storing data of a sample number N to be recorded in a period corresponding to a unit video signal; , From Up to the sampling frequencies f _s1 , f _s2 , ..., f _si ..., f
n of _sk , ... f _sn (a natural number _satisfying 1 ≦ i ≦ n, 1 ≦ k ≦ n)
When there are types, the maximum number of samples according to the above n types of sampling frequencies
N _{1 (max)} , N _{2 (max)} … N _{i (max)} ,… N _{k (max)} ,… N _{n (max)} (Α1, α2 ..., αi ..., αk ..., αn: natural number), the minimum number of samples according to the n types of sampling frequencies
N _{1 (min)} , N _{2 (min)} … N _{i (min)} ,… N _{k (min)} ,… N _{n (min)} (Β1, β2 ..., βi ..., βk ..., βn: natural number), and the first sampling frequency among the above n types of sampling frequencies
The arrangement of data in the storage means according to f _s1 and the arrangement of data in the storage means according to the second sampling frequency f _s2 are N _{1 (max)} / N _{2 (max)} = f _s1 / A control means for controlling f _s2 or N _{1 (min)} / N _{2 (min)} = f _s1 / f _s2 is provided, and data is arranged on the tape based on the data stored in the storage means. A digital data magnetic recording device characterized by the above.