JPS6329377A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To attain the stable identification of a field by recording a difference if number of sampled digital sound signal per field or channel does not reach a maximum sampling number, making a dummy data as a continuous data string and arranging it together with a digital sound signal thereby simplifying a circuit constitution. CONSTITUTION:In fixing maximum sampling number NMAX per channel to be recorded in one field, if the number of sampling N of a field to be recorded does not reach the maximum sample number NMAX per field, a dummy data corresponding to its difference (NMAX-N) sampling is formed to be a consecutive data string and arranged together with the digital sound signal and subjected to recording/reproducing. Further, the identification signal of a field whose sampling number is respectively fs/fv+alpha and fs/fv-beta is provided at every data block in one field. That is, the dummy data is formed into a consecutive data string, it is arranged together with the digital sound signal and recorded/ reproduced. Further, the identification signal is recorded at every data block.

Description

Detailed Description of the Invention [Field of Industrial Application] This invention converts an audio signal into a digital signal, or converts an audio signal that has already been converted into a digital signal together with a video signal or into an audio signal. The present invention relates to a magnetic recording and reproducing device that records and reproduces only signals.

[Problem that the invention seeks to solve]

When recording and playing back digital audio signals on a helical scan VTR, there are cases where analog audio input signals are digitally converted on the VTR and then recorded and played back, and digital audio input signals from other devices, broadcast signals, etc. are recorded. It is conceivable that the data may be played back. At this time, the sampling frequency of the digital audio input signal input from another source does not necessarily match the sampling frequency of the digital audio signal converted into digital data in the VTR, and therefore The number of samples also takes on variable values.

Furthermore, if the sampling frequency f is not an integer multiple of the field frequency fu, only an integer number of samples can be recorded in one field, so the number of samples per channel is N.
u = Li2 /fvJ 10ct and No = Lf 3
/fv'.

A possible method is to absorb the fraction of f s /fv by repeating two types of fields -β at a certain ratio. In other words, even at one sampling frequency, the number of samples per channel is two, Nx and No.
There are 71 types of rules.

Here, when the maximum number of samples NMAX per channel that can be recorded in one field is fixed, if the number of samples N in the field to be recorded does not reach the maximum number NMAX that can be recorded in the l field, then Difference (NWAX
Although it is necessary to record dummy data corresponding to the samples of -N), the circuit configuration becomes complicated depending on how the dummy data is arranged when recorded.

In addition, the number of identification signals per field for the field with the number of samples of 1fS/lvj+α and the field with the number of samples of j, fs/fvJ-β is small, and the data in the field is not recorded over the entire area. In such cases, stable identification cannot be performed because the identification signal is lost due to a dropout of the reproduced signal caused by dropout or the like.

This invention was made to solve the above-mentioned problems, and it simplifies the operation and circuit configuration associated with dummy data arrangement, and also reduces the number of samples per channel to L.
This allows stable discrimination between fs/fvj + ex and Lfs/fvJ -β field.

[Means to solve the problem]

In the recording and reproducing apparatus according to the present invention, dummy data corresponding to (NMAX-N) samples are made into a continuous data string, arranged together with a digital audio signal, and recorded and reproduced, and the number of samples is /fv+α, f
An identification signal for the s/fv-β field is provided for each data block within one field.

[Effect]

In the present invention, the dummy data becomes a continuous data string, and then is arranged and recorded and reproduced together with the digital audio signal. Also, an identification signal is recorded for each data block.

〔Example〕

In the embodiment of the present invention, a VTR when the video signal is an NTSC color television signal,
Magnetic tape fζ, digital audio signal (hereinafter simply referred to as PC
It is written as M data. ) is recorded and played back. In addition, the two-yield frequency f y in the NTSC system
=59.94 Hz.

First, Table 1 shows examples of the sampling frequency fs, the number of channels, the number of quantization bits, and the number of samples per channel in one field.
It is called ff.

Next) FIG. 2(a) is a block diagram showing an example of signal processing during recording and reproduction in this embodiment, respectively.

(b) First, during recording, the analog audio input signal is input from the analog audio signal input terminal (t+71) and A/D converted, and the digital audio input signal is input from the digital audio signal input terminal and then sent to the interface circuit ( After passing through c), the digital audio signal processing circuit (7)
The digital signal is encoded into a digital signal in a predetermined recording format by adding an error correction code (in this example, a double Reed-Solomon code) and performing interleaving, and then modulated by a modulation circuit). The signal passes through the recording amplifier -I@ and is recorded on the magnetic tape 4 by the magnetic head -■@.

On the other hand, a video input signal is input from the video signal input terminal ■, and after being subjected to signal processing such as modulation by the video signal processing circuit 0υ, it passes through the recording amplifier C2 and is sent to the same magnetic tape by the magnetic head ■. It is recorded on the pen.

@8 Figure (a) is a VHS system VTR in the NTSC system.
The spectrum of the recorded video signal of V
This is a spectrum of a recorded Hi-FiFM audio signal of a TR, and the recorded Hi-FiFM signal is deeply recorded in a layer below the recorded video signal on the magnetic tape. Here, in this embodiment, when a digital audio signal is recorded together with a video signal, it is assumed that, like the FM audio signal, deep recording is performed in the lower layer of the recorded video signal in a band as shown in FIG. 4(c).

During playback, the signal reproduced from the magnetic tape by the magnetic header I (c) is amplified by the preamplifier, demodulated by the demodulation circuit, and sent to the digital audio signal processing circuit. After being decoded in step 4, it is D/A converted and output as an analog audio output signal 3η or as a digital audio output signal through an interface circuit. - Magnetic head - LICa
The signal reproduced by 3 is amplified between preamplifiers, subjected to processing such as demodulation in a video signal processing circuit Op, and then output as a video output signal (6). Although an example has been shown above in which recording and playback are performed together with a video signal, there are also cases where recording and playback is performed only with an audio signal.

Now, one embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, (1) is L and R channel PCM
Data input terminal group, (2) is a dummy data input terminal group, (3) is a two-manpower (A, B) 1 output (to) selection circuit,
(4) is a data time axis compression circuit, (5) is a data array circuit, (6) is an 8D block delay circuit, (7) is
D block delay circuit, (8) is a group of 29D block delay circuits, (9) is a C2 parity-encoding circuit, QO
is a C1 parity/encoding circuit, (b) is a data array circuit output data group, □□□ is an N*/No switching signal, and 口 is an N x /No identification signal input circuit.

However, in this embodiment, D=4, and D indicates the amount of delay corresponding to one block in FIG. 4, and as shown in FIG. 5, one block at a time is processed as serial data. It is equal to the repetition period when recording.

Also, 0 to 37 attached to the recorded data written on the right end of Figure 1.
Hereinafter, the number will be referred to as word number.

First, the recorded data structure in one embodiment of the present invention will be described in the fourth embodiment.
As shown in the figure. Data within one field consists of a pre-ampule, a data area consisting of 134 blocks, and a post-ampule. Furthermore, the data in the l block includes a header (4 Byte'), PCM data (L and R2 Bytes each, total 12 Bytes) by even-numbered sampling.
= 6 samples), C2 parity which is an error correction code (total 6B
8 bytes in yte), PC by odd-numbered sampling
M data, error correction code c2 length (total 6
It consists of the remaining 3 bytes in Byte) and C1 parity (4 bytes).

After data having such a data structure is subjected to a predetermined modulation, it is recorded on a track of a VTR, as shown in FIG.

Here, the maximum number of samples per channel recorded in the l field is NMAX = 6 x 134 = 804 samples.

In Figure 1, for the field with the number of samples Nm = 804 in Mode I shown in Table 1, NMAX and N
Since they are equal, all PCM data is recorded in the PCM data area within one field.

On the other hand, for the field with sample number ND=798, (
NWAX-ND) = 6 (sample) data as dummy
Data.

In this embodiment, the dummy data is sequentially stored in the array circuit (5) of the field to be recorded, starting from the first data of the input data, that is, as Lo'+R6't L1'*R1'''. (5) Assume that f is input. Here, PCM data group LO+ in mode I
RO+ L4 +R1+... and array circuit (5) input data group L6' + RO' * Ll' + R1'
. . . and the relationship in the time axis direction of the recorded data group is shown in FIG. As can be seen from this figure, the PCM data that spanned the entire field period is the only one in the recorded data group that has a shorter time width than the field period. It is necessary to shorten the time interval between data (compress in the time axis direction) before inputting the data to the array circuit (5).

First, in the case of a field with the number of samples Nx=804 in mode I, each data input to the PCM data input terminal group (1) T-6+ R6, Ll l R1+ ...+
Since dummy data is not recorded in Lson l R11118 by the selection circuit (3), all PCM
The data becomes an input data group to the array circuit (5). At this time, FIG. 7(a) shows the PCM data group and the array circuit (5).
Indicates the relationship with the input data group.

After that, the data time axis compression circuit (4) selects the selection circuit (
The time interval of the output data of step 3) is shortened and input to the array circuit (5).

Array circuit (5) Each data L6'+ of input data group
RO'+L+'+R1'+...+ Lens +
For R@'ox, D block (L in this case)=4.

) Delay circuit (7) and 8D block delay circuit (6) delay D blocks and 8D blocks, respectively.
2 parity-encoding circuit (9) (02 parity-
is generated, the even-numbered sampled PCM data and the odd-numbered sampled PCM data are separated,
Interleaving is performed by D to 29D block delay circuits (8) that delay D to 29D blocks together with C2 parity, and C1 parity encoding circuit G
After generating 01 parity with O, it is outputted from the array circuit (5) output terminal group (b) as an output data group of the array circuit (5), and a header is added to form a 1-block recording data group. FIG. 8 shows the arrangement of one block recording data group at this time. However, here, word No.
The data array is expressed by taking the block No. in the horizontal direction and the block No. in the vertical direction, but in reality, the data string of the No. i-th block is followed by the data string of the No. (i+1)-th block, respectively, as serial data. The signal is modulated as follows and recorded as shown in FIG.

Next, for the field with the number of samples ND=798 in mode I, the data L for 6 samples is consecutively recorded from the first array circuit (5) input data recorded in the L field.

+ RO' + Ll' + R1' +...,
Among the dummy data groups, DLo,
The selection circuit (3) is operated by the Nx/No switching signal (a) so that DRo, ..., DL5, DRs are input, and the data time axis compression circuit (4) After the time interval is compressed, the array circuit (5)
is input. At this time, the PCM data group and array circuit (
5) The relationship between input data groups is shown in FIG. 7(b). After that, Lo l RO *..., LA, A, R79T in the PCM data group are selected by the selection circuit (3), processed by the data time axis compression circuit (4), and then Sequentially, the array circuit (50ζ is input. After that, the number of samples Nx
Similarly to the field, the PCM data of dummy data becomes a recording data group.

The case of mode 1 in Table 1 has been described above. Table 1
The same applies to other modes in . For example, in mode ■, the number of samples Nm = 586, Nn 5
32, and in the feed of Nx, (NWAX
-Nx) = 268 (samples), that is, the input data group of the array circuit (5) (data in the array circuit (5), LO' + R6' + L4' + R1'
,...+Lf67+R1'6F as dummy data, then PCM data L. + Rfl + Ll +
R1+"'+LSAS+R6qIl is input to the array circuit (5).

In addition, in mode ■, 12-bit, 4-channel (A, B, C, D) PCM data is
As shown in the figure, after converting to 16-bit 2-channel PCM data, for example, 4-channel data A@
*Be *CO* DO; Az + B1 +
C1+ DI... is the top 8 of 12-bit Ao
bit (Aou), remaining lower 4 bits (Ao/ ), and 8-bit data (AC+)/), which is a combination of the lower 4 bits of C0 (Co/), for a total of 16 bits, is set to mode I.
After setting it to Lo in , data arrangement is performed in the same way as in mode I.

The arrangement of the PCM data and dummy data described above can be summarized as follows. Array circuit (5) Input data group is j-L'(n) =LHo4n+kR'(n)
= R11118 n, m, and ni' can be expressed as integers. The PCM data becomes array circuit input data in the field of the number of samples NM, 1≦≦1, and in the field of the number of samples No. (in this case, 2≦k).
The range is ≦3. kl + k, l in each mode
Table 2 shows the values of k. (However, mode (2) is the value obtained after converting the 16-bit data of mode (2) as described above.) Table 2 Dummy data is input for all array circuit input data outside the above range. FIG. 10 shows the relationship between PCM data and array circuit (5) input data.

Furthermore, 1 bit in 1 word of the header shown in FIG.
are the identification signals of the field with the number of samples N1 and No. For example, here, the identification signal is W, the words M, S, B,
By controlling the identification signal input picture MQ3 using the Nx/Nm switching signal (2), in the field Nl, W, word M, S, and B are set to 0, and N
In field D, it is set to 1. - The embodiments of the present invention during recording have been described above.

Next, an example during reproduction will be described with reference to FIG. The signal reproduced from the magnetic tape 4 by the magnetic head 1 (in Fig. 2 (b)) is demodulated by the demodulation circuit (to) (in Fig. 2 (b)), and is converted into a signal having the same structure as the recorded data. The data is input as data to the reproduction array circuit input terminal group of the reproduction array circuit. Thereafter, if there is an error in the reproduced data between the C1 parity and decoding circuit, all the erroneous data is corrected if the error is within the capability of the error correction code. Then, in the 1st to 29th block delay circuits, the samples are de-interleaved and the even-numbered samples are separated from the odd-numbered samples, and then the even-numbered samples are re-sampled as before. The corrected sample and the odd-numbered sample are made to be continuous, and errors in the reproduced data are corrected in the C2 parity/decoding circuit. Here, CI
, C2 parity/decoding circuit.

In both cases, even if there are so many errors in the reproduced data that error correction is impossible, the original value can be estimated from the previous and subsequent values. Correct the mistake.

The signal is then delayed by the D block delay circuit (7) and the 8D block delay circuit (6) and output from the reproduction array circuit.

In addition, an identification signal detection circuit detects the identification signal recorded in each data block in the reproduced data, determines whether the number of samples in the reproduced field is N1 or NB, and uses the determination signal to detect the data time axis. Controls the decompression circuit l, extracts only the PCM data from the data output from the reproduction array circuit, performs time axis expansion, restores the PCM data that was time axis compressed during recording, and adjusts the time interval. The PCM data is made to be equally spaced and continuous, and is output from the reproduced PCM data output terminal group.

Finally, a helical scan VTR (VH in this example)
5), the reproduction signals of the two rotary heads are switched at the timing of the rise and fall of an 80 Hz head switching pulse signal, and the front and rear shift ζ of the recorded data of each field is shown in Figure 4. Buri angle, like
Post angle is provided, so during playback (this,
The starting point of the data in the l field does not disappear, and in addition, for each block, one word M, S, B of the header is used as an identification signal for the field with the number of samples Ng and the field with the number of samples NM. one of them
Since the 84th block has a crossing identification signal recorded,
Unless an extremely large burst error occurs due to head clogging, etc., the identification signal will be detectable and a stable N
m/N! Can distinguish one field. Furthermore, C1
When generating parity, C1 parity including W
Even more stable discrimination is possible by rubbing the

In this example, the case where the video signal is the NTSC system is shown, but in the case of the PAL or SECAM television system, the procedure is the same except that the values of NΣ and NB and the number of blocks in one field are different from the case of the NTSC system. You can think about it. Number of blocks and N1N when implementing the present invention in PAL and SECAM television systems
An example of B is shown in Table 3.

Table 8 Furthermore, in this embodiment, the dummy data is inputted continuously as the input data to the array circuit (5) at the beginning of the field, but the dummy data may be input not at the beginning of the field but in the middle.

〔Effect of the invention〕

As described above, according to the present invention, when the number of samples of a field to be recorded does not reach NMAX, the input data of the field to the array circuit is continuous, so that the circuit configuration is simplified.

Furthermore, the discrimination signals of fields with sample numbers N1 and N3 are set to 1.
Since each block constituting the field data is inputted, the determination can be made stably even when the reproduced signal from the head is lost over a relatively long period of time.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration during recording according to an embodiment of the present invention, FIG. 2 is a block diagram showing the recording and reproducing process according to an embodiment of the present invention, and FIG. FIG. 4 is a frequency spectrum diagram showing the frequency allocation of a digital audio signal modulated wave, a VHS system H4-FiFM audio signal, and a video signal in one embodiment. FIG. 4 shows the data structure within one field in one embodiment of the present invention. The conceptual diagram shown in FIG. 5 is a VTR in an embodiment of the present invention.
FIG. 6 is a conceptual diagram showing the relationship between recording tracks and recording data. FIG. 6 is a conceptual diagram showing the relationship between a PCM data group, a selection circuit output data group, and a recording data group. FIG. 7 shows PCM data and dummy data in mode I of an embodiment of the present invention.
FIG. 8 is a conceptual diagram showing the relationship between data and array circuit input data. FIG. 8 is a conceptual diagram showing a data array when one field has 804 samples in MODE, which is an example of the present invention. FIG. 12 bits 4 in mode ■ of the embodiment
A conceptual diagram showing the conversion method from channel PCM data to 16-bit 2-channel PCM data, Figure 1θ is as follows.
FIG. 11 is a conceptual diagram showing a generalized relationship between PCM data, dummy data, and array circuit input data in each mode of an embodiment of the present invention, and FIG. 11 shows a configuration during playback of an embodiment of the present invention. FIG. 2 is a block diagram showing one embodiment. (1) is a digital audio signal (PCM data) input terminal group, (2) is a dummy data input terminal group, and the mouth is Nx
/ND identification signal input circuit. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] In a helical scan VTR that records and reproduces a digital audio signal obtained by converting an audio signal into a digital signal together with a video signal or only as a digital audio signal,
The number of samples N of digital audio signals per field and per channel is N=■fs/fv■^-^α_-_β ■■: Indicates the integer part fs: Sampling frequency fv: Field frequency α, β: Positive integer If the number of samples in the field to be recorded does not reach the maximum number of samples that can be recorded in one field N_M_A_X, the difference (N_M_A_X - N
), and after making the dummy data into a continuous data string, arrange it together with the digital audio signal, and then record and reproduce the dummy data. (2) A certain number of data such as digital audio signals and their error correction codes to be recorded in one field.
When consisting of a block, the number of samples of the digital audio signal is ■fs/fv■+α.■fs/fv
2. The magnetic recording and reproducing apparatus according to claim 1, wherein an identification signal with a field corresponding to -β is recorded for each data block.