JP3066046B2 - Video tape recorder - Google Patents

Description

The present invention relates to a magnetic recording / reproducing apparatus of a helical scan system, and particularly to a magnetic recording / reproducing apparatus provided with a PCM audio recording area of a plurality of channels on an extension of a video track.

(B) Conventional technology A PCM audio area is provided on the extension of the video track,
In a PCM magnetic recording / reproducing apparatus that records and reproduces a CM signal in the same manner as a video signal (FM signal), the tape pattern is as shown in FIG. In PCM recording, PCM-converted audio signals are divided into 1-field units.
An error correction code is added, the 2-channel audio data is rearranged, divided into three parts, compressed, modulated, and recorded by a rotating head. That is, the audio data of one field is divided into three and recorded on three tracks. Also,
For block addresses, CRCC (Cyclic Redundancy)
Check code) to check whether the block address is correct or not. On the other hand, the head arrangement on the cylinder is as shown in FIG. 4, and the R / P head for recording and reproducing PCM audio has a two-channel configuration of Ach and Bch. Recording of one-field audio is performed on three tracks of Ach and Bch, respectively.
h records on Bch. 4ch recording is enabled. Conventionally, when performing 2ch recording, a method is used in which recording is performed only on Ach and no signal is input to Bch.

FIG. 5 shows the signal format of one field. 1
Each field (Ach, Bch) consists of 67 blocks, and the audio signal consists of 16 bits per sample.
After being converted into a PCM signal, it is divided into upper and lower 8 bits to make each one symbol, and one sample is composed of data of two symbols. 800 samples per field period
It is a sample and consists of 1600 symbols. To this, 8 symbols of ID data are added, and the total number of symbols is 1608. Also, parity for error correction of 4 symbols each in each block.
By adding C1 and C2, the number of symbols in one block becomes 32.

Such an apparatus is disclosed in, for example, National Technical Report Vol. 32, No. 4, PP.

(C) Problems to be Solved by the Invention In recording and reproducing PCM signals using a recording medium such as a magnetic tape, signal dropout (loss) occurs due to dust, scratches, deformation, etc. of the magnetic tape, and correction is impossible. May occur.

(D) Means for Solving the Problems The present invention relates to a video tape recorder for recording PCM audio signals of a predetermined number of channels on a corresponding track, wherein the PCM of a channel smaller than the predetermined number of channels is used.
When recording the M audio signal, the PCM audio signal of the same channel is recorded on a plurality of tracks together with the identification code by reversing the data recording order.

(E) Operation By using the method of the present invention, data dropout can be easily compensated.

(F) Embodiment FIG. 1 shows a configuration diagram of an embodiment of the present invention. FIG. 1 shows a block diagram of a recording system. Ach records are Ch1, Ch
The signal input from 2 is recorded in a conventional manner. Ch1,
The signal input from Ch2 is A / D converted (101, 102),
The data is output as serial data alternately and the S / P converter (10
5, 106) to be converted to parallel data and output to both the Ach and Bch sections. Therefore, the signal output to the Ach unit is stored in the memory (110) in a conventional manner, an error correction code is added (107), and then the signal is read from the memory (110), and the 8/14 converter According to (114), the data is converted into 14-bit data. At this time, the data is divided into blocks as shown in FIG. 5, and a block address and a CRCC for the block address are added at the beginning of the block (10
8). Then, the signal converted to 14 bits is added with a Sync signal so that the beginning of the block can be detected (116), and the P / S
The data is converted to serial data by the converter (118).
It is output to the tape from the R / P head Ach () in FIG. 4 and recorded in the PCM audio Ach section () of the tape pattern shown in FIG. The signal format recorded by Ach is the same as the conventional one as shown in FIG. 5, and the recording order is the same.

On the other hand, in the Bch unit, it is determined whether there is a signal input to Ch3 and Ch4 by the 2ch / 4ch determination circuit (120). When there is a signal input, a signal (4ch, 2ch identification signal) for identifying 4ch input and 2ch when there is no signal output is output. The signal selector (121) is operated by the identification signal, and the input signal is selected from ch3 and ch4 in the case of 4ch input, and the input signals from Ch1 and Ch2 in the case of 2ch input. In the case of 4-ch input, the input signals from Ch3 and Ch4 are recorded by Bch in the same manner as Ach.

However, in the case of 2ch input, the following is applied to the signals input from Ch1 and Ch2. Signal memory (111)
When an address different from Ach is selected and stored by the address selector B (113) according to the 4ch or 2ch identification signal. Next, an error correction code (108) and a 2ch recording flag (122) for identifying 2-channel recording are added and read from the memory (111). At this time, the memory (11
1) In the above, since the data is stored at an address different from that of Ach, the output order of the signals from the memory (111) is different from that of Ach. Then, as in the case of Ach, the block is divided for each block, and a block address and a CRCC for the block address are added at the beginning of the block (109).

Then, the data is converted to 14 bits (115), a sync signal is added (117), and the data is converted to serial data by the P / S converter (119) and output to the tape from the R / P head Bch (11) in FIG. Then, it is recorded in the PCM audio Bch portion () of the tape pattern shown in FIG. At this time, if the signal format is as shown in FIG. 6, the recording order of the signals can be reversed only by the different block addresses. The 2ch recording flag is added using IDs 1 to 8. Next, FIG. 2 shows a block diagram of a reproducing system. R / P head output Ach, Bc
In both cases, as before, the distortion is corrected using an equalizer (123, 124) of a transversal filter to correct the amplitude distortion caused by the recording / reproducing, and the comparators (125, 126) are used. The analog data is converted to digital data, then the beginning of the block is detected by the Sync detector (127, 128), and the serial data is converted to parallel data by the S / P converter (129, 130). Divide into blocks. At this time, in the Bch section, the 2ch recording flag detector (149) determines whether the recording is 2ch recording or 4ch recording. In the case of 2ch recording, a 2ch determination signal indicating that it is determined to be 2ch recording is output.

Next, convert 14-bit data to 8-bit data (131, 132) A
In the ch section, data is stored in the memory (137) according to the address detected by the block address detector (133). However, in the case of 2ch recording, the block address of Bch is different from that of Ach.
The block address (134) is changed to the same as Ach (150), and the memory (138) is used according to the changed address.
Is stored in the memory. On the other hand, in the case of 4ch recording, since there is no 2ch determination signal, it is stored in the memories (137, 138) according to the detected block address similarly to Ach.

Next, error correction (135, 136) of data stored in the memory (137, 138) is performed for both Ach and Bch, and the data is read from the memory (137, 138). Then, depending on the presence or absence of the 2ch determination signal, a 2ch / 4ch changeover switch (139, 14)
0) changes, and in the case of 2ch recording, both signals of Ach and Bch become 1
Is input to two signal discriminators (151).
A signal is input to each of the interpolation circuits (141, 142) of h and Bch. The signal determiner (151) selects and outputs a highly reliable signal and outputs it to the interpolation circuit (141). The interpolation circuit (141) operates only when the interpolation processing is necessary and when the operation is unnecessary, the signal only passes through. Then P /
The parallel data is converted to serial data by the S converter (143), and two channels (CH1 and CH2 or CH3 and CH
4) Separately output and output by D / A converter (145, 146)
It is converted into an analog signal and output.

Here, in the signal determiner (151), first, Ach,
Error correction for both Bch signals (detects whether an error has occurred or not (is not correctable). If an error correction error occurs (if correction is not possible), the flag indicating that is turned on Therefore, if either the Ach or Bch flag is ON (uncorrectable), the signal whose flag is OFF (corrected or error-free) is output. When the signal flag is OFF (corrected or no error has occurred), it is determined whether the signals of both channels are the same signal. If the signals are the same, the signal is output. Outputs the signal with no error correction, and if both channels have error correction, outputs the signal with the least number of corrections. Only when it is disabled, the interpolation circuit (141) Created by interpolation processing is performed. Thus, by using the method according to the invention, the frequency of the interpolation process is performed is reduced, noise is reduced by the drop-out signal.

Also, since dust attached to a magnetic tape or the like has dispersed data, it is unlikely that both Ach and Bch signals will be damaged.Therefore, by using Bch as a backup as in the present invention, either Ach or Bch can be used. Is often reliable. Also, since scratches and deformations in the magnetic tape occur in a continuous area, if the recording order of the Ach and Bch signals is changed as in the present invention, the same signal is not recorded in an adjacent area, so they are mutually dropped out. It becomes easy to supplement the signal.

(G) Effects of the Invention According to the present invention, when recording and reproducing PCM signals using a recording medium such as a magnetic tape, dust on the magnetic tape,
Even if the signal drops out due to scratches, deformation, etc.,
In the case of 2ch recording, since the data recording order of the backup signal is reversed, the same area is not recorded in an adjacent area, and signals which are mutually dropped out are supplemented to easily compensate for the dropout portion. be able to.

[Brief description of the drawings]

1 and 2 are block diagrams showing the configuration of the embodiment, and FIG.
FIG. 4 is an explanatory diagram showing a track pattern, FIG. 4 is an explanatory diagram showing an arrangement of heads, and FIGS. 5 and 6 are explanatory diagrams of a signal format. …… PCM audio area, 120 …… 2ch / 4ch judgment circuit, 122…
... 2ch recording flag adder, 113 ... address selector.

Claims (1)

(57) [Claims] 1. A video tape recorder for recording PCM audio signals of a predetermined number of channels on a corresponding track, wherein the PCM of a channel smaller than the predetermined number of channels is provided.
A video tape recorder characterized in that when recording an M audio signal, a PCM audio signal of the same channel is recorded on a plurality of tracks, together with an identification code, with the data recording order reversed.