JPS6356878A - Digital audio recording method - Google Patents

Abstract

PURPOSE:To attain excellent recording and reproduction without effect of the difference between track widths by making a division ratio of a block to each track different and preparing clocks of multi-system having different frequencies in recording and reproducing a digital audio signal to a device having plural track widths. CONSTITUTION:The digitized audio data is split into plural blocks Y, C in the unit of frames or fields, the block is divided into plural tracks in response to the ratio of root of plural recording track widths TWY, TWC and the time axis compression in response to the block number by buffer memories 411, 412 is applied for each track. Thus, in recording the digitized audio signal in plural tracks Y, C having a different recording track width, each audio channel and each block in the channel keep the same recording and reproducing state and an excellent reproducing signal is obtained without biased occurrent of error.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method Q for recording digitized audio in a video tape recorder (hereinafter referred to as VTR) number.

2. Description of the Related Art In recent years, audio equipment recorded in a digital signal format, such as compact discs, has been gaining momentum. These digital devices are not only used for audio but also for V.
This also extends to video equipment such as TR.

On the other hand, so-called component recording, in which a luminance signal (Y) and a color signal (C) are recorded separately, is considered effective for improving image quality in VTRs, and various methods have been tried. For example, the Y signal is 4.5M1 (Z band is recorded on one channel without compression, R-Y, B
A Y/C separated two-channel recording method is considered in which each color difference signal of -Y is compressed twice every horizontal scanning period (H) in a band of 1.6 MHz and recorded in the other channel.

FIG. 5 shows a tape format as an example of a method for realizing digital audio recording on such a VTR.

501 and 502, compressed digital audio channels 1 and 2 are recorded on the extension of the Y and C signal tracks, respectively, and the tape is wound around the cylinder at an angle of ρ.
This is a method of recording using an area increased from 18o0. Since there are two video tracks, two audio channels can also be recorded independently using the respective tracks.

However, in the Y/C separated two-channel recording method as described above, the recording frequency is 1 and 5 on the C signal track.
3M1 (z, which is twice Mllz, and 4 of the Y signal track
．． There is too much room compared to 5 Mllz. Conversely, as long as the same track width is used, the Y signal track, which has a large impact on the image, has a 60% difference in bandwidth, and the required performance is stricter than the C signal track, which has less visual impact. . Therefore, in order to obtain a well-balanced image, a method may be considered in which the Y/C track widths are made different. For example, in the NTSC mode, the Y signal track width is 44 μm and the C signal track width is 3671 m.

In addition, PAL mode requires shorter wavelength recording than NTSC mode.
/SECAM mode, Y signal track width is 60μm,
The C signal track width is 36 μm.

However, in the above recording method, no consideration is given to the use of a digital audio recording/playback device that is recorded on an extension of the video track, so the S/N of the C track decreases and errors occur more frequently. If there is a dropout under these conditions, the difference between tracks will become even more pronounced, and there is a risk that the reproduced audio quality will become extremely unbalanced between channels.

Generally, when an error occurs, the correction ability changes exponentially with respect to the error rate before correction, so the difference in error rate in the initial state tends to widen greatly in the final state. Therefore, it is necessary to record and reproduce data on a plurality of tracks under the same conditions.

It is not impossible to accommodate this by mounting a dedicated digital audio recording/playback head with the same track width on the cylinder, but this would require a significant increase in the number of heads to be installed, which would lead to problems with the size of the cylinder and increase costs. The problem remains.

Problem to be Solved by the Invention The problem to be solved by the present invention is that in a VTR device composed of a plurality of recording tracks with different track widths, the digitized audio signal to be recorded on the extension of the track width is The purpose is to record and reproduce 'Vζ without being affected by the difference.

To solve the problems, the present invention solves the problems by dividing the digitized audio data into a plurality of blocks in units of one field or one frame, and dividing the square root ratio of the recording track width value. This includes a step of distributing each block to a plurality of tracks according to the block tfl'vζ, and a step of compressing the time axis according to the block tfl'vζ in a backup memory for each track, so that recording is performed on a plurality of tracks.

Effect of the Invention With the above-described configuration, the present invention allows each audio channel and each block within the channel to maintain an equivalent recording/reproduction device when recording digitized audio using a plurality of tracks with different recording track widths, thereby preventing errors. A good reproduced signal can be obtained without uneven generation of signals.

Example The present invention will be explained below with reference to the drawings.

FIG. 1 shows a recording tape format according to one embodiment of the invention. Although it is almost the same as the tape format shown in FIG. 6, the audio channels recorded in digital audio recording areas 101 and 102 are a mixture of channels 1 and 2. In addition, TWY and 'rwc in the diagram are Y
and the width of the C signal track.

FIG. 2 shows the frequency-output characteristics of a recording/reproducing apparatus according to an embodiment of the present invention. 201 indicates a signal output level, and 202 indicates a noise level. From Figure 2, apply a predetermined modulation,
When the highest recording frequencies are fl and fl, the S/N is approximately equal to Δ.

Generally, S/N depends on the square root of the track width, so (S/N)Y (S/N). cx='I'w
Therefore, in the present invention, in order to record the necessary amount of data under uniform conditions within a certain recording area, the S/N reduction due to the difference in track width is The recording frequency is determined for each track so that it can be compensated for by the difference Δ in frequency characteristics shown in the figure.In other words, the total number of data blocks to be recorded is changed for each track.

For example, Twy = 6071m shown in the conventional example term,
In the case of Twc-36μm, the S/H difference is approximately 2.2 dB
becomes.

On the other hand, the frequency characteristics of recording and reproduction largely depend on the recording density used; for example, in the region where the recording wavelength is long,
This shows the characteristics of the -order system of 10GT. Therefore, 2.2dB
In order to compensate for the S/N difference, 111b=1.29. However, in reality, it is often used in areas of even higher density recording, so the above frequency ratio is usually smaller.

FIG. 3 shows the block-by-block signal format of two audio channels recorded on each track.

In step (1), one field or one frame of the video signal is divided into n blocks for each audio channel. In step (2), each channel is mixed alternately and combined into one system, and in the next step (3), a total of 2n blocks are distributed to Y and C tracks according to the f1/b ratio. In the case of Figure 3, there are 2n pu07
An example is shown in which the area is divided into 2 m : 2 (nm)K.

If an integer ratio cannot be obtained due to the relationship between f 1/ f 2 and 2n, it is necessary to select recording frequencies f, , f2 so that the Y and C tracks are as long as possible and can be distributed in blocks. There is.

In reality, these operations are performed in (1) and (2) by memory address conversion and clock pulse switching.

(3) can be executed immediately without taking steps. However, for the sake of explanation, it is presented in an easy-to-understand format.

FIG. 4 is a schematic diagram of a recording/reproducing apparatus according to an embodiment of the present invention, which uses the signal format described in FIG. 3. In the figure, 4Q1 and 402 are analog audio input terminals, 403 and 404 are human/D converters, 405 is a multiplexer, 406 is a data bus, 407 is a memory in which data is stored in field units or frame units, and 408
409 is an error correction code generation circuit, 409 is a block address generation circuit, 410 is a synchronization signal generation circuit, 411, 412
is a buffer memory that compresses data in blocks,
413 and 414 are modulators, 415 and 416 are recording amplifiers, 417 and 418 are recording heads, 419420 are playback heads, 421 and 422 are playback amplifiers, 423 and 424 are demodulators, and 426 and 426 are time base collectors (TB
C), 427 is a data bus, 428 is a memory, 429 is an error detection circuit, 430 is an error correction circuit, 431 is a demultiplexer, 432, 433 is a D/person converter, 434,
436 is an analog audio output terminal.

Next, the operation will be explained. Since the rotary head type VTR used in one embodiment of the present invention separates the video signal by Y2O and performs two-channel simultaneous recording, two sets of two-channel bare heads are provided for recording and reproducing.

Two-channel analog audio signals inputted from input terminals 401 and 402 are converted into digital signals by human/D converters 403 and 404, and time-division multiplexed by a multiplexer 405. The multiplexed digital audio signal is written to the memory 407 via the data bus 406 in units of one field or in units of frames.

Once the data is stored in the memory 407, the process moves on to generating an error correction code. Although not shown in detail here because they are not directly related to the present invention, Harrity codes, adjacent codes, Reed-Solomon codes, etc. are commonly used as error correction codes. The correction ability and redundancy are selected depending on the purpose.

An error correction code is generated from the data read out from the memory 407 at high speed in the error correction code generation circuit 40B.
The generated code is written to the memory 407 again via the data bus 406, and this is repeated for one field or one frame period.

Next, compressed reading from the memory 407 is started by intermittent locking, which is stopped during periods other than data and error correction codes. The reading order corresponds to the recording order of the Y and C tracks shown in (3) of FIG.
C) Racks are alternately executed in block units. A predetermined block address is added to the read data by the address generation circuit 409, and a block synchronization code is added from the synchronization signal generation circuit 410, and the data is written alternately to the buffer memory 1J411 and 412 in units of blocks.

The signal strings divided into two systems for each track are subjected to time axis conversion in the buffer memory 1J411, 412, and the readout clock frequency is controlled so that the recording frequency becomes equal to a predetermined frequency f, f2. From then on, backup memory 411
, 412 are continuously output from the modulator 41.
3,414 receives a predetermined modulation operation, and the recording amplifier 415
, 416, the recording head 41 is supplied to the recording head 418, and the 2
Simultaneous recording of channels is performed. As mentioned above, the recording tape pattern is as shown in FIG.

Next, we will move on to an explanation of the operation of the reproduction system.

Reproduction signals detected from the tape by reproduction heads 419 and 420 are amplified by reproduction amplifiers 421 and 422.

Equalization and pulse shaping operations are performed, and then the demodulator 423
．． At step 424, the original data string is restored. Using the block synchronization code detected from the reproduced signal sequence as the write start timing, the TBCs 425 and 426 absorb time axis fluctuations of the reproduced signal. This TBC425,426
The frequencies flowing through the two signal systems are different until the time of writing, but after the time of reading, time division processing can be performed using a common clock.

The two jitter-free playback signal streams are sent to the data memory 428 via the data bus 427 for each block.
It is written in units of fields or frames. At this time, the memory 428
is stored at a predetermined address.

After data for one field or one frame period and an error correction code are written, correction using the error correction code is performed. First, the data read from the memory 428 is subjected to a syndrome check by the error detection circuit 429, and the presence or absence of errors, the number of errors, and the location of the errors are detected.

For error data, the corresponding data is stored in the data memory 42.
The error correction circuit 430 performs calculations with the error pattern obtained by reading out the error pattern again from 8.

After the correction operation is completed, the data string is read out in time series from the data memory 428, and the time-division multiplexed data string is divided into continuous signals for each channel by the demultiplexer 431, and converted into analog signals by the D/person converters 432 and 433. The audio signals are converted and output from output terminals 434 and 435.

In the embodiment of the present invention described above, when digitized audio is recorded on a plurality of tracks with different recording track widths, each audio channel and each block within the channel can maintain the same recording and playback state. This makes it possible to obtain a good reproduced signal without uneven occurrence of errors.

Effects of the Invention The present invention provides a simple method for recording and reproducing digital audio in a device having two track widths with different recording and reproducing conditions by changing the division ratio of the plotter to each track and preparing two systems of clocks with different frequencies. This can be achieved with a configuration that has great effects.

[Brief explanation of drawings]

FIG. 1 is a recording tape format diagram according to an embodiment of the present invention, FIG. 2 is a frequency characteristic diagram of recording and reproduction according to an embodiment of the present invention, and FIG. 3 is a signal format diagram according to an embodiment of the present invention. FIG. 4 is a schematic diagram of a recording/reproducing apparatus according to an embodiment of the present invention, and FIG. 5 is a diagram of a conventional recording tape format. Name of agent: Patent attorney Toshio Chio and 1 other person 1st
Figure 2 Tail No. I (Figure 5

Claims (1)

[Claims] A method in which a video signal is dividedly recorded on a plurality of recording tracks having different track widths, and audio corresponding to the video signal is digitally recorded on the plurality of recording tracks,
dividing the digitized audio data into a plurality of blocks in units of one field or one frame;
The method further comprises: distributing the blocks to the plurality of tracks according to the square root ratio of the plurality of recording track width values; and compressing the time axis according to the number of blocks in a buffer memory for each track. Digital audio recording method.