JPS63104263A - Multiple speed reproduction method for tape recorder - Google Patents

Abstract

PURPOSE:To obtain a multiple-speed reproduced sound of a high quality by prohibiting the decoding processing for codes with a long recording interval and controlling the state of the recording corresponding to a speed multiplication number N in case of the multiple-speed recording of a PCM audio signal that is recorded on an inclined track on a magnetic tape by a rotary head. CONSTITUTION:The locus of a head on a track at the time of double speed reproduction is shown in the figure. An A represents a track recorded by a head AH, and a B shows a track recorded by a head BH. Since the data are reproduced from dispersed tracks, the interleaving pair relation between the data reproduced by the head AH and that reproduced by the head BH in the one turn of a cylinder, collapses. This means that the even-number sample of L-channel and the odd-number sample of R-channel in a frame (n) and the odd-number sample of L-channel and the even-number sample of R-channel in frame n+1 are reproduced, hence sounds in different fields are mixed and outputted. Therefore, one of the heads is prohibited of reproducing, and the reproduction is executed only with the other channel. In such a way, the multiple speed reproduction is attained with a high quality.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a double-speed reproduction system for PCM audio signals recorded in diagonal tracks on a magnetic tape by a rotary head.

BACKGROUND OF THE INVENTION In recent years, digitalization of audio has progressed, and compact discs (CDs) have been realized.

As for tape recorders, a rotary head type tape recorder (hereinafter abbreviated as R-DAT) is being considered which has high quality and high functionality due to digitization.

An overview of R-DAT is described in rR-DAT development/commercialization trends and technical issues (Japan Industrial Technology Center; Industrial Technology Seminar T-1416) J.

Like the VTrl, the R-DAT performs helical scanning using a rotary head and records and reproduces data using the azimuth recording method.

Figure 4 shows an overview of the Toranoku Formaft.

Audio PCM signal, tracking signal (ATF)
, subcode signals (SUB; search data, etc.) are recorded in a time-division manner.

FIG. 5 shows a data distribution diagram between tracks. l frame (sampling frequency 48K 1lzlL'y 288
0 sample, 1440 samples each for Lch/Rch) is interleaved on two tracks, so that the data is located above and below the (1) track.

FIG. 6 shows a block diagram of R-DAT.

The left and right channels of analog signals are input to the input terminals 1.2.

FIG. 7 shows a time chart during recording. Memory (R
AM) 10 contains 2 frames (RAlvHLl.

Stores data in RAM+21).

Input signals from input terminals 1 and 2 are passed through a low-pass filter 3.
, 4, is inputted to an analog-to-digital converter (ADC) 8 via sample-and-hold circuits 5 and 6 and a switch 7, and is converted into a digital signal. The converted digital signal is supplied to the PCM processor 9, subjected to interleaving processing, and stored in the memory 10 (RAM+11 area).

When the data for one frame has been stored, the head AH
The data to be recorded (Lch even number data, Rch odd number data) is encoded by the PCM processor 9, and the 8-bit data is converted into 10 bits according to a certain rule using an 8/10 converter (8-10 conversion method 2). 11. Parallel/serial data converter (converts 8-bit parallel data to 1-bit serial data) 12. Modulation circuit (performs NRZI modulation) 13,
The signal is supplied to head AH of rotary head 16 via recording amplifier 14 and switch 15, and recorded on tape 35. The data recorded by head BH (Lch odd number data, Rch even number data) is also recorded on the tape 35 in the same way as head AH.

Using the RAM tll area of the memory 10, in parallel with encoding and recording to tape,
The +21 area stores data corresponding to the next frame.

FIG. 8 shows a time chart during reproduction. The signals recorded on tape 35 are reproduced by heads AH and BH, and switches 15. Reproduction amplifier 17, waveform contemporary circuit 18. Data restoration circuit (consisting of PLL, obtains a reproduced clock and reproduced data) 19. Serial/parallel converter (converts serial data to 10-bit parallel data)20.
10/8 converter (performs inverse conversion of 8/10 conversion) 21
is supplied to the PCM processor 9 via the memory 1.
0 (RAM+11 area). Then, the PCM processor 9 performs decoding processing.

Thereafter, the PCM processor 9 performs a predetermined dinterleaving process, reads the data from the memory 10, and supplies the data to the error compensation circuit 22, where the error data is corrected by mean value interpolation, previous value hold process, etc. (For example, "Modern Digital Audio Technology J Ohmsha P76-P
77 for a detailed explanation. ) The output of the error compensation circuit 22 is sent to a digital-to-analog converter 23 . Switch 24. 2 through a deglitch circuit 25.26 and a low pass filter (LPF) 27.28.
channel is converted to an analog signal.

Memory 10 RAM (using 11 areas, head AH,
In parallel with storing and decoding the reproduced data from the BH, the RAM +21 area is used to perform analog output reproduction of data corresponding to the previous frame.

Servo processor 32. During recording, the cylinder motor 33 and the capstan motor 34 control the phase of cylinder rotation so that the tape and head come into contact with each other when the cylinder sends a recording current to the head, and the capstan runs the tape at a constant speed.

During playback, the cylinder controls the rotational phase of the cylinder so that the head contacts the tape when the playback head amplifier 17 is activated, and the capstan uses the tracking signal recorded on the tape to track the recorded track. Control tape advance so that the head traces.

The timing signal generator 31 has a sample hold 5.6
control No. 13, control signals for deglitch circuits 25 and 26,
ADC8DAC23 control signal.

It generates timing control signals for the PCM processor 9, control signals for the recording/reproducing system, and the like.

FIG. 9 shows the code structure of a PCM signal recorded on one track. The code uses a double de Solomon code system, and a first error correction series C1 and a second error correction series C2 are used.
generate.

The C1 series consists of 32 symbols, of which 28 are data symbols and 4 are P parity symbols, and the C2 series is composed of 32 symbols, of which 26 are data symbols and 6 are Q parity symbols. is C
After generating two series of Q parity, a C1 series of P parity is generated.

Further, C1 and 02 are arranged orthogonally.

Problems to be Solved by the Invention As described above, when double-speed playback is performed using a tape recorded using the correction code system with two-track interleaf and one-track completion, the head AH.

The interleave pairing property of data reproduced by BH is broken. Furthermore, multiple tracks are crossed during one head scan, resulting in poor reproduction due to azimuth loss, making it impossible to obtain correct audio reproduction data.

Means for Solving the Problems In order to solve the above problems, the double speed playback method of the present invention includes:
2 channels (L,
R) 2-trunk interleave in which the audio PCM signal is recorded with head AH in the first half with even channel samples, the second half with R channel odd samples, the first half recorded with head BH with R channel even samples, and the second half with L channel odd samples. When playing back a tape recorded with a track complete double error correction code added at a speed N times the normal playback speed, the recording format requires a long recording interval for data used as a correction code (R-DA).
In the case of T, decoding processing of C2 series) is prohibited, and
The reproduction state is controlled in accordance with the speed number N, and a PCM signal is output.

Effect: With the above configuration, high-quality double-speed reproduction sound can be obtained.

EXAMPLE An example of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of the trajectory of the head on the trunk during double speed playback. (When the track pitch is 13.591 μm) The tape is shown compressed significantly in the running direction of the tape.

In the figure, A is a track recorded with head AH, B is a trunk recorded with head BH, and n and n+1 represent frame numbers. That is, An and Bn are an interleaved pair.

When tracks are reproduced in discrete numbers as shown in FIG. 1, the head AH reproduces during one rotation of the cylinder.

For BH data, the interleaved bear relationship is broken. That is, L channel even samples of frame n and R
Odd channel samples, frame n+1 channel odd samples and R channel even samples are reproduced, and sounds of different frames are mixed and output. Furthermore, head AH
The head BH has a defective reproduction of Rch odd data, the head BH has a defective reproduction of Rch even data, and the decoding process in the C2 direction is likely to be defective, causing missed sounds etc. to be mixed into the reproduced sound and abnormal noises etc. to occur.

In this case, high-quality double-speed reproduction is possible by substantially reproducing only one head, prohibiting decoding processing in the C2 direction, and reproducing only one channel (L channel).

In addition, in the case of stereo playback, in order to prevent discomfort caused by playing only one channel, the data of the playback channel is
Channel and R channel.

In addition, in order to achieve a state in which only one head is actually playing,
For example, when the error flag supplied to the error compensation circuit is only for the head AH, the contents corresponding to the L channel odd samples and the R channel even samples may be forcibly set as errors. In this case, the contents corresponding to the R channel odd samples are also forcibly treated as errors.

To make the L channel and R channel the same data,
(Digital/Analog Converter) It is only necessary to respond to changes in the data supplied to the negative device for the L channel.

Figure 2 shows an example of the trajectory of the head on the track during triple-speed playback (in the case of track pitch 13.591 μm).
.

In FIG. 2, as in FIG. 1, the relationship between interleaved pairs is broken.

Further, head AH fails to reproduce L channel even data, and head 7 BH reproduces R channel even data, resulting in abnormal noise.

In this case, by prohibiting decoding processing in the C2 direction and reproducing only odd-numbered samples in both the L channel and the R channel, high-quality double-speed reproduction is possible.

In order to reproduce only odd-numbered samples, the error flags supplied to the error+iW compensation circuit may be forced to set the contents corresponding to even-numbered samples as errors for both L and R channels.

Figure 3 shows an example of the trajectory of the head on the track during 8x speed playback (for a track pitch of 13.591 μm).
.

In FIG. 3, as in FIG. 1, the relationship between the interleaved bears is broken.

Furthermore, the relationship in the C2 direction is also broken.

However, there is a possibility that L channel even samples and R channel odd samples can be reproduced.

In this case, by prohibiting the decoding process in the C2 direction and reproducing only the L channel even samples and the R channel odd samples, high quality double speed reproduction is possible.

In order to reproduce only the L channel even number samples and the R channel odd number samples, the error flag supplied to the error compensation circuit is set as follows.
It is sufficient to forcibly set the contents corresponding to the L channel odd number samples and the R channel even number samples as errors.

Effects of the Invention As described above, the present invention has two heads (AH, BH) 180
The two-channel (L, R) audio PCM signal for each time corresponding to one rotation of the rotary head with the relationship
2-track interleaf with L channel even samples in the first half recorded with head BH, R channel odd samples in the second half, R channel even samples in the first half recorded with head BH, L channel odd samples formed in the second half, 11-Rank Complete 2
When playing back a tape recorded with a heavy error correction code added at N times the normal playback speed, the recording format requires a long recording interval for the data used for the correction code (in the case of R-DAT). By prohibiting the decoding process of 02 series), controlling the playback state according to the number N of double speeds, and outputting a PCM signal, it is possible to obtain high quality double speed playback sound.

[Brief explanation of the drawing]

Figure 1 is an example of the trajectory of the head on the trunk during 2x speed playback with a trunk pitch of 13.591μm, and Figure 2 is an example of the trajectory of the head on the track during 3x playback with a track pinch of 13.591μm. Figure 3 shows a track pitch of 13.
An example of the trajectory of the head on the l-rack during playback at 591 μm and 8x speed, FIG. 9 is a schematic time chart during reproduction, and FIG. 9 is a code structure diagram of the PCM signal recorded on the l track. 9...PCM processor, 10...memory (RAM), 22...error compensation circuit. Name of agent Patent attorney Toshio Nakao 1 person Figure 3 Figure 4 - /h --- Edge Y quantitative j 5 direction Vr-f-7' - line 731'; l Figure 5 Figure 7 Section DΦ to

Claims (1)

[Claims] 2 channels (L, R) audio P for each time corresponding to one rotation of the rotating head with a 180° relationship between the two heads (A, B)
A two-track interleaf in which the CM signal is recorded by head A, with L channel even samples in the second half, R channel odd samples in the second half, R channel even samples in the first half recorded by head B, and L channel odd samples in the second half.
When playing back a tape recorded with one-track complete double error correction code added at N times the normal playback speed, decoding codes that have long recording intervals for data used as correction codes due to the recording format. control the playback state in accordance with the speed number N,
A double-speed playback method for a tape recorder that outputs PCM signals.