JPH05128748A - Digital signal recording and reproducing device - Google Patents

Abstract

PURPOSE:To prevent the deterioration of the sound quality from generating at a reproducing audio signal even when the trouble of a part of the rotary magnetic head occurs when the digital audio signal of a multi-channel is recorded and reproduced by plural rotary magnetic heads. CONSTITUTION:From an inner error correcting circuit 11 to an outer error correcting circuit 13, 4-channel multiplex reproducing audio data AP are supplied, the error correction is performed, and when there are the data where the error correction cannot be performed, error information ER are sent to a data selecting circuit 15. At the data selecting circuit 15, the data where the error correction cannot be performed are replaced with the data where there is not the error of other channel. Here, for the digital audio signal of 4 channels, 2 channels are the same, and the data to be replaced are the data of the same digital audio signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital signal recording / reproducing apparatus capable of recording / reproducing multi-channel digital audio signals.

[0002]

2. Description of the Related Art At present, tape recorders capable of recording and reproducing digital signals include rotary head recording type digital audio recorders which are also used at home, and 16 to 48 which are used as recording mixdown masters.
Fixed-head recording system for channel digital audio, multi-channel recording / reproducing device for business use, rotary head recording system capable of recording digital video signals and 4-channel digital audio signals, such as D-1 format and D-2 format There are VTRs and the like. In these digital signal recording / reproducing devices, a synchronizing signal, an ID signal, an error correction code and the like are added to digital data of images and sounds and recorded. When these additional signals are added and recorded and reproduced, errors occurring in the reproduced signal can be corrected according to the capability of the error correction code. In this regard, for example, a commercial digital VT
As R, "Broadcasting Technology" Vol. 43, No. 12 (1990
Year) pp. Each format is described in 1-26. Such a VTR for business uses a format in which the same audio signal is recorded twice by changing the recording area, which is highly reliable.

[0003]

As described above, in the digital recording / reproducing apparatus, many countermeasures are taken against the error at the time of reproducing. However, these countermeasures reduce the occurrence probability of the error. It doesn't stop and eliminate errors completely. A major cause of the error in the reproduction signal is a trouble of the magnetic tape and the magnetic head. Magnetic tape troubles include dropouts that occur in the reproduced signal due to scratches on the magnetic tape or peeling of the magnetic layer.The magnetic head troubles are clogging due to dust on the magnetic tape and damage to the magnetic head. And life due to wear. In particular, if there is a problem with the magnetic head, the signal may not be reproduced from this magnetic head, which significantly deteriorates the quality of the reproduced signal.

Professional digital VTRs and digital audio recorders are sometimes used in broadcasting stations for the purpose of transmitting broadcasting programs. It goes without saying that high quality is required for the signals sent by broadcasting, but even if the above problems occur and the image quality and sound quality are deteriorated, the contents of the received image and sound must be fully understood. Is the minimum required. For example, if a phenomenon such as the image freezes during output during output, which is likely to occur due to a trouble phenomenon of a digital device, or that the sound is interrupted and cannot be heard during broadcasting, these are irreversible at the broadcasting station. Not considered to be a serious accident.
Therefore, in a digital signal recording / reproducing apparatus which reproduces information by using a plurality of magnetic heads, it is desired to prevent deterioration of reproduced signals even when some magnetic heads have troubles.

An object of the present invention is to propose a digital signal recording apparatus capable of reducing the deterioration of an audio reproduction signal even if some magnetic head troubles occur in order to satisfy such a demand. is there.

[0006]

In order to achieve the above object, the present invention digitally processes input audio signals of a plurality of channels, records them, and reproduces them, when an error occurs in reproduced digital audio data. , Replace the digital audio data in which this error has occurred with the digital audio data of the channel in which no error is detected.

[0007]

Even if an error occurs in digital audio data of a certain channel during reproduction, this digital audio data is replaced with the digital audio data of another channel, so that the error in this channel is eliminated. In this case, if the digital audio information of these two channels is the same, the original audio signal can be restored in the error-corrected channel.

By the way, the audio signal sent from the broadcasting station is usually two channels, such as stereo broadcasting and bilingual broadcasting. Further, for example, a digital VTR for business use, which is used for sending out from a broadcasting station, can record 4-channel digital audio signals. Therefore, according to the present invention, of these four channels, the same audio signal as the two-channel audio signal used for broadcasting is recorded as another two channels, and these two are recorded in the original two-channel audio signal to be reproduced. If there is an error in the digital audio data of
This digital audio data can be replaced by digital audio data of the same content which is reproduced as a separate channel, whereby the error on a given channel can be completely eliminated. Therefore, it is possible to reproduce a two-channel audio signal which has higher reliability than the conventional method and has less quality deterioration even when a trouble of the magnetic head occurs.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. First, a recording system of an embodiment of the digital signal recording / reproducing apparatus according to the present invention will be described with reference to FIG. However,
In the figure, 19 is a video signal input terminal, 20 to 2
3 is an input terminal for audio signals of channels 0 to 3, 24 and 25 are A / D converters, 26 and 27 are switches, 28 and 29 are outer error correction code encoders, 30 is a system controller, and 31 is an inner error correction code. Encoders, 32, 33 are modulation circuits, 34,
Reference numeral 35 is a recording amplifier.

In FIG. 2, a video signal is input from the input terminal 19, processed by the A / D converter 24 to be a digital video signal, and supplied to the outer error correction code encoder 28. Also, the audio signals of channels 0 to 3 are input from the input terminals 20 to 23, and A
The digital audio signals a0 to a3 are encoded by the / D converter 25, respectively. The digital audio signals a0 and a1 are supplied to the outer error correction code encoder 29 as digital audio signals A0 and A1 of channels 0 and 1, respectively. Also, the switches 26, 27
Is controlled by the system controller 30, and the switch 26 controls the switching signal S from the system controller 30.
W1 selects one of the digital audio signals a0 and a2, and the switch 27 selects one of the digital audio signals a1 and a3, respectively, and corrects outer errors as digital audio signals A2 and A3 of channels 2 and 3, respectively. It is supplied to the code encoder 29.

That is, when the switches 26 and 27 are closed to the A side, the digital audio signals a0 and a1 are selected, and when the switches are closed to the B side, the digital audio signals a2 and a2 are selected.
Select 3. Therefore, when the switches 26 and 27 are closed to the B side, the four different digital audio signals a0 to a3 are supplied to the outer error correction code encoder 29 as the digital audio signals A0 to A3 of the respective channels 0 to 3 (hereinafter , This mode is 4
When the channel recording mode is closed to the A side, the digital audio signal a0 is converted into digital audio signals A0 and A2 of channels 0 and 2, and the digital audio signal a1 is converted into digital audio signals A1 and A3 of channels 1 and 3. Each is supplied to the outer error correction code encoder 29 (hereinafter, this mode is referred to as a 2-channel recording mode). That is, in the 2-channel recording mode, the digital audio signals A0 and A2 of channels 0 and 2 are the same, and the digital audio signals A1 and A3 of channels 1 and 3 are the same.

An outer error correction code encoder 28,
In 29, a digital video signal and a digital audio signal are divided into predetermined blocks (hereinafter, referred to as a synchronization block), and an error generated when reproducing the digital video signal and the digital audio signal is added to each block. An outer error correction code for correction, a sync signal indicating a break of a sync block, an ID signal indicating an attribute of data in a sync block, and other data necessary for signal processing of the device are added. In addition to that, there may be provided an area in which other desired information can be recorded, such as a user area in which the operator can freely record desired information. Further, in the outer error correction code encoder 29, the system controller 30 sends the mode signal MOD indicating the 2-channel recording mode and the 4-channel recording mode.
Are supplied, and mode information indicating these modes is added to each block of each digital audio signal.

The inner error correction code encoder 3 includes a digital video signal VS output from the outer error correction code encoder 28 and a digital audio signal output from the outer error correction code encoder 29.
1 is supplied. As will be described later, the inner error correction code encoder 31 forms a two-channel composite signal of a digital video signal and a digital audio signal, and the outer error correction code encoders 28 and 29 add the two-channel composite signal. An inner error correction code different from the outer error correction code is added in the data string direction. The outer error correction code and the inner error correction code provide a strong error correction capability.

Here, the synthesis of the digital video signal and the digital audio signal in the inner error correction code encoder 31 will be described with reference to FIG.

Outer error correction code encoder 28
The digital video signal VS from (FIG. 2) has 3 blocks in each field (blocks V0, V1, V2,
Each block is time-axis compressed to form two time-axis compressed digital video signals VS1 and VS2 composed of the same block.

Further, the digital audio signals A0 to A from the outer error correction code encoder 29 (FIG. 2) are also provided.
3 is also a block having a time length equal to 1/3 field period of the video signal at substantially the same timing (for example, in the case of the digital audio signal A0, A00, A0
, A02, ... Are blocks), and each block is a time-axis compressed digital video signal VS1, VS.
2, and the recording signals SR1 and SR2 are formed.

The recording signals SR1 and SR2 are obtained by synthesizing the time-axis compressed digital video signal VS1 and the time-axis compressed digital audio signal, and the synthesizing method is as follows.

That is, as shown in FIG. 3, the block V0 of the time-axis compressed digital video signals VS1 and VS2 is now taken into consideration.
To the digital audio signals A0, A1, A2,
The blocks of A3 are referred to as A00, A10, A20, and A30, and hereinafter, the blocks for the block V1 are A01 and A30.
11, A21, A31, the block for the block V2 is A02, A12, A22, A32, and the blocks for the block V3 are A03, A13, A23, A33, in the recording signal SR1, as is clear from FIG. , V2, V3, the digital audio signals A2, A3 for the previous block respectively
Blocks are time-axis compressed and time-divisionally synthesized, and after blocks V1, V2 and V3, blocks of digital audio signals A0 and A1 corresponding to these blocks are time-axis compressed and time-divisionally synthesized. Therefore, regarding the block V1, before that, the blocks A20 and A30 of the digital audio signals A2 and A3 are time-axis compressed and combined, and then the blocks A01 and A11 of the digital audio signals A0 and A1 are time-axis compressed. Are synthesized.

In the recording signal SR2, as is clear from FIG. 3, before the blocks V1, V2 and V3,
The blocks of the digital audio signals A0 and A1 for the immediately preceding blocks are time-axis compressed and time-divisionally combined, and after the blocks V1, V2, and V3, the digital audio signals A2 and A3 for these blocks.
Blocks are compressed on the time axis and synthesized in a time division manner.
Therefore, regarding the block V1, before that, the blocks A00 and A1 of the digital audio signals A0 and A1 are
0 is time-axis compressed and synthesized, and thereafter, blocks A21 and A31 of the digital audio signals A2 and A3.
Is compressed on the time axis and synthesized.

According to such a synthesizing method, the digital audio signals A0 and A1 are synthesized so that the blocks A00 and A10 are synthesized after the block V0 and before the block V1 of the digital video signal.
Each block of 0 to A3 is synthesized twice with a time-axis-compressed digital video signal.

The time axis compression / synthesis method as described above can be performed by using well-known time axis compression means and synthesis means.

In the inner error correction code encoder 31, a composite block of the time-axis compressed block of the digital video signal and the time-axis compressed block of the digital audio signal of the recording signals SR1 and SR2 is used as a synchronous block. The inner error correction code is added to each of these sync blocks, and a sync signal and an ID signal are also added.

The recording signals SR1 and SR2 output from the inner error correction code encoder 31 are code-converted into data strings having no DC component by the modulation circuits 32 and 33, respectively, and amplified by recording amplifiers 34 and 35. After that, it is supplied to a rotary magnetic head through a rotary transformer (not shown) and recorded on a magnetic tape. In this case, the transmission path of the recording signals SR1 and SR2 does not pass the DC component, but the recording signals SR1 and SR2 are code-converted into the data strings having no DC component by the modulation circuits 32 and 33 as described above. , The recording signal S is transmitted during the transmission on this transmission line.
No information loss occurs in R1 and SR2.

FIG. 4 is a block diagram showing a specific example of the magnetic tape running system in this embodiment. R0 to R3 are recording rotary magnetic heads, P0 to P3 are reproducing rotary magnetic heads, and 36 is a rotary drum. 37 is a magnetic magnetic tape, 38 is a tape guide, 39 is a rotary drum motor, 40 is a capstan motor, 41 is a capstan, 42 is a pinch roller, 43 is a rotary drum pulse generator, 44 is a capstan frequency generator, and 45 is a control. The head 46 is a servo circuit.

In FIG. 3, the recording rotary magnetic heads R0 to R0
The R3 and the reproducing rotary magnetic heads P0 to P3 are installed on the side surface of the rotary drum 36. Recording rotary magnetic head R
0 and R2 and the reproducing rotary magnetic heads P0 and P2 have the same azimuth angle (for example, +15 degrees), and the recording rotary magnetic heads R1 and R3 and the reproducing rotary magnetic heads P1 and P3 also correspond to the recording rotary magnetic heads R0 and R2. Reproducing rotary magnetic head P0,
Different from P2 but same azimuth angle (eg -15 degrees)
Is. Further, the recording rotary magnetic heads R0 and R1, the recording rotary magnetic heads R2 and R3, and the reproducing rotary magnetic heads P0 and P
1. The reproducing rotary magnetic heads P2 and P3 are arranged close to each other to form a head pair, and the respective head pairs are sequentially arranged on the rotating drum 36 by 90 °, as shown in the drawing.

The tape guide 3 is attached to the rotary drum 36.
8, the magnetic tape 37 is wound around about 180 °. The magnetic tape 37 is held by a capstan 41 and a pinch roller 42 during recording and normal reproduction, and the capstan 41 is rotated by a capstan motor 40, so that the magnetic tape 37 travels in the Y direction. The rotary drum 36 is rotated by the rotary drum motor 39 in the direction of arrow X at a cycle of 2/3 field of the video signal. Rotating drum motor 39 and capstan motor 40
Are controlled by the servo circuit 46.

The drive control by the servo circuit 46 is performed as follows. That is, the rotary drum motor 39 is provided with the rotary drum pulse generator 43,
From this rotating drum pulse generator 43, a pulse signal phase-synchronized with the rotation of the rotating drum motor 39 is generated once each time the rotating drum motor 39 rotates once.
The servo circuit 46 generates a drive voltage according to the phase difference between this pulse signal and the reference signal (here, since it is VTR, the synchronizing signal of the input video signal is generally used as this reference signal). The rotary drum motor 39 is controlled so that the rotation phase of the rotary drum motor 39 is phase locked to this reference signal. Further, the capstan motor 40 is provided with a capstan frequency generator 44, and the capstan frequency generator 44 generates a signal having a frequency proportional to the rotation frequency of the capstan motor 40. The servo circuit 46 refers to this signal to detect the traveling speed of the magnetic tape 37, and controls the capstan motor 40 so that the traveling speed of the magnetic tape 37 becomes a predetermined speed.

Further, the servo circuit 46 records the control signal CTL in the longitudinal direction of the magnetic tape 37 by the control head 45 during recording. Here, the rotary drum 36 rotates half a turn to rotate the recording rotary magnetic heads R0 and R0.
1 or each time the recording rotary magnetic heads R2 and R3 record two helical tracks, the servo circuit 46 records the control signal CTL. At the time of reproduction, the traveling phase of the magnetic tape 37 is detected by the control signal CTL reproduced by the control head 45, and the capstan motor 40 is controlled to make the traveling phase of the magnetic tape 37 a prescribed one. During reproduction, the servo circuit 46 controls the rotational phase of the capstan motor 40 so that the reproduced control signal CTL is locked in a predetermined phase relationship with the reference signal.

The recording signal SR1 output from the recording amplifier 46 of FIG. 2 is supplied to the recording rotary magnetic heads R1 and R3, and the recording signal SR output from the recording amplifier 35 of FIG.
2 is supplied to the recording rotary magnetic heads R0 and R2. Therefore, the recording rotary magnetic heads R1 and R are attached to the magnetic tape 37.
3 records the recording signal SR1 every half rotation of the rotating drum 36 (one-third field period of the video signal), and the recording rotary magnetic heads R0 and R2 record the recording signal SR2 every half rotation of the rotating drum 36. Therefore, when the rotary drum 36 is rotated by half, the recording rotary magnetic heads R0 and R1 respectively generate the recording signal SR.
2 and SR1 are simultaneously recorded, and the recording rotary magnetic heads R2 and R3 simultaneously record recording signals SR2 and SR1 in the next half rotation, and a recording signal for 1/3 field is recorded on each helical track. During reproduction, the reproducing rotary magnetic heads P1 and P3 are used to perform recording rotary magnetic heads R1 and R.
The helical track formed in 3 is simultaneously reproduced and scanned to reproduce the reproduced signal SP1, and the reproduced rotary magnetic head P
0 and P2 simultaneously reproduce and scan the helical tracks formed by the recording rotary magnetic heads R0 and R2, and reproduce the reproduction signal SP2.

FIG. 5 is a view showing a specific example of a recording pattern on the magnetic tape 37 by the above recording, where T
R0 to TR3 are helical tracks, V is a digital video signal recording area, and A0 is a digital audio signal A.
A recording area of 0, A1 is a recording area of the digital audio signal A1, A2 is a recording area of the digital audio signal A2, A3 is a recording area of the digital audio signal A3, and 47 is a control track. The same reference numerals are attached.

In the figure, the helical track TR0 is formed by the recording rotary magnetic head R0 of FIG. 4, and hereinafter, the helical tracks TR1, TR2, TR3 are respectively recording rotary magnetic heads R1, R2, R3 of FIG. It was formed by. Therefore, two adjacent helical tracks TR0 and TR1, and two adjacent helical tracks TR2 and TR3 are simultaneously recorded. The recording rotary magnetic heads R0 and R2 are supplied with the recording signal SR2 shown in FIG. 3, and as described above, the rotary drum 36 (FIG. 4).
Rotates once in the 2/3 field period of the video signal, so that the sequential helical tracks TR0 are synchronized with every other synchronization block (here, blocks V1, V3, ...) Of the recording signal SR2 shown in FIG. Blocks) are recorded, and every other synchronous blocks (here, synchronous blocks including blocks V2, V4, ...) Of the recording signal SR2 are also recorded on the sequential helical track TR2. On the contrary, since the recording rotary magnetic heads R1 and R3 are supplied with the recording signal SR1 shown in FIG. 3, the recording signal SR1 shown in FIG.
Every other synchronized block (here, block V1,
V3, ..., Synchronous blocks including V3 ... Are recorded, and every other synchronous block (here, blocks V2, V) of the recording signal SR1 is also recorded on the sequential helical tracks TR3.
4) is recorded.

In this way, two helical tracks are simultaneously recorded at every half rotation of the rotary drum 36. As is clear from the explanation with reference to FIG. 3, the two helical tracks recorded at the same time are recorded. The video signals are the same. Therefore, the helical tracks TR0, TR1,
This means that the video signal and the audio signal for one field are recorded twice on six continuous helical tracks of TR2, TR3, TR0 and TR1.

In each of the helical tracks TR0 to TR3,
As is apparent from the recording signals SR1 and SR2 shown in FIG. 3, one block (FIG. 3) of the digital video signal processed as described above is recorded in the recording area V at the center thereof, and both ends thereof are recorded. Recording areas A0 to A3 shown in FIG.
Then, the digital audio signal processed as described above is recorded block by block.

That is, the recording signals SR1 and SR shown in FIG.
2, in the recording areas A0 and A1 at the lower end of the helical track TR0, the digital audio signal A0,
The time-axis-compressed blocks of A1 are recorded in order. If these are blocks A00 and A10, respectively, in the recording areas A2 and A3 at the upper end of the helical track TR0, the time-axis compression of the digital audio signals A2 and A3 is performed. The recorded blocks A21 and A31 are recorded in order. In the recording areas A2 and A3 at the lower end portion of the helical track TR1 which is recorded at the same time, the time-axis-compressed blocks A20 of the digital audio signals A2 and A3 are recorded.
A30 is recorded in order, and the recording area A0 at the upper end of the A30,
In A1, digital audio signals A0 and A1 time-axis-compressed blocks A01 and A11 are recorded in order.

The same applies to the helical tracks TR2 and TR3 simultaneously recorded by the next half rotation of the rotary drum 36, and the recording area A at the lower end of the helical track TR2.
0 and A1, the time-axis-compressed blocks A01 and A11 of the digital audio signals A0 and A1 are sequentially arranged, and the time-axis-compressed blocks A2 and A3 of the digital audio signals A2 and A3 are sequentially recorded in the upper recording areas A2 and A3.
2, A32 are recorded in order. In the recording areas A2 and A3 at the lower end of the helical track TR3, the time-axis compressed blocks A21 and A31 of the digital audio signals A2 and A3 are recorded in order, and in the recording areas A0 and A1 at the upper end thereof, digital blocks are recorded. Audio signal A
Blocks A02 and A12, which are time-compressed with 0 and A1, are recorded in order.

FIG. 1 is a block diagram showing a reproducing system for the recording system described in FIG. 2. Reference numerals 1 and 2 are reproduction preamplifiers, 3 and 4 are reproduction equalizers, 5 and 6 are data strobe circuits, and 7 and 8 are. Demodulation circuit, 9 and 10 are synchronization signal detection circuits, 11 is an inner error correction circuit, 12 and 13 are outer error correction circuits, 14 is a video error correction circuit, 1
5 is a data selection circuit, 16 is a system controller, 1
Reference numerals 7 and 18 are D / A converters.

In FIG. 4, the reproduction signal SP1 reproduced by the reproduction rotary magnetic heads P1 and P3 of FIG. 4 is amplified by the reproduction preamplifier 1, and then the frequency characteristic deteriorated by the tape head system is corrected by the reproduction equalizer 3. It is supplied to the data strobe circuit 5. Similarly, the reproduction signal SP2 reproduced by the reproduction rotary magnetic heads P0 and P2 in FIG.
After being amplified by the reproduction preamplifier 2, the reproduction equalizer 4 corrects the frequency characteristic deteriorated by the tape head system and supplies it to the data strobe circuit 6. In the data strobe circuits 5 and 6, the PLL generates a reproduction clock from the timing information of the level transition of the input signal, and each is used as a strobe signal to detect the logic level of the reproduction signal. The output signals of the data strobe circuits 5 and 6 are converted by the demodulation circuits 7 and 8, respectively, into a data string that is the reverse of the modulation circuits 32 and 33 in FIG. Modulation circuit 3
The output signals of 2 and 33 are supplied to the sync signal detection circuits 9 and 10, respectively, and the sync signals for each of the above sync blocks are detected. Subsequent reproduction signal processing is performed based on the timing of this synchronization signal.

The inner error correction circuit 11 performs error correction processing or the like on the basis of the detected sync signal in units of data included in the sync block with reference to the ID signal and inner error correction code added at the time of recording. After that, it is separated into a digital video signal and a digital audio signal. In this case, in this digital video signal, a field block is extracted from either one of the reproduction signals SP1 and SP2, and this is expanded in the time axis to form a continuous signal. Further, the digital audio signal AP from the inner error correction circuit 11 is
The time-axis-compressed digital audio signals reproduced from the lower end and the upper end of each helical track in FIG.
Moreover, the time between blocks is adjusted and added, and the digital audio signals A0, A1, A2, A3 shown in FIG. 3 are added.
And these are time-division multiplexed in units of sample data.

The digital video signal output from the inner error correction circuit 11 is the outer error correction circuit 1
2, the error correction process is performed using the outer error correction code, and the video error correction circuit 14 further performs the error correction process using the correlation. This uses, for example, data of the same contents around line correlation, field correlation, etc., and corrects an error that cannot be corrected by the inner error correction circuit 11 or the outer error correction circuit 12. The digital video signal output from the video error correction circuit 14 is converted into an analog signal by the D / A converter 17 and output.

The time division multiplexed digital audio signal AP output from the inner error correction circuit 11 is
The outer error correction circuit 13 performs error correction processing using the outer error correction code, and supplies the data selection circuit 15 as a time division multiplexed digital audio signal AP '. If there is an error that cannot be corrected, the outer error correction circuit 13 also supplies error information ER indicating this to the data selection circuit 15. As described above, the magnetic tape 37 (FIG. 3) which is reproduced by detecting the mode information indicating the 2-channel recording mode added by the outer error correction code encoder 29 of FIG. When it is found that the magnetic tape has been recorded, or when the system controller 16 (the system controller 3 in FIG.
(It may be the same as 0), the data selection circuit 15 receives the mode signal MOD indicating the 2-channel recording mode, and the data selection circuit 15 cannot correct the error in the inner error correction circuit 11 or the outer error correction circuit 13. As shown in FIG. 6, the data is subjected to error correction processing.

That is, in FIG. 6, the digital audio signal AP from the outer error correction circuit 13 is a parallel signal in which 4-channel digital audio data is time-division multiplexed as described above, and each digital audio signal When the sampling frequency is Fs, 4-channel sample data is included in the period of 1 / Fs. However, in the figure, "A0-0", "A0-1",
“A0-2” is sample data of a digital audio signal of audio channel 0, and audio channel 1, audio channel 2, and audio channel 3 are indicated by slashes and numerical values attached to A1, A2, and A3, respectively.

Now, sample data A0-0, A0- of the digital audio signal of audio channel 0
1 and A0-2 cannot be error-corrected by the inner error correction circuit 11 or the outer error correction circuit 13, the data selection circuit 15 instructs the outer error correction circuit 13 to output these sample data A0-0, A0-1, A
The error information ER of "H" (high level) is supplied at the timing of 0-2. Here, the data selection circuit 15 delays the supplied output digital audio signal AP of the outer error correction circuit 13 by its sample period 1 / Fs and outputs it, but when the error information of "H" is supplied,
Instead, the sample data of another channel having the same information content as the sample data at this time is output. In the example of FIG.
Sample data A0-0, A of audio channel 0
Since the error information ER is supplied at the timing of 0-1, A0-2, these sample data A0-0, A0-
Instead of 1, A0-2, sample data A2-0, A2-1, A2-2 data of audio channel 2 is output.

The time-division multiplexed digital audio signal AP 'from the data selection circuit 15 is supplied to the D / A converter 18, divided into each channel and converted into an analog signal for output.

In this way, by recording the audio signal on the magnetic tape in the 2-channel recording mode, even if there is an error that cannot be corrected by the error correction code in a certain channel at the time of reproduction, it is automatically the same. The audio data of the channel having no error in the information content will be used instead of this, so that a reproduced audio signal of high quality can always be obtained, and the usability becomes practically good.

Next, the data selection circuit 15 in the case where a trouble occurs in three reproducing rotary magnetic heads among the four reproducing rotary magnetic heads P0 to P3 in FIG. 4 and a reproducing signal cannot be obtained from them. The operation will be described with reference to FIGS. 7 and 8.

In FIG. 6, it is assumed that the helical track indicated by diagonal lines cannot obtain a reproduced signal due to a trouble of the reproducing rotary magnetic head, and the reproduced signal can be obtained only from the outlined helical track TR. As shown in the figure, when the digital audio signal is reproduced only from every third helical track TR, the time-axis-compressed blocks of the digital audio signals A0 to A3 are reproduced from a certain helical track TR. As is apparent, each block of the digital audio signals A0 and A1 reproduced from a certain helical track TR is composed of data of 1/3 field period.
The blocks of the digital audio signals A2 and A3 reproduced from are each composed of data of the next 1/3 field period. When the next helical track TR is reproduced, blocks of digital audio signals A0 and A1 which are data for the next 1/3 field period are obtained.

This is shown in FIG. 8. Digital audio signals A0 and A1 are obtained for every 1/3 field period and for every 1/3 field period.
Digital audio signals A2, A in the 1/3 field period in which 0, A1 are missing (hatched with hatching)
3 will be obtained. The digital audio signals A0 to A3 are supplied to the outer error correction circuit 13 as time-division multiplexed signals as described above. In the outer error correction circuit 13, the digital audio signal A
The error information ER is output during the period in which 0 and A1 are missing. The data selection circuit 15 uses the error information ER to interpolate the missing period of the digital audio signal A0 with the digital audio signal A2 to obtain the digital audio signal A0.
The missing period of 1 is interpolated with the digital audio signal A3.

Thus, as shown in FIG. 8, a digital audio signal OUTA0 (OUTA2) in which the digital audio signal A0 and the digital audio signal A2 are interpolated with each other is obtained, and the digital audio signal A1 and the digital audio signal A1 are obtained. A digital audio signal OUT which is interpolated with the audio signal A3
A1 (OUTA3) is obtained, but if the digital audio signals A0 and A2 are the same and the digital audio signals A1 and A3 are the same, the digital audio signal OUTA0 (OUTA2) is completely error-corrected. Original digital audio signal A0
Alternatively, it becomes the digital audio signal A2, and the digital audio signal OUTA1 (OUTA3) becomes the original error-corrected original digital audio signal A1 or digital audio signal A3.

As described above, in this embodiment, even if the rotary magnetic head has no trouble, it is possible to reproduce a sufficiently error-corrected audio signal if at least one can be reproduced. Such an embodiment can be applied to a digital VTR for business such as broadcasting. That is, regarding the broadcasting station, the audio signal transmitted from the broadcasting station is usually two channels, such as stereo broadcasting and bilingual broadcasting. A digital VTR used in a broadcasting station can record 4-channel digital audio signals. So, applying the example to this,
Of these four channels, the same audio signal as the two-channel audio signal used for broadcasting is recorded as another two channels, and an error is generated in these digital audio data in the original two-channel audio signal that is reproduced during reproduction. Then, as described above, this digital audio data can be replaced with digital audio data of the same content reproduced as another channel, thereby completely eliminating the error in the predetermined channel. Therefore, it is more reliable than the conventional method, and even if a magnetic head trouble occurs,
It is possible to reproduce a 2-channel audio signal with little quality deterioration.

[0050]

As described above, according to the present invention,
When recording / reproducing a multi-channel digital audio signal with a plurality of recording / reproducing magnetic heads, even if some of these recording / reproducing magnetic heads cannot be reproduced, the recorded audio signals should be reproduced with good sound quality. You can

[Brief description of drawings]

FIG. 1 is a block diagram showing a reproducing system of an embodiment of a digital signal recording / reproducing apparatus according to the present invention.

FIG. 2 is a block diagram showing a recording system for the reproducing system shown in FIG.

FIG. 3 is a diagram showing a specific example of a method of synthesizing a digital video signal and a digital audio signal in the recording system shown in FIG.

FIG. 4 is a plan view showing the vicinity of a rotary drum in the embodiment shown in FIGS. 1 and 2.

5 is a track pattern diagram on a magnetic tape by the rotary magnetic head in FIG.

FIG. 6 is a diagram showing an operation of the data selection circuit of FIG. 1 when a 1-channel digital audio signal cannot be error-corrected.

FIG. 7 is a diagram showing that three of the four reproducing rotary magnetic heads cannot reproduce.

8 is a diagram showing an operation of the data selection circuit of FIG. 1 in the state shown in FIG. 7.

[Explanation of symbols]

 11 Inner error correction circuit 12, 13 Outer error correction circuit 15 Data selection circuit 18 D / A converter 20-23 Audio signal input terminal 25 A / D converter 26, 27 switch 29 Outer error correction code encoder 31 Inner error correction code encoder 36 rotating drum 37 magnetic tape R0 to R3 rotating recording magnetic head P0 to P3 rotating reproducing magnetic head

Claims (4)

[Claims] 1. A pair of recordings is provided on a side surface of a rotary drum, wherein two recording heads paired with two recording heads and two reproducing heads paired with two reproducing heads are provided. The heads simultaneously record the recording signals on the magnetic tape, the recording head pairs alternately record the recording signals on the magnetic tape, and the reproducing heads forming the pairs simultaneously reproduce the recording signals from the magnetic tape. The reproducing head pair alternately reproduces the recording signal from the magnetic tape, digitally processes input audio signals of a plurality of channels, and supplies the recording signals as digital audio data to the recording head. A digital signal recording that processes a playback signal consisting of digital audio data of multiple channels from In the recording / reproducing apparatus, a first means for detecting an error in the digital audio data reproduced by the reproducing head pair, and the digital audio data in which the error is detected by the digital audio data of another channel in which the error is not detected. A digital signal recording / reproducing apparatus comprising: second means for substituting. 2. The digital signal recording / reproducing apparatus according to claim 1, wherein at least one channel input audio signal among the plurality of channel input audio signals is the same signal as another channel input audio signal. 3. The special mode according to claim 1, wherein the input audio signal of at least one channel among the input audio signals of the plurality of channels is the same signal as the input audio signals of other channels, and the special signal is added to the recording signal. A digital signal recording / reproducing apparatus characterized by adding a mode signal indicating a mode. 4. A third means for detecting the mode signal from a reproduction signal from the reproducing head pair according to claim 3, wherein the second means is replaced according to a detection result of the third means. A digital signal recording / reproducing apparatus characterized in that it is adapted to perform an operation.