JPH05258206A - Magnetic recording and reproducing device - Google Patents

Abstract

(57) [Summary] [Structure] Recording or reproduction is performed on these tracks by a head corresponding to each track group consisting of a helical track for recording and reproducing video signals and a mixed video / audio track for recording and reproducing video and audio signals. The magnetic recording / reproducing apparatus includes means for detecting the state of the reproduction signal from each reproducing head and switching the head corresponding to the mixed video / audio track based on the output thereof. According to the present invention, even when a head is clogged, the track corresponding to this head is scanned by changing the corresponding relationship to another head in good condition,
It is possible to provide a magnetic recording / reproducing apparatus capable of improving the error rate of an audio signal, reducing the possibility of error correction / interruption of voice extremely, and stably reproducing an 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 VTR (video tape recorder) for recording and reproducing a video signal and an audio signal in the form of a digital signal, and a rotary head scans a helical track on a magnetic tape to output the signal. The present invention relates to a magnetic recording / reproducing device for recording / reproducing data.

[0002]

2. Description of the Related Art Generally, in a digital VTR, since the amount of information of a video signal is large and the recording data rate is high,
In many cases, recording / reproduction of a digital video signal is performed by dividing into a plurality of channels of two or more channels. For example, in a commercial digital VTR, the D1 format of 4-channel division and the D2 format of 2-channel division are examples. In these digital VTRs, digital audio signals are also divided and recorded in all channels, and audio recording areas are provided on all helical tracks. However, in the case of multi-channel recording of 4 to 8 channels or more, if the audio signal is divided and recorded in all channels, the following problems occur.

(1) The information amount of an audio signal per track is extremely smaller than that of a video signal, and there is a high possibility that audio data will be lost due to a burst error.

(2) Since it is necessary to provide a gap area (edit gap) for editing the audio signal independently of the video signal for all the tracks, data redundancy increases.

(3) Audio signal readout / processing /
In order to realize the special editing of re-recording, an audio pre-play head preceding the recording head is required, but the pre-play heads must be attached in the same number as the normal play heads. Along with that, the number of channels of the rotary transformer also increases.

[0006] Therefore, the present applicant has filed Japanese Patent Application No. 3-3003.
The 72 patents filed the following applications to solve these problems. That is, N helical tracks are treated as a track group, and each of these N helical tracks (NK) is used as a video-only track to record or reproduce only a video signal, and the remaining K tracks are mixed video / audio tracks. As described above, recording or reproducing is performed in a form in which a video signal and an audio signal are mixed. As a result, the problems (1) to (3) described above can be solved, for example, the number of pre-read heads can be significantly reduced. Hereinafter, such an audio signal recording system will be referred to as an N · K recording system.

FIG. 8 is a track pattern diagram on the magnetic tape in the N.K recording system when N = 4 and K = 1. T1, T2, T3, T5, T6, and T7 are tracks dedicated to video, and T4 and t8 are video / audio mixed tracks. Tracks with the same symbol (for example, T1) are assumed to be scanned by the same recording head (or reproducing head). Video / audio mixed track T
In T4 and T8, 801 is a video recording area and 802 is an audio recording area. FIG. 9 shows more detailed contents of the audio recording area 802 in the mixed video / audio tracks T4 and T8. In this example, audio signals of 8 channels (8 systems) are recorded in 8 areas (each area shown as 1 to 8 in FIG. 9) with an edit gap, and are independently edited for each audio channel. can do.

In the digital VTR, signals are recorded on the magnetic tape by the magnetic flux generated between the head gaps. Therefore, if magnetic powder or the like adheres to the head gap, the recording head or the reproducing head will be clogged and the generation of magnetic flux will be hindered, and recording / reproducing cannot be performed well. Digital V for multi-channel recording
In the case of TR, since the number of heads is large, the possibility is high. If the N / K recording system as described above is used, it is assumed that the video-only tracks T1, T2, T3, T5, T6, T
When one of the playback heads corresponding to 7 causes a clogging, the channel cannot be error-corrected, but by interpolation / replacement (error correction) by peripheral pixels on the screen,
Practical enough image quality can be obtained. Particularly, the larger N is, the more difficult it becomes to detect the image quality deterioration due to the error correction. However, when one of the reproducing heads corresponding to the mixed video / audio tracks T4 and T8 causes a clogging, only the reproducing head corresponding to this track reproduces the audio signal. There is a risk that the audio may be interrupted because it cannot be played at all. It is important to avoid interruptions in voice, as you will notice them without listening carefully.

Therefore, in the technique of the above-mentioned Japanese Patent Application No. 3-300372, an error correction code is added to an audio signal of a predetermined period in the NK recording method, and then the difference 2
The recording is divided into at least two video / audio mixed tracks which are scanned by more than one head and recorded. Particularly, for example, as a product code structure in which an equal amount or more of outer code error correction symbols are added to the original data and then inner coding is performed, recording is performed by dividing into two video / audio mixed tracks (T4 and T8 in the above example). In this case, of the two heads corresponding to the mixed video / audio track, even if one head is clogged, the error can be completely corrected. That is, it is possible to prevent the audio data from being weakened due to head clogging or burst error even though the audio data is concentratedly recorded on some tracks.

However, in this example, if one of the two heads corresponding to the mixed video / audio track is used for a long period of time with the head clogged, most of the error correction capability of the audio signal is clogged with the head. It has already been used to correct errors due to, and the remaining error correction capability is weakened. Therefore, even if a short burst error occurs in a video / audio mixed track corresponding to the head that is not clogged, there is a high possibility that the audio signal cannot be error-corrected, and error correction (interpolation / replacement) increases. However, in the worst case, voice interruption may occur.

As described above, in the conventional N / K recording type digital VTR, when the head corresponding to the video / audio mixed track is clogged, the error correction capability of the audio signal is significantly deteriorated, and the audio Error correction / interruption is likely to occur.

[0012]

As described above, N helical tracks (N−K) are used as video-only tracks to record or reproduce only video signals, and the remaining K tracks are mixed video / audio tracks. In a conventional digital VTR that records or reproduces a video signal and an audio signal in a mixed manner, when the head corresponding to the mixed video / audio track is clogged, the error correction capability of the audio signal is significantly deteriorated. However, there is a problem that audio error correction / interruption is likely to occur, and it becomes impossible to record / reproduce audio signals.

An object of the present invention is to provide a magnetic recording / reproducing apparatus capable of stably reproducing an audio signal even when the head is clogged in view of this point. ..

[0014]

In order to solve the above problems, the present invention records and reproduces each helical track on a magnetic recording medium corresponding to each of a plurality of recording and reproducing heads provided in a rotating means. In a magnetic recording / reproducing apparatus for recording or reproducing a signal on each helical track while the head scans, a detecting means for detecting a state of a reproducing signal reproduced by each reproducing head, and each reproducing head based on an output of the detecting means. A means for changing the correspondence with each of the helical tracks is provided.

The other is for a track group on a magnetic recording medium in which a plurality of dedicated video tracks for recording / reproducing video signals and a plurality of mixed video / audio tracks for recording / reproducing video and audio signals are repeated. A magnetic recording / reproducing apparatus that records or reproduces a signal on each helical track while each recording / reproducing head scans each helical track corresponding to each of the plurality of recording / reproducing heads provided on the rotating means. Correspondence between the detecting means for detecting the state of the reproduction signal from the head and the recording / reproducing head for scanning the video-only track based on the output of the detecting means and the recording / reproducing head for scanning the mixed video / audio track. And a means for changing.

[0016]

According to the present invention, the detecting means for detecting the state of the reproduced signal from each head causes a clogging or an error rate in the reproducing head which scans a mixed video / audio track among the reproducing heads. To detect that. When the reproducing head scanning the mixed video / audio track is clogged or the error rate is deteriorated by the means for switching the correspondence of the reproducing head scanning the mixed video / audio track based on the output of the detecting means. It is possible to scan a mixed video / audio track with another reproducing head having a good reproducing condition. As a result, the error rate of the audio signal can be improved and the possibility of error correction / interruption of the voice can be made extremely low.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. Below, in order to make the explanation easier to understand,
An embodiment in which the present invention is applied to a digital VTR with N = 4 and K = 1 will be shown. That is, the track pattern is composed of three video dedicated tracks and one audio / video mixed track. Of course, even in the case of a combination of different N and K such as N = 8 and K = 1, the essence does not change.

FIG. 2 shows the head arrangement on the rotary drum in this embodiment. On the rotating drum, there are eight recording heads R1 to R8, eight reproducing heads P1 to P8, two audio preceding reproducing heads A4 and A8, and four erasing heads E.
1.E4, E5, E8 are installed. The magnetic tape is wrapped around a rotating drum about 180 degrees. Two heads (for example, P1 and P5) opposed to each other on the rotary drum by 180 degrees form a set, and either one of the two heads becomes active depending on the rotation phase of the rotary drum. It is assumed that the recording heads R1 to R8 and the reproduction heads P1 to P8 correspond to the tracks T1 to T8 of FIG. 8, respectively. The preceding reproducing heads A4 and A8 reproduce the tracks T4 and T8 ahead in time.

Here, the structure of the erasing head in this embodiment will be described. Normally, each recording head R1 to R
It is usual to mount a total of eight erasing heads in order to erase tracks prior to eight. In this embodiment, however, the erasing heads are mounted by paying attention to the editing form of the video signal / audio signal. The erase heads are reduced to four. Of these, two are dedicated video track erasing heads E1 and E5, and the remaining two are video / audio mixed track erasing heads E4 and E8.

When editing, the video signal and the audio signal of each channel must be independently rewritten. However, since it is only necessary to edit the video signal in units of one field, it is not necessary to delete the video-only tracks one by one. Dedicated track erasing head E1
E5 is a head E for erasing mixed video / audio tracks
The head is about 3 times wider than that of 4.E8, and simultaneously erases three adjacent video tracks during half rotation of the rotary drum. The head for erasing mixed video / audio tracks is
This is an erasing head that erases only one audio mixed track. FIG. 3 shows how the erase heads E1 and E4 (and the recording heads R1 to R4) scan the tracks T1 to T4.

With such an erase head structure, the number of erase heads can be significantly reduced. In this embodiment, the number is changed from 8 to 4. Also,
For example, in the case of 8-channel recording and N = 8 and K = 1, the number of erasing heads is 16 to 4 by providing an erasing head that simultaneously erases 7 (= N−K) video-only tracks. Reduced to. Of course, instead of one erasing head for erasing seven simultaneously, two erasing heads for erasing four and three respectively may be provided.

FIG. 1 shows a digital VTR in this embodiment.
2 is a schematic configuration diagram of FIG. 102 is a video signal dividing circuit, 1
03a to d are video recording processing circuits, 106 is an audio recording processing circuit, 107 is a video / audio switching circuit, 104a to d are recording processing circuits, 108a to d are reproduction processing circuits, 109 is a channel switching circuit, and 110a.
˜d is a video reproduction processing circuit, 111 is a video signal matching circuit, 113 is an audio reproduction processing circuit, 115 is a head selection determining circuit, and 116 is a servo circuit. In FIG. 1, the illustration of the preceding reproducing head, the erasing head, etc. is omitted.

A video signal input from the video input terminal 101 is divided into four channels by a video signal division circuit 102 according to a predetermined rule, and a video recording processing circuit 103 is provided.
Outer code (C2) encoding, shuffling, and other processes are performed at a to d. On the other hand, the eight audio signals input from the audio input terminal 105 are subjected to outer code (C2) encoding, shuffling, and other processing by the audio recording processing circuit 106, and then are processed by the video / audio switching circuit 107 in the fourth channel. It is multiplexed with the video signal.
In each channel, the recording processing circuits 104a to 104d perform inner code (C1) encoding, modulation, synchronous block formatting, serialization, and the like, and then the recording signals are recorded by the recording heads R1 to R8.

4 reproduced by reproducing heads P1 to P8
The reproduction signals of the channels are subjected to processing such as equalization, clock extraction, parallelization, synchronization detection / demodulation, and inner code (C1) decoding in the reproduction processing circuits 108a to 108d, and then the channel replacement circuit 109 replaces the channels (described later). ) Is done. At this time, in the fourth channel, the reproduction video signal and the reproduction audio signal are separated. The video signal reproduction processing circuits 110a to 110d perform deshuffling, outer code (C2) decoding, error correction, and the like, and after the channels are integrated by the video signal matching circuit 111, the video signal is output from the video output terminal 112. It On the other hand, in the audio reproduction processing circuit 113, after performing deshuffling, outer code (C2) decoding, error correction, and the like, eight audio signals are output from the audio output terminal 114. The description so far regarding FIG. 1 is the same as that of the conventional digital VTR corresponding to the NK recording system.

From the reproduction processing circuits 108a to 108d, the error monitoring signals 118a to 118d are respectively sent to the head selection determining circuit 1.
15 are supplied. The color monitor signals 118a to 118d are generated as follows. In C1 decoding in the reproduction processing circuits 108a to 108d, a C1 error detection pulse is generated when a code word whose syndrome is not zero is detected, and the counter counts the number of this C1 error detection pulse every predetermined unit time. At this time, two heads (for example, P
Gates are set so that counting can be performed for each of 4 and P8). The error count value of a predetermined unit time for each reproducing head is output as error monitoring signals 118a to 118d.

In the head selection determining circuit 115, based on the error monitoring signals 118a to 118d from each channel and various status information given from the servo circuit 116, first, the error rate of the reproducing heads P1 to P8, particularly clogging (or (A condition equivalent to clogging due to head life etc.) is detected. It is assumed that when the servo lock state is set in the normal reproduction, the reproduction signals from other heads have few errors, but only the reproduction signals from one certain head have extremely many errors. Here, in order to distinguish between an error due to head clogging and a short-time burst error, a state in which the C1 error detection rate per unit time exceeds a predetermined rate (for example, 90%) is for a fixed time (for example, 10 seconds) or more. Only when the reproduction is continued, it is determined that the reproduction head is clogged.

To detect the clogging of the head,
Instead of using the above method, synchronization detection error may be monitored, or analog means such as dropout detection may be used together.

When the clogging of the head is detected, a warning to that effect is also displayed. However, there are cases where head cleaning cannot be performed immediately because of VTR operation, such as in unattended operation. Further, when the error rate deteriorates due to the life of the head, cleaning the head has no effect.

Therefore, in the present embodiment, the correspondence between the reproducing head and the track is selected and determined from a plurality of combinations based on the result of the clogging determination by the head selection determination circuit 115, and the head selection determination circuit 115 switches the channel. Head selection instruction signals 119 and 120 are output to 109 and the servo circuit 116.

For example, it is assumed that the reproducing head P4 is determined to be clogged. Since the reproducing head P4 is a head corresponding to the video / audio mixed track T4, the audio signal may be deteriorated as it is. Therefore, the head selection determining circuit 115 changes the correspondence between the reproducing heads and the tracks from the standard state so that the reproducing heads that are not clogged scan the mixed video / audio tracks to improve the error rate of the audio signal. Channel switching circuit 109 and servo circuit 116
The head selection instruction signals 119 and 120 are output to. Here, since there is no clogging other than P4, the change is instructed as follows. Playback head in standard track state Playback head after change to support T1: P1 P7 T2: P2 P8 T3: P3 P1 T4: P4 P2 T5: P5 P3 T6: P6 P4 T7: P7 P5 P8 P8, that is, P8: P8: Truck T4 / T8
The reproducing head corresponding to is changed from P4 / P8 to P2 / P6. FIG. 4A shows the correspondence between the reproducing head and the tracks in the standard state. FIG. 4B shows a correspondence relationship between the reproducing head and the track after the change. Such correspondence is not limited to these two types, and may be a form in which the reproducing head is cyclically shifted from the standard state. In particular, a set of reproducing heads having the highest error rate without causing clogging may scan a mixed video / audio track. In the case of an azimuth recording type VTR, it is necessary to replace the tracks so that the same azimuth track and head correspond.

In the above example, the clogging reproducing head P is used.
4 is modified to scan the video dedicated track T6. Therefore, the video signal of the second channel corresponding to T6 cannot be error-corrected. However, as described above, the image quality deterioration due to this is minimized by the error correction technique.

When the correspondence between the reproducing head and the track is changed as described above, the correspondence between the audio preceding reproducing head and the track and the correspondence between the erasing head and the track also change, but these heads are used only during recording and editing. No, there is no problem because it is not used during normal playback.

The above-mentioned change of the correspondence between the head and the track is realized by changing the servo phase relation in accordance with the head selection instruction signal 120 in the servo circuit 116. The main elements of the servo circuit 116 are:
There are drum servos and capstan servos. These also include velocity servos and phase servos, but velocity servos are not directly related to the present invention and will not be described. The phase servo basically controls the motor (drum motor / capstan motor) by comparing the phases of the reference signal and the comparison signal and converting the phase error into an analog amount (voltage). In the following, the operation of the phase servo in this embodiment will be simplified and described.

FIG. 5A is a timing chart showing the operation of the servo circuit during reproduction in the standard state, which corresponds to FIG. 4A. A standard frame pulse is input from the terminal 117 of FIG. 1 and serves as a phase reference. Figure 5 (a)
As shown in, the drum rotation pulse supplied from the drum motor is subjected to the drum phase servo so that the drum rotation pulse is locked with a delay of time t1 with respect to the reference frame pulse. At this time, the switching signal of the reproducing head on the rotary drum is always in a fixed phase with respect to the drum rotation pulse, and is assumed to be as shown in FIG. However, in the figure, the reproducing heads P2, P6, P4,
Only P8 is shown. In addition, the playback control frame pulse generated from the control signal played back by the control head from the control track provided in the longitudinal direction of the tape is capstan phase servo applied so that the phase matches the reference frame pulse as shown in the figure. It is supposed to be.

FIG. 5B is a timing chart when the reproducing head and the track are associated with each other by the capstan servo as shown in FIG. 4B. The reproduction control frame pulse is phase-locked in the state where it precedes by a time t2 as compared with FIG. t2 is the reproducing head P2
And P4 (or P6 and P8) on the rotating drum, that is, a time corresponding to a drum rotation of 90 degrees.

FIG. 5C is a timing chart in the case where the reproduction servo is associated with the track as shown in FIG. 4B by the drum servo. The phase is locked when the drum rotation pulse is delayed by the time t3 (= t1 + t2) with respect to the reference frame pulse, that is, when delayed by the time t2 as compared with FIG.

In the case of the digital servo system, the phase error between the two signals is detected by counting the time difference between the two signals with a clock pulse. Therefore, by manipulating the value of this counter appropriately, as shown in FIG.
Phase lock at a phase different from the standard state as in (c) can be easily realized. Of course, such correction is possible even in the case of the analog servo system. These may be considered to be essentially the same as the tracking adjustment function.

In both cases of FIGS. 5B and 5C, FIG.
The correspondence between the reproducing head and the track shown in (b) is realized. Comparing the cases of FIGS. 5B and 5C,
The case of (c) is superior in that the timing of reproducing the predetermined data (for example, the data of the track T4) with respect to the standard frame pulse is almost the same as that of FIG. 5A (FIG. 5C). ) P2 timing and FIG.
(The timing of P4 in (a) is almost the same). In the case of (b), the timing at which the predetermined data is reproduced with respect to the reference frame pulse is earlier (the timing of P2 in FIG. 5B is earlier than the timing of P4 in FIG. 5A).
Usually, a reproduction field memory is provided in each of the reproduction processing circuits 110a to 110d in FIG. 1, and since this time difference can be absorbed therein, there is almost no problem. The correspondence between the reproducing head and the track may be changed by using both the capstan servo and the drum servo.

The 4-channel reproduction data reproduced in correspondence with the reproduction heads and tracks different from the standard state is exchanged by the channel exchange circuit 109 of FIG. 1 in accordance with the head selection instruction signal 119. That is, in the channel switching circuit 109, the reproduction processing circuits 108a, b, c, d are connected to the video signal reproduction processing circuits 110a, b, c, d in this order in the standard state corresponding to FIG. To function. When the correspondence between the reproducing head and the track is changed as shown in FIG. 4B, the reproduction processing circuits 108a, b, c, d are connected to the video signal reproduction processing circuits 110c, d, a, b in this order. To function. Similarly, in the case of other correspondences, the correspondence is returned to the standard state.

In a multi-channel digital VTR, a track is scanned so that each reproducing head crosses the track during variable speed reproduction (shuttle reproduction, slow reproduction, etc.). The channel exchanging circuit 109 is originally necessary even in a normal digital VTR in order to distribute reproduction data of different tracks sequentially read from a certain head during variable speed reproduction to the original channel. Therefore, the circuit of this part is not particularly increased by the present invention.

As described above, in the present embodiment, even when the reproducing head for scanning the mixed video / audio track is clogged, another reproducing head in good condition scans the mixed video / audio track. You can

Here, when clogging of the reproducing head is detected, if the correspondence between the reproducing head and the track is changed immediately during reproduction, video and audio will be output until the servo is disengaged and locked again. It may be disturbed. In order to avoid this, the head correspondence change may be performed from the time of the next reproduction after the servo lock state is once released by the stop operation or the like.

Further, if the reproduction state from the same track as before the change is determined to be bad, that is, if the correspondence between the reproducing head and the track is changed, that is, if it is determined that the change in the correspondence is not effective, at the time of recording. Another possible cause is clogging of the recording head. In this case, the correspondence may or may not be restored as long as there is no great difference in the reproduction state from other tracks.

Since there are many cases where it is desired to give priority to the image quality of a video signal over the margin of an audio signal,
It is desirable to allow the user to select such a head correspondence changing function by operation.

Here, a supplementary description will be given of the error correction system for video / audio signals in this embodiment. The error correction code has a product code configuration of Reed-Solomon code for both video signals and audio signals. Of these, the number L1 of data symbols of the inner code C1 and the number S of parity symbols
1 is common to the video signal and the audio signal. The configuration of the outer code C2 differs between the video signal and the audio signal.

Regarding the audio signal, the conventional N · K
The product code is the same as in the recording method, and the data is recorded in two video / audio mixed tracks in a distributed manner. FIG. 6 shows the structure of an error correction matrix of a 1-channel audio signal for a predetermined period.

First, 6 symbols of C2 parity symbols are added to 4 symbols of data in the vertical direction, and then C1 parity symbols of S1 symbols are added to data of L1 symbols (or C2 parity symbols) in the horizontal direction. is doing. In the error correction matrix of FIG. 6, the C2 code has an erasure correction capability of up to 6 symbols, and errors of 6 or less C1 code words can be completely corrected. afterwards,
A total of 10 C1 codewords are divided into 5 pieces and recorded on 2 video / audio mixed tracks T4 and T8, respectively. By the encoding and track distribution as described above, even if the head corresponding to one of the two mixed video / audio tracks is clogged, the error can be completely corrected.

Next, the video signal will be described. video·
Since it is necessary to provide an audio recording area in the audio mixed track, the video recording area is smaller than the video dedicated track. Therefore, regarding the video signal, as described in detail in Japanese Patent Application No. 3-300372, the ratio of the information amount of the effective video signal of the video / audio mixed track to the information amount of the effective video signal of the video-dedicated track is a predetermined integer. As a ratio, the distribution rule of the video signal to each track is simplified. In this embodiment, this integer ratio is assumed to be EA to EV (EA <EV).

FIG. 7 shows the structure of an error correction matrix of a video signal of one field for one channel. Unlike the embodiment of Japanese Patent Application No. 3-300372, the error correction of the video signal is completed in each of the four channels in this embodiment. FIG. 7A shows a video-only track, and FIG. 7B shows a video / audio mixed track. As shown in FIG. 7A, the number of data symbols and the number of parity symbols of the outer code C2 of the video dedicated track are L2V and S2V, respectively. Further BV
Error correction matrices are arranged side by side. It is assumed that the recording / reproducing order is such that the BV block is moved in the horizontal direction in the matrix in the figure and then the next row is transferred. That is, the C2 code is interleaved with the BV block. Similarly, as shown in FIG. 7B, the number of data symbols of the outer code C2 of the video / audio mixed track,
The numbers of parity symbols are L2A and S2A, respectively.
Further, BA error correction matrices are arranged side by side, and C
The two codes are interleaved with BA blocks.

In order to make the redundancy of the video / audio mixed track and the video dedicated track equal, the following method can be considered. That is, the number of parity symbols S2A of the outer code is made smaller than S2V, and the number of interleaved blocks BA is made shorter than BV. Specifically, L2A / L2V = S2A / S2V = EA / EV, BA =
BV or L2A = L2V, S2A = S2V, BA / BV = EA /
It should be EV. However, with either method,
There is a problem that the burst error correction capability of the video / audio mixed track becomes lower than the burst error correction capability of the video dedicated track.

Therefore, in the video / audio mixed track of the present embodiment, the redundancy is made different from the video dedicated track, the interleave block number BA is made equal to BV, the parity symbol number S2A is made equal to S2V, and only the data symbol number L2A is made. Use short code as outer code (L2
A / L2V = EA / EV). As a result, even for a video / audio mixed track, it is possible to guarantee the burst error correction capability of the video signal that is exactly the same as that of the video-only track. Since the shaded area in FIG. 7B is only shortened as compared with FIG. 7A, the processing circuits are almost the same configuration in the video / audio mixed track and the video dedicated track with only a slight change in control. Can be As described above, in the present embodiment, the error correction method for audio signals and video signals is also suitable for the NK recording method.

By the way, since it is the final object of the present invention to keep the error rate of the video / audio mixed track in a good state, the following method can be considered as a method of achieving it.

(1) Although an auto-tracking technique is known in which the reproducing head is mechanically moved to follow and scan the track, it is difficult to make all the reproducing heads movable in terms of space and cost. Therefore, only the playback head that scans the mixed video / audio track is set to auto-tracking.

(2) The delayed reproduction audio data from the preceding reproduction head and the reproduction audio data from the normal reproduction head for scanning the mixed video / audio tracks are selected to have the better reproduction condition. This can be realized, for example, as follows. First, the data from the preceding reproducing head is delayed by an amount corresponding to the time difference from the normal reproducing head, and then written into the memory for each block together with the flag indicating the error state of the block. Next, this flag is compared with the flag indicating the error state of the block of data from the normal playback head, and if the data from the normal playback head has fewer errors, this is overwritten in the memory, and Perform processing.

(3) A spare reproducing head for scanning a mixed video / audio track is provided. Same video
It suffices to arrange the audio mixed tracks so that two (or more) heads scan. At this time, the head width and the depth of the head gap of the spare reproducing head may be different from those of the normal reproducing head, and the reproducing characteristics may be different.

Even when the above methods (1) to (3) are adopted, since it is sufficient to apply the method not to all N tracks but only to K tracks, the increase in the number of heads and processing circuits can be minimized. be able to.

The present invention can be applied not only to the N / K recording method for audio signals described above, but also when it is desired to improve the error rate of a specific channel.
For example, a compression coding recording type digital VT in which the most important compression coding parameters are recorded in a certain track.
In R, the present invention may be applied by considering the track as the video / audio mixed track of the above-described embodiments.

The present invention is not limited to the above-mentioned embodiment, but various applications are possible. In the above embodiment, only the clogging of the reproducing head is focused, however, for example, the clogging of the recording head (or the reproducing head) is monitored by simultaneous reproduction even during recording, a warning is issued, and the correspondence between the recording head and the track is changed. You may record it again. However, in this case, a channel switching circuit is required on the recording side. Also, in order to perform editing, it is necessary to increase the number of erasing heads as compared with the above embodiment.

[0059]

According to the present invention, even when a head corresponding to an audio / video signal mixed track is clogged, the head having no clogging can be changed by switching the correspondence with another head. A magnetic recording / reproducing device that can convert audio signal mixed tracks to improve the audio signal error rate, reduce the possibility of audio error correction / interruption, and play audio signals stably. Can be provided.

[Brief description of drawings]

FIG. 1 is a digital VTR according to an embodiment of the present invention.
FIG.

FIG. 2 is a head layout diagram on a rotary drum in the embodiment.

FIG. 3 is a correspondence diagram of an erase head and a track in the same embodiment.

FIG. 4 is a correspondence diagram of a reproducing head and a track in the embodiment.

FIG. 5 is a timing chart showing the operation of the servo circuit in the embodiment.

FIG. 6 is a configuration diagram of an error correction matrix of an audio signal in the embodiment.

FIG. 7 is a configuration diagram of an error correction matrix of a video signal in the embodiment.

FIG. 8 is a track pattern diagram on a magnetic tape.

FIG. 9 is a diagram showing the contents of an audio recording area of a video / audio mixed track.

[Explanation of symbols]

 109 channel switching circuit 115 head selection determination circuit 116 servo circuit 118a-b error monitoring signal 119, 120 head selection instruction signal 801 video recording area 802 audio recording area T1 to T3, T5 to T7 video dedicated track T4, T8 video / audio mixed Tracks R1 to R8 recording heads P1 to P8 reproducing heads A4, A8 preceding reproducing heads E1, E4, E5, E8 erasing heads

Claims (2)

[Claims] 1. A signal is provided on each helical track while each recording and reproducing head scans each helical track provided on a magnetic recording medium corresponding to each of a plurality of recording and reproducing heads provided on a rotating means. In a magnetic recording / reproducing apparatus for recording or reproducing, a detection means for detecting a state of a reproduction signal reproduced by each reproduction head, and a correspondence relationship between each reproduction head and each helical track based on an output of the detection means. A magnetic recording / reproducing apparatus comprising: a switching unit. 2. A track group provided on a magnetic recording medium in which a plurality of video dedicated tracks for recording and reproducing video signals and a plurality of mixed video / audio tracks for recording and reproducing video and audio signals are repeated. ,
In a magnetic recording / reproducing apparatus for recording or reproducing a signal on each helical track while each recording / reproducing head scans each helical track corresponding to each of a plurality of recording / reproducing heads provided in a rotating means, Detecting means for detecting a state of a reproduced signal from each reproducing head; each recording for scanning the video dedicated track based on the output of the detecting means; and each recording for scanning the reproducing head and the mixed video / audio track And a means for switching the correspondence with the reproducing head.