JPH09180410A - Signal recording/reproducing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To expand signal recording regions and utilize the regions efficiently by a method wherein audio and video signals A and V which are read out and reproduced by audio and video reproducing advance heads which precede recording heads are overwritten on the regions of audio and video signals A and V by the recording heads. SOLUTION: Recording heads record audio and video signals A and V on the audio and video sectors AS and VS of the track TR1 of a magnetic tape 1 which runs in the direction of an arrow. Audio and video advance heads A and V which precede the recording heads are positioned on tracks TR2 and TR3 which are apart from the track TR1 on which the recording heads record signals by distances W13 and W14 respectively. Therefore, the signals which are read out and reproduced by the advance heads A and V can be overwritten on the regions of the respective signals A and V of the same track TR1 by the recording heads. With this constitution, the signal recording regions of the tape 1 can be expanded and utilized efficiently and, further, a recording wavelength can be extended to use economical heads and tapes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention reads out and reproduces an audio signal and / or a video signal recorded on a tape-shaped recording medium, and then overwrites the read-out audio signal and / or video signal area. The present invention relates to a signal recording / reproducing method.

[0002]

2. Description of the Related Art Conventionally, a digital video tape recorder which records and reproduces digital audio signals and video signals by a so-called helical scan system in which a magnetic tape is used as a recording medium and a head obliquely scans the magnetic tape ( Digital VTR) exists.

In this digital VTR, recording of an audio signal and a video signal is performed, and timing processing of a time code indicating a recording time of the audio signal and the video signal, which is recorded in real time in the longitudinal direction of the magnetic tape, is performed. The audio signal and the video signal which have already been recorded are reproduced and edited, and the edited signal is overwritten on the reproduced audio signal and the video signal and re-recorded to perform pre-read editing or audio mix editing. can do.
In order to perform these processes, first, the already recorded audio signal and video signal are read out and the reproduction process is performed. A reproducing head (hereinafter referred to as an advance head) for reading out the recording signal needs to be attached at a position ahead of the position of the recording head by a time required for the reproducing process of the audio signal and the video signal.

For example, as shown in FIG. 3, a magnetic tape 1 whose front surface is a magnetic surface runs in the direction of an arrow, and an upper drum 2
When performing pre-read editing when the drum 2 composed of a and the lower drum 2b rotates in the forward direction with respect to the running direction of the magnetic tape 1, the advance head 4 provided in the drum 2 is used to move the magnetic tape 1 to the magnetic tape 1. After the recorded audio signal and video signal are read out, reproduced, and edited, the edited audio signal and video signal are overwritten in the read audio signal and video signal areas by the recording head 3.

At this time, the mounting position of the advance head 4 on the drum 2 is equal to the time required for the reproduction processing of the audio signal and the video signal read by the advance head 4 scanning the track.
The position is higher than the mounting position of. Accordingly, the distance between the track position scanned by the advance head 4 and the track position scanned by the recording head 3 is h.
Becomes

[0006]

By the way, the range in which the data signal can be recorded by the recording head 3 on the magnetic tape 1 is at the position shown in FIG. Position A that can be touched
Up to position C. Here, the advance head 4
At the position shown in FIG. 3, the position B ′ on the magnetic tape 1 is shown.
~ Only the position C'can be contacted, and the position A '
It is not possible to reproduce the recording signal in the range of to position B '. As a result, the upper and lower signal recordable range on the magnetic tape 1 is from the position of line BB 'to the position of line CC'. That is, from the position of the line AA 'to the position of the line BB' is a useless area where no signal is recorded.

In recent years, a desired number of frames of a video signal are subjected to data compression as one unit, so-called one group, and the compressed video signal is transmitted to a transmission line.
Techniques for recording on a recording medium have been developed. As the number of frames forming one group increases, the compression rate can be increased and the efficiency of transmission or recording can be increased if the data compression processing is performed with the same image quality as the conventional one. However, conversely, the time required for the compression process becomes long.

As described above, the longer the time required for the compression and expansion of the audio signal and the video signal, the larger the distance h between the advance head 4 and the recording head 3.
That is, since the mounting position of the advance head 4 on the drum 2 becomes higher, the area where no signal is recorded becomes wider.

Further, since the signal recordable range is further narrowed, in order to record an audio signal and a video signal having the same data amount as in the conventional case with a fixed tape length,
The recording wavelength must be shortened.

In view of the above situation, the present invention provides a signal recording / reproducing method capable of extending the signal recording area for recording the audio signal and the video signal and increasing the recording wavelength. .

[0011]

A signal recording / reproducing method according to the present invention reads a recorded audio signal by a first reproducing head preceding a recording head and reproduces it, and / or the above recording. After the second reproduction head preceding the head reads and reproduces a video signal corresponding to the audio signal, which is recorded on a track different from the track on which the audio signal is recorded, The recording head overwrites the read audio signal and / or video signal area with the reproduced audio signal and / or video signal.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the position of a track on a magnetic tape which is recorded / reproduced by using the signal recording / reproducing method according to the present invention.

The magnetic tape 1 whose front surface is the magnetic surface side runs in the direction of the arrow, and a drum (not shown) on which two reproducing heads, so-called advance heads and recording heads, are mounted is in the running direction of the magnetic tape 1. When rotating in the forward direction, the audio signal advance head, which is the first reproducing head preceding the recording head, reads the recorded audio signal and reproduces it, and /
Alternatively, the video signal advance head, which is the second reproducing head preceding the recording head, records a video signal corresponding to the audio signal on a track different from the track on which the audio signal is recorded. After reading the video signal that is being reproduced and reproducing the video signal,
Alternatively, the area where the video signal is read is overwritten with the audio signal and / or the video signal subjected to the reproduction processing.

Table 1 shows an example of specifications for recording and reproducing signals.

[0016]

[Table 1]

The magnetic tape 1 is a 1/2 inch tape, and the tape width W ₁ is 12.65 mm. The width W ₃ from the lower edge of the magnetic tape 1 to the predetermined position is 1.1 mm, and the control track CT for controlling scanning on the track and the elapsed time at the time of signal recording are provided between the widths W _3. The time code track TT shown is formed.

The diameter W _{10 of the} drum is 8
1.4 mm, wrap angle 196 °, lead angle θ 4.6
The recording head is 18 ° and the rotation speed is 75 Hz.
Two units are mounted facing each other at 0 °. Tracks with a track pitch of 32 μm are formed by recording signals with these recording heads.

The number of tracks required to record an audio signal and a video signal for one frame is 5 for NTSC signal at 525 lines / 30 frames and 6 for PAL signal.
There are 6 lines in 25 lines / 25 frames. The number of video syncs is 192 per track, the number of audio and other syncs is 98 per track, and the total number of syncs per track is 290.

Numerical values other than the track pitch so-called track pattern in Table 1 are the signal-to-noise ratio so-called S / N ratio of the head and the magnetic tape 1, the off-track characteristics of the device and the servo system, and the ease of signal processing and system design. It is determined by sex and so on.

The recording head is set so as to project into contact with the magnetic tape 1 with a constant width W ₇ from the lower edge of the magnetic tape 1. This width W ₇ is 0.65 mm
It is. Further, at the start and end of the signal recording operation of the recording head, there is a margin of 2 ° shown by widths W ₁₁ and W ₁₂ . A signal recording operation is performed by this recording head, whereby an audio sector AS, which is an area of the audio signal in the range from position A to position C, and position C to position B.
Video sector VS, which is the area of the video signal in the range up to
Tracks consisting of and are sequentially formed.

Next, the pre-read editing of audio signals and video signals will be specifically described.

During pre-read editing of the audio signal and the video signal, the audio signal of the audio signal and the video signal recorded by the recording head is read by the advance head for audio signal which is the first reproducing head. After the reproduction processing, the video signal is read and reproduced by the video signal advance head which is the second reproduction head.

Here, the time required to reproduce and output the audio signal and the video signal read by each advance head, so-called system delay, is the signal processing time for 11 frames for the video signal. Is the signal processing time for two frames. In this way, since the audio signal and the video signal have different system delays, the corresponding audio signal and the video signal at the same time are not recorded in one track but are separated by a predetermined time. Are recorded in each.

Since the audio signal does not require a system delay as much as the video signal, the audio signal is recorded from a position where the recording head first comes into contact with the tape-shaped recording medium to a predetermined position, and the video signal is recorded. Recording is performed from a position continuous with the audio signal to a position where the recording head finally contacts the tape-shaped recording medium. That is, the audio sector AS is arranged on the entrance side of the track, and the video sector VS is arranged on the exit side of the track.

The audio signal advance head is provided on a drum (not shown) so that the track on which the reproduction operation is performed by the audio signal advance head and the track on which the signal recording operation is performed by the recording head are separated by a distance W _13. It is arranged.

This distance W ₁₃ is 0.032 × 6 × 2 = 0.384 mm. That is, the advanced head for audio signals is
It is mounted at a position higher than the recording head by 0.384 mm. This audio signal advance head reads the audio signal of the audio sector AS and performs reproduction processing. For example, position A of the track TR ₁
When the audio signal up to the position C is read and the reproduction process is performed, when the audio signal advance head is located on the track TR ₂ , the recording head is located on the track TR ₁ . As a result, after the reproduction processing of the audio signal of the track TR ₁ read by the audio signal advance head, the recording head
The same track TR ₁ can be overwritten.

The advanced head for video signals is
A track, on which the reproducing operation is performed by the video signal advance head, and a track, on which the signal recording operation is performed by the recording head, are arranged on a drum (not shown) so as to be separated by a distance W ₁₄ .

This distance W ₁₄ is 0.032 × 6 × 11 = 2.112 mm. That is, the video signal advance head is mounted at a position higher by 2.112 mm than the recording head. With this video signal advance head, the video signal of the video sector VS is read out and reproduced. For example, when the video signal from position C to position B of the track TR ₁ is read out and reproduced,
When the video signal advance head is located on the track TR ₃ , the recording head is located on the track TR ₁ . Thus, the video signal of the track TR ₁ read by the video signal advance head can be overwritten on the same track TR ₁ by the recording head after the reproduction processing.

Next, specific values of the recording start positions of the audio signal and the video signal will be described.

The start position of the audio sector AS shown on the line AA "-A 'in FIG. 1 is (0.384 / tan4.607 ° + 81.4π × (2 ° / 360 °)) sin4.
607 ° + 0.65 = 1.147, and the value of the distance W ₄ is 1.147 mm.

Audio sector A in one track
Since the ratio of S is 98 sync / 290 sync, the video sector VS shown on the line C-C "-C 'is shown.
The starting position of is from the bottom edge of the magnetic tape 1, {(81.4π × ((196-2) ° / 360 °) × sin4.607 ° ＋ 0.
65) −1.147} × (98/290) + 1.147 = 4.720, and the value of the distance W ₅ is 4.720 mm.

On the other hand, in the conventional signal recording / reproducing method, the start position of the audio sector AS shown on the line AA 'in FIG. 2 is (2.112 / tan4.607 °) from the lower edge of the magnetic tape 1. + 81.4π × (2 ° / 360 °)) sin4.
607 ° + 0.65 = 2.869, and the value of the distance W ₆ is 2.869 mm.

Here, the end of the track shown on the line BB "-B 'in FIG. 1 or the line BB' in FIG. 2 from the lower edge of the magnetic tape 1 in FIGS. 1 and 2. The distance W ₂ to the position is 11.719 mm, so that the effective width of signal recording, which is the range in which tracks TR ₁₁ and TR ₁₂ are formed by the conventional signal recording / reproducing method, is W ₂ −W ₆ = 11.719−2.869 = 8.85 mm, whereas the effective width of signal recording, which is the range in which the tracks TR ₁ , TR ₂ and TR ₃ are formed by the signal recording / reproducing method according to the present invention, is W ₂ -W ₄ = 11.719-1.147 = 10.572m
m.

That is, 10.572 / 8.85 = 1.20, and in the signal recording / reproducing method according to the present invention, the effective width of signal recording on the magnetic tape 1 can be expanded by about 20%. As a result, the shortest recording wavelength for signal recording can be increased by about 20%.

The above-described embodiment shows the case where the rotating direction of the drum is the forward direction with respect to the running direction of the magnetic tape, and the audio signal is input to the entrance side of the track where the recording head starts the signal recording operation. The signal is recorded,
When the drum rotation direction is opposite to the running direction of the magnetic tape, an audio signal is recorded on the exit side of the track where the recording head finishes the signal recording operation. The effective width of recording can be expanded to the same width as the above-described embodiment.

[0037]

As is apparent from the above description, the signal recording / reproducing method according to the present invention is the first method that precedes the recording head.
The playback head reads the recorded audio signal and performs playback processing, and / or a second playback head preceding the recording head, which is a video signal corresponding to the audio signal, After reading and reproducing the video signal recorded on a track different from the track on which is recorded, the recording head reproduces the audio signal and / or the reproduced audio signal in the read audio signal and / or video signal area. Since the effective width of signal recording on the tape-shaped recording medium can be widened by overwriting the video signal, the number of channels of the audio signal can be increased,
Other data signals can be recorded, or the amount of data for error correction can be increased to enhance the error correction processing.

Since the recording wavelength can be extended, an inexpensive head or tape-shaped recording medium can be used, and the head can have a sufficient depth to prolong the life of the head. .

[Brief description of the drawings]

FIG. 1 is a diagram showing track positions recorded / reproduced using a signal recording / reproducing method according to the present invention.

FIG. 2 is a diagram showing track positions recorded / reproduced using a conventional signal recording / reproducing method.

FIG. 3 is a diagram showing a relationship between a magnetic tape and a head.

[Explanation of symbols]

 1 magnetic tape

Claims (3)

[Claims] 1. A signal recording / reproducing method for reading out and reproducing an audio signal and / or a video signal recorded on a tape-shaped recording medium, and then overwriting the read-out audio signal and / or video signal area. The first reproduction head preceding the recording head reads out the recorded audio signal and performs reproduction processing, and / or the second reproduction head preceding the recording head, corresponds to the video signal corresponding to the audio signal. In addition, after the video signal recorded on a track different from the track on which the audio signal is recorded is read and reproduced, the recording head causes the read audio signal and / or the video signal to be recorded in the area. Overwriting the audio signal and / or the video signal processed by the above reproduction processing Signal recording and reproducing method and butterflies. 2. The signal recording / reproducing method according to claim 1, wherein the first reproducing head, the second reproducing head, and the recording head obliquely scan the tape-shaped recording medium. . 3. When the recording head travels in the forward direction with respect to the traveling direction of the tape-shaped recording medium, the audio signal is output from a position where the recording head first contacts the tape-shaped recording medium. The signal according to claim 1, wherein the video signal is recorded up to a predetermined position, and the video signal is recorded from a position continuous with the audio signal to a position where the recording head finally contacts the tape-shaped recording medium. Recording and playback method.