JP3257243B2 - Digital video signal recording method and recording apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for recording a digital video signal, and more particularly to a so-called MP.
The present invention relates to a digital video signal recording method and the like capable of directly recording data obtained by encoding a video signal by an EG method and obtaining a reproduced image having excellent image quality during variable speed reproduction.

[0002]

2. Description of the Related Art After converting a video signal into a digital signal, a so-called discrete cosine transform (hereinafter, DCT: Discrete Cosin) is performed.
e Transform Transform. ) And data compression by variable-length coding such as so-called Huffman coding, and a digital video tape recorder (hereinafter simply referred to as digital) which records the obtained digital video signal on a magnetic tape by a tilt azimuth recording method, that is, a rotating head. VTR
That. ) Is under development. In such a digital VTR, a mode for recording a video signal of the current television system such as the NTSC system (hereinafter, referred to as an SD mode) and a video signal of a so-called high definition television system (hereinafter, HDTV: High Definition Television). (Hereinafter referred to as HD mode).

In the SD mode, a video signal is compressed and recorded into a digital video signal of about 25 Mbps, and in the HD mode, an HDTV signal is compressed and recorded into a digital video signal of about 50 Mbps.

In this conventional digital VTR, it is conceivable that an input digital video signal, that is, input data, is directly recorded on a magnetic tape, and data recorded on the magnetic tape is reproduced and directly output. . That is, by adding a function of directly recording / reproducing a digital video signal (data) to a conventional digital VTR, an input digital video signal is decoded once, for example, an HDTV signal is reproduced, and the HDTV signal is reproduced. There is no need to re-encode by a predetermined encoding method and record it on a magnetic tape, and there is an advantage that hardware is not wasted.

Specifically, for example, the so-called MPEG system, that is, JTC (Joint Technical Committe) of the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC).
e) SC (Sub Committee) WG (Working Gr)
oup) 11 when a digital video signal obtained by encoding a video signal is transmitted according to the video coding method standardized in 11 or when a digital video signal reproduced from an optical disc is supplied. It is very convenient to have a function of directly recording / reproducing the digital video signal.

Here, the above-described MPEG is used as the encoding method.
The so-called ATV (Adva)
nced Television) will be described. FIG.
It is a block diagram which shows the structure of the transmission system of TV system. FIG.
In 5, 101 is a video compression encoder, and 102 is an audio encoder. Video compression encoder 1
01 is supplied with a video signal of the HDTV system from the input terminal 103. An audio signal is supplied from an input terminal 104 to the audio encoder 102.

The video compression encoder 101 is an MPEG
According to the method, the input HDTV signal is encoded to perform data compression. That is, the video compression encoder 10
1 encodes and compresses the HDTV signal by using a high-efficiency encoding method combining DCT and motion compensation prediction encoding. As shown in FIG. 26, the video compression encoder 101 outputs data of an intra-coded picture (referred to as an I-picture) and a forward-predicted coded picture (P The data of a picture (referred to as a picture) and the data of a picture (referred to as a B picture) subjected to bidirectional prediction encoding are output in a predetermined order. In an I picture, DCT transform is performed independently without using a correlation with another picture. In P-pictures, motion-compensated prediction coding from an earlier I-picture or P-picture is performed, and the difference signal (so-called prediction error) is subjected to DCT. In a B picture, motion-compensated predictive coding is performed from the preceding or succeeding I picture or P picture, and the difference signal is DCT-transformed.
The period at which the I picture appears is a GOP (Group Of Picture)
is called. In this example, (M = 3, N = 9).

Reference numeral 106 denotes a transport encoder. The transport encoder 106 generates a packet from video data encoded by the video compression encoder 101, audio data encoded by the audio encoder 104, and additional information from the input terminal 107. .

FIG. 27 shows the structure of a packet.
As shown in FIG. 27, the packet length of the transmitted packet is 188 bytes. At the beginning of this packet, a ring header having a fixed length of 4 bytes and an adaptation header having a variable length are provided, followed by transmission data consisting of video data or audio data.

In FIG. 25, reference numeral 108 denotes a channel modulator. The packet generated by the transport encoder 106 is supplied to a channel modulator 108. The channel modulator 108 modulates this packet using a carrier having a predetermined frequency. The output of the channel modulator 108 is output terminal 1
09 is output.

In the ATV system, an HDTV signal can be transmitted at, for example, about 19 Mbps by the above-described image compression. This is the same as the S
It is lower than the recording rate in D mode (about 25 Mbps). Therefore, a signal (data) sent by the ATV system can be directly recorded in the SD mode of the digital VTR. As described above, when the transmitted signal is directly recorded on the digital VTR, it is not necessary to decode the HDTV signal from the transmitted signal as described above and input the HDTV signal to the digital VTR, thereby eliminating waste of hardware. . Also, since it can be recorded in SD mode,
Long recording time.

However, when an ATV signal is directly recorded on a digital VTR in the SD mode, a problem arises in that good variable-speed reproduction cannot be performed for the following reasons.

That is, as described above, in the ATV system, compression (encoding) in accordance with the MPEG system is performed. In this method, as described above, intra-picture coded I picture data, forward predicted coded P picture data, and bidirectional predicted coded B picture data are sent. At the time of variable speed reproduction, since the head crosses tracks on the magnetic tape, data of continuous pictures cannot be obtained. If continuous picture data is not obtained, P picture and B picture data cannot be decoded. Only I-picture data encoded in a picture can be decoded. Therefore, at the time of variable speed reproduction, variable speed reproduction is possible by using only the data of the I picture among the data to be reproduced.

However, if a signal transmitted by the ATV system is directly recorded on a digital VTR, a packet including an I picture cannot be sufficiently picked up during variable speed reproduction. In addition, it is uncertain in what positional relationship the data of the I picture is recorded. For this reason, at the time of variable speed reproduction, data of the I picture corresponding to a specific portion of the screen is lost, and only the screen of that portion is lost. In some cases, updating cannot be performed for a while, and the image quality during variable speed playback deteriorates.

In view of this, the applicant of the present application first sets an area that can be reproduced at the time of variable-speed reproduction (hereinafter, referred to as an area) as an area for variable-speed reproduction. It has been proposed to extract data, record the data as variable speed reproduction data in an area for variable speed reproduction, and record the ATV signal as it is in other areas of the video sector. In this case, at the time of variable-speed reproduction, an area for variable-speed reproduction is reproduced, and a screen is formed from I-picture data reproduced from this area.

[0016]

However, the area that can be reproduced during variable-speed reproduction varies depending on the variable-speed reproduction speed. For this reason, it is difficult to set a plurality of variable playback speeds. For example, when data for variable-speed reproduction is recorded in a common area among the areas that can be reproduced at 17-times speed, 9-times speed, and 4-times speed, at three speeds of 4 times speed, 9 times speed, and 17 times speed. Variable speed reproduction is possible, but it is difficult to perform variable speed reproduction at other speeds.

Further, as a drum configuration of a digital VTR, for example, two heads having different azimuths are used as one drum.
There are various types of drums, such as a configuration in which a rotary drum is disposed facing 80 degrees (a 180-degree facing head) and a configuration in which two heads having different azimuths are arranged in the same phase on a rotary drum (double azimuth head). If the configuration is different, the position on the track traced by the head at the time of variable speed reproduction is shifted, and there is a problem that the compatibility of the magnetic tape cannot be obtained between digital VTRs having different drum configurations.

The present invention has been made in view of such circumstances. For example, when an ATV signal is directly recorded on a recording medium, variable-speed reproduction can be easily performed at a plurality of variable-speed reproduction speeds. It is another object of the present invention to provide a digital video signal recording method and a recording apparatus capable of ensuring compatibility of a recording medium between apparatuses having different drum configurations.

[0019]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a digital video signal recording method for recording a digital video signal on a magnetic tape by a tilted azimuth recording system using a plurality of heads having different azimuths. In the recording method, a first area and a second area are provided in each track on a magnetic tape, and data obtained by encoding a video signal by adaptively switching between intra-picture encoding and inter-picture prediction encoding is input. When the input data is recorded in the first area, and the data obtained by intra-coding of the input data is recorded in the second area as data for variable speed reproduction, the data on each track By changing the distance from the recording start position to the second area between adjacent tracks having different azimuths, a plurality of
° In either the case of the opposed head or the case of the double azimuth head, the data for variable speed reproduction is recorded so as to have a sufficient margin from both ends of the head trace area.

Further, the present invention relates to a digital video signal recording apparatus for recording a digital video signal on a magnetic tape by a tilted azimuth recording system using a plurality of heads having different azimuths from each other. Data obtained by encoding a video signal by adaptively switching the encoding, input data, extract data obtained by intra-coding from the input data, and use the data for variable speed reproduction as variable speed reproduction data extraction means; The input data and the variable-speed reproduction are recorded such that the input data is recorded in a first area of each track on the magnetic tape, and the variable-speed reproduction data from the variable-speed reproduction data extracting means is recorded in a second area. Multiplexing means for time-division multiplexing the data for recording, and the distance from the recording start position on each track to the second area is different from the azimuth Different with between tracks,
And control means for controlling the multiplexing means so as to have a sufficient margin from both ends of the head trace area regardless of whether the plurality of heads at the time of reproduction are 180 ° facing heads or double azimuth heads. I do.

In the digital video signal recording apparatus according to the present invention, the plurality of heads are two magnetic heads disposed to face the rotary drum by 180 degrees, and the two magnetic heads are alternately provided with the input signal. The data and the data for variable speed reproduction are recorded on adjacent tracks.

In the digital video signal recording apparatus according to the present invention, the plurality of heads are two magnetic heads arranged in the same phase on a rotating drum, and the two magnetic heads simultaneously receive the input data and the variable speed reproduction. Is recorded on adjacent tracks.

In the digital video signal recording apparatus according to the present invention, the first and second magnetic heads of the A channel in which the plurality of heads are arranged 180 degrees opposite to the rotary drum, and the first and second magnetic heads of the A channel are provided. B-channel first and second magnetic heads disposed in phase with the first and second magnetic heads, respectively, wherein the first magnetic head and the second magnetic head are alternately arranged, and The first magnetic head and the second magnetic head of each channel simultaneously record the input data and the data for variable speed reproduction on adjacent tracks.

[0024]

[0025]

According to the present invention, when a digital video signal is recorded on a magnetic tape by a tilted azimuth recording method using a plurality of heads having different azimuths, a first area and a second area are formed on each track on the magnetic tape. Provide.
Then, data obtained by encoding the video signal by adaptively switching between intra-picture encoding and inter-picture prediction encoding is input, and the input data is recorded in the first area, and the image of the input data is recorded. When recording data obtained by inner encoding as data for variable speed reproduction in the second area, the distance from the recording start position on each track to the second area is set between adjacent tracks having different azimuths. In a different manner, the data for variable speed reproduction is recorded so as to have a sufficient margin from both ends of the head trace area regardless of whether the plurality of heads at the time of reproduction are 180 ° facing heads or double azimuth heads. In the magnetic tape recorded in this manner, the data for variable-speed reproduction can be obtained regardless of whether the second area is reproduced at variable speed with a digital VTR of, for example, a 180-degree facing head or at the time of variable speed reproduction with a digital VTR of a double azimuth head. Can be played with a margin.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a method and apparatus for recording a digital video signal according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a video recording / reproducing system using a digital VTR to which the present invention is applied. In FIG. 1, reference numeral 1 denotes a channel demodulator. An ATV signal, that is, modulated transmission data, is input to the channel demodulator 1 from an input terminal 2. The channel demodulator 1 demodulates modulated transmission data and reproduces packetized transmission data.

3 is a digital VTR to which the present invention is applied.
It is. Digital VTR of this tilt azimuth recording system
3 is an interface and format converter 4,
A recording / reproducing unit 5; The data of the packet from the channel demodulator 1 is supplied to the transport decoder 6 via the interface and the format converter 4 and also to the recording / reproducing unit 5.
The data transferred to the recording / reproducing unit 5 via the interface and format conversion unit 4 is recorded on the magnetic tape by the recording / reproducing unit 5 by a rotating head. Further, the interface and format converter 4 formats the data to be sent to the recording / reproducing unit 5 so that when the recording data recorded by the recording / reproducing unit 5 is reproduced at a variable speed, the reproduction screen becomes good. This will be described in detail later.

The recording / reproducing unit 5 converts the video signal into a DC signal.
The data is subjected to T conversion, variable-length coding, compression, and recording on a magnetic tape by a rotating head. That is, the recording / reproducing unit 5 can set an SD mode for recording a video signal of the NTSC system or the like and an HD mode for recording an HDTV signal. As described above, the recording / reproducing unit 5 is set to the SD mode when directly recording the ATV signal supplied via the interface and the format converting unit 4, that is, the transmission data.

The transport decoder 6 corrects the data of the packet supplied via the interface and format converter 4, and extracts the data and additional information from the packet.

Reference numeral 7 denotes a video expansion decoder, and reference numeral 8 denotes an audio decoder. The video expansion decoder 7 decodes the Huffman code and performs inverse DCT conversion in accordance with the MPEG system, expands the transmitted data, and forms a baseband signal of the HDTV system. The output of the transport decoder 6 is supplied to the video expansion decoder 7 and the audio decoder 8. Video expansion decoder 7
Then, the transmitted data is expanded and converted into an analog signal to form an HDTV signal. The HDTV signal thus formed is output from the output terminal 9. The audio data is decoded by the audio decoder 8, and the obtained audio signal is output from the output terminal 10. Further, the additional information output from the transport decoder 6 is output from the output terminal 11.

FIG. 2 shows a digital VT to which the present invention is applied.
FIG. 4 is a block diagram illustrating a configuration of a recording system of R3. This figure 2
In the figure, 21 is an input terminal for a video signal or HDTV signal of the current television system such as the NTSC system. When recording an external video signal, a video signal of the current television system or H
A component video signal of a DTV signal is supplied.
The component video signal from the input terminal 21 is A / D
The component video signal is supplied to a converter 22 and is converted into a digital signal by the A / D converter 22.

Reference numeral 23 denotes a DCT compression circuit. The DCT compression circuit 23 encodes and compresses the input video signal by DCT transform and variable length coding. That is, the component video signal converted into a digital signal from the A / D converter 22 is supplied to the DCT compression circuit 23,
In the DCT compression circuit 23, the data is divided into blocks, shuffled, and subjected to DCT. Data (DCT coefficients) obtained by DCT conversion is buffered in a predetermined buffer unit. Then, the total code amount in the predetermined buffer unit is estimated, an optimal quantization table is determined so that the total code amount is equal to or less than a predetermined value, and quantization is performed using the optimal quantization table. Then, after being subjected to the variable length coding, it is framed.

A switch circuit 24 switches between recording the transmitted ATV signal and recording the video signal from the input terminal 21. An ATV signal is supplied to the terminal 24A of the switch circuit 24 via the interface and the format converter 4 described above. The output of the DCT compression circuit 23 is supplied to a terminal 24B of the switch circuit 24. When recording the transmitted ATV signal, the switch circuit 24 is set to the terminal 24A side. When recording a video signal from the input terminal 21, the switch circuit 24
Is set on the terminal 24B side.

Reference numeral 25 denotes a framing circuit. The framing circuit 25 frames the recording data supplied via the switch circuit 24 into predetermined sync blocks, and performs an error correction encoding process.

Reference numeral 26 denotes a channel encoder. The output of the framing circuit 25 is supplied to a channel encoder 26 and modulated. The output of the channel encoder 26 is supplied to a rotary head 28 via a recording amplifier 27. Thus, the compressed video signal from the input terminal 21, the HDTV signal, or the ATV signal from the input terminal 2 is recorded on the magnetic tape (not shown) by the rotary head 28.

That is, in such a recording system, when recording a transmitted ATV signal, the switch circuit 24 is switched to the terminal 24A side. As a result, the signal of the ATV system input via the interface and the format converter 4 is
5, modulated by a channel encoder 26, and recorded on a magnetic tape by a rotating head 28.

On the other hand, when recording a video signal from the input terminal 21, the switch circuit 24 is switched to the terminal 24B. As a result, the video signal from the input terminal 21 is encoded and compressed by the DCT compression circuit 23, framed by the framing circuit 25, modulated by the channel encoder 26, and recorded on the magnetic tape by the rotary head 28. .

When recording an ATV signal, the interface and format conversion unit 4, as will be described later, reproduces an area (hereinafter referred to as an area) during variable-speed reproduction in order to improve image quality during variable-speed reproduction. ) Is a trick play area, and the trick play area
Data is arranged so that picture data is recorded. At the time of variable speed playback, I
The picture data is read, and the I picture data is decoded.

FIG. 3 is a block diagram showing a configuration of a reproduction system of the digital VTR 3. As shown in FIG. In FIG. 3, the recording signal of the magnetic tape is reproduced by the rotary head 28 and supplied to the channel decoder 52 via the reproduction amplifier 51. The channel decoder 52 demodulates a reproduction signal by a demodulation method corresponding to the modulation method of the channel encoder 26 of the recording system described above.

Reference numeral 53 denotes a so-called TBC (Time Base Corrector).
It is. The TBC 53 removes time axis fluctuation of the reproduction signal. That is, the write clock based on the reproduction signal and the read clock based on the reference signal are supplied to the TBC 53, and the output of the channel decoder 52 is supplied. Then, the TBC 53 removes a time axis fluctuation component in the reproduction signal.

Reference numeral 54 denotes a deframing circuit. The deframing circuit 54 corresponds to the framing circuit 25 of the recording system, and performs an error correction process and the like of the reproduced data from the TBC 53.

Reference numeral 55 denotes a switch circuit. The switch circuit 55 is switched between a case of reproducing an ATV signal and a case of reproducing a component video signal. The output of the deframe circuit 54 is supplied to a switch circuit 55. If the playback signal is an ATV signal,
The switch circuit 55 is switched to the terminal 55A side. When the reproduction signal is a component video signal, the switch circuit 55 is switched to the terminal 55B side.

Reference numeral 56 denotes a DCT decompression circuit. The DCT decompression circuit 56 corresponds to the DCT compression circuit 23 of the recording system. That is, the DCT decompression circuit 56 decompresses the variable-length code that is the reproduction data and performs inverse DCT transform to decompress the compressed and recorded component video signal into the original baseband video signal. That is, the output of the terminal 55B of the switch circuit 55 is supplied to the DCT expansion circuit 56, and the DCT expansion circuit 56
The reproduction data is returned to the baseband video signal, and this video signal is output from the output terminal 57.

Reference numeral 59 denotes a packet selection circuit. The output of the terminal 55A of the switch circuit 55 is supplied to the packet selection circuit 59. Then, at the time of normal reproduction of the ATV signal, the packet selection circuit 59 selects all the packets of the reproduction data supplied via the switch circuit 55. On the other hand, at the time of variable-speed reproduction, only I-picture data is valid. At the time of variable-speed reproduction, the packet selection circuit 59 selects and outputs I-picture data packets obtained by reproducing the trick play area. The output of the packet selection circuit 59 is output from the output terminal 60.

Reference numeral 61 denotes a controller. The controller 61 performs control for switching between normal reproduction and variable-speed reproduction. The controller 61 is supplied with a mode setting signal from the input unit 62. According to this mode setting signal,
It controls the servo circuit 63 and the packet selection circuit 59.
Then, at the time of variable speed reproduction of the ATV signal, the servo circuit 63 uses the tracking signal such as ATF to add phase information to the tape speed control, and the positional relationship between the head trace and the track is always kept the same. The phase is fixed so that the head traces the trick play area in the track. That is, during variable speed playback,
The trick play area is reproduced, and the data of the I picture recorded in the trick play area is reproduced.

The output from the output terminal 60 is sent to the video expansion decoder 7 shown in FIG. 1 and decoded.
As will be described later, in this embodiment, the I picture 1
All data for the screen is recorded in the trick play area. Therefore, at the time of variable-speed reproduction, the actual screen is also updated collectively for one screen, and a variable-speed reproduction image that is easy to see can be obtained.

Here, the digital VT to which the present invention is applied
The variable speed reproduction in R will be described in detail.

FIG. 4 is a block diagram of the digital VTR.
It is a figure showing composition of a track. One track includes an audio sector SEC1, a video sector SEC2, and a subcode sector SEC3. As shown in FIG. 5, a video data capacity of 135 sync blocks is prepared in the video sector SEC2. At the beginning of each sync block, a 5-byte sync and ID are added. Spare data (VAUX) equivalent to three sync blocks is added to these video data. Then, double error correction codes (C1, C2) are added using the product code.

As described above, one track of the video sector S
EC2 can record 135 sync blocks of video data. In the SD mode, the number of rotations of the drum is 150 Hz, two heads having different azimuths are arranged on the rotating drum, and data is recorded in azimuth on ten tracks per frame. Then, as shown in FIG. 6, when recording an ATV signal (hereinafter, referred to as an ATV signal), if 75 bytes of 77 bytes of data area in one sync block are used for data recording, 75 × 8 × 135 × 10 × 30 ≒ 24 Mbps is a data rate that can be used for recording.

On the other hand, the data rate of the ATV signal is 19M
bps. Therefore, the transmitted ATV
When a signal is recorded in the SD mode, there is a margin in a recording area. Therefore, in order to improve the image quality during variable speed reproduction, S
When recording an ATV signal in the D mode, data necessary for variable speed reproduction, that is, I picture data, is recorded in duplicate. In this embodiment, the I-picture data to be recorded in the extra recording area is, for example, all the data for one picture (low-frequency coefficient data of the I-picture). Thereby, at the time of variable-speed reproduction, it can be updated in units of one screen.

FIG. 7 is a conceptual diagram when recording and reproducing an ATV signal. A main area A1 and a trick play area A2 are provided on a video sector of the magnetic tape 31. The trick play area A2 corresponds to the above-mentioned marginal recording area, and this area is provided in an area that can be reproduced during variable-speed reproduction. At the time of recording, the input ATV signal bit stream (or data stream) is recorded in the main area A1 as it is,
It is supplied to the decode circuit 34. VLD decode circuit 3
Reference numeral 4 decodes the ATV signal to detect a break in DCT coefficients that have been subjected to variable length coding. The output of the VLD decode circuit 34 is supplied to a counter 35. Counter 3
Reference numeral 5 counts the number of DCT coefficients to detect a data portion necessary for variable speed reproduction. The output of the counter 35 is supplied to the data separation circuit 36. The data separation circuit 36 extracts a data portion necessary for variable speed reproduction from the input bit stream based on the output of the counter 35.

Here, the data necessary for variable speed reproduction is A
Only the low frequency coefficients of each block of the I picture of the TV signal are included. The I-picture data required for this variable-speed reproduction is E
It is supplied to the OB addition circuit 37. The EOB adding circuit 37 adds an EOB indicating the end of the block. The data of the I frame necessary for the variable speed reproduction, that is, the low frequency coefficient of each block of the I picture is recorded in the trick play area A2.

At the time of normal reproduction, the main area A
1 is decoded. During variable speed playback,
Only the trick play area A2 is reproduced and decoded. Therefore, at the time of variable speed reproduction, only the low frequency coefficient of each block of the I picture is sent to the video expansion decoder 7. In order for this to be able to be decoded by a normal video decompression decoder, the transmitted data structure must be the same as a normal bit stream. Therefore,
After the low-frequency component is extracted from each block during recording, an EOB indicating the end of the block is added.

Next, a method of determining a trick play area for recording data for variable speed reproduction will be described.

First, the recording rate of the digital VTR is set to 24.948 Mbps and the AT
Assuming that the data rate of the V signal is 19.2 Mbps, 135 × (19.2 / 24.948) = 104 sync blocks of the video sector of each track are used as a main area for recording data for normal reproduction. 135-104 = 31 sync blocks can be used as trick play areas for recording data for variable speed reproduction.

FIG. 8 shows a variable speed reproduction (for example, 17 × speed).
FIG. 5 is a diagram showing a trajectory of an A head of two heads having different azimuths (hereinafter, referred to as A and B heads). As shown in FIG. 8, when the A head traces, the area indicated by TP becomes a reproducible area.
This reproducible area (hereinafter referred to as a reproducible area TP) is used as a trick play area for recording data for variable speed reproduction. In a VTR of helical scan and azimuth recording, data reproduced from the reproducible area TP has a burst shape as shown in FIG. If the position on the track of the reproducible area TP is fixed by ATF or the like and data for variable speed reproduction is recorded in the reproducible area TP, the data is always reproduced.

In this embodiment, the trick play area is determined as follows. If the maximum speed of the magnetic tape at the time of variable speed reproduction is selected to be an odd multiple speed of normal reproduction, that is, (2N + 1) times speed (N is an integer), an area which can be reproduced when reproduced at this maximum speed is a trick play area (hereinafter, referred to as a trick play area). Trick play area TP). For example, in FIG. 8 described above, the maximum speed at the time of variable speed reproduction is set to 17 times speed which is an odd multiple speed of normal reproduction. An area that can be reproduced when reproduced at 17-times speed is selected as a trick play area TP.
Then, data for variable speed reproduction (hereinafter, referred to as trick play data) is recorded in the trick play area TP. At this time, the recording of the same trick play data is repeated on the same azimuth track by the same number of tracks as the multiple of the maximum speed at the time of variable speed reproduction. For example,
If the maximum speed at the time of variable speed reproduction is 5 × speed, the double speed number is 5, so that trick play data is repeatedly recorded over five tracks T1 to T5 of A azimuth as shown in FIGS. 10A and 10B. Here, in these figures, those having the same number assigned to the trick play area are:
It represents the same trick play data.

When the trick play area is set in this way, at the time of reproduction, the maximum speed at the time of variable-speed reproduction and 1.
5x speed, 2.5x speed, 3.5x speed, ..., (N +
0.5) Double speed variable speed reproduction is possible.

In other words, the tape speed during variable speed reproduction is
1.5x speed, 2.5x speed, 3.5x speed, ...
When the speed is set to (N + 0.5) times, as shown in FIGS. 11 and 12, all portions of the track having the same azimuth can be reproduced by two scans. That is, FIG. 11 is a diagram showing the trajectory of the A head when the maximum variable speed reproduction speed is 7 times speed and the variable speed reproduction is performed at 3.5 times speed. in this case,
As shown in FIG. 12A, both ends of the track of A azimuth are reproduced in the first scan, and as shown in FIG. 12B, the middle part of the track of A azimuth is reproduced in the second scan. In these two scans, A
All parts of one track of the azimuth track are reproduced. If the same trick play data is repeatedly recorded on each track of A azimuth, all the data of one track of A azimuth can be reproduced by these two scans.

Therefore, the maximum speed at the time of variable speed reproduction is (2
When the trick play data is repeatedly recorded on the (2N + 1) track of the A azimuth when the speed is (N + 1) times, the speed is (2N + 1) times, 1.5 times, 2.5 times,
.., (N + 0.5) times speed guarantees reproduction of trick play data, and variable speed reproduction at these speeds is possible. In the reverse direction, the (2N-1) times speed becomes the maximum.

As described above, the maximum speed at the time of variable speed reproduction is set to (2
N + 1) double speed, the area traced by the head at this maximum speed is selected as a trick play area, and the same trick play data is repeatedly recorded on the same azimuth track by the same number of tracks as the double speed of the maximum speed. In addition to the maximum variable speed reproduction speed, variable speed reproduction at 1.5 times speed, 2.5 times speed,..., (N + 0.5) times speed is possible.

By the way, in a digital VTR, FIG.
There are three types of head arrangements as shown in FIGS. FIG. 13 shows that the azimuths are different from each other, that is, A
Azimuth head HA1 and B azimuth head HB1
Are disposed on the rotating drum 180 degrees opposite to each other, and 9000
Rotated at rpm is shown. In FIG.
A azimuth head HA2 and B azimuth head HB
2 are arranged in the same phase on the rotating drum, that is, a pair of heads HA2 and HB2 in a double azimuth head configuration are arranged on the rotating drum and rotated at 9000 rpm. FIG. 15 shows two pairs of heads having a double azimuth head configuration (a double azimuth head composed of an A azimuth head HA3 and a B azimuth head HB3, and an A azimuth head HA4 and a B azimuth head H).
B4 (double azimuth head made of B4) is arranged on the rotating drum 180 ° opposite to each other and rotated at 4500 rpm.

In order to cope with these three types of drum configurations, trick play data is recorded on a tape by a method as shown in FIGS.

That is, for example, if the maximum speed reproduction speed is 5
Assuming double speed, first, trick play data for one track is divided into five tracks T11 to T15 of A azimuth.
Record repeatedly. Then, the next one track of trick play data is transferred to the corresponding B azimuth 5
Recording is repeatedly performed on the two tracks T21 to T25.

By doing so, the above-described FIG.
In the case of the 180-degree opposing head shown in FIG. 16, trick play data for the first one track of the head HA1 of A azimuth is replaced with the head HB of next B azimuth as shown in FIG.
In step 1, trick play data for the next one track is reproduced. In the case of the double azimuth head shown in FIG. 14 described above, as shown in FIG.
By performing one scan simultaneously with the A2 and B azimuth heads HB2, two tracks of trick play data are reproduced at a time.

FIG. 18 shows the possible tape speeds for each drum configuration. In FIG. 18, in the case of a 2-pair double azimuth head (4500 rpm), the scan angle of the head is doubled at the same tape speed, and as a result, the maximum tape speed at the time of variable speed reproduction is half that of the other cases. .

By the way, when the trace of the head was examined in detail, it was found that in order to completely support a plurality of types of drum configurations, that is, in order to ensure the compatibility of the magnetic tape between digital VTRs having different drum configurations. ,
It has been found that the distance between the gaps of the double azimuth head must be considered.

That is, if the data rate of the ATV signal is 19.2 Mbps as described above, the area that can be used as a trick play area is 31 sync blocks per track. For example, the track width TW is 12 μm (TP = 10 μm) and the maximum speed during variable speed playback is 17 ×, each burst-shaped area traced by the head has a length equivalent to 12 to 13 sync blocks, and ideally all these areas are tricked. Although it can be used as a play area, in consideration of drum jitter, head linearity, tape tension variation, etc., the length of one trick play area is set to 4 sync blocks, and this trick play area is set to 6 sync blocks.
Places. Therefore, the trick play area per track is 24 (= 4 × 6) sync blocks.

FIG. 19 is a diagram showing the head trace in each drum configuration in detail. FIG. 19A shows the case of a 180-degree facing head. In this case, for example, an area RA1 consisting of 12 sync blocks is traced by the head HA1 of A azimuth, and an area RB1 of 12 sync blocks is traced by the head HB1 of B azimuth. In contrast, in the case of a double azimuth head, FIG.
As shown in FIG. 9B, the head HA2 of A azimuth
The area RA2 of 2 sync blocks is traced, and the area RB2 of 12 sync blocks is traced by the head HB2 of B azimuth.

In the case of a 180-degree opposing head, as shown in FIG. 19A, trick play areas TPA and TPB each composed of four sync blocks are divided into areas RA.
1, if provided at the center of RB1, a margin of 4 sync blocks can be provided at both ends.

On the other hand, in the case of a double azimuth head, FIG.
As shown in FIG. 9B, a shift of 5 sync blocks corresponding to the gap distance GL occurs between the area RA2 traced by the head HA2 and the area RB2 traced by the head HB2. Accordingly, in order to cope with both the 180-degree opposing head and the double azimuth head, the trick play area TPB includes an area RB1 traced by the head HA1 indicated by a thick line in FIG. 19B and a head HB2.
Must be provided in a common part of the area RB2 to be traced. That is, as shown in FIG. 19C, the trick play area TPA needs to be provided from seven sync blocks from the left end of the area RA1 (or RA2), and the trick play area TPB needs to be provided from two sync blocks from the left end of the area RB2.

As described above, the trick play area TPA,
By selecting TPB, trick play data can be reproduced at the time of variable-speed reproduction regardless of whether the head is a double azimuth head or a 180 ° facing head. The head HB2 is a sync block, and the left margin is two sync blocks with respect to the head HB2.

Therefore, for example, as shown in FIG. 20A, a trick play area TPA and a trick play area TP
B is provided shifted from the recording start position on the track by two sync blocks. In the case of the 180-degree opposing head, as shown in FIG. 20B, when tracking is performed so that the trick play area TPA and the trick play area TPB are at the center, the left margin with respect to the head HA1 becomes 3 sync blocks, The right margin for HB1 is 3 sync blocks, and a sufficient margin can be secured at both ends.

On the other hand, in the case of the double azimuth head, FIG.
As shown in 0C, when tracking is performed so that the left margin for the head HA2 is 6 sync blocks, the right margin for the head HA2 can be 2 sync blocks, and the left margin for the head HB2 is 3 sync blocks. It can be a block. That is, the margin can be increased as compared with the case shown in FIG.

FIG. 21 is a diagram showing the usable tape speed at this time. In the case of the double azimuth head configuration, the gap distance GL is limited to 5 sync blocks at the maximum variable speed reproduction speed, but does not depend on the other speeds. By the way, in the above description, the inter-gap distance GL is assumed to be 5 sync blocks. However, if the inter-gap distance GL is made smaller, the margin can be made larger.

By the way, a trick play area for, for example, a maximum of 31 sync blocks that can be secured is provided in each track, and the same trick play data is repeatedly recorded on each track by 17 tracks. , 31 × 75 × 8 × 10 × 30
/ 17 = 328 Kbps. On the other hand, the data rate of the I picture is the data rate of the entire bit stream,
Although it depends on the GOP structure, input picture, etc., N = 9, M =
Taking the GOP structure of FIG. 3 (see FIG. 26) as an example, from the average data amount: I / P = 2, P / B = 2.5, 17.4 × 5 / (1 × 6 + 2.5 × 2 + 5) = 5.4M
bps (assuming video data: 17.4 Mbps), which is the average I-picture data rate.

Therefore, if it is attempted to record all the data of I-pictures in an overlapping manner, that is, for example, repeatedly on 17 tracks, the time required for recording becomes long. For example, most of the I-pictures inputted every 9 pictures are recorded. become unable. Therefore, in order to reduce the data rate of the I picture to be recorded redundantly, only the low frequency coefficient is extracted from each block constituting the I picture and recorded.

By the way, in order to reduce the data rate of the I picture recorded in the trick play area as described above, if only low frequency coefficients are extracted from each block constituting the I picture and recorded, the image quality at the time of variable speed reproduction is obtained. Although the resolution is deteriorated, it is considered that the image quality is sufficient because the reproduction is performed at a variable speed.

At the time of variable speed reproduction, trick play data recorded in the trick play area redundantly is always reproduced. The reproduction data in the trick play area is in a burst form. The trick play data reproduced from the trick play area during the variable speed reproduction is sent to the video expansion decoder 7. Since the reproduction data is in a burst form, an error code is inserted during a time when there is no data. For this reason, data in the time when there is no data is ignored by the video decompression decoder 7.

Here, the specific configuration of the interface and format converter 4, the framing circuit 25, the deframing circuit 54, and the packet selecting circuit 59 that constitute this digital VTR will be described. In addition, FIG.
Circuits having the same functions as the circuits shown in FIGS. 2, 3 and 7 are denoted by the same reference numerals and description thereof will be omitted.

As shown in FIG. 22, for example, as shown in FIG. 22, an interface and a format converter 4 constituting a recording system of the digital VTR 3 are provided with a buffer memory 71 for temporarily storing an ATV signal and a video signal packet for extracting a video signal packet from the ATV signal. A multiplexer 72, a depacket circuit 73 for decomposing the video signal packet from the demultiplexer 72 into packets, a syntax analysis circuit 74 for analyzing a header of each packet to extract I picture data, and a DCT coefficient VL for detecting breaks
A D decode circuit 34; a counter 35 for counting the number of DCT coefficients; and the data separation circuit 36 for extracting trick play data based on the output of the counter 35.
A multiplexer 75 for time-division multiplexing the ATV signal stored in the buffer memory 71 and the trick play data from the data separation circuit 36, and a control circuit 76 for controlling the multiplexer 75.

The interface and format converter 4 extracts trick play data necessary for variable speed reproduction from the ATV signal, and time-division multiplexes the trick play data into the ATV signal to form recording data. The distance from the recording start position on each track to the trick play area is different between adjacent tracks.

That is, the buffer memory 71 temporarily stores the input ATV signal, and stores the stored ATV signal.
The signal is read out, for example, in sync block units and supplied to the multiplexer 75.

On the other hand, the demultiplexer 72 extracts a video signal packet from the ATV signal and supplies it to a depacket circuit 73. The depacket circuit 73 decomposes the video signal packet into each packet.

The syntax analysis circuit 74 analyzes the header of each packet decomposed by the depacket circuit 73, and
The packet including the data of the I picture is extracted and supplied to the data separation circuit 36.

The VLD decoding circuit 34 decodes each packet supplied from the depacket circuit 73 and detects a break of the variable length coded DCT coefficient. The counter 35 counts the number of DCT coefficients and detects, for example, a low-frequency coefficient of I-picture data.

Based on the output of the counter 35, the data separation circuit 36 calculates trick play data necessary for variable speed reproduction, that is, low frequency coefficients of each block of the I picture, from the packet data supplied from the data separation circuit 36. It is extracted and supplied to the EOB adding circuit 37. The EOB adding circuit 37 adds the low frequency coefficient of each block of the I picture to E
OB is added and supplied to the multiplexer 75 in sync block units.

The multiplexer 75 controls the AT read from the buffer memory 71 under the control of the control circuit 76.
The V signal and the trick play data from the data separation circuit 36 are time-division multiplexed so that the trick play area is different between adjacent tracks.

That is, for example, the control circuit 76
When the ATV signal read from the buffer memory 71 and the trick play data from the data separation circuit 36 are time-division multiplexed based on the Hz reference signal, the trick play data recorded on the A azimuth track is B
Control is performed to delay the trick play data recorded on the azimuth track by two sync blocks. The recording data obtained by time-division multiplexing of the ATV signal and the trick play data in this manner is
2 (shown in FIG. 2).

As shown in FIG. 22, the framing circuit 25 includes a C2 parity circuit 77 for adding outer parity and a framing circuit 78 for adding inner parity and the like. Then, the C2 parity circuit 77
The outer parity C2 is added to the recording data supplied from the multiplexer 75, and the framing circuit 78 adds the inner parity C1 and a 5-byte sync and ID, and supplies the same to the channel encoder 26.

Thus, trick play data necessary for variable speed reproduction, that is, low frequency coefficients of I picture data extracted from the ATV signal, are recorded in the trick play area at different positions between adjacent tracks on the magnetic tape,
This magnetic tape is connected to a digital V
The digital VTR of the TR and the double azimuth head can reproduce the data with a margin. In other words, digital VTs with different drum configurations
The compatibility of the magnetic tape can be ensured between R.

As shown in FIG. 23, for example, as shown in FIG. 23, a deframing circuit 54 constituting a reproduction system of the digital VTR 3 includes a deframing circuit 81 for performing error correction of reproduced data using an inner parity C1, and an outer parity C2.
Error correction circuit 8 for correcting errors in reproduced data
2 is provided.

Then, the deframing circuit 81 outputs
Channel decoder 52 via C53 (shown in FIG. 3)
The error of the reproduction data supplied from is corrected by the inner parity C1 and supplied to the error correction circuit 82.

The error correction circuit 82 corrects an error in the reproduction data supplied at the time of normal reproduction by using the outer parity C2. By the way, this error correction circuit 82
At the time of variable speed reproduction of the TV signal, that is, error correction is not performed on reproduction data including only trick play data. When the component video signal is reproduced, the output of the error correction circuit 82 is output to the switch circuit 55 (FIG. 3).
Is supplied to the DCT decompression circuit 56 via the
When the V signal is reproduced, it is supplied to the packet selection circuit 59 via the switch circuit 55.

As shown in FIG. 23, the packet selection circuit 59 includes a demultiplexer 83 for distributing reproduction data between normal reproduction and variable-speed reproduction, and a buffer memory 84 for temporarily storing reproduction data during variable-speed reproduction. , The data for which error correction could not be performed by the inner parity C1 is set to 0.
And a selector 86.

Then, as described above, the demultiplexer 83 decodes each packet of the ATV signal,
At the time of normal reproduction of the V signal, all packets of the reproduction data supplied from the error correction circuit 82 are supplied to the selector 86. At the time of variable speed reproduction, the data of the I picture reproduced from the trick play area is supplied to the buffer memory 84. .

The buffer memory 84 temporarily stores the data reproduced from the trick play area, and supplies the stored data to the error processing circuit 85 when the data for one screen is prepared. 85
The data of the I picture from the buffer memory 84 is set to 0, the data for which error correction could not be performed using the inner parity C1 in the deframing circuit 81 is set to 0, and the invalid data, which cannot be reproduced by variable speed reproduction, is set to 0. Is supplied to the selector 86.

The selector 86 selects the reproduction data supplied directly from the demultiplexer 83 during normal reproduction of the ATV signal, and selects the reproduction data supplied from the error process circuit 85 during variable-speed reproduction, and Output to the decompression decoder 7 (shown in FIG. 1).

That is, although one screen (only low frequency coefficients) of an I picture is recorded in the trick play area,
Just sending the reproduced data to the video decompression decoder 7 does not guarantee that the display timing (1/30 second) and the timing of the boundary of the I picture match, and the actual screen update is not updated collectively for one screen. Will be partially updated. Therefore, before sending the reproduction data to the video expansion decoder 7, the data for one screen is completely reproduced and aligned, and then the reproduction data is transmitted to the video expansion decoder 7. By doing so, the actual screen is also updated collectively for one screen, and a variable-speed playback image that is easy to see can be obtained. The recording system buffer memory 71 and the reproduction system buffer memory 84 may be used as a common buffer memory, and may be switched between recording and reproduction.

Note that the present invention is not limited to the above-described embodiment. For example, the audio sector SEC1 can be used as a trick play area. That is, as shown in FIG. 4, one track includes an audio sector SEC1, a video sector SEC2, and a subcode sector SEC3. When directly recording the bit stream of the ATV signal, the video sector SEC2
Since all data can be recorded in the audio sector S,
EC1 becomes unnecessary. Therefore, this audio sector S
EC1 is used as a trick play area to store trick play data.

More specifically, as shown in FIG. 24, the audio sector SEC1 is used as a trick play area, and the maximum target tape speed is selected to be (2N + 1) times.
The same trick play data is recorded on the (2N + 1) track. At this time, by changing the position where trick play data is recorded between adjacent tracks as described above, digital VTRs having different drum configurations are provided.
The compatibility of the magnetic tape can be ensured between them.

At the time of reproduction, at (2N + 1) times speed, tracking is performed so that the audio sector SEC1 is always reproduced. In addition, 1.5 times speed, 2.5 times speed,
.., (N + 0.5) double speed, all data of the audio sector SEC1 of the same azimuth is reproduced by two scans. Therefore, reproduction of trick pre-data is guaranteed at (2N + 1) times speed, 1.5 times speed, 2.5 times speed,..., (N + 0.5) times speed. Thus, if the audio sector SEC1 is a trick play area,
There is no need to provide a trick play area on the video sector.

Also, for example, in the above embodiment, the ATV
A digital VTR for recording a signal of the system has been described, but data obtained by encoding a video signal by adaptively switching between intra-picture encoding and inter-picture prediction encoding is input to the digital VTR for recording this data. Needless to say, the present invention can be applied.

[0104]

As is apparent from the above description, according to the present invention, when recording a digital video signal on a magnetic tape by the inclined azimuth recording method using a plurality of heads having different azimuths, each track on the magnetic tape is recorded. Are provided with a first region and a second region. Then, data obtained by encoding the video signal by adaptively switching between intra-picture encoding and inter-picture prediction encoding is input, and the input data is recorded in the first area, and the image of the input data is recorded. When recording data obtained by inner encoding as data for variable speed reproduction in the second area, the distance from the recording start position on each track to the second area is set between adjacent tracks having different azimuths. Differently, the data for variable speed reproduction is recorded so that a sufficient margin from both ends of the head trace area is recorded regardless of whether the plurality of heads at the time of reproduction are 180 ° facing heads or double azimuth heads. The magnetic tape recorded in this manner can be dubbed even when the second area is reproduced at a variable speed by, for example, a digital VTR of a 180 ° facing head. Even when variable speed reproduction in a digital VTR of the azimuth heads, data for variable speed reproduction can be reproduced with a margin. That is, compatibility of the magnetic tape can be secured between digital VTRs having different drum configurations.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a video recording / reproducing system to which the present invention has been applied.

FIG. 2 is a block diagram showing a configuration of a recording system of a digital VTR to which the present invention is applied.

FIG. 3 is a block diagram showing a configuration of a reproduction system of the digital VTR.

FIG. 4 is a diagram showing a configuration of a track on a magnetic tape in the digital VTR.

FIG. 5 is a diagram showing a configuration of a video sector.

FIG. 6 is a diagram illustrating a configuration of a sync block.

FIG. 7 is a block diagram for explaining the principle of a recording operation in the digital VTR.

FIG. 8 is a diagram showing a specific example of a trick play area.

FIG. 9 is a diagram showing a waveform of a reproduction signal during variable speed reproduction.

FIG. 10 is a diagram showing a specific example of a trick play area.

FIG. 11 is a diagram showing a head trajectory for explaining an operation at the time of variable speed reproduction.

FIG. 12 is a diagram showing data reproduced in one scan for explaining an operation during variable speed reproduction.

FIG. 13 is a plan view showing a specific head arrangement of the digital VTR.

FIG. 14 is a plan view showing a specific head arrangement of the digital VTR.

FIG. 15 is a plan view showing a specific head arrangement of the digital VTR.

FIG. 16 is a diagram showing a head trajectory for explaining an operation at the time of variable speed reproduction.

FIG. 17 is a diagram showing a head trajectory for explaining an operation during variable speed reproduction.

FIG. 18 is a diagram illustrating a relationship between a drum configuration and a variable speed reproduction speed.

FIG. 19 is a diagram showing a head trajectory for each drum configuration.

FIG. 20 is a diagram showing a specific example of a trick play area.

FIG. 21 is a diagram showing the relationship between the drum configuration and the variable speed reproduction speed when the maximum speed reproduction speed is 17 times speed.

FIG. 22 is a block diagram showing a specific configuration of a recording system of the digital VTR.

FIG. 23 is a block diagram showing a specific configuration of a reproduction system of the digital VTR.

FIG. 24 is a diagram showing a specific example in which a trick play area is provided in an audio sector.

FIG. 25 is a block diagram showing a configuration of an ATV transmission system.

FIG. 26 is a diagram illustrating a configuration of a GOP in the MPEG system.

FIG. 27 is a diagram illustrating a configuration of a packet in the ATV system.

[Explanation of symbols]

 3 Digital VTR 4 Interface and Format Converter 5 Recording / Reproducing Unit 34 VLD Decoding Circuit 35 Counter 36 Data Separation Circuit 71 Buffer Memory 72 Demultiplexer 73 Depacket Circuit 74 Syntax Analysis Circuit 75 Multiplexer 76 Control Circuit

Claims (5)

(57) [Claims] 1. A plurality of heads having different azimuths from each other.
In a digital video signal recording method for recording a digital video signal on a magnetic tape according to a gradient azimuth recording method used , a first area and a second area are provided on each track on the magnetic tape, and intra-picture encoding and inter-picture coding are performed. Data obtained by encoding a video signal by adaptively switching predictive encoding is input, the input data is recorded in the first area, and data obtained by intra-coding of the input data is shifted. When recording the data for reproduction in the second area, the second data is recorded from the recording start position on each track.
The distance to the area is made different between the adjacent tracks having different azimuths, so that a plurality of
In case of facing head or double azimuth head
In any case, merge from both ends of the head trace area
A method for recording digital video signals, characterized in that the data for variable speed reproduction is recorded so as to have sufficient performance . 2. A plurality of heads having different azimuths from each other.
In a digital video signal recording device that records a digital video signal on a magnetic tape, data obtained by encoding a video signal by adaptively switching between intra-picture encoding and inter-picture predictive encoding is used according to the gradient azimuth recording method used. Variable speed reproduction data extraction means for extracting data obtained by intra-coding from the input data and converting the data into data for variable speed reproduction; and input data in a first area of each track on a magnetic tape. Multiplexing means for time-divisionally multiplexing the input data and the data for variable-speed reproduction so that the data for variable-speed reproduction from the variable-speed reproduction data extracting means are recorded in the second area; Rutotomoni different distance from the start position to the second region between tracks <br/> adjacent the azimuth are different, multiple heads during reproduction
Head is 180 ° facing head or double azimuth
Head trace area both ends
Recording apparatus in a digital video signal, characterized in that it comprises a control means for controlling said multiplexing means so that not enough a margin from. 3. The method according to claim 1, wherein the plurality of heads are 180
3. The magnetic head according to claim 2, wherein the two magnetic heads alternately record the input data and the data for variable speed reproduction on adjacent tracks. A recording device for digital video signals. Wherein said plurality of heads are two magnetic heads disposed in phase with the rotary drum, the two magnetic heads simultaneously records the data of the input data and the speed for reproduction in a track adjacent 3. The method according to claim 2, wherein
An apparatus for recording a digital video signal according to the above. 5. The method according to claim 1, wherein the plurality of heads are 180
A-channel first and second magnetic heads disposed opposite each other and B-channel first and second magnetic heads disposed in phase with the A-channel first and second magnetic heads, respectively. sequence by the magnetic head, the first magnetic head and the second magnetic head is an alternating, at the same time a second magnetic head of the first magnetic head and each channel of each channel, respectively, the input data and the variable speed reproduction 3. The digital video signal recording apparatus according to claim 2, wherein data for recording is recorded on adjacent tracks.