JPH0644505A - Magnetic recording/reproducing device - Google Patents

Abstract

PURPOSE:To realize a specified double speed reproduction with no noises at least regarding the information of a high data rate by recording/reproducing the information of plural kinds of different data rates on the same digital VTR. CONSTITUTION:At the time of recording the information of a high data rate, the error of digital data to a terminal 50 is corrected and coded by an encoder 51, its channel is devided and the code of 2ch is outputted to a modulator 52. It is transformed into a signal fit for recording and recorded on a tape by magnetic heads 71A to 72B on a drum 57. A pair of tracks are roughly simultaneously recorded/reproduced by a set of heads whose azimuth angles are different and four tracks are scanned per one rotation of the drum. At the time of recording a low data rate, an information quantity is made to a 1/r head rotation number R/2 and a tape speed V/2. By this constitution, all fields recorded without any noises by the 1/r double speed reproduction of at least high data rate information are reproduced and a complete 1/r double reproduction is realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus for recording / reproducing plural kinds of information signals having different data rates.

[0002]

2. Description of the Related Art As a magnetic recording / reproducing apparatus (VTR) for recording and reproducing, for example, a video signal as an information signal on a magnetic tape, there is a digital VTR for recording / reproducing data obtained by digitizing the video signal. FIG. 8 shows a conventional block configuration of this digital VTR. For example, 50 is a digital data input terminal for a video signal, 31 is a recording processing section, 32 is a digital modulator, and 53 and 54 are almost 180 on the rotary drum 57. Heads 58 having mutually different azimuths, which are arranged to face each other, a magnetic tape 58, a digital data output terminal 60, a reproduction processing unit 41, and a digital demodulator 42.

Digital data such as a video signal input to the digital data input terminal 50 at the time of recording is recorded by a recording processing unit.
In 31, it is output to the modulator 32 as an error correction coded digital code for detecting and correcting an error.
The modulator 32 converts the input digital code into a signal of a form suitable for recording, and the magnetic head 53 on the rotating drum 57,
It records on the magnetic tape 58 with 54.

During reproduction, the signals reproduced by the magnetic heads 53 and 54 are converted into the original digital code by the demodulator 42, and the reproduction processing section 41 performs error correction decoding for detecting and correcting a code error caused by the recording and reproduction process. By doing so, digital data having the same signal form as that at the time of recording is output to the digital data output terminal 60.

By the way, when recording a video signal,
HDTV that is being put to practical use and N that is the current TV signal
It is desired that different signal forms of TSC, that is, video signals having different information contents can be recorded by the same digital VTR. It is also desired that even the video signals of the same signal form can be recorded with the same VTR with digital codes having different amounts of information corresponding to the length of the recording time. In other words, it is necessary to be able to perform recording / reproduction corresponding to different data rates with the same VTR.

[0006]

However, the structure of the conventional digital VTR shown in FIG. 8 can only cope with recording and reproduction at a single data rate.

The present invention has been made to solve the above problems, and is a VTR capable of recording / reproducing information of plural kinds of different data rates with the same digital VTR.
In the above, it is an object of the present invention to realize a predetermined double speed reproduction with no noise at least for information of a high data rate.

[0008]

SUMMARY OF THE INVENTION A digital VTR according to the present invention has a high data rate information (first information) recorded or reproduced at a normal speed with respect to a predetermined value of each of a head rotation speed and a tape speed. Low data rate information (second information) whose amount of information is approximately 1 / r of the first information
The number of revolutions of the head and the tape speed in the recording of information) or the reproduction at the normal speed are set to 1 / r of the respective predetermined values. Then, the first information is reproduced at 1 / r speed or 1
/ (2 · r) double speed reproduction, the head rotation speed and the tape speed are respectively 1 with respect to the respective predetermined values of the head rotation speed and the tape speed when the first information is recorded or the normal speed reproduction is performed. / R.

[0009]

In the 1 / r speed reproduction of the first information, r
The reproduction information of one field obtained by compressing the information of one field sequentially reproduced for each field period by 1 / r times is used continuously for the r field period.

Further, in the 1 / (2 · r) double speed reproduction of the first information, one of the fields constituting one frame is selected in one field sequentially reproduced every r field periods. Then, the reproduction information for each field obtained by time compression to 1 / r is continuously used for the (2 · r) field period.

[0011]

【Example】

Example 1. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 illustrates a recording / reproducing system block when recording / reproducing corresponding to high data rate information (first information) and low data rate information (second information). In the figure, 50 is, for example, a digital data input terminal for a video signal, 51 is an encoder, 52 is a digital modulator consisting of, for example, two channels, 71A and 71B are a set and 72.
The other pair of A and 72B has approximately 18 on the rotary drum 57, respectively.
Two azimuths facing each other 0 degrees
A set of heads, 58 is a magnetic tape, 60 is a digital data output terminal, 61 is a decoder, 62 is a two-channel digital demodulator, 65 is a selector, and 66 is a compressor.

First, the case of recording the first information will be described. Digital data relating to the first information such as a video signal input to the digital input terminal 50 at the time of recording is subjected to error correction coding for detecting and correcting an error in the encoder 51, and channel division corresponding to the number of recording channels. Then, for example, 2-channel digital codes are output to the digital modulators 52, respectively. The modulator 52 converts the input two-channel digital code into signals of a form suitable for recording, and outputs the two signals on the rotary drum 57.
Data is recorded on the magnetic tape 58 by the pair of magnetic heads 71A to 72B.
In this case, different azimuths θ arranged at almost the same position
One set of magnetic heads 71A and 71B of 1 and θ2 and 72A and 72B
A pair of (2) tracks having different azimuths are alternately recorded and reproduced alternately by the other set, and four tracks are scanned per one rotation of the rotary drum. It should be noted that the head rotation speed and the tape speed at the time of recording the first information are R and V, respectively.

FIG. 2 shows a track trace state in the case of performing the recording corresponding to the first information described above. 1 in the figure
Is a head scanning direction, 2 is a tape running direction, and a pair (two) of tracks 81A and 81B of the tracks 81A to 82B on the magnetic tape 58 are, for example, magnetic fields of different azimuths θ1 and θ2 arranged at substantially the same position. Recording is performed almost simultaneously by one set of heads 71A and 71B, and tracks 82A and 82B are recorded by another set of magnetic heads 72A and 72B having different azimuths .theta.1 and .theta.2. Here, for example, the information of the 1-field period T in the first information input to the input terminal 50 is
It is assumed to be composed of four tracks 81A to 82B in the time T required for one rotation of the drum.

FIG. 3 is a timing chart at the time of recording the first information described above. FIG. 3 (a) shows time, and FIG. 3 (b) shows two channels concerning the first information output from the encoder 51 or the modulator 52. Recording signals of, for example, D1A and D1
The four signals B, D2A, and D2B form a recording signal of the first information corresponding to one field. Then, in the T / 2 period in which the drum makes a half rotation, the recording signals D1A and D1B of the two channels are transferred to the heads 71A and 71B, respectively.
Recorded simultaneously by the recording tracks 81A and 81 of FIG.
Formed as B. Time T / when the drum next rotates half a turn
In the T / 2 period from 2 to time T, the recording signals D2A and D2B of two channels are simultaneously recorded by the heads 72A and 72B, respectively, and the recording track 82 of FIG.
Formed as A and 82B, one revolution of the drum, ie 1
81A to 82B at time T corresponding to the field period
4 tracks are formed.

Next, in the normal speed reproduction, the head rotation speed is set to R and the tape speed is set to V as in the case of recording the first information, and reproduction is performed in the same track trace state as during recording. FIG. 3B together with the time of FIG. 3A reproduced from the recording track of FIG. 2 by the magnetic heads 71A to 72B.
The 2-channel reproduction signal shown in (1) is converted into the original 2-channel digital code by the demodulator 62 composed of at least 2 channels, and the decoder 61 performs error correction decoding for detecting and correcting a code error caused by the recording and reproduction process. ,
Digital data relating to the first information having the same signal form as that at the time of recording is output to the digital data output terminal 60 by performing one channel by channel combination.

Next, the case of recording a low data rate, that is, the second information will be described. It should be noted that here, in order to make the description easy to understand, the amount of information of the second information is set to 1/2 (1 / r) of the first information. Accordingly, the head rotation speed is R / 2 and the tape speed is V / 2. In the encoder 51, the digital data relating to the second information such as the video signal input to the digital input terminal 50 during recording is subjected to error correction coding for detecting and correcting an error,
In addition, channel division corresponding to the number of recording channels is performed and, for example, 2-channel digital codes are output to the modulator 52, respectively. The modulator 52 converts the input two-channel digital code into signals of a form suitable for recording, and two sets of magnetic heads 71 on the rotary drum 57.
Recording on the magnetic tape 58 with A to 72B. In this case, a pair (two) tracks of different azimuths are alternately recorded almost simultaneously by one set of different azimuths θ1 and θ2 magnetic heads 71A and 71B and another set of 72A and 72B which are arranged at substantially the same position. Reproduction is performed, and four tracks are scanned per one rotation of the rotary drum.

FIG. 4 shows a track trace state when the recording corresponding to the second information described above is performed. In the figure, 1 is a head scanning direction, 2 is a tape running direction, and a pair (two) of tracks 91A and 91B among tracks 91A to 92B on the magnetic tape 58 are arranged at, for example, substantially the same position and different. Recording is performed almost simultaneously by one set of magnetic heads 71A and 71B of azimuths θ1 and θ2, and tracks 92A and 92B are recorded almost simultaneously by another set of magnetic heads 72A and 72B of different azimuths θ1 and θ2. Since the head rotation speed is R / 2 and the tape speed is V / 2, the information of one field period T in the second information input to the input terminal 50 is 1/2 of that of the drum.
It is composed of two tracks 91A and 91B at the time T required for rotation.

FIG. 3 (c) is a timing chart of a recording signal of two channels relating to the second information output by the encoder 51 or the modulator 52 at the time of recording the above-mentioned second information. For example, two signals E1A and E1B are used. The recording signal of the second information corresponds to one field. During the period T when the drum makes a half rotation, the recording signal E of 2 channels is
1A and E1B are simultaneously recorded by the heads 71A and 71B, respectively, to form recording tracks 91A and 91B in FIG. During the period from the time T when the drum rotates half a turn to the time 2T, the recording signal E of 2 channels is recorded.
2A and E2B are simultaneously recorded by heads 72A and 72B, respectively, and are formed as recording tracks 92A and 92B in FIG.

That is, at the time of recording the second information, both the head rotation speed and the tape speed are set to 1/2 of those at the time of recording the first information. The track patterns created are exactly the same.

Next, in the normal speed reproduction of the second information, the head rotational speed is set to R / s as in the recording of the second information.
2. The tape speed is V / 2, and reproduction can be performed in the same track trace state as when recording. The reproduced signals of the two channels shown in FIGS. 3 (a) and 3 (c) reproduced from the recording tracks of FIG. 4 by the magnetic heads 71A to 72B are processed by the demodulator 62 composed of at least two channels to obtain the original digital code of the two channels. The digital data output terminal 60 has the same signal form as that at the time of recording by performing error correction decoding for detecting and correcting a code error generated in the recording / reproducing process in the decoder 61 and performing one channel by channel combination. Digital data relating to 2 information is output.

Further, description will be made of a case where the above-mentioned first information is reproduced at 1/2 speed (1 / r speed reproduction).
The values of the head rotation speed and the tape speed in the 1/2 speed reproduction are the same as those in the case of the recording or the normal speed reproduction of the second information, in other words, the 1/2 times the value of the recording of the first information. 1 / 2R and 1 / 2V where
And Therefore, as described above, one set of heads 71A and 71B and another set of heads 72A and 72B are used to record the track relating to the first information shown in FIG. You can do a head trace just like. FIG. 5 (a) shows the time expressed on the same time axis as FIG. 3 (a), and FIG. 5 (b) shows the two-channel reproduction signal output from the demodulator 62 during the 1/2 speed reproduction.

As is clear from comparison with the timing chart at the time of recording the first information shown in FIG. 3 (b), for example, reproduction is performed by the two-channel heads 71A and 71B. Two-channel digital codes D1A and D1 that constituted the first information in the 1/2 field period T / 2 during recording
B is reproduced in a time T twice that at the time of recording. And so on
2 reproduced by 2-channel heads 72A and 72B
The channel digital codes D2A and D2B are also reproduced in the time T twice as long as the time of recording. That is, the recording signal of the first information in the predetermined period is reproduced in a state in which the reproduction is finished in a period twice as long as the predetermined period in the 1/2 speed reproduction, and the time is extended twice as much as the recording time. It will be.

The two-channel reproduction signal output from the demodulator 62 during the 1/2 speed reproduction shown in FIG.
The decoder output shown in FIG. 6 (b) is obtained by performing the error correction decoding for detecting and correcting the code error generated in the recording / reproducing process and the one-channel conversion by the channel combination, which is input to 61. The decoder output of FIG. 6 (b) is represented in FIG. 6 (a) on the same time axis as that of FIG. 3 (a).
In FIG. 6 (b), F1, F2, F3, F4, F5, F6
... is information in 1-field units for each 2 · T period of 2 fields that is twice as long as the time of recording.
F1 is a reproduction signal D1 of 2 channels in FIG. 5 (b).
A, D1B, D2A, and D2B, and F2 is D
From 3A, D3B, D4A, and D4B, F3 is D5
From A, D5B, D6A, and D6B, F4 is D7, D
This is a field synthesized from 7B, D8A, and D8B. Here, F1, F3, F5, etc. belong to odd fields, and F2, F4, F6
Etc. belong to the even field. Then, in the adjacent odd field F1 and even field F2, the frame FR1 is changed to the adjacent odd field F3.
A frame FR2 in the even field F4, and a frame FR3 in the adjacent odd field F5 and even field F6.

The decoder output of FIG. 6 (b) is input to the selector 65, and as shown in FIG. 6 (c), for example, F1, F2, F.
After being selected in the field order of 3, F4, F5, etc., a compressor 66 composed of, for example, a field memory, etc.
Is compressed in half at. The 1/2 time compression can be easily realized by, for example, reading the information of the sequential field written in the memory included in the compressor 66 at a speed twice as fast as the writing. FIG. 6 (d) shows one field period T at the time of ½ speed reproduction, which is read from the compressor 66 with a delay of about T period with respect to the writing of information for each sequential field and time-compressed to ½. It is information for each one field. At this time, in the compressor 66, the above-mentioned one-field period T, which is time-compressed to 1/2, is used.
Information for each one field is read out and output continuously for two field periods. As a result, the information F1, F2, F3, F4, etc. for each field is sequentially output for two field periods in succession, as shown by the alternated portions in FIG.

That is, the information F1 and F1 for each field, which coincides with the original one-field period T at the time of recording.
2, F3, F4, etc. are sequentially 2 fields (1 frame)
Since the minute information is output after being composed, there is no noise and all recorded fields are reproduced.
/ 2x speed reproduction can be realized.

Note that the capacity of the memory included in the compressor 66 is at most the data obtained in the 2 field period 2 · T at the output of the selector 65 in FIG. 6C (for example, the data of F1). If the memory has twice the capacity of the above, normal compression operation can be performed without overlapping the writing and reading for the compression in the same memory area.

When recording the first and second information, the first information input to the digital input terminal 50 is recorded.
The information and the second information may be information compressed by a high-efficiency encoder for reducing the recording data rate not shown in FIG. In this case, the digital data at the normal speed reproduction relating to the first and second information output to the digital data output terminal 60 and the first information relating to the first information are reproduced.
The digital data output from the compressor 66 in the 1/2 (1 / r) double speed reproduction may be decoded by a high efficiency decoder (not shown).

Further, the high efficiency encoding described above may be performed in the encoder 51 of FIG. In this case, it is advisable to perform high-efficiency decoding by the decoder 61 of FIG. 1 both during normal speed reproduction of the first and second information and during 1/2 (1 / r) double speed reproduction of the first information. In the 1/2 speed reproduction of the first information, the digital data output from the compressor 66 may be decoded by a high efficiency decoder (not shown).

Example 2. 1 / of the first information in the first embodiment
In the processing at the 2 × speed reproduction, all the recorded fields were reproduced, but only one of the odd or even fields forming one frame is used to reproduce the 1/4 speed (1/4) speed of the first information. (2 · r) double speed reproduction) can be configured. Also in the 1/4 speed reproduction in this embodiment, the values of the head rotation speed and the tape speed are the same as those of the second value.
The same values as in the case of recording or normal speed reproduction of the information of 1), in other words, 1/2 · R and 1/2 · V which are ½ times the values of the recording of the first information. Figure 7
6 (b) is the same as the decoder output of FIG. 1 shown in FIG. 6 (b). In Fig. 7 (b), F1, F2, F3, F4, F
5, F6, F7, F8, F9, F10 ... are information of one field unit for each 2T period 2.T, which is twice as long as that at the time of recording, and F1 is shown in FIG. 5 (b). 2-channel reproduction signals D1A, D1B, D2A,
And D2B, and F2 is D3A, D3B, D4
From A and D4B, F3 is D5A, D5B, D6A,
And D6B, F4 is D7, D7B, D8A, and D
This is a field synthesized from 8B. Here, F1, F3, F5, etc. belong to odd fields, and F2, F4, F6, etc. belong to even fields.

The decoder output of FIG. 7 (b) is input to the selector 65, and as shown in FIG. 7 (c), for example, F1, F3, F5.
After selecting only odd fields such as, the compressor 66 composed of field memory etc.
Time compressed to. The 1/2 time compression can be easily realized by, for example, reading the information of the sequential field written in the memory included in the compressor 66 at a speed twice as fast as the writing. Figure 7 (d) shows the compressor 66
It is information of one field unit for every one field period T at the time of ¼ speed reproduction, which is time-compressed to ½ and read out. At this time, the compressor 66 reads out and outputs the information F1, F3, F5, etc. in 1-field units for each 1-field period T, which has been time-compressed to 1/2, continuously for 4 field periods. As a result, Fig. 7 (d)
The information F1, F3, F5, etc. for each field are successively output for four field periods in succession, as indicated by alternating solid and dotted lines.

That is, the information F1 and F1 for each field that coincides with the original one-field period T at the time of recording.
Since 3 and F5 and the like sequentially form information for 4 fields (2 frames) and are output, one-fourth speed reproduction with no noise, which consists of either one of the fields constituting one recorded frame Can be realized.

In the second embodiment, the capacity of the memory included in the compressor 66 is at most the data obtained in the 2 field period 2.T at the output of the selector 65 in FIG. , F1 data), the memory does not overlap writing and reading for the compression in the same memory area, and a normal compression operation can be performed.

The field used in the 1/4 speed reproduction is the even field F selected by the selector 65.
2, F4, F6, F8 and the like may be used. further,
The odd field and the even field may be mixed.

Since the operation of recording the first information and the second information or reproducing at the normal speed in the second embodiment is the same as that in the first embodiment, the description thereof is omitted here.

When recording the first and second information, the first information input to the digital input terminal 50 is recorded.
The information and the second information may be information compressed by a high-efficiency encoder for reducing the recording data rate not shown in FIG. In this case, the digital data at the normal speed reproduction relating to the first and second information output to the digital data output terminal 60 and the first information relating to the first information are reproduced.
The digital data output from the compressor 66 in the / 4 speed reproduction may be decoded by a high efficiency decoder (not shown).

Further, the above high efficiency encoding may be performed in the encoder 51 of FIG. In this case, both the normal speed reproduction for the first and second information and the 1/4 speed reproduction for the first information are performed as shown in FIG.
It is preferable to perform high efficiency decoding by the decoder 61 of. The first
In the 1/4 speed reproduction of information, the digital data output from the compressor 66 may be decoded by a high efficiency decoder (not shown).

In the first and second embodiments, the case where the information amount of the second information is 1/2 of that of the first information has been described, but the present invention is not limited to this, and generally 1 / This embodiment can be applied as the information amount of r. That is, in recording the second information or reproducing the normal speed, the number of head rotations and the tape speed may be set to 1 / r when recording the first information or reproducing the normal speed, respectively. Further, if the head rotation speed and the tape speed are set to be the same as those at the time of recording the second information or at the normal speed reproduction, 1 / r speed reproduction or 1 of the first information described in Embodiments 1 and 2 or 1 is performed. / (2 · r) double speed reproduction can be realized.

In the above-described Examples 1 and 2, recording and reproduction were performed on two channels, but the number of channels is not limited to two, and if the number of channels is one or more, the above Examples 1 and 2 are Can be applied. Furthermore, in the above-described Embodiments 1 and 2, the time required for one rotation of the drum in recording the first information or reproducing at the normal speed was described as being the same as the one-field period T. However, they are the same. You are not limited to being.

In the first and second embodiments described above, the digital VTR in which recording is performed digitally has been described, but the same concept as in the first and second embodiments can be applied to the analog VTR. .

[0040]

As described above, according to the present invention, the head rotation speed and the tape speed are set to the respective predetermined values with respect to the predetermined head rotation speed and the predetermined tape speed in the recording of the first information or the normal speed reproduction. 1 / r, the amount of information is approximately 1 / r of the first information (a positive number larger than r: 1)
Recording the second information consisting of or reproducing at normal speed,
In a magnetic recording / reproducing apparatus capable of recording a plurality of types of information or reproducing at a normal speed, the first number recorded on a recording medium by setting the head rotation speed and the tape speed to 1 / r of the respective predetermined values. 1 information is 1 / r
Double speed reproduction or 1 / (2 · r) double speed reproduction can be performed.

As described above, according to the present invention, at least at the 1 / r speed reproduction of the first information, there is no noise at all and the recorded field is completely reproduced at the 1 / r speed reproduction. Can be realized.

As described above, according to the present invention, at least in the 1 / (2 · r) times speed reproduction of the first information, the noise which is formed by one of the fields constituting one recorded frame is used. There is no complete 1 / (2
・ R) Double speed reproduction can be realized.

[Brief description of drawings]

FIG. 1 is a block diagram for explaining signal processing during recording and reproduction in an embodiment of the present invention.

FIG. 2 is a diagram showing a track trace state in recording the first information or reproducing at a normal speed for explaining the embodiment of the invention.

FIG. 3 is a diagram showing a timing chart in the case of recording first and second information for explaining the embodiment of the invention.

FIG. 4 is a diagram showing a track trace state during recording of second information or normal speed reproduction for explaining an embodiment of the present invention.

FIG. 5 is a diagram showing a timing chart of a demodulator output signal during ½ × speed reproduction and ¼ × speed reproduction of the first information in the first and second embodiments of the present invention.

FIG. 6 is 1 / th of the first information according to the first embodiment of the present invention.
It is a figure which shows the timing chart of a 2x reproduction signal.

FIG. 7 is 1 / th of the first information according to the second embodiment of the present invention.
It is a figure which shows the timing chart of a 4x speed reproduction signal.

FIG. 8 is a diagram illustrating an operation during recording / reproduction in a conventional VTR.

[Explanation of symbols]

 1 head scanning direction 2 tape running direction 50 digital data input terminal 51 encoder 52 modulator 57 rotating drum 58 tape 60 digital data output terminal 61 decoder 62 demodulator 65 selector 66 compressor 71A head 71B head 72A head 72B head 81A recording track 81B recording track 82A recording track 82B recording track 91A recording track 91B recording track 92A recording track 92B recording track

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toru Inoue 1 Baba Institute, Nagaokakyo City Electronic Product Development Laboratory, Mitsubishi Electric Corporation

Claims (3)

[Claims] 1. The first information is recorded or reproduced at a normal speed on a recording medium running at a predetermined traveling speed by scanning a predetermined number of heads provided on a rotating drum rotating at a predetermined drum rotation speed, The recording medium that travels at 1 / r of the predetermined traveling speed by scanning of the predetermined number of heads provided on the rotating drum that rotates at 1 / r of the drum rotation speed (r: a positive number larger than 1). Above, about 1 / r of the first information
Of the heads of the predetermined number provided on the rotating drum which records or reproduces the second information consisting of the information amount of 1) and rotates at 1 / r of the predetermined drum rotation number (a positive number larger than r: 1). By scanning, the first information recorded on the recording medium traveling at 1 / r of the predetermined traveling speed is reproduced at 1 / r speed or 1 / (2 · r) speed. Magnetic recording / reproducing device 2. In the 1 / r speed reproduction of the first information, the reproduction of each field obtained by compressing the information of one field sequentially reproduced every r field period to 1 / r on the time axis 2. The magnetic recording / reproducing apparatus according to claim 1, wherein the information is continuously used for the r field period. 3. In the 1 / (2 · r) double speed reproduction of the first information, one of the fields constituting one frame is selected in one field sequentially reproduced every r field period. 2. The magnetic recording / reproducing apparatus according to claim 1, wherein reproduction information for each field obtained by compressing the time axis to 1 / r is continuously used for a period of (2.r) fields.