JPH06261278A - Signal recording/reproducing device - Google Patents

Abstract

PURPOSE:To realize variable speed reproduction at plural kinds of speeds without adding high speed search data by arranging digital data in a prescribed position on a track which a reproducing head always passes through. CONSTITUTION:With respect to helical scan tracks 1, 2 recorded on a magnetic tape by a head attached to a rotary drum, for instance, in a 9-fold speed head locus 3 at the time when only a tape feeding speed is set to a 9-fold speed, and a 3-fold speed head locus 4 at the time when it is set to a 3-fold speed, digital data required for variable speed reproduction is arranged in a part 5 which the head traces in common. In such a way, since data required at the time of high speed search can be obtained, variable speed reproduction at three kinds or more of medium speeds can be executed without adding high speed search data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal recording / reproducing apparatus for recording / reproducing a digital signal with a rotary head.

[0002]

2. Description of the Related Art Conventionally, in a signal recording apparatus for recording and reproducing a signal on a belt-shaped recording medium such as a magnetic tape by a helical scan using a rotary head, when the traveling speed of the recording medium is made variable at the time of reproduction, at the time of variable speed reproduction. Since the head locus of No. 1 is different from the head locus at the time of recording, it was very difficult to reproduce the data required for reproduction at a plurality of medium speeds. Conventionally, in order to solve this, Japanese Patent Application No. 63-24
As shown in No. 5109, the high-speed reproduction speed is limited to one type, and the data for high-speed reproduction is recorded at the position corresponding to the head locus at this speed. However, with such a method, it is impossible to obtain a reproduced image at three or more medium speeds including the 1 × speed.

An example of a high speed search of a conventional signal recording / reproducing apparatus will be described below with reference to the drawings.

FIG. 16 is a diagram showing a tape pattern of a conventional signal processing device. In FIG. 16, reference numerals 1 and 2 are helical scan tracks recorded on the tape by a head attached to a rotary drum, and are recorded obliquely on the tape. Adjacent tracks have different recording azimuths, and are devised to reduce crosstalk between tracks during reproduction.

FIG. 15 shows an example of a scanner.
A rotary drum 56 rotates in the direction of the arrow. 5
Reference numeral 5 is a magnetic tape for recording signals, which is a rotary drum 56.
Further, the vehicle is traveling at a predetermined speed while being obliquely wound 180 degrees. Reference numerals 59 and 60 are heads for recording and reproducing signals, and are distinguished by R and L because the azimuth angles are different. Reference numerals 61 and 62 are auxiliary heads for reproduction and are not used in this description.

The track shown in FIG. 16 is shown in FIG.
This is a recording pattern when the magnetic tape 55 is run at a normal speed using the scanner of FIG. Heads 59 and 60 are used as the recording heads. On the other hand, the head locus is 63 when only the tape feeding speed is set to 8 times. At this time, the two heads 59 and 60 diagonally cross the eight tracks. Since each head can reproduce only the track of the same azimuth, only the area indicated by 65 can reproduce the signal on the recording track. In addition, when the head locus when the tape is run at 16 times speed is obtained, the locus shown by 64 in the figure is obtained. At this time, the area where the signal can be reproduced is the area indicated by 66.

As shown in this figure, in a signal recording / reproducing apparatus for recording / reproducing by helical scanning, if variable speed reproduction is performed by changing only the tape feeding speed, the head locus changes according to the tape running speed. Therefore, the location where the head can reproduce data differs depending on the traveling speed.

In the conventional signal recording / reproducing apparatus, in order to realize variable speed reproduction such as high speed search, high speed search data is recorded in the area indicated by 65 and the area indicated by 66. That is, the VT for recording and reproducing the video signal
In R, a subcode area is provided at a position corresponding to the pattern traced by the reproducing head at a fixed fixed speed on the tape pattern recorded / reproduced by the helical scan.
Still image information is recorded in the sub-code area and the data is reproduced to obtain a high-speed reproduction image.

[0009]

However, in such a conventional signal recording / reproducing apparatus, since necessary data is arranged in accordance with the head locus of a special reproducing speed, normal reproduction and another fixed double speed reproduction are performed. It was not possible to select various search speeds because it was not possible to reproduce the data for high speed reproduction at other speeds.

When a search image is to be obtained at various reproduction speeds by this method, variable speed reproduction is performed by recording high speed reproduction data on all head loci corresponding to the reproduction speed. Can also be considered. However, when data is arranged on the head locus at all speeds, it is necessary to record a large amount of high-speed search data in addition to the data that is normally reproduced in normal reproduction, so from the viewpoint of recording efficiency, , Was an irrational way.

The present invention is intended to solve the above problems, and an object thereof is to provide a signal recording / reproducing apparatus capable of variable speed reproduction at a plurality of medium speeds of three or more types without adding high-speed search data. I am trying.

[0012]

In order to achieve the above object, the present invention uses a head mounted on a rotary drum to divide a digital signal into a plurality of tracks on a tape-shaped recording medium and performs a helical scan. A signal recording / reproducing apparatus for recording / reproducing, wherein the tape-shaped recording medium has a variable speed reproduction at a certain position on a track which a reproducing head always passes at a plurality of medium speeds including three times or more including a 1x speed. It has a configuration in which digital data required at times is arranged, and enables reproduction of required data at a plurality of reproduction speeds.

Further, the track for recording / reproducing digital data required for variable speed reproduction is a track selected periodically from a plurality of tracks recorded / reproduced on a tape-shaped recording medium. Is convenient for variable speed playback.

Data to be recorded / reproduced at a certain position on the track which the reproducing head always passes at a plurality of medium speeds,
If the recorded data is a video signal and the aim is to obtain a reproduced image at multiple medium speeds, one video
It is desirable that the image data is a frame or field that is intermittently extracted at a ratio of the screen, or a part of the image data in the frame or field. As a part of the image data in the frame or in the field, it is preferable to use mainly the low frequency component of the image or the high-order bit component of the quantized image.

When the recorded image data is data that has been transformed by orthogonal basis transformation such as discrete cosine transformation, among the coefficients after transformation, basis coefficients that mainly represent the low-frequency component of the image, and
Further, if the higher-order bit component of the coefficient is used, these data can be used as high-speed search image data because these data are important components forming an image. In addition, if accurate time management is required for high-speed search, it is necessary to include time information in the data. Further, by including the data identification signal in the data, the degree of freedom of the content of the high speed reproduction data can be increased.

[0016]

According to the present invention, the data required for high-speed reproduction of three or more speeds including the 1 × speed is arranged at the position where the head always traces at all the determined speeds, so that it is necessary for the high-speed search. You can get the data. For example, it is possible to obtain a reproduced image at a plurality of speeds with a digital VTR of the type that records image data compressed using a variable length coding technique, which has been very difficult in the past.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 to 6 are views showing a tape pattern in the first embodiment of the present invention.

In the figure, reference numerals 1 and 2 denote helical scan tracks recorded on the tape by a head attached to a rotary drum, and are recorded obliquely on the tape. Adjacent tracks have different recording azimuths, and are devised to reduce crosstalk between tracks during reproduction. FIG. 14 shows an example of the scanner used at this time. A rotary drum 56 rotates in the direction of the arrow. Reference numeral 55 denotes a magnetic tape for recording a signal, which runs at a predetermined speed while being obliquely wound around the rotary drum 56 by 180 degrees.

Reference numerals 57 and 58 are heads for recording and reproducing signals, and since the azimuth angles are different,
It is distinguished by R and L. These heads are mounted on the rotating drum 56 so as to face each other by 180 degrees.

Tracks 1 and 2 shown in FIG. 1 are recording patterns when the magnetic tape 55 is run at a normal speed by using the scanner of FIG. On the other hand, the 9 × speed head locus 3 is the head locus when only the tape feeding speed is set to 9 × speed. At this time, the R head 57
The L head 58 and the L head 58 cross nine tracks diagonally in one scan. Further, the head locus when the tape feeding speed is set to the triple speed is represented by the triple speed head locus 4, and each head crosses three tracks diagonally.

In FIG. 1, the portions painted black are
This is an area where the head commonly traces at 3 × speed and 9 × speed. If data to be used for high speed search is placed at this location, 3 × speed search and 9 × speed search can be performed. In addition, as the location where the head traces in common at the 3 × speed and the 9 × speed, the location 6 at both ends of the track shown in FIG. 2 can be considered. Furthermore, as shown in FIG.
The data may be arranged at both the locations of 6 and 6.

FIGS. 4 to 6 show the loci of the head at −3 × speed and −9 × speed. 7 is a -9x speed head locus, and 8 is a -3x speed head locus. From these FIGS. 4 to 6, it is possible to reproduce the data at the −3 × speed and −9 × speed at the places where the data can be reproduced at the 3 × speed and the 9 × speed shown in FIGS. 1 to 3.

These locations are not limited to the locations shown in the figure, and may be anywhere on the tape as long as the head traces commonly at various tape feed speeds. In any case, the track and location selected is
The track and place are selected periodically from the recording track. If the head azimuth is taken into consideration when the tape feed speed is an odd multiple speed of normal reproduction, R, L
It is efficient that the heads face each other by 180 degrees, but this is not the case. For example, two heads may be attached to one side of the drum. If the heads are facing 180 degrees,
Considering the head azimuth, the tape running speed is an odd Nth multiple speed, and there are many places where data can be reproduced commonly at each multiple speed, which is efficient, but is not particularly limited. Further, when the winding angle of the tape around the drum is different, the head locus is different, and accordingly, the data may be arranged at a location where the heads commonly trace.

FIGS. 7 and 8 are diagrams showing a tape pattern of the second embodiment of the present invention. This is an example in which the tape speed is 2 times the Nth power. At this time, as for the form of the scanner, it is preferable to collect two heads having opposite azimuths on one side of the drum, as in the configuration shown in FIG. In FIG. 15, reference numeral 56 is a rotary drum, 55 is a tape 59, 6
0 is heads R and L of mutually opposite azimuths, 61 and 62
Is an auxiliary head for reproduction. The auxiliary playback head may or may not be used.

FIG. 7 is a diagram showing head trajectories at 4 × speed and 8 × speed using the scanner configuration shown in FIG. 9 shows the head locus at 8 × speed, and 10 shows the head locus at 4 × speed. The area that is commonly traced at both speeds is the area indicated by 11.
Further, FIG. 8 shows head trajectories 13 and 1 at −4 × speed and −8 × speed.
2 is shown, and the commonly traced portions are the same as the 4 × speed and the 8 × speed. Therefore, if the data is arranged at the portions shown in FIG. 7, it can be used as both the forward direction data and the backward direction data.

These locations are not limited to the locations shown in the figure, and may be any location as long as the head traces commonly at various tape feeding speeds. In any case, the selected track and place are tracks and places periodically selected from the recorded tracks.
Further, when the tape feed speed is an even multiple speed of normal reproduction, it is efficient to mount the R and L heads together on one side in consideration of the head azimuth, but this is not the only option. For example, by mounting an auxiliary head for reproduction on the other side of the drum, the portion commonly traced at each speed during reproduction is enlarged to twice as large as in the case without the auxiliary head. .

When the reverse azimuth heads are collectively provided on one side of the drum, the tape running speed is a certain integer Nth multiple speed, and the data can be commonly reproduced at each double speed in consideration of the head azimuth. Many, efficient but not particularly limited. Further, when the winding angle of the tape around the drum is different, the head locus is different, and accordingly, the data may be arranged at a location where the heads commonly trace.

FIG. 9 shows an example of a block configuration for outputting a signal with the above-mentioned tape pattern. The input is assumed to be an analog video signal, but this is not the case. Hereinafter, the input signal will be described as an analog video signal. 15
Is an input terminal to which a recorded video signal is input. The input video signal is first converted by the AD conversion circuit 16 into a digital signal having a predetermined number of quantization bits at a predetermined sampling clock. Next, the digital data is subjected to predetermined signal processing in the signal processing circuit 17. The predetermined signal processing is, for example, processing by means for removing redundant components of the input image and compressing the image.

FIG. 10 shows an example of the compression means. This is a block diagram of a compression method using the motion compensation DCT method. The motion compensation DCT method compresses a frame selected periodically in the input image data using only the data in the frame, and regarding the remaining frames,
This is one of the methods of compressing and transmitting the difference from the previous frame, and the discrete cosine transform, which is one of the orthogonal prespecified transforms, is used for intraframe compression and interframe compression. Further, when calculating the difference between frames, the motion vector of the image with respect to the previous frame is detected, and the difference is calculated after matching the motions, thereby significantly improving the compression rate.

In FIG. 10, reference numeral 30 is an input terminal and 31 is a subtracter, which is used to calculate the difference from the previous frame image. Refresh switch 4 when compressing in frame
0 and 41 are off, and the subtractor 31 does not operate. The input image is input to the DCT circuit 32 and subjected to discrete cosine transform (DCT). The discrete cosine transform is usually
It is done in two dimensions. If the discrete cosine transform is performed in the unit of 8x8, a coefficient of 8x8 is also obtained as the transform result (Fig. 13a). The obtained coefficient has a direct current (DC) component in the upper left and is an average value of an image in an 8 × 8 block before conversion. Then, as shown in FIG. 13A, the DC component becomes a horizontal high frequency component in the right direction and a vertical high frequency component in the downward direction. Although each DCT-processed data is originally a continuous quantity, each of the 64 coefficients is obtained as a digital value of about 11 bits because it is operated using a digital circuit.

This data is then supplied to the quantization circuit 33,
Optimal bit allocation is made for each frequency component. Normal,
The low-frequency component is an important component that constitutes an image, so that the bit allocation is increased, and the high-frequency component is not so important in composing the image, so the bit allocation is reduced. Specifically, the quantization table as shown in FIG.
The optimum bit is assigned by dividing the coefficient after CT. In the example shown in FIG. 13B, since the DC component is divided by 8, the lower 3 bits are truncated. In this way, the optimum bit is assigned to each frequency component and becomes the output of the quantization circuit 33.

The output of the quantization circuit 33 is then subjected to variable length coding by the VLC circuit 42. What is variable length coding?
This is a method of assigning a short code length to data that has a statistically high probability of occurrence. By this method, the statistically redundant component of the data is removed. VLC may or may not be performed by the device and is appropriately selected. In this way, the intra-frame compressed data is output to the output terminal 43. The output of the quantization circuit 33 is the inverse quantization circuit 34.
Undoes the quantization.

The inverse quantization is the reverse of the quantization, as shown in FIG.
This is done by multiplying the quantization table in (b). As a result, the level of each frequency component is returned to the original level. Each coefficient returned to the original level by the inverse quantization is restored to the original image signal by using the inverse DCT circuit 35. The restored signal is delayed by one frame by the delay circuit 37 without operating the adder 36 when the image data is in-frame. The delayed image is the motion estimation circuit 3
At 9, the amount of motion from the input image is calculated, and the image is moved by the motion compensation circuit 38 based on the amount of motion to match the input image. In this way, the motion-compensated image is used by the subtracter 31 to calculate the difference from the next image.

Then, the images of the following several frames are in the operation of compressing the difference from the previous frame. The operation of the system is
This is the same as during intra-frame compression, but during inter-frame compression operation, the refresh switches 40 and 41 are turned on. The refresh switch 41 is turned on when calculating the difference between frames and is used to operate the subtractor 31. The refresh switch 40 is repeatedly turned on and off at the same cycle as 41. When on,
It is used to operate the adder 36, add the inter-frame difference data and the previous frame data, and restore the frame.

Then, if necessary, VLC is performed, and the intraframe compressed data and the interframe compressed data are periodically output to the output terminal 43 as output data. Normal,
The data order is output by zigzag scanning as shown in FIG. The intra-frame compression cycle is appropriately set according to the compression rate and the like.

The data subjected to the signal processing necessary for recording in this way is then transferred to the data shuffling circuit 18
Then, the order of the data is rearranged to the order of recording on the tape. The data shuffling circuit 18 is shown in FIG.
It is a circuit having the block configuration shown in FIG. In FIG. 11, 44 is an input terminal to which a signal is input. The input signal is first separated by the search data separation circuit 45 into the data to be recorded at the location traced by the head in common for each speed and other data as the high speed search data described above.

In the case of a video signal, the high-speed search data is preferably an important component that constitutes a video frame image. As the important component, a low-frequency component and high-order bit component of intra-frame data are considered. The separated search data and the other data are rearranged in the shuffling memory circuit 46 so that the recording pattern becomes the above-described pattern and output to the output terminal 47.

The data shuffled for high-speed search is added with an error correction code by an error correction code adding circuit 19 and then modulated by a modulation circuit 20 to be used for recording, and a recording head 21 is used. , Is recorded on the tape-shaped recording medium 22. The recording pattern is as described above.

At the time of reproduction, the data reproduced by the reproducing head 23 is demodulated by the demodulation circuit 24 and the error correction circuit 2
After the correctable error is corrected in 5, the data deshuffling circuit 26 restores the data arrangement. The data deshuffling circuit 26 is the data shuffling circuit 18.
It plays a role of returning the high-speed search data and other data periodically arranged on the track on the tape to the original arrangement. The data whose order has been restored by the data shuffling circuit 26 is restored to the original image by the video signal processing circuit 27.

The video signal processing circuit 27 is a circuit which performs a process reverse to that of the video signal processing circuit 17. The image restoration circuit corresponding to FIG. 10 is shown in FIG. In FIG. 12, although the VLC processing is not performed on the recording side, the decoding (VLD) block of variable length coding is not shown,
When VLC is performed, VLD is required first.

The data input from the input terminal 48 is quantized by the inverse quantization circuit 49 after being subjected to VLD processing if necessary. The inverse quantization circuit 49 has the same configuration as the inverse quantization circuit 34 used at the time of recording. The quantized data is then subjected to inverse discrete cosine transform in the IDCT circuit 50. When the output data of the IDCT circuit 50 is the intra-frame compressed data, the adder 51 does not operate. In the case of inter-frame difference data, the restoration signal output to the output terminal 54 is delayed by one frame in the delay circuit 52, and after the motions are matched in the motion compensation circuit 53, added to the output data of the IDCT circuit 50. , The frame image is restored and output to the output terminal 54. Finally, this signal is converted back to the original analog video signal by the DA conversion circuit 28 and output to the output terminal 29.

At the time of high speed search, only the high speed search data may be reproduced by the above-mentioned reproducing means. In addition to the intra-frame image signal, the high-speed search data may be any signal necessary for the search, such as a signal indicating the time of data. In this case, the signal processing circuit 17 for recording and reproducing,
Each of 27 may be a circuit corresponding to the signal content. Also, an identification code is added to the search data,
Therefore, if the contents of the data can be discriminated, the degree of freedom is increased and the device can be provided with versatility.

As described above, in the present embodiment, since the variable speed reproduction data is arranged at the position where the head commonly traces at each reproduction speed, the necessary data can be obtained at various reproduction speeds.

[0044]

As described above, according to the present invention, data required for high-speed reproduction of three or more kinds of speeds including 1x speed is arranged at a position where the head always traces at all determined speeds. By doing so, it is possible to obtain the necessary data during high-speed search. For example, it is possible to obtain a reproduced image at a plurality of speeds with a digital VTR of a type that records image data compressed using a variable length coding technique, which has been very difficult in the past.

[Brief description of drawings]

FIG. 1 is a tape pattern diagram showing a head trace at a 3 × speed and a 9 × speed according to an embodiment of the present invention and a position where a head traces in common.

FIG. 2 is a tape pattern diagram showing head trajectories at 3 × speed and 9 × speed according to another embodiment of the present invention, and a position commonly traced by the head.

FIG. 3 is a tape pattern diagram showing head trajectories at 3 × speed and 9 × speed according to still another embodiment of the present invention, and a position commonly traced by the head.

FIG. 4 is a tape pattern diagram showing head trajectories at −3 × speed and −9 × speed of one embodiment of the present invention, and a position where the head commonly traces.

FIG. 5 is a tape pattern diagram showing head trajectories at −3 × speed and −9 × speed according to another embodiment of the present invention and a position where the head traces in common.

FIG. 6 is a −3 × speed and −9 of yet another embodiment of the present invention.
Tape pattern diagram showing the head trace at double speed and the position where the head traces in common

FIG. 7 is a tape pattern diagram showing head trajectories at 4 × speed and 8 × speed according to one embodiment of the present invention, and a position commonly traced by the head.

FIG. 8 is a tape pattern diagram showing head trajectories at −4 × speed and −8 × speed according to one embodiment of the present invention, and a position where the head commonly traces.

FIG. 9 is a block diagram of an apparatus for implementing the present invention.

FIG. 10 is a block diagram showing a compression means by a motion compensation DCT method.

FIG. 11 is a block diagram showing a data shuffling circuit.

FIG. 12 is a block diagram showing a restoration unit based on a motion compensation DCT method.

13A is a conceptual diagram showing data after discrete cosine transform and zigzag scanning, and FIG. 13B is a conceptual diagram showing a quantization table.

FIG. 14 is a configuration diagram showing a scanner and a tape used as an example in the present invention.

FIG. 15 is a configuration diagram showing a scanner and a tape used as an example in the present invention.

FIG. 16 is a tape pattern diagram showing a conventional example.

[Explanation of symbols]

1, 2 Helical scan track 3 9x speed head locus 4 3x speed head locus 5, 6 Location where head is traced commonly at 3x speed and 9x speed 7-9x speed head locus 8-3x speed head locus 9 8x speed head locus 10 4x speed head locus 11 Where the head traces in common at 4x speed and 8x speed 12-8x speed head locus 13-4x speed head locus 14 Where the head traces commonly at 4x speed and 8x speed 11 4x speed head locus 5 , 6 Where the head traces in common at 3x and 9x speed 6 Where the head traces in common at 3x and 9x speed 15, 30, 44, 48 Input terminal 21 Recording head 22, 55 Recording tape 23 Playback head 29 , 43, 47, 54 Output terminals 31, 51 Subtractor 32 Adder 56 Rotating drum 57, 59 R head 58, 6 L head 62 auxiliary R head 61 auxiliary L Head

Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location H04N 5/92 H 4227-5C

Claims (8)

[Claims] 1. A head mounted on a rotating drum,
A signal recording / reproducing apparatus which divides a digital signal into a plurality of tracks on a tape-shaped recording medium and records / reproduces by helical scanning, wherein the speed of the tape-shaped recording medium is three or more kinds including N speeds. The signal characterized by arranging digital data required for variable-speed reproduction at a certain position on the track which the reproducing head always passes at the medium speed, and reproducing the necessary data at N kinds of medium speeds. Recording / playback device. 2. A track for recording / reproducing digital data required for variable-speed reproduction is a track selected periodically from a plurality of tracks recorded / reproduced on a tape-shaped recording medium. Claim 1 characterized by the above-mentioned.
The described signal recording / reproducing apparatus. 3. Data recorded / reproduced at a certain position on a track which a reproducing head always passes at three or more medium speeds including 1 × speed at a ratio of one screen to a plurality of video signal screens. 3. The signal recording / reproducing apparatus according to claim 1, wherein the image data constituting the frame or field intermittently extracted or a part of the image data in the frame or field. 4. Data to be recorded / reproduced at a certain position on a track which the reproducing head always passes at N or more medium speeds including three speeds including 1 × speed, after performing orthogonal base conversion on the video signal, and after conversion. 2. The data after being quantized with a certain quantization width in the amplitude direction with respect to each coefficient of 1. and the data including most of low-frequency components forming an image. 4. The signal recording / reproducing device according to any one of 1 to 3. 5. The signal recording according to claim 3, wherein the quantization width in the amplitude direction of the signal at the high speed reproduction is larger than the quantization width in the amplitude direction of the signal at the 1 × speed reproduction. Playback device. 6. The signal recording / reproducing apparatus according to claim 4, wherein the orthogonal basis transform is a discrete cosine transform. 7. Data to be recorded / reproduced at a certain position on a track which a reproducing head always passes at three or more medium speeds including 1 × speed includes time information of the data recorded on the medium. The signal recording / reproducing apparatus according to claim 1, wherein the signal recording / reproducing apparatus is a signal. 8. An identification signal representing the content of reproduced data is included in data recorded / reproduced at a position on a track which a reproducing head always passes at a plurality of medium speeds. 8. The signal recording / reproducing apparatus according to any one of 1 to 7.