JPH0970005A - High speed reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an output of a video image of the same degree of image quality in the cue operation and the review operation by providing a means driving a recording medium at a recording medium drive speed expressed respectively by each specific formula in the cue operation and the review operation. SOLUTION: Heads 4a, 4b are fitted to a cylinder 3 and a drive means 2 drives a magnetic tape 1 in which one plane of image data are dividedly recorded on M-tracks. In this case, the recording medium is driven at a speed of L=(M-α)×W at a forward high speed reproduction and at a speed of L=(M+α)×W at a reverse high speed reproduction, where W is a track width, a is a preset constant, and L is a vertical direction component of a locus of a center line of the heads drawn on the tape 1 with respect to a track by one helical scanning.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high speed reproducing apparatus used for a digital video tape recorder or the like for reproducing and outputting an image at a speed higher than a normal speed.

[0002]

2. Description of the Related Art In recent years, with the development of magnetic recording / reproducing technology and highly efficient compression technology of image data, video tape recorders have been digitized. These devices are required to realize not only normal recording / reproducing but also high-speed reproducing operation as realized by VHS. But,
In general, in a tape recording / reproducing system using heli-cal scanning of compressed digital image data, the image quality of high-speed reproducing operation is not desirable, and improvement of the image quality is an important issue. Therefore, many proposals for improvement have already been submitted, but they can be roughly classified into two types: a method of recording special data for high-speed reproduction and a method of high-speed reproduction using only normal recording / reproduction data. .

As a method for recording special data for high speed reproduction, a method using two kinds of compression ratios (Japanese Patent Laid-Open No. 63-
No. 179679), a method of providing a high-speed reproduction-only track separately from the heli-cal scan track (Japanese Patent Laid-Open No. 4 (1998) -54991).
No. 325969), a system for recording high-speed reproduction data in a sub data area (Japanese Patent Laid-Open No. 4-346584), and the like. These systems require dedicated hardware for generating dedicated data for high-speed reproduction, and cannot take full advantage of the recording density on the tape when focusing on normal reproduction.

On the other hand, as a method for high-speed reproduction using only normal recording / reproduction data, shuffling and deshuffling are used to rearrange data so that data at the same time are adjacent to each other on the screen to improve high-speed reproduction image quality. However, there is a method (for example, JP-A-5-252476 and JP-A-5-266597) that is compatible with the image quality of normal reproduction by expanding only the basic data portion that can be expanded by a single data block during high-speed reproduction. is there. This system does not require special hardware for generating and recording dedicated data for high speed reproduction. The HD DIGITAL VCR CONFERENC (HD DIGITAL VCR CONFERENC) is a standard for digital video tape recorders that adopt the latter method.
E) Specification of Consumer
Youth Digital VCRs, Eusings, 6.3 mm
・ Magnetic tape (Specification of Consume
r-Use Digital VCRs Using 6.3mm Magnetic Tape (hereinafter abbreviated as DVC format) has been proposed.

A conventional example of a basic high-speed reproducing apparatus based on the DVC format will be described below.

FIG. 10 is a block diagram showing the structure of this conventional high-speed reproducing apparatus. In FIG. 10, the magnetic tape 1
Is a magnetic tape drive unit 10 that can be driven at normal speed and high speed.
Driven by 2 and a set of heads 4a of the cylinder 3
4b, and the output data block is connected to the error correction unit 5 via the terminal A. The correction output of the error correction unit 5 is stored in the memory 7 via the capture selection switch 6 that opens / closes according to the correction result. The data block selected and read from the memory 7 is decompressed by the decompression processing unit 8 and then temporarily stored in the output memory 9 and output from the terminal B as an image.

With respect to the conventional high-speed reproducing apparatus having the above-mentioned structure, the recording form on the magnetic tape 1 will be described first, and the operation will be described in the forward high-speed reproducing operation (hereinafter abbreviated as queue operation) and reverse operation. A high-speed playback operation in one direction (hereinafter referred to as a review operation) will be sequentially described.

In the conventional example, the recording form of the magnetic tape 1 is based on the above-mentioned DVC format. First, the recording form of the magnetic tape 1 and the output image will be described with reference to FIGS. 2, 3, and 4. The correspondence will be described. FIG. 2 is a shape diagram showing a recording form of the magnetic tape 1. One frame of image data is composed of 1350 data blocks, and on the magnetic tape 1, as shown in FIG. 2, it is divided and recorded in 10 tracks. Each track contains 135 data blocks. The data block (0, 1) in the figure means the first data block of the 0th track. According to the DVC format, data blocks of audio data and accompanying information other than image data are recorded on the magnetic tape 1, but this is omitted because it has no direct relationship with this conventional example.

FIG. 3 is a structural diagram showing the structure of a one-frame screen. The screen of one frame in FIG. 3 is divided into rectangular areas called 1350 macroblocks, and each macroblock corresponds to a data block on the magnetic tape 1 in FIG. Further, 135 data blocks recorded on one track on the magnetic tape 1 correspond to macroblocks aligned in one strip-shaped area on the screen as shown in FIG. FIG. 4 is a structural diagram showing a form of data compression in a video segment composed of five macroblocks.

In FIG. 4, one video segment includes a data block (0, 1), a data block (6, 28),
Data block (2, 55), data block (8, 8)
2), which corresponds to the video segment corresponding to the data block (3, 109), which is composed of five macroblocks that are in a positional relationship apart from each other on the screen as shown by the hatched portion in FIG. In addition, the video segment is divided into data of 30 compression units in FIG.
Data of 6 compression units is stored in one data block. Each compression unit is composed of basic data and high frequency data, and the high frequency data is divided and stored from one data block to a free area of another data block of the same video segment as indicated by an arrow X in the figure. There is. Therefore, if decompression processing is performed using all compressed data consisting of basic data and high frequency data to restore the original image, five data blocks included in the video segment are reproduced from the same frame of the magnetic tape 1. Must be in line.

On the other hand, when five data blocks are not aligned from the same frame, such as in the case of high-speed reproduction, decompression processing is performed by using only basic data without using high-frequency data to obtain a restored image. You can

Next, as a conventional operation, a cue operation will be described. Now, it is assumed that the magnetic tape drive unit 102 drives the magnetic tape 1 at a speed 9.5 times the normal speed, and the rotation speed of the cylinder 3 is the same speed as in the normal reproduction. FIG. 11 shows scan loci for two scans drawn on the magnetic tape 1 by the center points of the heads 4a and 4b. In FIG. 11, the locus of the head 4a is drawn by a half rotation of the cylinder 3, and the locus of the head 4b is drawn by a subsequent half rotation of the cylinder 3. Since the drive speed of the magnetic tape 1 is 9.5 times, a certain head locus traverses 9.5-1 = 8.5 tracks, and the track number corresponding to the start position of each scan. Is 9.5-10 = -0.5, that is, it decreases by 0.5. Assuming that the tracks on the magnetic tape 1 are generated with even azimuth angles for even-numbered tracks and minus azimuth angles for odd-numbered tracks, respectively, and the head 4a has a plus azimuth angle and the head 4b has a minus azimuth angle. In the two scans shown in (1), the data block in the hatched portion is reproduced from the magnetic tape 1.

The error correction unit 5 inputs the reproduced data block, performs error correction processing in data block units, and fetches the corrected data block to select the switch 6.
In addition, when the reliability of the corrected data block after processing is sufficient, the fetch selection switch 6 is turned on, and when it is determined that the reliability is low, the fetch selection switch 6 is turned off. That is, the data blocks that have undergone the error / error correction processing are stored in the memory 7 only via the selection switch 6 without error.

FIG. 12 is a distribution diagram of data blocks stored in the memory 7. As in FIG. 3, FIG. 12 is drawn corresponding to the positional relationship on the screen. 2 shown in FIG.
A reproduced data block obtained by scanning a plurality of times is stored on the memory 7 in a hatched portion in FIG. 12, that is, in a belt-shaped region that is sloping down to the right in correspondence with the relationship between the locus of the head and the azimuth angle. Further, by repeating the scan 20 times, the entire state of FIG. 12 is obtained, and the data of one entire frame is updated on the memory 7. In addition, the strip-shaped area that is updated each time one scan advances moves up and down on the screen by 0.5 track width.

The decompression processing unit 8 sequentially reads the data blocks from the memory 7, performs decompression processing, and transfers the image data as the decompression result to the output memory 9. The signals for two fields of the image are sequentially output from the output memory 9 via the terminal B according to the interlace definition. Here, the decompression processing of the decompression processing unit 8 is in units of video segments in FIG. 4, and as described above, since the high frequency data is not used and only the basic data is decompressed, the data blocks of the same frame are arranged. Even in a high-speed playback operation that does not exist, the expansion processing can be performed without any failure and the image data can be expanded normally. As shown in the hatching in FIG. 3, one video segment is composed of five separated data blocks for one frame.

FIG. 5 is a diagram showing the order of data blocks read from the memory 7 by the decompression processing unit 8. In FIG. 5, the decompression processing unit 8 reads out the data blocks in the order of numbers in the drawing,
The decompression process is executed in units of five data blocks, and the data blocks are transferred to the corresponding position in the output memory 9. The decompression processing unit 8 reads the data for one frame and the decompression process is completed in the time of one frame of image output, that is, about 1/3 in the case of NTSC
It takes 0 seconds. To summarize the characteristics of the reading order of the 1-frame data, the screen is read from top to bottom with one frame time as shown by the arrow in FIG.

FIG. 13 shows the image output frame and the head 4.
6 is a timing chart showing the timing relationship of scans a and 4b. In FIG. 13, while the decompression processing unit 8 is reading the data for one frame, the head 4a and the head 4b each perform five times, a total of 10 times.
Are scanning. The scanned data block is also stored in the memory 7, so the memory 7
The reading of the data block by the decompression processing unit 8 and the writing of the data block by the error processing unit 5 are simultaneously executed in parallel. As a result, the state of the memory 7 at the moment shown in FIG. 13C is composed of diagonal combinations of data blocks over 20 frames on the magnetic tape 1 as shown in FIG. At the timing of D in FIG. 13 after the completion of scanning, the newly obtained data blocks of frame number 21 to frame number 30 are stored, so the memory 7 stores 20 frames of data of frame number 11 to frame number 30. Will be configured. If the data block input in the period C to D in FIG. 13 is stored in the memory 7 faster than the data block at the corresponding position in the memory 7 is read to the decompression processing unit 8, the data block D At the timing, it is also transferred to the output memory 9. On the other hand, when the data is stored in the memory 7 later than being read by the decompression processor 8, the old data block has been transferred to the output memory 9. In this way, since the input and output images are executed in parallel for the same memory, the mutual relationship causes
The state of the output memory 9 at the timing of D is the magnetic tape 1
It will be composed of a combination of the above data blocks for about 30 frames.

As described above, in the conventional queue operation, the error correction unit 5 writes a data block on a single surface of the memory 7 and the decompression processing unit 8 reads the same surface,
Despite the operation of obliquely scanning the image-compressed recording type magnetic tape 1 over a plurality of tracks,
The data block reproduced by using the memory 7 is reconstructed, and the data at the same time is arranged in the proximity portion on the screen, so that a high-speed reproduction image can be output.

Next, the review operation will be described. The review operation differs from the cue operation in that the magnetic tape drive unit 2 drives the magnetic tape 1 and the head 4
a and 4b are the scan loci drawn on the magnetic tape 1, the overall configuration of the data stored in the memory 7, and the overall configuration of the data stored in the output memory 9, and the operation of each of the other parts is the cue operation described above. Exactly the same.

FIG. 8 shows the scanning loci of two times the center points of the heads 4a and 4b are drawn on the magnetic tape 1. It is assumed that the magnetic tape drive unit 102 is driving the magnetic tape 1 in the opposite direction to the normal reproduction at a speed 9.5 times that of the normal reproduction, that is, -9.5 times. At this time,
In FIG. 8, since the drive speed of the magnetic tape 1 is -9.5 times, the locus of one head is -9.5-1 = -10.5.
Book, that is, 10.5 tracks,
The direction is opposite to that of the cue operation in FIG. The track number corresponding to the start position of each scan is increased by -9.5 + 10 = 0.5, that is, by 0.5. FIG. 9 is a structural diagram of data stored in the memory 7 as a result of this scan. The hatched portion in FIG. 9 shows the distribution of the data blocks stored in the two scans in FIG. By repeating the scan 20 times, the entire state of FIG. 9 is obtained, and the data of one entire frame is updated on the memory 7. The order of reading the data blocks from the memory 7 of the decompression processing unit 8 is
It is exactly the same as in the case of the above cue, as shown in FIG.
As a result, the image data is output to the output memory 9 and is composed of data blocks of 30 frames including frame numbers 0 to 29.

[0021]

However, since the above-described conventional configuration is a configuration in which the data block is read and output from the memory 7 in parallel with the writing of the data block to the memory 7, there is a mutual relationship between the input order and the output order. Affects the quality of the output image. In queue operation, memory 7
As shown in FIG. 12, the position of the data block to be written to is a strip-shaped area that is downward to the right, and the area moves upward by 0.5 tracks for each scan, but in the review operation, as shown in FIG. The strip-shaped area that rises to the right moves downward by 0.5 tracks for each scan. That is, in the cue operation and the review operation for each scan, the movement of the position of the data written in the memory is in the opposite direction. On the other hand, the read order of the data read from the memory 7 for screen output is always from the top to the bottom of the screen as shown in FIG. There is a problem in that the image quality of the output image differs visually depending on the review operation.

The present invention solves the above problems.
It is an object of the present invention to provide a high-speed device capable of outputting images of similar image quality in the cue operation and the review operation.

[0023]

In order to achieve this object, an image correction apparatus of the present invention is a tape-shaped recording in which image data on one surface is divided and recorded in M tracks having a track width W. When a constant α is set in advance for the medium and the center line of the head is the vertical direction component L with respect to the track of the trace drawn on the recording medium by one helicoptal scan, L is set during forward high speed reproduction (cue operation). = (M-α)
× W, and L = during high-speed reverse playback (review operation)
This is a configuration including drive means for driving at a recording medium transfer speed of (M + α) × W.

[0024]

According to the present invention, the writing position for each scan in the memory for the queue operation and the review operation is moved by the same amount in the same direction, that is, the upward direction or the downward direction. The influence of the mutual relationship is the same, and the image quality of the cue operation and the image quality of the review operation are similar.

[0025]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a block diagram of a high-speed reproducing apparatus according to an embodiment of the present invention. The configuration of this embodiment is different from the configuration of the conventional example of FIG. 10 described above only in that the magnetic tape drive unit 2 having a different drive speed of the magnetic tape 1 is used. The same components are assigned the same reference numerals and explanations thereof are omitted.

With respect to the high-speed reproducing apparatus of the present invention configured as described above, a forward high-speed reproducing operation (cue operation),
The reverse high-speed reproduction operation (review operation) will be sequentially described below.

First, the cue operation will be described. Now, it is assumed that the magnetic tape drive unit 2 drives the magnetic tape 1 at a speed 10.5 times the normal speed, and the rotation speed of the cylinder 3 is the same speed as in the normal reproduction.

FIG. 6 shows a scan locus for two times drawn on the magnetic tape 1 by the center points of the heads 4a and 4b. The locus of the head 4a in FIG.
, And the locus of the head 4b is drawn by the subsequent half rotation of the cylinder 3. Now, the speed of 10.5 times is set to a value of α = 0.5 with respect to one frame composed of a track width W and M = 10 tracks, and is perpendicular to a certain head miraculous track. Component L is L
= (10-0.5) × W = 9.5W. As a result, the trace of one head is 10.
5-1 = 9.5 tracks are crossed, and the track number corresponding to the start position of each scan is 10.
5-10 = 0.5, that is, it increases by 0.5.

FIG. 7 is a distribution diagram of data blocks stored in the memory 7. The data block obtained by one scan is stored in the strip-shaped area on the lower right side shown in FIG. 7, and the strip-shaped area is moved downward by 0.5 tracks for each scan. Become. The decompression processing unit 8 reads out the data from the memory 7 in the order shown in FIG. 5 and outputs the video for high-speed reproduction through the output memory 9, which is exactly the same as the conventional example.

Next, the review operation will be described. In this embodiment, the review operation is exactly the same as the review operation of the conventional example described above. Now, the magnetic tape drive unit 2 drives the magnetic tape 1 at -9.5 times the normal speed. FIG. 8 shows a scan locus for two times in which the center points of the heads 4a and 4b are drawn on the magnetic tape 1. Now, the speed of -9.5 times is set to be the vertical direction for one head miraculous track, with a track width W and α = 0.5 for one frame composed of 10 tracks. The component L is L = (10 + 0.5) × W
This means that the setting is = 10.5W. As a result, one head locus is -9.5-1 = -10.5.
This means that the number of tracks, that is, 10.5 tracks is crossed, and the track number corresponding to the start position of each scan is increased by -9.5 + 10 = 0.5, that is, 0.5. FIG. 9 is a distribution diagram of the data blocks stored in the memory 7, but the data is stored in the upward-sloping strip-shaped area shown in FIG. 9 by one scan, and the strip-shaped area is 0. It will move down by 5 tracks.

In both the queue operation and the review operation, the data block is read from the memory 7 and output in parallel with the writing of the data block in the memory 7, so that the mutual relationship between the input order and the output order is obtained. Affects the image quality of the output image as in the conventional example. However, according to the present embodiment, in the cue operation, the position of the data block to be written in the memory 7 is moved downward by 0.5 track for each scan as shown in FIG. 7, and in the review operation, it is also shown in FIG. To move down by 0.5 tracks. That is, in the cue operation and the review operation for each scan, the movement of the position of the data written on the memory is in the same direction, and the movement amount is the same.
Therefore, the order of reading from the memory 7 for screen output,
The influence of the mutual relation of the writing order becomes the same in the cue operation and the review operation, and it is possible to obtain the output image of the same visual quality.

In the present embodiment, α = 1.5, and the locus may be L = (10−1.5) × W in the queue operation and L = (10 + 1.5) × W in the review operation. In that case, the speed setting is 9.5 times speed for the cue operation and 10.5 times speed for the review operation, and the movement amount of the locus for each scan is 0.5 track upward in both the cue operation and the review operation.

[0034]

As described above, according to the present invention, a preset constant α is set for a tape-shaped recording medium in which image data of one surface is divided into M tracks having a track width W and recorded. When the center line of the head drawn on the recording medium by one helicopter scan is L in the vertical direction with respect to the track, L = (M-α) × W during forward high-speed reproduction (cue operation) In addition, by providing a driving unit that drives at a recording medium transfer speed of L = (M + α) × W during high speed reverse playback (review operation), the writing position in the memory for each scan of the cue operation and the review operation can be set. In both cases, the same amount of movement is performed in the same direction, either upward or downward. Therefore, the effect of the mutual relationship between the input order and the output order on the memory is about the same, and the images of the queue operation and the review operation are similar. It is possible to achieve quality and realize natural video output without any discomfort.

Further, since it can be realized at an extremely low cost without requiring special hardware for it, its effect is particularly great in the consumer field.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a high-speed playback device according to an embodiment of the present invention.

FIG. 2 is a shape diagram showing a recording form of a magnetic tape 1.

FIG. 3 is a structural diagram showing the structure of a one-frame screen.

FIG. 4 is a structural diagram showing a form of data compression.

FIG. 5 is a structural diagram showing a reading order of data blocks.

FIG. 6 is a shape diagram showing a scan locus of a center point of a head in a cue operation.

FIG. 7 is a structural diagram of data stored in a memory 7 by a queue operation.

FIG. 8 is a shape diagram showing a scan locus of the center point of the head in the review operation.

FIG. 9 is a structural diagram of data stored in the memory 7 in a review operation.

FIG. 10 is a block diagram of a conventional high-speed playback device.

FIG. 11 is a shape diagram showing a scan locus of the center point of the head in the cue operation.

FIG. 12 is a structural diagram of data stored in the memory 7 by a queue operation.

FIG. 13 is a timing chart of an image output frame and head scanning.

[Explanation of symbols]

 1 magnetic tape 2 magnetic tape drive unit 3 cylinders 4a, 4b head 5 error correction unit 6 capture selection switch 7 memory 8 expansion processing unit 9 output memory

Claims (1)

[Claims] 1. A cylinder, a head attached to the cylinder, and a drive unit for moving a tape-shaped recording medium in which image data of one surface is divided and recorded in M tracks, and the drive is provided. When the width of the track is W, a preset constant is α, and a vertical direction component of a track drawn by the center line of the head on the recording medium with respect to the recording medium by one helicoptal scan is L, L for fast forward playback
= (M-α) × W, and L = (M +
A high-speed reproducing device driven at a recording medium transfer speed of α) × W.