JPH1051731A - Video signal storage system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To learn the content of a recorded medium without reproduction by extracting pictures from a video signal during recording at every prescribed time one by one, generating the pictures reduced at a constant rate, sequentially storing them in the prescribed positions of a memory and constituting the picture constituted of the plural reduced pictures extracted until recording terminates. SOLUTION: An input signal converted in an AC converter 2 is written into a field memory 4 by a write circuit 3. At that time, only a field which an extraction timing generator 14 selects is written. When writing completes, a thinning/ read circuit 5 thins and reads data. Data is compressed in a data compression circuit 6 and it is written into the prescribed position of a memory 7. At the time of writing, numbers from a tape number generator 13 are given in accordance with respective tapes. The input signal is inputted to a recording/ reproduction device 12, regular recording is executed and the tape numbers are multiplexed and are recorded in the tape.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a storage system for video signals, and more particularly to a storage system for knowing the contents of a medium recorded by a recording apparatus using a tape-shaped storage medium without reproducing the medium.

[0002]

2. Description of the Related Art The most primitive method of knowing the recorded contents of a medium recorded by a recording device is to fill in a label and attach it. This method requires the user to fill out each time.However, in order to avoid the complexity, the video tape recorder also uses a method of automatically storing the recording conditions at the same time as recording in the internal memory. ing.

[0003]

In the prior art, the conditions at the time of recording by a video tape recorder, that is, channel number, recording date and time, stereo or mono, tape speed, and the like are mainly used. Related information could not be targeted. For this reason, the recorded contents can only be inferred from these supplementary information, and have to be said to be insufficient in practical value.

[0004] On the other hand, the problem that the contents of a recorded tape cannot be understood by reproduction is caused by the problem of increasing the number of tapes whose contents are unknown even in ordinary households. The fact is that it is being done. The present invention has been made in view of such problems of the related art,
An object of the present invention is to provide a video signal storage system that allows the user to know the content of a recorded medium without reproducing the content.

[0005]

In order to achieve the above-mentioned object, an image is extracted one by one from a video signal being recorded at a predetermined time interval, and an image reduced at a predetermined ratio is formed at a predetermined position in a memory. In order to form an image composed of a plurality of reduced images extracted until the recording is completed.

It is also an effective method to determine the sampling interval from a predetermined recording time according to the number of reduced images that can be accommodated in one image. It is also effective to assign a number to the tape at the time of recording by the video tape recorder and to assign a corresponding number to an image composed of a plurality of reduced images extracted during the recording.

[0007] Further, a frame data selecting means is provided in a recording apparatus using a moving picture compression system using both motion compensation inter-frame prediction and DCT, and only intra-frame coded frame data is taken out and data thinning is performed in DCT block units. It is also effective to make a reduced image. Furthermore, image data and D
In a method of compressing and reducing using a CT and storing in a memory, it is also effective to set the DCT coefficient corresponding to the frequency at which aliasing occurs to 0.

[0008]

In a video tape recorder equipped with a video signal storage system configured as described above, when a tape recorded by the machine is inserted, the contents are recorded at a fixed time interval during recording. Since a plurality of reduced images that have been captured in the built-in memory as still images can be formed into one image and read out, the entire outline can be viewed on a multi-screen without playing the tape.

When the recording time is known in advance, the interval of extracting images is determined according to the number of reduced images that can be accommodated in one image. Images are evenly extracted from almost the entire recorded content. Therefore, there is no bias in the contents of the multi-screen, and it is easy to grasp at a glance the whole. Also, by assigning a number to a tape during recording by a video tape recorder, the number can be automatically read when the tape is inserted after recording, and a multi-screen can be automatically displayed from the memory of the corresponding number.

[0010] In a video recorder using a motion picture compression system that uses both motion compensated inter-frame prediction and DCT, a frame data selection means for extracting only intra-frame coded frames is provided, and data thinning is performed in units of DCT blocks. By doing so, a reduced image can be created. Also, if the image data is DC
In the method of compressing and reducing using T and storing in a memory, filtering can be performed by setting the DCT coefficient corresponding to the frequency at which aliasing occurs to 0.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 is a block diagram of a video tape recorder embodying the present invention. FIG. 2 is a view for explaining the structure of image data when forming a 16-divided multi-screen according to the embodiment of the present invention.

A video signal is input from the input terminal 1 and
It is guided to the converter 2, the sampling timing generator 14 and the recording / reproducing device 12. For convenience, the line from the input terminal 1 is written with one line each, but the signal input to the AD converter 2 is usually Y,
There are three types of signals such as Cr, Cb or R, G, B,
The AD converter 2 is also configured to correspond to each signal. For example, in the case of R, G, and B inputs, three AD converters having equivalent functions are generally used.

The input signal converted into a digital signal by the AD converter 2 is written to the field memory 4 by the writing circuit 3. At this time, the writing circuit 3 is driven by a sampling signal for one field generated by the sampling timing generator 14 in synchronization with the input signal. Therefore, sampling timing generator 1
Only the field selected by 4 is written to the field memory 4.

When writing of the input signal to the field memory 4 is completed, the input signal is thinned out and read out by the thinning-out reading circuit 5. The method of subtracting the time is, for example, 1/4 in the horizontal direction and 1/2 in the vertical direction in the case of a 16-divided multi-screen. The thinned-out data enters the data compression circuit 6 and is compressed and written to a predetermined position in the memory 7. Normally, data summation requires a product-sum operation and takes a long processing time. However, in the present invention, there is no problem because the next image is sampled at regular intervals and data is compressed.

At the time of writing, a number from a tape number generator 13 is assigned to the memory 7 in correspondence with each tape. This number is automatically generated internally and is finite, but if you secure a number corresponding to the number of tapes to be recorded and stored, it will not be touched to return to the beginning when it reaches the upper limit.

On the other hand, the input signal enters the recording / reproducing apparatus 12 where normal recording is performed and the tape number output from the tape number generator 13 is multiplexed and recorded on the tape. This multiplexing method includes, for example, a method of inserting a video signal in a vertical blanking period and a method of inserting a video signal in a control track.

Next, when the tape on which the tape number is written is inserted into the recording / reproducing apparatus 12, the apparatus reads the number and transfers it to the memory 7 via the tape number generator 13. The memory 7 sequentially reads out the memory contents of the designated tape number and sends it to the data decompression circuit 8. The circuit has a function of restoring compressed data and writes data to the frame memory 9. When all the data has been written, the contents are repeatedly read at the speed of a normal video signal, converted into an analog video signal by the DA converter 10, and output to the output terminal 15 via the switch 11.

Next, the structure of the image data will be described with reference to FIG. The field memory 4 may have approximately 640 horizontal pixels and 240 vertical lines in a normal television signal. The number of lines in the vertical direction is 525 in the case of the NTSC system, but is 262.5 in the field unit due to interlace. Therefore, here, 640 × 480 used on the computer screen will be used and the number of lines will be described as half the number, ie, 240. This figure is an explanatory diagram when a reduced image is configured into a 16-divided multi-screen.

The data of 640.times.240 pixels written to the field memory 4 is thinned out to 1/4 in the horizontal direction and 1/2 in the vertical direction to create image data having 160.times.120 pixels. As a result, the sampling frequency will drop, so in order to remove aliasing in both the horizontal and vertical directions,
It is desirable to include an aliasing filter (not shown). The thinned data is compressed into N-byte data. Here, N differs depending on the compression method and degree.

For example, in a compression method using DCT (Discrete Cosine Transform) and a Huffman code, which is referred to as a JPEG method, a single still image is often reduced to about 50 kilobytes. Therefore, in 16 divisions, it is expected to be about 3 kilobytes per sheet. Of course, since this value greatly changes depending on the image itself, it cannot be said unconditionally.

The data compressed to N bytes is stored in the memory 7
This memory is sorted by tape number, and storage locations are prepared from No. 1 to No. 16 and stored in order. When data is read from the memory 7, the data is read from the tape number 1 to 16 in the order, expanded by the data expansion circuit 8 and written to a predetermined position of the frame memory 9.

The expanded data is 160 × 12 before compression.
However, when this data is written to the frame memory 9, the number of lines in the vertical direction is set to 1 in the interlace method.
/ 2 is written in the first field and the remaining half is written in the second field to compose a frame. Of course, in the case of the sequential scanning method, it is not necessary to thin out the data, and it is sufficient to write the data for 120 lines as it is.

Writing to the frame memory 9 is performed in such a manner as to assemble a 16-divided image as shown in FIG. When reading out the frame memory 9, scanning is performed from the upper left to the right in the same procedure as that of the normal frame memory.
A split multi-screen signal is output.

FIG. 3 shows a VT using the so-called MPEG system in which the present invention uses both motion compensation inter-frame prediction and DCT.
It is a general | schematic explanatory block diagram of the Example applied to R. A digital video signal is input to an input terminal 19, and motion compensation is performed by a motion estimation circuit 20, a DCT circuit 21, a quantization circuit 22, an inverse quantization circuit 26, an IDCT (inverse DCT) circuit 25, a frame memory predictor 24, and the like. Discrete cosine transform quantization is performed by performing inter-frame prediction.

The signals produced here are of three types: intra-coded frames (called I pictures), forward predicted coded frames (called P pictures), and bidirectional predicted coded frames (called B pictures). is there. The I picture is coded only in one frame, the P picture is restored together with the I picture data, and the B picture is
This is a frame restored using picture data.

The output of the quantization circuit 22 enters the variable length coding circuit 23, and an MPEG code is obtained. Usually VT
This code is used when an image signal is transmitted through a transmission path such as R, but it is not necessary to explain the present invention, so that the processing after variable length coding is not described. Variable length coding circuit 23
Is input to a block thinning circuit 27 which is one component of the embodiment of the present invention. This circuit extracts only the I picture, and further thins out the signal in units of DCT blocks.

The data of the signal decimated in block units enters the memory 28 and is sequentially written in the corresponding locations indicated by the tape numbers. This operation is the same as the writing and reading to and from the memory 7 in the embodiment of FIG. The data read from the memory 28 is decoded by the variable length decoding circuit 29 and passed through the inverse quantization circuit 30 to obtain the ID.
The image data is returned to the CT circuit (inverse DCT) 31 and stored at a predetermined position in the frame memory 32. If this frame memory 32 is read, multi-screen digital data can be obtained from the output terminal 33.

When the image signal is reduced, as a result, the sampling frequency becomes lower in accordance with the reduction ratio. To avoid this, an aliasing filter is usually provided so that the signal component is less than half the sampling frequency. In the present invention, two-dimensional DCT is used as a data compression method, and
This filtering is performed in the state of being converted.

In general, when a two-dimensional discrete cosine transform is performed on a video signal, its coefficients are arranged in order from the DC component to the frequency of the AC component. That is, the frequency increases as the distance from the DC component in both the horizontal and vertical directions increases. These coefficients are normalized and quantized with reference values called quantization tables, respectively. Therefore, in the case of inverse quantization, the same table as that used for quantization is used.

In this DCT-converted state, filtering is performed by setting the coefficient corresponding to the frequency at which aliasing occurs to 0. This operation can be performed in the state quantized from DCT or after variable-length decoding in FIG. 3, but is preferably performed before variable-length coding from the viewpoint of reducing the data size.

[0031]

Since the present invention is configured as described above, it has the following excellent effects.

(1) The contents of a tape recorded by a video tape recorder can be viewed on a multi-screen without reproducing the tape.

(2) Since the sampling interval is determined in accordance with the recording time and the number of reduced images that can be accommodated, the reduced images forming the multi-screen cover the entire recording content and have no bias, so at first glance Easy to understand the contents.

(3) By automatically assigning a number to a tape when recording with a video tape recorder, the tape can be read simultaneously with the insertion of the tape and the corresponding multi-screen can be projected.

(4) A multi-screen can be created even in a recording apparatus using a moving picture compression method using both motion compensation inter-frame prediction and DCT.

(5) Compress image data using DCT,
In the method of constructing a multi-screen by reducing and storing in a memory, an aliasing filter can be applied by manipulating DCT coefficients.

[Brief description of the drawings]

FIG. 1 is an example of a block diagram of a video tape recorder embodying the present invention.

FIG. 2 is a diagram illustrating a structure of image data when a 16-divided multi-screen is configured according to an embodiment of the present invention.

FIG. 3 is a block diagram of a main part in a case where the present invention is applied to a moving picture compression type recording apparatus using both motion compensation inter-frame prediction and DCT.

[Explanation of symbols]

 1.19 Input terminal AD converter 3. Write circuit 4. Field memory 5. 5. Thinning-out reading circuit 6. Data compression circuit Memory 8. Data expansion circuit 9. Frame memory 10. AD converter 11. Switch 12. Recording and playback device 13. Tape number generator 14. 15. Extraction timing generator 15.33 Output terminal Thinned data 17. Compressed data 18. Decompressed data 20. Motion estimation circuit 21. DCT circuit 22. Quantization circuit 23. Variable length coding 24. Frame memory predictor 25. IDCT circuit 26. Inverse quantization circuit 27. Block thinning circuit 28. Memory 29. Variable length decoding circuit 30. Inverse quantization circuit 31. I DCT circuit 32. Frame memory

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location H04N 7/32 H04N 7/137 Z

Claims (5)

[Claims] 1. An image is extracted one by one from a video signal being recorded at a predetermined time interval, an image reduced at a predetermined ratio is created and sequentially stored in a predetermined position in a memory, and is stored by the end of the recording. A video signal storage method comprising forming an image composed of a plurality of extracted reduced images. 2. The video signal storage system according to claim 1, wherein an extraction interval is determined from a predetermined recording time according to the number of reduced images that can be accommodated in one image. . 3. The video tape recorder according to claim 2, wherein a number is assigned to the tape at the time of recording, and a corresponding number is also assigned to a single image composed of a plurality of reduced images extracted during the recording. Item 4. The video signal storage method according to Item 1. 4. A recording apparatus using a moving picture compression method using both motion compensation inter-frame prediction and DCT discrete cosine transform, wherein a frame data selection means is provided, and only intra-coded frame data is taken out, and a block unit of DCT is taken out. 2. The video signal storage system according to claim 1, wherein the data is thinned to obtain a reduced image. 5. A method according to claim 1, wherein in a method of compressing and reducing image data using DCT and storing the compressed image data in a memory, a DCT coefficient corresponding to a frequency at which aliasing occurs is set to 0. The described video signal storage method.