JPH0272780A - Image recording and decoding systems - Google Patents

Abstract

PURPOSE:To efficiently encode an image signal and to reproduce it in a reverse direction at high speed by measuring the amount of encoded data at the time of performing encoding, performing the encoding by utilizing in-frame correlation at every prescribed quantity of codes, and recording the signal according to a decide rule. CONSTITUTION:Information with respect to encoding classification in a code switching part 5 is sent to a flag generating part 6, and a flag generated at the part is outputted to a code data buffer 10. The encoded data accumulated in the buffer 10 is sent to a recording processing part 11, and is recorded on a recording medium. A part encoded by utilizing the in-frame correlation is arranged at interval of constant quantity of codes, and the interval is set at 1/n of the amount of data recordable on one circumference of an optical disk. By employing such system, the encoded part can always start on a line advancing from the center of the optical disk to the circumference. Therefore, decoding can be performed successively by skipping to a different track at that position and performing the decoding since the data on which the in-frame encoding is recorded on that track.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an image recording method for highly efficiently encoding moving images and recording them on a recording medium such as a compact disk CCD or an optical disk, and an image recording method for recording on the recording medium. Regarding the decoding method of (accumulated) encoded image data, in particular, when decoding the encoded image data recorded on the recording medium, performing special reproduction such as high-speed forward playback and high-speed reverse playback. An image decoding method that allows for
This invention relates to an image recording method that enables special playback.

[Prior art]

Conventionally, as a method for realizing high-speed forward playback and high-speed reverse playback from encoded image data recorded (stored) on a recording medium such as an optical disk, for example, Japanese Patent Application Laid-Open No. 63-9579 has been proposed.
As disclosed in Publication No. 1, an image signal is divided into blocks each consisting of multiple pixels, and the image signal is encoded by combining a variable length code and a fixed length code so that the amount of encoded data is the same for each block. There are some devices that can provide decoded images that are easy to understand when played back at high speed on a VTR.

Further, when recording images on an optical disk or the like, for example, one example is used to enable special reproduction such as high-speed reproduction.

Video High Density Disk System (VHD)
) method, the number of frames recorded on one revolution of the optical disc is constant and the vertical synchronization signals are recorded in a line from the center to the circumference on the optical disc.In the case of special playback, There are devices that enable high-speed forward playback and high-speed reverse playback by skipping tracks at the position of this vertical synchronization signal.

[Problem to be solved by the invention]

However, the former method uses only intra-frame correlation, and has problems in terms of poor coding efficiency and the amount of information that can be stored.

In addition, with the method that utilizes intra-frame correlation and inter-frame correlation of moving images, which was conventionally used for TV conferences, it is possible to encode with less than half the amount of data compared to the case where only intra-frame correlation is used. However, a decoding method that enables high-speed forward playback and high-speed reverse playback has not been realized.

In addition, in the latter method, frame-by-frame data without consideration of encoding compression is possible only at certain times, and it is difficult to combine it with encoding technology.

In particular, it is efficient to use interframe coding to reduce the amount of data required for storage, but using interframe coding enables random access and high-speed reverse playback. There was no way to record images.

The present invention has been made to solve the above problems.

An object of the present invention is to provide an image recording method and image decoding method that utilizes an image encoding method used in TV conferences, etc., and can efficiently reproduce encoded data obtained by encoding an image signal at high speed in forward and reverse directions. The above-mentioned and other objects and novel features of the present invention, which are based on providing a system for converting images, will become clear from the description of the present specification and the accompanying drawings.

[Means to solve the problem]

In order to achieve the above object, the present invention has means for dividing an image signal into block lines each consisting of a plurality of lines, and encoding the video signal using intra-frame correlation of a moving image, and for each block line, inter-frame/frame correlation. The intra-frame encoding method is switched and encoded according to predetermined rules, and flag information indicates whether the block line was encoded using intra-frame correlation or inter-frame correlation. An image recording method in which the resulting image encoded data is encoded by an image encoding means that generates and indicates the data, and is recorded on a recording medium such as an optical disk, and the interframe/intraframe encoding method is switched. As a rule, when encoding. The amount of encoded data is measured, and each predetermined amount of code is encoded using intra-frame correlation, so that when recorded on the recording medium, the encoded portion within the frame is distributed from the center of the disk toward the circumference. The main feature is that it is equipped with a means for recording data so that they are lined up in a row.

The image decoding method decodes encoded data recorded on a recording medium such as an optical disk using an image recording method, and includes an inter-frame and intra-frame decoding means corresponding to the encoding method and detecting flag information. a flag detection means, a memory for recording the decoded image signal, a track,
It is equipped with a position changing means for changing the position on the recording medium such as a sector, and a control means for specifying the position change on the recording medium, and during high-speed playback, the control means specifies the decoding position on the recording medium. the position changing means detects flag information at the decoding position, the flag information is detected by the flag detecting means at the decoding position, only the part using the intra-frame correlation is decoded and recorded in memory, and the decoded image is continuously output. The main feature is that special reproduction such as high-speed forward playback and high-speed reverse playback can be performed by The interframe/intraframe encoding method is switched and encoded in accordance with predetermined rules for each block line.

As a rule for switching between this interframe/intraframe encoding method, when encoding, the amount of encoded data is measured,
Encoding is performed using intra-frame correlation for each predetermined amount of code, and when recorded on the recording medium, the encoded portions within the frame are recorded in a line from the center of the disk toward the circumference. As a result, image recording can be performed in which encoded data obtained by efficiently encoding an image signal can be reproduced at high speed in the forward and reverse directions.

Further, inter-frame and intra-frame decoding means corresponding to the encoding method for encoded data recorded by the image recording method, and flag detection means for detecting flag information;
By being equipped with a memory for recording decoded image signals, a position change means for changing the position on the recording medium such as a track or sector, and a control means for specifying the position change on the recording medium, high-speed During playback, the position changing means skips to a decoding position on the recording medium specified by the control means.

The flag information is detected by the flag detection means at the decoding position, only the part using the intra-frame correlation is decoded and recorded in memory, and the decoded images are continuously outputted for high-speed forward playback and high-speed reverse playback. You can perform special playback such as playback.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be specifically described using the drawings.

Note that throughout the description of the embodiments, parts having the same functions are given the same reference numerals, and repeated explanations thereof will be omitted.

[Example I]

FIG. 1 is a block diagram showing a schematic system configuration of an image recording method according to Embodiment 2 of the present invention.

In FIG. 1, 1 is an input terminal, 2 is a block dividing section,
3 is a DCT conversion unit, 4 is a quantizer, 5 is a code switching unit, 6 is a flag generation unit, 7 is a frame memory, 8 is a motion compensation processing unit, 9 is a variable length encoding circuit, 10 is a code data buffer, 11 is a recording processing section, and 12 is a code amount calculation section.

Here, intraframe encoding refers to performing encoding processing of five image information only within each frame. Furthermore, interframe encoding refers to encoding in three dimensions (horizontal direction, vertical direction, and two time axis directions) that also utilizes the correlation between consecutive frames.

OCT transform is a type of orthogonal transform that uses only a removal function, and mainly utilizes the electric scum vector density on the coefficients after the transform to achieve efficient encoding. , refers to using only the removal function.

In the image recording method of this embodiment (2), as shown in FIG. 1, an image signal input to an input terminal 1 is divided into a plurality of block lines by a block division section 2. If the encoding means that utilizes the inter-frame correlation of the moving image is selected 41, the image signal of the block line is subtracted from the predicted image that utilizes the previous frame, and is also subtracted from the predicted image that utilizes the intra-frame correlation. If an encoding method is selected,
The signal is sent as is to a discrete cosine (hereinafter referred to as DCT) transform unit 3, where it is subjected to DCT transform, which is one of orthogonal transforms. Thereafter, each transform coefficient is quantized by a quantizer 4, sent to a variable length encoding circuit 9, subjected to variable length encoding, and outputted to a code data buffer 10. In addition, when the output of the quantizer 4 is encoded using interframe correlation, the sum with the predicted image signal is calculated to generate the same decoded image signal as that decoded on the receiving side, It is sent to the frame memory 7 for use in motion compensation processing. The encoded output of the variable length encoding circuit 9 and the code length information of the flag information of the flag generation section 6 are sent to the code amount calculation section 12, which calculates the amount of encoded data and sends it to the code switching section 5. The code switching unit 5 compares the amount of coded data with a predetermined value, and if the conditions are met, switches to the coding method using intra-frame correlation.

For example, the encoding means for the current block line is switched between intra-frame and inter-frame correlation so that the amount of code between block lines encoded using intra-frame correlation is constant. Specifically, the predicted image signal sent from the frame memory 7 is usually subtracted from the input image signal, but the predicted image signal sent from the frame memory 7 is cut every certain number of block lines.

The input image signal is directly sent to the DCT conversion section 3. The information on the encoding type of the code switching section 5 is sent to the flag generating section 6, which generates a uniquely detectable flag and outputs it to the code data buffer 10. The frame memory 7 stores a decoded image of the coded image one frame before, and the motion compensation processing unit 8 performs motion compensation processing on the current image signal and the image signal one frame before, and the predicted image signal is is configured.

The motion predicted image obtained by the motion compensation processing section 8 is stored in the frame memory 7 and also sent to the code switching section 5.

The motion compensation process, for example, divides the image No. 41 into blocks each consisting of a predetermined plurality of pixels, and calculates a certain predetermined value between some pixels included in the block and an encoded past image block. Block matching is performed within the specified range, and a motion vector indicating the direction in which the block moved is determined from between the blocks where the error between the blocks is the smallest.

As a result, a predicted image signal of the current image signal can be constructed from blocks with smaller errors.

In the above-mentioned embodiment I, motion compensation processing was performed as a method using interframe correlation, but of course other processing, such as one that takes interframe differences, may be used. Similarly, as an encoding method using intra-frame correlation, other than DCT transformation, methods such as predictive encoding and block encoded vector quantization may be used. Furthermore, for block division, one frame may be divided into multiple parts, or one frame may be regarded as one block line.
The encoded data stored in the encoded data buffer 10 is
The data is sent to the recording processing section 11 and recorded on a recording medium. In optical discs, etc., the recording area (length recorded on the medium) differs between the inside and outside of the circumference at a recording position with the same central angle of the recording medium, but the recording processing unit 11 uses the same central angle regardless of this. A certain amount of data is recorded at a recording position with a corner.

Using intra-frame correlation, the coded part is at constant code amount intervals, and if this 1ffl interval is set to 1/n of the amount of data that can be recorded in one rotation of the optical disk, intra-frame correlation can be used. However, the encoded portion always begins on a line from the center of the optical disc toward the circumference.

2 and 3 are diagrams showing an example in which encoded data generated in the variable length encoding circuit 9 is recorded (M product) on an optical disk such as a laser disk (LD), and 31 is a flag information , 32 is intraframe encoded data, and 33 is interframe encoded data.

According to the present embodiment I, when the code switching unit 5 is configured so that the amount of code between block lines encoded using the intra-frame correlation is constant.

When the amount of data that can be recorded on one track (one round) on an arc is constant, the data encoded within a frame is distributed in the circumferential direction from the center of the laser disk (LD), as shown in Figure 2. If the nine tracks arranged in a line have different amounts of recorded data, the encoded portion within the frame must be in a -column, as shown in FIG.

In this case.

If the block line continuation roll using intra-frame coding is selected in accordance with the recording data amount of one track, the result will be similar to that shown in FIG. 2.

When using the image recording method of this embodiment (■), the portions in which encoding is used in the frame are lined up in a line from the center toward the circumference, so if you skip to a different track at this position and decode it, you can return to that track. Since the intra-frame coded data is also recorded, continuous decoding is possible, so special playback can be performed.

[Example ■]

FIG. 4 is a block diagram showing a schematic system configuration of an image decoding method according to Embodiment 2 of the present invention.

In FIG. 4, 13 is an encoded data reading section, 14
15 is a readout controller, 15 is a playback method switching unit,
16 is a flag detection unit, 17 is a variable length code decoder, 18
is an inverse quantization unit, 19 is an inverse DCT transformation unit, 20 is a frame memory, 21 is a selector, 22 is a motion compensated image generation unit,
23 is an output terminal.

As shown in FIG. 4, in the image decoding system of the embodiment (2) of the present invention, a reproduction method switching unit 15 determines an encoded data readout route according to a reproduction method such as normal, forward, or reverse. The read controller 14 instructs the encoded data read unit 13 to move the position of the read head according to the determination result of the reproduction method switching unit 15. The encoded data readout unit 13 changes the readout position according to instructions from the readout controller 14 and reads out the recorded (accumulated) data. The read data is sent to the flag detection unit 16, and it is checked whether it is a coded part using intra-frame correlation. Based on the detection result, a variable length code decoder 17 performs variable length decoding using a corresponding variable length code table. According to the decoded quantization index, a decoded value is obtained in the inverse quantization section 18, and inversely transformed in the inverse DCT transform section 19. If the inversely transformed data has been interframe coded, it is summed with the motion predicted image created by the motion compensated image generation unit 22 and stored in the frame memory 20. If intraframe encoding is used, the output from the inverse DCT transform unit 19 is stored as is in the frame memory 20.

The selector 21 writes the image data of the decoded block line based on the inter-frame and intra-frame code conditions input from the flag detection unit 16, the position information of the image data to be decoded, and the reproduction conditions from the reproduction method switching unit 15. The address on the frame memory 20 to be set is set. The motion compensated image generation unit 22 generates a motion predicted image from the past frames stored in the frame memory 20 using the motion vector information decoded by the variable length code decoder 17. The decoded image signal of the frame memory 20 is sent to the output terminal 23
is output to.

If a certain track of the laser disc (LD) is reissued one round later and the track is advanced to the first track, normal playback will occur. To perform high-speed playback in the case of Figure 2, 1. For example, after decoding from A to B in the figure, skip to C and continue playback, decoding and presenting only the intra-frame encoded part, high-speed playback is possible. becomes. Similarly, if you skip from B to D, you can play in the opposite direction.

As can be seen from the above description, according to the present embodiment H, encoded data recorded by the image recording method is detected by interframe and intraframe decoding means corresponding to the encoding method, and flag information. a memory for recording the decoded image signal, a position changing means for changing the position on the recording medium such as a track or sector, and a control means for specifying the position change on the recording medium. As a result, during high-speed playback, the position changing means skips to the decoding position on the recording medium specified by the control means, the flag detecting means detects flag information at the decoding position, and the flag information is detected within the frame. By decoding only the portion that uses correlation and recording it in memory, and continuously outputting the decoded images, high-speed forward playback,
Special playback such as high-speed reverse playback can be performed.

The present invention has been specifically explained above based on examples, but
It goes without saying that the present invention is not limited to the embodiments described above, and can be modified in various ways without departing from the spirit thereof.

〔Effect of the invention〕

As described above, according to the present invention, moving images can be encoded and recorded with high efficiency by switching between intraframe encoding and interframe encoding.

Furthermore, data recorded (stored) on a laser disc or the like can be reproduced at high speed in the forward or reverse direction using the image recording method.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a schematic system configuration of an image recording method according to Embodiment I of the present invention, and FIGS. 2 and 3 show that the encoded data generated in the variable length encoding circuit 9 is FIG. 4 is a block diagram showing a schematic system configuration of the image decoding method according to the embodiment (2) of the present invention. In the figure, 1...input terminal, 2...block division section, 3
. . . DCT transform unit, 4 . . Quantizer, 5 . Code switching unit, 6 . - Variable length encoding circuit, 10... code data buffer, 11... recording processing section, 12... code amount calculation section, 13... encoded data reading section, 14... reading controller,
15... Reproduction method switching section, 16... Flag detection section, 17... Variable length code decoder, 18... Inverse quantization section, 19... Inverse DCT transformation section, 20... Frame memory , 21...Selector, 22...Motion compensation image generation unit, 23...Output terminal.

Claims (2)

[Claims] (1) A means for dividing an image signal into block lines each consisting of a plurality of lines, and a means for encoding the video signal using intra-frame correlation of a moving image, and a means for encoding the video signal using inter-frame correlation; The interframe/intraframe coding method is switched and encoded according to predetermined rules, and the block line is encoded using intraframe correlation or interframe correlation. This is an image recording method in which the image is encoded by an image encoding means that generates and indicates flag information, and the obtained encoded image data is recorded on a recording medium such as an optical disk, and the interframe/intraframe code is The rule for switching the encoding method is that when encoding, the amount of encoded data is measured, and each predetermined amount of code is encoded using intra-frame correlation, and when recorded on the recording medium, the encoded data amount is An image recording method characterized by comprising means for recording such that the digitized portions are aligned in a line from the center of the disk toward the circumference. (2) An image decoding method for decoding encoded data recorded on a recording medium such as an optical disk by the image recording method according to claim (1), and interframe and intraframe decoding means corresponding to the encoding method. , a flag detection means for detecting flag information, a memory for recording the decoded image signal, a position change means for changing the position on the recording medium such as a track or sector, and a position change means for changing the position on the recording medium. and control means for specifying, during high-speed reproduction, the position changing means skips the decoding position on the recording medium to a point specified by the control means, and the flag detecting means detects flag information at the decoding position. ,
Image decoding characterized by decoding only the portion using intra-frame correlation and recording it in memory, and performing special reproduction such as high-speed forward playback and high-speed reverse playback by continuously outputting the decoded images. method.