JPS63274274A - Compression recording system for picture - Google Patents

Abstract

PURPOSE:To attain inverted reproduction from an optional picture unit by providing a coder generating a prediction error data being the result of adding a required data for accurate picture reproduction at the inverted reproduction in a compressed picture part by a picture unit prediction coding. CONSTITUTION:As to a picture part compressed by an inter-frame prediction coding, a prediction circuit 10 and a code conversion circuit 5 are controlled by a coding control circuit 22 so that a prediction error data added with the data requires for the formation of the initial picture at the inverted reproduction is to be generated. In using the coder 21 to record a compression picture data into a CD-ROM 6, the inter-frame prediction made is set to the prediction circuit 10 as to a picture data V(i, j). In reproducing a signal reversely in the recording order, the polarity of a prediction error data E(i, j) supplied from the CD-ROM 6 is properly to be inverted and then a decoding control circuit 32 acts like giving a negative sign to the output of an inverse quantization circuit 14 except for a prediction error data E(i, j)' with respect to a split read at the initial state of the inverted reproduction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image compression recording system that takes into consideration reverse playback in predictive encoding of a moving image signal.

[Prior Art] There has been an attempt to provide an interactive video source for educational or entertainment purposes by storing image data obtained by compressing and encoding a color moving image into an audio signal and a CD-ROM. being done. For example, when storing an hour's worth of color images on a CD-ROM, etc., which has a limited storage capacity and is difficult to make compact, the average of 5
It is necessary to compress data down to bytes, and the compression ratio in that case reaches 1/120. For this reason, normal color images are
If digital image data is simply stored on a CD-40M, which requires 600 bytes per frame and a transfer rate of about 18 Mbytes/sec, and has a storage capacity of about 540 Mbytes, the playback time will be only about 30 seconds. , becomes almost impractical.

However, by introducing a high-efficiency encoding method that consists of prediction error recording using predictive encoding and unequal length code recording as shown below, it is possible to record normal audio data without increasing the rotation speed of the playback device. A color image CD-ROM with a display time of approximately one hour was proposed, similar to the CD-ROM. High-efficiency coding methods were originally developed for the purpose of reducing the average number of bits per pixel of an image, and in particular, predictive coding using interframe DI''CM (differential pulse code modulation). predictive coding)
This method is said to be suitable for processing television signals in which the correlation between frames is high and the frame difference signal is small.

This predictive encoding method uses image data regarding pixels in an X-Y two-dimensional image plane! This is a compression method that subtracts a predicted value predicted using data from the previous frame and encodes the difference as prediction error data. In that case, since the prediction error data is approximately approximated by a Laplace distribution, in the conventional compressed image data recording/reproducing system 1 shown in FIG. A nonlinear quantization circuit using compression is used. The encoder 2 supplies input image data to a quantization circuit 3 via a subtracter 4 that takes the difference between the input image data and its predicted value. One of the prediction error data converted from a level value to a level number in the quantization circuit 3 is converted into an unequal length code in the code conversion circuit 5 and recorded on the CD-110M 6, while the other is converted into an unequal length code in the code conversion circuit 5. It is fed back to the subtracter 4 via 7. This local decoder 7 positively feeds back the output of an inverse quantization circuit 8 that performs inverse processing of quantization, that is, converting from a level number to a level value, to an adder 9 via a prediction circuit 10. A configuration is adopted in which the obtained locally decoded signal is supplied to a subtracter 4.

By the way, although the prediction circuit 10 is based on inter-frame prediction, it is supplemented by interweaving intra-frame prediction. That is, for image units of a plurality of frames forming a moving image, each frame is divided into strip-like splits of m vertical stages, for example, i0 km (k=0, 1...
2. ,, )th frame, the image data for each split is V(lj+km), V(2,i+km)
, −, V(m, i+kn), a split reflex method is adopted that improves the image quality by performing predictive coding using intra-frame prediction on the image data V (j, i+km) of the first split. . The split refreshed by intra-frame prediction is an encoding control circuit that controls the prediction mode of the prediction circuit IO! 1, the refresh effect is circulated frame by frame to ensure that the refresh effect is uniform throughout the image. For this reason, CD
- The prediction error data recorded in the ROM 6 relates to image data V (i, j) of split number i and frame number j, and at jf-i 10km, prediction error data E (i, j)-V by inter-frame prediction. (i, j) −V (i, j) is generated, and at j=i+km, prediction error data E (i, j)' −F [V (ij)] by intra-frame prediction is generated. However, V (i, D is the predicted value of V (i, j), that is, the image data V (i, j-1) before the frame!, and F represents the intraframe encoding function. Note that the dash code is , indicates that the prediction is based on intra-frame prediction. FIG. 4 is an example of a prediction error data string when the number of splits m is 4.

On the other hand, the decoder 1 decodes the prediction error data E (i, D or E (i, j)' read from the CD-40M6.
2 is a code inverse conversion circuit 13 that inversely transforms the prediction error data code-converted by unequal length encoding and returns it to an equal length code;
It consists of an inverse quantization circuit +4 that inversely quantizes the output of the code inverse conversion circuit 13, an adder 15 that forms image data V (i, D) from the output prediction error data of the inverse quantization circuit 14, and a prediction circuit I6. .

Adder! 5 adds the output of the prediction circuit 16 based on its own output to the output of the inverse quantization circuit 14, and by cyclic addition of the output of the prediction circuit 16 to the prediction error data, the image data V (i, D A decoding control circuit 17 is connected to the prediction circuit 16.
Prediction mode control is executed in accordance with the prediction mode used in the process of generating error data. In addition, the decoder ■
Image data V (i, D, j≠i+
km, the predicted value V (i, D is predicted error data E
(i, D is obtained by adding V (i, j) = V (i, j) + E (i, D, and at j = i + km, V (i, D = G [E ( i, j)' where G represents the intra-frame decoding function.

[Problems to be Solved by the Invention] The conventional compressed image data recording/reproducing system 1 described above is based on C
I) - Since the ROM 6 was configured assuming only forward playback, in which the ROM 6 is played back in accordance with the recording order, for example, during so-called reverse playback, in which the prediction error data is played back in the reverse order, the decoder I2 Since there is no past data required by the prediction circuit 16 in the image as an initial value, normal reverse playback cannot be performed not only from the middle of an image but also from the last image, and even if reverse playback is attempted, However, there are problems in that a meaningless image that is about a distance away from the original image is reproduced, and that it is not possible to reproduce the image signal in reverse by simply repeating subtraction by the difference between frames or within a frame.

Means for Solving Problem U] This invention solves the above problem, and converts a moving image signal consisting of a plurality of image units into images for each image part. nn Yamauchi predictive coding interwoven with both 'image units 1? Compressed image data is compressed by U predictive encoding and stored as prediction error data on a recording medium 1. - Compression recording system for recorded images
・In the image portion compressed by the image rp-regular T-measure encoding, an encoder is provided to generate prediction error data to which data necessary for accurate image reproduction during reverse reproduction is added. It is characterized by this.

[Operation] This invention allows a moving image signal consisting of a plurality of image units to be
Each part of the image is compressed by image unit amount predictive coding while interweaving intra-image unit predictive coding, and is recorded on a compressed image data recording medium as prediction error data. By generating prediction error data to which data necessary for accurate image reproduction during reverse playback is added, reverse playback can be performed from any image unit.

[Example] Hereinafter, an example of the present invention will be described with reference to FIG. 1.2. FIG. 1 is a system configuration diagram showing an embodiment of a compressed image data recording/reproducing system to which the image compression recording system of the present invention is applied, and FIG. FIG. 2 is a diagram showing the contents of prediction error data.

In FIG. 1, the compressed image data recording/reproducing system 20 is
The configuration of the compression recording system for images including the code 'a21' is different from the conventional one. This encoder 21 is CI)-
This is an improvement over the conventional recording method, which anticipated reverse playback of the ROM 6 and recorded with only forward playback in mind. That is, the prediction circuit 1 generates prediction error data to which data necessary for forming an initial image during proper reproduction is generated for the image portion compressed by intra-frame predictive coding.
0 and the code conversion circuit 5 are controlled by the encoding control circuit 22.

Here, compressed image data is recorded on the CDltOM6 using the encoder 21. In this case, as mentioned above, the i-th split of the j-th frame (j≠i+km)
For the image data V (i, D), the prediction circuit 10 is set to the frame 11 ']' 1 (II+ mode).

On the other hand, for the image data V (i, D) related to the split to be refreshed by intra-frame prediction, the intra-frame prediction mode is set for the prediction circuit 10, and the prediction error data is calculated by the intra-frame prediction calculation F [V (i, j)]. E (i, D' is increased by i. However, the prediction error data E (i, D' obtained here is not immediately recorded, and the encoding control circuit 22 first records the prediction error data E (i, D
''s local decoded output, that is, the intra-frame predicted value G[E(
i, D' ], the image data of the moe frame V (i,
Then, after recording the data E(i, j), the intra-frame prediction error data E(i, j)' is continuously recorded. In other words, intra-frame prediction error data E (i, D'
As shown in FIG. 2, data E (i, D) necessary for forming the next image that matches the first image during reverse playback are always recorded.

On the other hand, regarding the decoder 31, CD-Summer? Inverse quantization circuit 13 and prediction circuit 1 are used to cope with reverse playback of OM6.
5 is controlled by the decoding control circuit 32, and the intra-frame p measurement error data E (i, j)' which is first read out against the recording order during reverse playback in the i-th frame 10 km.
As for the predicted value c[E
(i, j)'] and further generates data E(i, j
) Prediction error data E(il, j) read out following
, E(i-2,j), , , are configured to generate predicted values using inter-frame correlation.

Furthermore, in order to eliminate the difference in tense between decoding by intra-frame prediction and decoding by inter-frame prediction, a delay circuit 33 having a delay time of 14 I-frame periods is interposed between the dequantization circuit I4 and the adder 15. The decoding control circuit 32 operates the changeover switch 3 in the intra-frame prediction mode.
4, the output of the inverse quantization circuit 14 is delayed by one frame period. Furthermore, when reproducing data backwards from the recording order, the polarity of the prediction error data E (i, D) supplied from the CD-ROM 6 must be appropriately inverted, so that the decoding control circuit 32 The configuration is such that the outputs of the inverse!1 quantization circuit 13 are given a negative sign except for the prediction error data E(i, j)' regarding the split read out.

By the way, if you play the CD or ROM 6 in reverse, the decoder 3
1, the decoding is stopped until the first intra-frame prediction error data E(ij)' is supplied, and when the first intra-frame prediction error data E(i, D' is supplied, the decoding control circuit 32 switches the prediction mode of the prediction circuit 1G to the intraframe prediction mode, and actual decoding starts.In this case, the prediction error data E(i, j )'teeth,
Intra-frame decoding is performed as is without adding a negative sign, and the image data G is the same as the local decoding output obtained in the encoding process.
[E(i,D']) is reproduced, and this forms the leading image during reverse reproduction.

Note that there is a difference in tense by one frame between the first image G [E (i, D'] and the image that is subsequently played in reverse. In decoding based on prediction, the changeover switch 34 is switched to the delay circuit 33 side, and the tenses are unified by delaying the signal for the I frame period.

On the other hand, from the data E (i, j) sent following the prediction error data E (i, D'), a negative sign is attached to the output of the inverse quantization circuit 13, and decoding by interframe prediction is performed. Therefore, following G [E (i, D' ), G [E (i, D' ] - E (i, D, that is, V (i, j-1)) is reproduced. Then, V(
i, j-1) f: Then, V (i-1, j-1),
V (i-2, j-1), , , (1), decoding based on inter-frame prediction is performed sequentially, and similar decoding is performed for other subsequent frames.

In this way, the compressed image data recording/playback system 20 compresses a moving image signal consisting of a plurality of frames by interframe predictive encoding while interweaving intraframe predictive encoding every frame, and compresses the video signal as prediction error data. CI)-
At the same time as recording in the ROM 6, the image portion V (i, D) is compressed by intra-frame predictive coding, and the data E (i
, D that is G L E (i, j)' ] −V (i
-1, D is added to the prediction error data E (reverse 1 since the configuration is configured to generate i, D').
By forming an initial image necessary for decoding and subtracting additional data E (i, D) from this initial image, the next image can be reproduced, and the image can be reproduced while sequentially subtracting prediction error data. The backward decoding of prediction error data based on prediction using correlation between frames 11 is performed by
can be executed accurately. Furthermore, since the prediction error data encoded by intra-frame prediction is inserted for each frame, a series of video images consisting of multiple frames can be played in reverse from any frame, not just the end. .

In the above embodiment, the compressed image data recording medium is not limited to the CD-ROM 6, but may be other media such as a video tape.

Furthermore, in the above explanation, inter-frame differential encoding was taken as an example of a predictive encoding method that utilizes the correlation between image units, but other methods such as motion compensated inter-frame presetting ff111 can also be used. be. Further, it is also possible to perform orthogonal transform encoding and vector t-quantization on prediction error data generated in these encoding processes. For example, when performing orthogonal transform encoding, encoder 2! Quantization circuit 3 in
There is an orthogonal transform circuit in the +7Q stage of the
An inverse orthogonal transform circuit is required at the subsequent stage, and an inverse quantization circuit in the third decoder! An inverse orthogonal transform circuit is required at the subsequent stage of 4. In this case, what is recorded on the recording medium is prediction error data converted into conversion coefficient components.
The essence of the encoder 21 and decoder 31 remains unchanged. Also,
vector! When performing 1 quantization, a vector index circuit for vector quantization is provided before the quantization circuit 3 in the encoder 21, and a vector for inverse vector 1i quantization is provided after the inverse quantization circuit 8. - An index inverse transform circuit is required for each, and a vector/index inverse transform circuit for inverse vector quantization is also required at the subsequent stage of the inverse quantization circuit I4 in the decoder 3. in this case,
What is recorded on the recording medium is a vector index converted from the P measurement error data, but the essence of the encoder 2I and reconstructor 3I remains the same.

[Effects of the Invention] As explained in [2] above, the present invention allows a moving image signal consisting of a plurality of 1119 image positions to be divided into 111^ for each middle image.
In the image part compressed by image unit predictive coding while interweaving image unit predictive coding, the image is compressed by image intermediate spacing/measurement coding, and is recorded on a compressed image data recording medium as prediction error data. The configuration is such that prediction error data is generated with data necessary for accurate image reproduction during reverse playback. By forming an initial image and subtracting additional data from this initial image, the next image can be reproduced. Furthermore, by sequentially subtracting prediction error data and reproducing the image, the image rY: L rank [t mI using the correlation at 1
It is possible to accurately perform backward decoding of prediction error data based on 6 for j, and since the prediction error data encoded by image-wise circular prediction is inserted for each middle image, it is possible to perform backward decoding of prediction error data based on 6 for j. This provides excellent effects such as being able to reversely reproduce a series of moving images consisting of a unit from any image, not just the last one.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a compressed image data recording/reproducing system to which the image compression recording system of the present invention is applied, and FIG. 2 is a block diagram of the (CI) shown in FIG. 1.
- A diagram showing the contents of prediction error data recorded in ROM,
Fig. 3 is a system configuration diagram showing an example of a conventional compressed image data recording/+Ij raw system, and Fig. 4 is a diagram showing the contents of prediction error data recorded on the CD-110M shown in Fig. 3. It is. 3, , , ri) Child circuit, 41. subtractor, 5
．． ,. code conversion circuit, 6. ,,CD-ROM,7,. Local decoder, 10. , ,Prediction circuit, 20. , , Compressed image data recording/iI'f generation stem, , Encoder,
22. ,,encoding control circuit. ,′”＋ゝf °゛

Claims (1)

[Claims] A moving image signal consisting of a plurality of image units is compressed by inter-image unit predictive coding while interweaving intra-image unit predictive coding for each image unit, and the image is recorded as prediction error data on a compressed image data recording medium. An image compression recording system comprising: an encoder that generates prediction error data to which data necessary for accurate image reproduction during reverse reproduction is added in an image portion compressed by intra-image predictive encoding; compression recording system.