JPH06350964A - Picture reproducing device and picture decoder - Google Patents

Abstract

PURPOSE:To attain a special reproduction with simple configuration when a digital picture is compressed and recorded through the use of inter-frame coding. CONSTITUTION:Compressed picture data are reproduced from a recording medium by a reproduction section 11, a heater extract section 12 extracts a header from reproduced picture data, and an in-frame coding extract section 13 extracts picture data subjected to infra-frame coding from information of the header. Then an invalid data addition section 14 adds invalid picture data other than extracted infra-frame coding data and the result is provided as an output to a picture decoder 40.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reproducing apparatus and an image decoding apparatus used when reproducing a digital compressed image recorded on a recording medium.

[0002]

2. Description of the Related Art With the development of image compression technology, an apparatus for compressing and recording / reproducing a digital image has been developed.

An example of the conventional image recording / reproducing apparatus described above will be described below with reference to the drawings.

FIG. 11 is a block diagram of a conventional image recording / reproducing apparatus. In FIG. 11, reference numeral 91 is an intra-frame DC
An image encoding unit using a T encoding circuit, a recording unit 92,
3 is a recording medium, 94 is a reproducing section, and 95 is an intra-frame DCT
This is an image decoding unit using a decoding circuit.

The operation of the image recording / reproducing apparatus configured as described above will be described below.

A digital image taken in from a camera or the like is input to an intra-frame DCT encoding circuit 91, subjected to DCT, variable length code, etc. in frame units, and then converted into a recording format in a recording section 92 and subjected to error correction code. It is added and recorded on the recording medium 93. During playback, playback unit 9
4, the reproduced signal is error-corrected, the format is converted for decoding, and then the image decoding unit 95 performs variable length decoding and inverse DC.
A decoded image is obtained by decoding with T. Intra-frame coding is usually completed in one frame or one block composed of 8 × 8 pixels, so that only part of the data can be played back. It is possible to obtain images of which the contents can be discriminated (for example, Takakura et al., "Study on variable playback image quality of digital VCR", 1992 Television Society Annual Conference).
Proceedings, pages 93-94).

On the other hand, FIG. 12 is a block diagram of a conventional image decoding apparatus using a motion compensation and inter-frame differential encoding method. In FIG. 12, 4 is an image decoding unit which is a buffer 4
1, variable length decoding circuit 42, inverse quantization circuit 43, inverse DCT
It is composed of a circuit 44 and a motion compensation circuit 45. Reference numeral 5 is a frame memory.

The operation of the image decoding apparatus configured as described above will be described below. The compressed image data is input to the buffer 41, sequentially subjected to variable length decoding, inverse quantization, inverse DCT, and decoded into real time data. Since the interframe coding method is adopted, the difference between the normal frames is coded. Therefore, in order to restore the image data, the block obtained by motion-compensating the data of the previous frame stored in the frame memory 5 and the decoded difference data are added to obtain the decoded image data.

Compared with the intra-frame coding method shown in FIG. 11, the inter-frame differential coding method suppresses image quality deterioration from the viewpoints of transmitting a difference and effectively transmitting a motion component by motion compensation. It is known that a high compression rate can be obtained (for example, ISO / IEC / DIS 11172 Information T
echnology -Coding of moving pictures and associate
d audio for digital storage media up to about 1.5M
bps mo, 1992, p. 61).

[0010]

However, the configuration shown in FIG. 11 has a drawback in that the compression rate cannot be increased as compared with the interframe coding because the intraframe coding circuit is used.

On the other hand, when the inter-frame differential encoding method is used in the image encoding unit and the decoding unit as shown in FIG. 12, the above problem is solved, but since the differential data is encoded, the image of the previous frame is The image of the current frame cannot be reproduced without reproduction, and there is a drawback that a desired image cannot be obtained during fast-forwarding and rewinding in which only a part of the image can be reproduced.

In view of the above problems, the present invention provides an image reproducing apparatus and an image decoding apparatus which enable special reproduction even when interframe coding is used.

[0013]

In order to solve the above problems, an image reproducing apparatus of the present invention comprises a reproducing section for reproducing compressed image data from a recording medium, and a header extraction for extracting a header from the reproduced image data. Section, an intra-frame encoding / extracting section that extracts intra-frame encoded image data from the image data by using the information of the header, and a header or an invalid image of compressed image data that cannot be reproduced in the extracted image data. It is provided with a configuration of an invalid data adding unit that adds at least one of the data and outputs it to the image decoding apparatus.

Further, the image decoding apparatus of the present invention, when an image decoding unit for decoding compressed image data, a frame memory for storing the decoded image data, and a non-decodable signal are input for a predetermined period or more, Controlled so as to extract the intra-coded part from the compressed image data, write only the intra-coded part to the frame memory, and not update the contents of the frame memory other than the intra-frame coded part. The special reproduction control unit is provided.

[0015]

According to the present invention, since only the intra-coded block can be extracted and reproduced by the above-mentioned structure, special reproduction can be performed even by using the inter-frame coding.

[0016]

Embodiments of the image reproducing apparatus of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a first embodiment of an image reproducing apparatus of the present invention. In FIG. 1, reference numeral 1 denotes an image reproducing apparatus, which comprises a reproducing section 11, a header detecting section 12, an intra-coded block extracting section 13, and an invalid data adding section 14. Further, 2 is a recording medium, 3 is a recording unit, and 40 is an image decoding device.

2 and 3 are explanatory diagrams showing the format of the compressed image, and FIG. 4 is a detailed configuration diagram of the header detection unit 12, the intra-coded block extraction unit 13, and the invalid data addition unit 14. 5 and 6 are explanatory views showing an example of the format of the special reproduction compressed image data 16.

The image reproducing apparatus configured as described above will be described below with reference to FIGS. 1, 2, 3, 4, 5, and 6.

In FIG. 1, it is assumed that the input image data is compressed by interframe coding. The compressed image data is converted by the recording unit 3 into a recording format, added with an error correction code, and recorded on the recording medium 2 as in the recording unit 92 in the conventional example. During normal reproduction, the reproduction unit 11 performs error correction on the reproduction signal, converts the format for decoding, and then transmits the reproduction image data to the image decoding apparatus 40.

2 and 3 are explanatory views showing an example of the data format of the compressed image. Inter-frame compression coding, which is commonly used at present, divides a frame into blocks of about 16 × 16 pixels. Next, whether the inter-frame coding, that is, the difference is coded in the block unit or the intra-frame coding, that is, the original data itself is coded, calculates the amount of information to be sent, and selects the smaller one. To do. Therefore, the differential coded data and the intra-frame coded data are mixed in one frame of compressed data.

Considering special reproduction such as fast forward and rewind, only a part of the recorded data can be reproduced. If the partially reproduced data is a difference, the data to be added is necessary, but there is no guarantee that the data to be added will also be reproduced. In FIG. 2, the intra-frame coding block is arranged after the specific header pattern. At this time, it is assumed that the header pattern has a flag indicating whether the following data includes the inter-frame coded block or is composed of only the intra-frame coded block. Further, in FIG. 3, the data following the header pattern includes interframe coding and intraframe coding blocks, but the position of the intraframe coding block is specified in the header pattern by the number of bits from the header pattern, etc. You can understand without decrypting.

When the image data of the formats shown in FIGS. 2 and 3 are recorded, it is assumed that the special reproduction mode signal 15 requesting special reproduction is input. The reproduced image data is first input to the header detection unit 12, the content of the ROM 121 in FIG. 4 is compared with the comparator 122 to check the header pattern, and only the image data including the intra-frame coded block after the header pattern is intra-frame coded extraction unit. Send to 13. In the intraframe coding / extracting unit 13, the timing generation circuit 132
Then, a signal indicating the position of the intra-frame coded block is generated from the input data, sent to the gate 131, only the intra-frame coded block is extracted from the image data, and sent to the invalid data addition unit 14.

The invalid data adding section 14 stores the intra-frame coded block in the memory 141, and according to the timing generated by the timing generation circuit 143.
Header pattern and memory 14 stored in the ROM 142
1. Intra-frame encoded data stored in No. 1, ROM 14
The invalid data stored in 2 is output to the image decoding device 40 as the special reproduction compressed image data 16 by switching the selector 144.

FIG. 5 shows an example of the special reproduction compressed image data 16, in which a header is added immediately before the extracted intra-frame coded block, and the other is 0 as invalid data in order to prevent the same thing as the header pattern from being detected. It is outputting.
In this case, the data output format is the same as that of the compressed image data, but the header pattern is the same as that of the image decoding device 40.
However, it is only necessary to add the minimum amount that can decode the image data, for example, the header of an intra-coded block to be decoded, and it is not necessary to add all the headers of the blocks that cannot be reproduced.

The image decoding device 40 receives the output, but since the block corresponding to the inter-frame coding has the invalid data inserted therein and the portion cannot be decoded, the image data of the previous frame is held. On the other hand, since the reproduced intra-frame coded block can be correctly decoded, only the intra-frame coded block is updated.

As described above, according to the present embodiment, the above-described configuration makes it unnecessary for the image reproducing apparatus to decode the parts other than the header, and a part of the image is displayed during special reproduction, so that the contents can be understood. Become.

In the above embodiments, the special reproduction compressed image data 16 is added with the invalid data 0 in the invalid data adding section 14, but the present invention is not limited to this, and the header pattern is detected by the image decoding device 4 without error. When the format is selected to be possible, indefinite data as shown in FIG. 6x may be added. In general, the probability that indefinite data is decoded as normal image data by the image decoding device is extremely low, so that adding arbitrary indefinite data does not cause any practical problem.

Further, in the above embodiments, the gate 131 extracts only the intra-frame coded block, but the reproduced header pattern is also extracted at the same time and the header pattern is also output to the image coding apparatus 40. The same effect can be obtained.

FIG. 7 is a block diagram of the image reproducing apparatus according to the second embodiment of the present invention. The difference from the first embodiment is that the special reproduction mode signal is converted to the special reproduction compressed image data 1
This is a point to be sent to the image decoding device 40 together with 6. In the first embodiment, when invalid data is input during special reproduction, the image decoding apparatus holds the image of the previous frame. However, depending on the decoding device, depending on the error occurrence condition, the inter-frame encoded frame retains the previous frame image data, or replaces it with the image data of the intra-frame encoded frame sent before. May be switched. Therefore, by sending the special reproduction mode signal together with the special reproduction compressed image data, the processing during the special reproduction can be surely performed.

In the above embodiments, only the apparatus for recording and reproducing the image data compressed by using the inter-frame coding has been described, but it is easy to combine it with the recording / reproducing apparatus using the intra-frame coding. , But not limited to this.

In the first embodiment, the invalid data is added between the intra-frame coding blocks, but the present invention is not limited to this. The intra-frame coding extracted from the image data of several frames in the memory 141 is also possible. The same effect can be obtained by collecting the blocks and continuously outputting the intra-coded blocks to the image decoding device 4.

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

FIG. 8 is a block diagram of an embodiment of the image decoding apparatus of the present invention. In FIG. 8, 4 is an image decoding unit and 5 is a frame memory, which is similar to the image decoding unit 4 and the frame memory 5 in FIG. 12 which is a conventional example. 6 is a trick play control unit, which is composed of a CPU 61 and a memory 64. FIG. 9 is an explanatory diagram of an algorithm showing the operation of the CPU 61.

The image coding apparatus configured as described above will be described below with reference to FIGS. 8 and 9.

Normally, when the input compressed image data cannot be decoded, the image is updated only in the decoded portion and the image in the previous frame is held as it is in the uncompressed portion. Therefore, when there is an output as described with reference to FIGS. 5 and 6 in the first embodiment, it is possible to update only the intra-frame coding block without changing the conventional image decoding device. . The present embodiment provides an image decoding device that enables reproduction of a special reproduction signal without adding a function to the image reproduction device.

In FIG. 8, the image decoding section 4 is provided with
It is assumed that the compressed image data shown in FIG. 3 is input. C
The PU 61 is a decoding impossible flag 63 of the variable length decoding circuit 42.
To monitor. Further, the memory 64 stores the information of the header part which has been variable length decoded. When the undecodable block is detected for a predetermined period of time and it is determined that trick play is being performed instead of normal undecodable, the CPU 61 follows the algorithm of FIG. The positional information of the block indicating the conversion is detected. Next, the CPU 61 outputs the frame memory input / output control signal 62, extracts only the image data of the intra-frame coded block from the compressed image data, decodes it, and then writes it in the frame memory 5, and the other part outputs the image data. Control not to update.

As described above, according to the present embodiment, even if the compressed image data similar to that in the normal state is input, it is determined that the special reproduction is being performed on the image decoding device side. Obtainable.

FIG. 10 is a block diagram of the image decoding apparatus according to the second embodiment of the present invention. In the figure, the image decoding unit 4 and the frame memory 5 are the same as those in the above embodiment. The difference from the above embodiment is that the special reproduction control unit 6 is
The point is that it is composed of only U.

In FIG. 10, during special reproduction, the special reproduction mode signal 65 shown in the second embodiment is the special reproduction control unit 6
Entered in. In addition, the variable length decoding circuit 42 inputs a flag 66 indicating whether the input compressed image data is intra-frame encoded data. The CPU, which is the trick play control unit 6, controls only the intra-frame coded block to be written in the frame memory 5 at the time of trick play, and controls not to update the image data in other portions. In this embodiment, the above operation is performed when the special reproduction mode signal is input. Therefore, even when the image decoding apparatus is performing an operation such as changing an image to be held according to the error occurrence state as in the second embodiment, appropriate processing can be performed during special reproduction.

As described above, according to the present embodiment, only the intra-coded blocks reproduced by the image reproducing apparatus are decoded and displayed, and the other parts are not updated, so that the special reproduction image having a desired image quality can be obtained. It will be.

In the embodiment, the special reproduction mode signal 65
However, the present invention is not limited to this, and even if an undecodable input indicating that the inter-frame coded portion is undecodable is inputted instead of the special reproduction mode signal 65, The same effect can be obtained.

[0043]

As described above, according to the present invention, only the intra-coded blocks are extracted and sent to the decoding device, and the decoding device updates the display of only the intra-frame coded blocks.
Even with compressed image data using inter-frame coding, a reproduced image can be obtained during special reproduction. Further, since only the header is detected from the compressed data and the intra-frame coded block is extracted, it is not necessary to decode all the compressed image data during reproduction. Therefore, even when the inter-frame compressed image data is recorded in the recording / reproducing apparatus using the intra-frame encoding, the special reproduction function can be realized only by adding a simple circuit.

[Brief description of drawings]

FIG. 1 is a block diagram of an image reproducing apparatus according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a format of a compressed image of the present invention.

FIG. 3 is an explanatory diagram showing a format of a compressed image of the present invention.

FIG. 4 is a detailed configuration diagram of a first embodiment of an image reproducing apparatus of the present invention.

FIG. 5 is an explanatory diagram showing a format of special reproduction compressed image data in the first embodiment of the image reproducing apparatus of the present invention.

FIG. 6 is an explanatory diagram showing a format of special reproduction compressed image data in the first embodiment of the image reproducing apparatus of the present invention.

FIG. 7 is a block diagram of an image reproducing apparatus according to a second embodiment of the present invention.

FIG. 8 is a block diagram of the image decoding apparatus according to the first embodiment of the present invention.

FIG. 9 is an explanatory diagram of an algorithm showing the operation of the CPU 6 in the first embodiment of the image decoding apparatus of the invention.

FIG. 10 is a block diagram of an image decoding apparatus according to a second embodiment of the present invention.

FIG. 11 is a block diagram of a conventional image recording / reproducing apparatus.

FIG. 12 is a block diagram of a conventional image decoding device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 image reproducing apparatus 11 reproducing section 12 header detecting section 13 intra-coded block extracting section 14 invalid data adding section 2 recording medium 3 recording section 4 image decoding section 5 frame memory 6 special reproduction control section

Claims (6)

[Claims] 1. A reproducing section for reproducing compressed image data obtained by high-efficiency encoding a video signal from a recording medium, a header extracting section for extracting a header from the reproduced image data, and information on the header. And an intra-frame encoding / extracting unit for extracting intra-frame encoded image data from the image data, and at least one of a header of compressed image data that could not be reproduced or invalid image data is added to the extracted image data. An image reproducing apparatus comprising: an invalid data adding unit which outputs reproduced compressed image data to an image decoding apparatus. 2. The image reproducing apparatus according to claim 1, further comprising a recording unit for inputting the compressed image data and recording the compressed image data on a recording medium. 3. A switching unit for outputting compressed image data reproduced from a recording medium to an image decoding device during normal reproduction, and outputting the special reproduction compressed image data to the image decoding device only when a special reproduction mode signal is input. The image reproducing device according to claim 1, wherein 4. The image reproducing apparatus according to claim 1, wherein during special reproduction, a special reproduction mode signal is output to the image decoding apparatus together with the special reproduction image data. 5. An image decoding unit for decoding compressed image data obtained by high-efficiency encoding of a video signal, a frame memory for storing the decoded image data, and a case where an undecodable signal is input for a predetermined period or more. , Extract the intra-frame coded part from the compressed image data, write only the intra-frame coded part to the frame memory, and do not update the contents of the frame memory other than the intra-frame coded part An image decoding device comprising: a special reproduction control unit for controlling the above. 6. An image decoding unit for decoding compressed image data obtained by high-efficiency encoding a video signal, a frame memory for storing the decoded image data, and a special reproduction mode signal for inputting the decoded image data. A special reproduction control unit that controls so as to extract only the intra-coded portion of the frame and write it into the frame memory and not update the contents of the frame memory other than the intra-frame encoded portion. Image decoding device.