Image decoding device

Abstract

Bitstream analyzing unit 111 fetches a coded block pattern and a coded quantized DCT coefficient from each block in a bitstream. Entropy decoding unit 112 decodes the coded block pattern into a block pattern and decodes the coded quantized DCT coefficient into pairs of a run length and an effectiveness factor. Dequantization unit 115 generates orthogonal transformation coefficients from the pairs of a run length and an effectiveness factor. Inverse Discrete Cosine Transform (IDCT) unit 116 generates a difference image from the orthogonal transformation coefficients. Decode controlling unit 110 instructs first selecting unit 118 to select constants "0" output from first constant generating unit 117 when the image is a "skipped" block. Image storage unit 120 stores a plurality of reference frame pictures having been decoded. Image restoring unit 119 restores an original block by adding a decoded difference image to a reference block read from the reference frame pictures stored in the image storage unit 120.

Description

Technical field [0001] The present invention relates to an image decoding device, according to Moving Picture Experts Group (MPEG), to efficiently decode coded moving images. Background technique [0002] In recent years, people are enthusiastic about the research of high-efficiency coding and compression technology for moving images dominated by MPEG, and applying them in the fields of computer, communication, broadcasting and so on. [0003] According to this technique, a moving image is composed of many frame images, and each frame image is divided into many blocks (b1ock). Each divided block usually includes 64 pixels (8 pixels×8 pixels). Predictive coding is performed on each block in each frame of the moving image, and compressed by discrete cosine transform (DCT), quantization, variable length coding, etc., which is a kind of orthogonal transformation, to generate a compressed code string. The compressed code string (bit stream) undergoes variable-length coding reverse pro...

AI Technical Summary

Problems solved by technology

[0029] However, the above-mentioned existing image decoding apparatus has the following problem. Whether the block being decoded is included in the P picture or the B picture, and when an error occurs in the block being decoded as a skipped block, although it can be used in common device, but on the other hand, because the pixel value 0 is used as a pixel block to introduce inverse quantization processing and inverse discrete cosine transform processing, so unnecessary processing is performed, and the processing speed is reduced

[0030] Moreover, when a motion vector error occurs, after the image decoding process at the time of the error is completed, the slice including the block included in the error in the decoding must be read out, and processing for detecting the beginning of the next slice is necessary.

The problem is that if an error does not occur, processing is unnecessary and slows down the processing speed.

[0031] In addition, in the above-mentioned prior art, although the problem when processing in units of blocks is pointed out, the same problem also exists when the processing unit image is regarded as a macro block.

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