Picture compressing and expanding apparatus

• US 5,710,598 A
• Filed: 09/26/1995
• Issued: 01/20/1998
• Est. Priority Date: 09/28/1994
• Status: Expired due to Term

• Current Assignee: Megachips Corporation
• Original Assignee: Megachips Corporation
• Inventors: Tsuchitani, Takashi, Ukai, Yukihiro
• Primary Examiner(s): Britton, Howard W.
• Application Number:
  US08/534,032
• Time in Patent Office: 847 Days
• Field of Search: 348/408, 348/411, 348/412, 348/413, 348/416
• US Class Current: 375/240.2
• CPC Class Codes: H03M 7/425 for the decoding process only
• CPC Class Codes: H04N 19/13 Adaptive entropy coding, e.g. adaptive variable length coding [AVLC] or context adaptive binary arithmetic coding [CABAC]
• CPC Class Codes: H04N 19/423 characterised by memory arrangements H04N19/433 takes precedence
• CPC Class Codes: H04N 19/44 Decoders specially adapted therefor, e.g. video decoders which are asymmetric with respect to the encoder
• CPC Class Codes: H04N 19/60 using transform coding
• CPC Class Codes: H04N 19/91 Entropy coding, e.g. variable length coding [VLC] or arithmetic coding

Abstract

A decoding speed is improved. A processing method is changed in variable length decoders depending on whether only one piece of data is to be decoded or two or more pieces of data are to be decoded, thereby suppressing an increase in the size of hardware as much as possible and increasing a processing speed. Although irregular data are created in the first cycle when a large scale decoder having a slow processing speed processes data, a delay apparatus delays data which include the irregular data and data which are supplied from the large scale decoder without a delay are filled in the irregular data portion. As a result, the irregular portion of the data is compensated for and a relative delay of the processing is prevented.

Claims

1. A picture compressing and expanding apparatus comprising a compression part for compressing a picture signal and an expansion part for decoding and expanding data of variable length codes compressed by said compression part, wherein said expansion part comprises:

a small scale decoder for decoding one piece of compressed data;

a large scale decoder having a processing speed which is approximately half that of said small scale decoder and decodes two or more pieces of said compressed data;

input data control means for supplying said data of variable length codes compressed by said compression part to said small scale decoder and said large scale decoder at the same time;

first switching means for switching and outputting output data supplied from said small scale decoder and output data supplied from said large scale decoder;

delaying means for delaying output data supplied from said first switching means by a unit time;

second switching means for switching and outputting the output data supplied from said first switching means and output data supplied from said delaying means in accordance with a predetermined timing signal; and

timing control means for generating said predetermined timing signal which causes said second switching means to switch from the output data supplied from said delaying means to the output data supplied from said first switching means,

said small scale decoder comprises judging means for determining whether received data are one piece of data or two or more pieces of data, and

said timing means comprises;

irregular timing detecting means for detecting irregular data which are created when said first switching means switches the output data supplied from said small scale decoder and the output data supplied from said large scale decoder in accordance with a judgement signal which is yielded by said judging means for said small scale decoder; and

timing signal output means for said predetermined timing signal to said second switching means in accordance with a signal received from said timing control means.

2. A picture compressing and expanding apparatus, comprising:

a compression part for transforming a picture signal by orthogonal transformation to thereby non-reversibly compress said picture signal;

an expansion part for decoding and expanding the data which are compressed by said compression part and for outputting the data;

a filter part for filtering at least a portion of the data which are outputted from said expansion part by a predetermined smooth filtering and for outputting the data;

an output switching part for switching the data outputted from said expansion part and data outputted from said filter part; and

a switching control part for controlling switching performed by said output switching part, wherein said output switching part comprises;

block distortion predicting means for predicting a block distortion of the data outputted from said expansion part using a threshold which is determined in accordance with a data structure of a predetermined frequency space which is stored within said expansion part; and

timing signal generating means for generating said predetermined timing signal which causes said output switching part to switch from the data outputted from said expansion part to the data outputted from said filter part in accordance with a prediction result yielded by said block distortion predicting means only when a block distortion is predicted.

3. The picture compressing and expanding apparatus of claim 2, wherein said block distortion predicting means of said switching control part comprises judging means for determining whether components not belonging to a predetermined low frequency region of data transformed into the frequency space through predetermined two-dimensional transformation are all "0."

4. A picture compressing and expanding apparatus comprising a compression part for compressing a picture signal and an expansion part for decoding and expanding data of variable length codes compressed by said compression part so that said picture signal is processed through predetermined processing in pipelines in at least one of said compression part and said expansion part, said picture compressing and expanding apparatus being characterized in comprising:

enable means for detecting timing at which pipelines validly operate in accordance with a horizontal synchronizing signal and a vertical synchronizing signal which are inputted to said enable means and for thereafter outputting a predetermined enable signal; and

processing control means for permitting signal processing within said pipelines only when said predetermined enable signal is received from said enable means and for stopping signal processing within said pipelines when said predetermined enable signal is not received.

5. A picture compressing and expanding apparatus comprising a compression part for compressing a picture signal and an expansion part for decoding and expanding data of variable length codes compressed by said compression part so that said picture signal is processed through predetermined processing in pipelines in at least one of said compression part and said expansion part, said picture compressing and expanding apparatus being characterized in comprising:

enable means for detecting timing at which pipelines validly operate in accordance with a horizontal synchronizing signal and a vertical synchronizing signal which are inputted to said enable means and for thereafter outputting a predetermined enable signal;

enable signal delaying means for delaying said predetermined enable signal by the number of said pipelines which perform signal processing; and

processing control means for permitting signal processing within each one of said pipelines only when said predetermined enable signal corresponding to each one of said pipelines is received from said enable means or said enable signal delaying means and for stopping signal processing within said pipelines when said predetermined enable signal is not received.