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System for compression and decompression of video data using discrete cosine transform and coding techniques

  • US 5,253,078 A
  • Filed: 08/23/1990
  • Issued: 10/12/1993
  • Est. Priority Date: 03/14/1990
  • Status: Expired due to Term
First Claim
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1. A system for data compression and decompression, comprising:

  • video interface means for receiving and transmitting digitized images as a stream of composite pixels, each composite pixel being represented by data of a plurality of chrominance and luminance component types;

    block memory means for receiving and sorting, during data compression, said stream of composite pixels from said video interface means into single-component type data blocks, and for receiving and reconstituting, during data decompression, single-component type data blocks into said stream of composite pixels;

    discrete cosine transform means for performing, during data compression, a 2-dimensional discrete cosine transform on single-component type data blocks received from said block memory, and providing coefficients of said 2-dimensional discrete cosine transform, and for performing, during data decompression, a 2-dimensional inverse discrete cosine transform, and providing as output data said coefficients of said 2-dimensional inverse discrete cosine transform to said block memory means as single-component type data blocks;

    quantization means for attenuating, during data compression, higher frequency coefficients of said 2-dimensional discrete cosine transform, and for partially restoring, during data decompression, said higher frequency coefficients of said 2-dimensional discrete cosine transform, in preparation for said 2-dimensional inverse discrete cosine transform;

    zig-zag means for rearranging, during data compression, said coefficients of said 2-dimensional discrete cosine transform from "sequential" order into "zig-zag" order, and for rearranging, during data decompression, said zig-zag ordered coefficients of said 2-dimensional discrete cosine transform from a "zig-zag" order to a "sequential" order;

    data packing and unpacking means for packing, during data compression, said "zig-zag" ordered coefficients of said 2-dimensional discrete cosine transform as run length-represented coefficients of said 2-dimensional discrete cosine transform, and for unpacking, during data compression, said run length-represented coefficients of said 2-dimensional discrete cosine transform to said "zig-zag" ordered coefficients of said 2-dimensional discrete cosine transform;

    Huffman coding/decoding means for coding, during data compression, said run length-represented coefficients of said 2-dimensional discrete cosine transform into Huffman Codes, and for decoding, during data compression, said Huffman codes into said run length-represented coefficients of said 2-dimensional discrete cosine transform;

    first-in first-out memory means for temporary storage of said run length represented coefficients of said 2-dimensional discrete cosine transform such that said Huffman coding/decoding means operates asynchronously and independent of said data packing and unpacking means; and

    host interface means for transmitting, during data compression, said Huffman codes to a host computer, and for retrieving, during data decompression, said Huffman codes from a host computer.

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