EP0447203A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Data compression and decompression system and method
Assignee: LSI Corp
•
Filing: 1991-03-13
•
Granted: —
•
Expires: 2011-03-13
Abstract
Abstract In a digital video compression and decompression method and system, matrices of pixels in RGB, YUV or CMYK formats are accepted for data compression. The data are rearranged in 8x8 pixel blocks, each block being of one pixel component type. The pixel data are then subjected to a discrete cosine transform (DCT). A quantization step eliminates DCT coefficients having amplitude below a set of preset thresholds. The video signal is further compressed by coding the elements of the quantized matrices in a zig-zag manner. This representation is further compressed by Huffman codes. Decompression of the signal is substantially the reverse of compression steps. The inverse discrete cosine transform (IDCT) may be implemented by the DCT circuit. The circuits may be implemented in a single integrated circuit chip. Three levels of compression rate control are provided during processing of video data.
Inventors
- 👤 Alexandre Balkanski
- 👤 Stephen C. Purcell
- 👤 James W. Kirkpatrick, Jr.
- 👤 Mauro Bonomi
- 👤 Wen-Chang Hsu
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-26 02:45
CPC Classifications
H; H04; H04N; H04N19/00; H04N19/42; H04N19/60; H04N19/10; H04N19/102; H04N19/13; H04N19/90; H04N19/91
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
354 words
A system for data compression and decompression, comprising: video interface means for receiving and transmitting digitized images; discrete cosine transform means for performing, during data compression, a 2-dimensional discrete cosine transform on data received by said video interface means, 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 video interface for transmission as digitized images; 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, said run length-represented coefficients of said 2-dimensional discrete cosine transform representing runs of zero coefficients as run lengths of zero coefficients, 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 coefficient 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.
Claim 2
Dependent Claim
46 words
A system as claimed in claim 1 wherein the video interface means comprises: data synchronization means for providing, during "master mode" operation, and for receiving, during"slave mode" operations, synchronization signals, said synchronization signals provide synchronization between said system and external video equipment providing said digitized images.
Claim 3
Dependent Claim
37 words
A system as claimed in claim 1 or 2 wherein the video interface means comprises external buffer memory address generation means for generating external buffer memory address for storing video data in an external video memory buffer.
Claim 4
Dependent Claim
111 words
A system as claimed in claim 3 wherein the video interface means comprises video frame means for, during compression, receiving from said external video equipment and storing into said external video buffer memory horizontal line- by-line "video sequence" signals of said digitized images, and retrieving from said video buffer memory buffer into said video interface means "block video pixel" data corresponding to pixels in an area within said digitized images, and for, during decompression, receiving from said video interface means and storing into said external video buffer memory said "buffer video pixel" data of said digitized images, and providing said external video equipment said "video sequence" signals of said digitized images.
Claim 5
Dependent Claim
86 words
A system as claimed in claim 1, 2, 3 or 4 wherein the Huffman coding/decoding means comprises: Huffman table means for storing and providing Huffman code encoding tables during compression and Huffman code decoding tables during decompression; coding means for translating said run length-represented coefficients of said 2-dimensional discrete cosine transform into Huffman codes using said Huffman code encoding tables; and decoding means for translation of said Huffman codes to said run length-represented coefficients of said 2-dimensional discrete cosine transform using said Huffman code decoding tables.
Claim 6
Dependent Claim
87 words
A system as claimed in claim 5 wherein the coding means comprises: read control means for requesting from said first-in first-out memory means a run length represented coefficient of said 2-dimensional discrete cosine transform; coding address means for providing an address constructed from said run length-represented coefficient of said 2-dimensional discrete cosine transform to said Huffman table means for requesting an entry in said Huffman code encoding tables; and Huffman code output means for providing said entry in said Huffman code encoding tables as output Huffman code.
Claim 7
Dependent Claim
142 words
A system as claimed in claim 5 or 6 wherein the decoding means comprises: Huffman code receiving means for receiving a Huffman code; decoding address means for providing an address, constructed from either said Huffman code or a next address, to said Huffman table means for requesting an entry in said Huffman code decoding tables; decoding control means for examining said entry of said Huffman code decoding tables to determine if said entry of said Huffman code decoding tables is a run-length represented coefficient of said 2-dimensional discrete cosine transform or comprises a next address, and for providing said next address to said decoding address means when said entry of said Huffman code decoding table comprises a next address; and Huffman decode output means for providing said run-length represented coefficient of said 2-dimensional discrete cosine transform as an output Huffman decoded datum.
Claim 8
Independent Claim
53 words
A system as claimed in any preceding claim wherein the first-in first-out memory means provides a plurality of status signals indicating the usage of said first-in first-out memory means, and wherein said system comprises adaptive control means for varying compression ratios achieved on said digitized images during compression according to said status signals.
Claim 9
Dependent Claim
59 words
A system as claimed in claim 8 wherein the quantization means achieved attenuation of said higher frequencies coefficients of said 2-dimensional discrete cosine transform by combining each of said coefficients of said discrete cosine transform with a corresponding quantization constant, and wherein said adaptive control means varies compression ratios achieved on said digitized images by varying said quantization constant.
Claim 10
Dependent Claim
45 words
A system as claimed in claim 8 or 9 wherein the adaptive control means varies compression ratios achieved on said digitized image by zeroing said "zig-zag" ordered coefficients of said 2-dimensional discrete cosine transform after a predetermined number of said "zig-zag" ordered coefficients are received.
Claim 11
Dependent Claim
24 words
A system as claimed in claim 10 wherein the predetermined number is selected from a plurality of predetermined values according to said status signals.
Claim 12
Dependent Claim
88 words
A system as claimed in claim 8, 9, 10 or 11 comprising overall adaptive control means for enabling and disabling said adaptive control means, wherein said overall adaptive control means monitors and examines, at predetermined points in the course of receiving said digitized images, the compression ratio achieved on said digitized image against a set predetermined compression targets, and when any of said predetermined targets is exceeded, said overall adaptive control means enables said adaptive control means, otherwise said overall adaptive control means disables said adaptive control means.
Claim 13
Independent Claim
369 words
A method of data compression and decompression, comprising: providing a video interface means for receiving and transmitting digitized images; providing a discrete cosine transform means for performing, during data compression, a 2-dimensional discrete cosine transform on data received by said video interface means, 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 video interface for transmission as digitized images; providing a 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; providing a 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; providing a 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, said run length-represented coefficients of said 2-dimensional discrete cosine transform represent runs of zero coefficients as run lengths of zero coefficients, and for unpacking, during data decompression, 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; providing a 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 decompression, said Huffman codes into said run length-represented coefficients of said 2-dimensional discrete cosine transform; providing a first-in first-out 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 data unpacking means; and providing a 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.
References Cited (Backward Citations)
US7494242B2
Cited
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.