United States Patent 7,454,073
Chen , et al. November 18, 2008

Video compression using multiple variable length coding processes for multiple classes of transform coefficient blocks

Abstract

A method and apparatus to variable length code an ordered series of quantized transform coefficients of an image block. The method classifies the series into one of a plurality of classes. Each class has a corresponding coding process that is applicable to the statistical distribution of the coefficients in the series. The series is coded according to the particular corresponding coding process of the class of the classifying.


Inventors: Chen; Wen-hsiung (Sunnyvale, CA), Wu; Fang (Pleasanton, CA), Pelton; Gregory D. (Raleigh, NC), Toebes; John A. (Cary, NC)
Assignee: Cisco Technology, Inc. (San Jose, CA)
Appl. No.: 10/910,712
Filed: August 3, 2004

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United States Patent 7,454,076
Chen , et al. November 18, 2008

Hybrid variable length coding method for low bit rate video coding

Abstract

A method and an apparatus of image compression, and a memory to store a data structure for compression. The method includes, for an ordered series of quantized coefficients of a transform of an image block, forming from the series events each with a run of non-zero-valued coefficients in a first contiguous region defined by a breakpoint, a run of zero-valued coefficients in the first region, or a run of zero-valued coefficients in a second region defined by the breakpoint. The breakpoint defines the first region and a second continuous region in the series. Codewords are formed for each runlength of non-zero-valued and zero-valued coefficients in the first region according to a first and a second coding method, respectively, and a codeword is formed for the non-zero amplitudes according to a first amplitude coding method. The runlengths of zero-valued coefficients in the second region are encoding using a third coding method.


Inventors: Chen; Wen-hsiung (Sunnyvale, CA), Wu; Fang (Pleasanton, CA), Pelton; Gregory D. (Raleigh, NC), Toebes; John A. (Cary, NC)
Assignee: Cisco Technology, Inc. (San Jose, CA)
Appl. No.: 10/869,229
Filed: June 15, 2004

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United States Patent 7,483,584
Chen , et al. January 27, 2009

Extended hybrid variable length coding of transform coefficients for video compression 

Abstract

A method and an apparatus of image compression, and a memory to store a data structure for compression. The method includes, for an ordered series of quantized coefficients of a transform of an image block, forming from the series events that are a run of non-zero-valued coefficients in a first contiguous region defined by a breakpoint, a run of zero-valued coefficients in the first region, or a run of zero-valued coefficients that ends in a non-zero-amplitude coefficient in a second region defined by the breakpoint. A codeword is formed for each runlength of non-zero-valued and zero-valued coefficients in the first region using a first and a second coding method, respectively, and, and encoding the runs of zero-valued coefficient that end in a non-zero value in the second region according to a third coding method, including providing an exception codeword when the ending amplitude is not 1.


Inventors: Chen; Wen-hsiung (Sunnyvale, CA), Wu; Fang (Pleasanton, CA), Pelton; Gregory D. (Raleigh, NC), Toebes; John A. (Cary, NC)
Assignee: Cisco Technology, Inc. (San Jose, CA)
Appl. No.: 10/898,654
Filed: July 22, 2004

Full patent text at USPTO

United States Patent 7,471,840
Toebes , et al. December 30, 2008

Two-dimensional variable length coding of runs of zero and non-zero transform coefficients for image compression 

Abstract

A method, apparatus, and carrier medium to encode a series of quantized transform coefficients. The method includes identifying events that each includes a run of zero-valued coefficients preceding a run of one or more non-zero-valued coefficients, and for each such event, jointly encoding the run lengths of the preceding run of zero-valued coefficients and the following run of non-zero-valued coefficients with a codeword, such that for at least some events, relatively more likely-to-occur pairs of runlengths are encoded by a shorter codeword than relatively less likely-to-occur runlengths. The method further includes encoding each amplitude in the run of consecutive non-zero-valued coefficients, and encoding the signs of such coefficients. The method is applicable to encoding a region in the series where there is likely to be a cluster of non-zero-valued coefficients.


Inventors: Toebes; John A. (Cary, NC), Chen; Wen-hsiung (Sunnyvale, CA), Wu; Fang (Pleasanton, CA), Rosenfeld; Dov (Oakland, CA),
Assignee: Cisco Technology, Inc. (San Jose, CA)
Appl. No.: 10/922,508
Filed: August 18, 2004

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United States Patent 7,486,212
Chen , et al. January 27, 2009

Variable length coding for sparse coefficients 

Abstract

Coding quantized transform coefficients as occur in image compression includes, for a subset of coefficient amplitude values coding by a first method corresponding to each amplitude of the subset, events of a run of zero or more zero-valued coefficients ending in the single non-zero amplitude, coding by a second method events of a run of zero or more zero-valued coefficients ending in any single non-zero amplitude not in the subset, and coding by a third method the amplitude values of the concatenation of the non-zero amplitude not in the subset. The coding methods produce variable length codewords. The method is suitable for series that have scattered non-zero-valued coefficients.


Inventors: Chen; Wen-hsiung (Sunnyvale, CA), Toebes; John A. (Cary, NC)
Assignee: Cisco Technology, Inc. (San Jose, CA)
Appl. No.: 11/761,307
Filed: June 11, 2007

Full patent text at USPTO