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

Hybrid variable length coding method for low bit rate video coding


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

Full patent text at USPTO