Matrox Graphics Inc.

Simon Garneau

Jean-Jacques Ostiguy

Alain Champenois

Nicolas Jean

Bernard Antaki

Mathieu Girard

Oui Goi

Khalil Mawassi

A method and apparatus for compressing a data stream comprising a plurality of pictures are described. A first quantization parameter (QP) from a plurality of QPs is determined, for a static region in a current picture. The plurality of QPs change in accordance with a multi-step change from a start QP to a target QP and each one of the plurality of QPs is to be applied to a respective one from successive static regions in successive pictures. In response to determining, based upon statistics on static region(s) in the current picture which are associated with the first QP, that the first QP is selected, compression of the static region is caused based upon the first QP, and in response to determining that the first QP is not selected, compression of the static region is caused based upon a second QP that is greater than the first QP.

Motion-based adaptive quantization

A method and apparatus for compressing a data stream comprising a plurality of pictures are described. A first quantization parameter (QP) from a plurality of QPs is determined, for a static region in a current picture. The plurality of QPs change in accordance with a multi-step change from a start QP to a target QP and each one of the plurality of QPs is to be applied to a respective one from successive static regions in successive pictures. In response to determining that the static region is to be compressed based upon an inter prediction mode, compression of the static region is caused based upon the first QP; and in response to determining that the static region is to be compressed based upon an intra prediction mode, compression of the static region is caused based upon a minimum QP.

There is described herein motion-based adaptive quantization for compressing video streams. Motionless portions of pictures are detected and the compression quality of these portions is increased while the compression quality of non-motionless portions is decreased. The QP of a portion of image data, such as a macroblock, is modified for successive motionless portions from a start QP to a target QP in accordance with a multi-step change.

There is described an image compressing/decompressing method and device that provides the lossless data compression/decompression scheme in two separate modules. Partially entropy encoded/decoded data is written to memory by a first module after a first part of the process and retrieved by a second module to perform the second part of the lossless compression/decompression scheme.

Division of entropy coding in codecs

There is described herein a method and system for dynamically controlling the bit rate of a codec during image data compression by analyzing information output by a first module that processes the group of macroblocks as part of the compression scheme, and configuring a second module to process the group of macroblocks according to this analysis.

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Coteau-du-Lac, Canada

Simon Garneau