MDCP: Patent Abstact US05235623: Adaptive transform coding by selecting optimum block lengths according to variatons between successive blocks

US05235623 Adaptive transform coding by selecting optimum block lengths according to variatons between successive blocks

Assignee NEC Corporation

Assign./Filed Aug. 10, 1993/ Nov. 14, 1990

Inventors Sugiyama; Akihiko, Iwadare; Masahiro, Nishitani; Takao

Summary Transform coding with adaptable input block size.

Abstract Subblocks of input digital samples are stored into a buffer at frame intervals and segmented into blocks having an integral multiple of the length of the subblock. Each block is encoded into transform coefficients and stored into a memory. Each coefficient is squared and those of the squared transform coefficients which correspond to high-frequency components of the input digital samples are summed and a minimum value is detected therefrom as corresponding to an optimum block length. Those transform coefficients which correspond to the optimum block length are selected from the memory and multiplexed with a signal representative of the optimum block length. In a modification, interblock differences are detected between successive transform coefficients of equal block length and squared. Those of the squared interblock differences which correspond to equal block length are summed, producing a set of squared sums for each block length. A variation is detected between a representative squared sum of a given set and a representative squared sum of a successive set to identify a block length which corresponds to the variation as an optimum block length.

US05235623	Adaptive transform coding by selecting optimum block lengths according to variatons between successive blocks
Assignee	NEC Corporation
Assign./Filed	Aug. 10, 1993/ Nov. 14, 1990
Inventors	Sugiyama; Akihiko, Iwadare; Masahiro, Nishitani; Takao
Summary	Transform coding with adaptable input block size.
Abstract	Subblocks of input digital samples are stored into a buffer at frame intervals and segmented into blocks having an integral multiple of the length of the subblock. Each block is encoded into transform coefficients and stored into a memory. Each coefficient is squared and those of the squared transform coefficients which correspond to high-frequency components of the input digital samples are summed and a minimum value is detected therefrom as corresponding to an optimum block length. Those transform coefficients which correspond to the optimum block length are selected from the memory and multiplexed with a signal representative of the optimum block length. In a modification, interblock differences are detected between successive transform coefficients of equal block length and squared. Those of the squared interblock differences which correspond to equal block length are summed, producing a set of squared sums for each block length. A variation is detected between a representative squared sum of a given set and a representative squared sum of a successive set to identify a block length which corresponds to the variation as an optimum block length.