Stmicroelectronics S.r.l.

Sgs-Thomson Microelectronics S.r.l.

Roberta Bruni

Danilo Pietro Pau

Fabrizio Simone Rovati

Roberto Sannino

Anna Valsasna

The memory requirement of MPEG decoders and SQTV/IQTV systems may be reduced by recompressing the MPEG decoded data stream before storing pixels in an external RAM. An efficient compression method for recompressing video picture data based on the tree-search vector quantization (TSVQ) is made more effective by optimizing the way the quantizer is chosen for quantizing the differences among adjacent pel vectors. This method is based on premultiplying a read-only table using quantized complexity measures relative to the centroids of the tree-like scheme used in the TSVQ processing. A plurality of precalculated tables of quantization of the prediction error of a physical parameter of blocks of digital data are produced. For each one of the regions in which a block is divided, the calculated and quantized complexity measure provides an address that selects the most appropriate precalculated table for quantizing the prediction error. The adaptive tree-search vector quantization method is implemented in a corresponding hardware architecture.

Adaptive tree-search vector quantization in MPEG2 decoder

A hardware accelerator for a coding system for pictures includes an array of lines and columns of pixels, and calculates the variance of macroblocks of a digitized video image for a real-time coding of the current image together with the preceding and successive images, according to the MPEG-2 video algorithm. The architecture minimizes the silicon area needed for implementing the hardware accelerator for a cost-effective reduction on the CPU of the coding system. The use of a plurality of distinct filter/demultiplexers of known architectures is eliminated by conveying the incoming pixels to the respective input lines of distinct variance calculation paths by the use of a simple counter.

Macroblock variance estimator for MPEG-2 video encoder

A method for reducing the RAM requirement for temporarily storing a stream of data blocks in a coding/decoding system of information transferable by blocks, includes the steps of: compressing and coding the data by blocks through a tree search vector quantization (TSVQ); storing TSVQ compressed and coded data in the RAM; and decoding and decompressing in a subsequent reading of the data stored in the RAM the coded and compressed data, thereby reconstituting the stream of digital data blocks. The method may include fixing a certain scanning path of each data block of the stream to be decomposed into vectors of preestablished dimensions; coding the first vector of the scanning of a certain block of data in an unmodified manner; generating a replica vector of the last coded vector and calculating a prediction error vector; quantizing according to a binary search in a table of read-only quantized vectors the prediction error, by coding its address in the table; and repeating several of the steps for all the vectors of the scanning of each input data block.

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Seregno, Italy

Roberta Bruni