Importance

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Abstract

Methods and apparatus for implementing video decoders at a lower cost than known video decoders are described. The methods include data reduction techniques, simplified inverse quantization techniques, and dynamically varying prediction filter complexity as a function of whether luminance or chrominance data is being processed. In various embodiments, data representing portions of B frames which will not be displayed is identified and discarded, e.g., without performing a decoding operation thereon. Portions of I and P frames which will not be displayed are identified and decoded at a reduced resolution and/or using simplified inverse quantization techniques. The decoded I and P frame data is stored for use when making subsequent predictions if required. Another data reduction technique involves applying different amounts of downsampling to different image portions with no or little downsampling being performed on image portions located at or nearest to the image's center of interest as determined from information included in a received encoded bitstream. Simplified inverse quantization techniques of the present invention which are suitable for use when processing data from P or B frames involve performing a simplified non-MPEG compliant inverse quantization operation. The inverse quantization operation of the present invention is implemented by treating an additive factor, k, as having a value of zero for both predictively and intra-coded data and/or by eliminating the mismatch control operation normally performed as part of an MPEG compliant inverse quantization operation.

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First Claim