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US 8,542,731 B2Granted
Method and apparatus for video codec quantization
AssigneeThomson Licensing
InventorsAlexandros Michael Tourapis, Jill MacDonald Boyce, Peng Yin
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Abstract
An encoder, a decoder, and corresponding methods are provided for encoding and decoding video signal data for an image block. The encoder includes a quantizer for receiving transform coefficients for the image block, and for adaptively performing dead-zone quantization based on coefficient positions and coefficient distributions of the transform coefficients.
Claims16
An encoder for encoding video signal data for an image block, comprising:
- a quantizer for receiving transform coefficients for the image block, and for adaptively performing dead-zone quantization based on coefficient positions and coefficient distributions of the transform coefficients to form quantization levels, wherein said quantizer adaptively performs the dead-zone quantization by determining a preliminary quantization level using a fixed dead-zone/rounding control, and repeating the dead-zone quantization based on the preliminary quantization level and using a coefficient quantization level dependent dead-zone/rounding control;
- and
- an inverse quantizer for de-quantizing the quantization levels to generate reconstructed levels, wherein a rounding parameter used for de-quantizing a quantization level of a transform coefficient is determined by the quantization level.
A method for encoding video signal data for an image block, comprising the steps of:
- receiving transform coefficients for the image block;
- adaptively performing dead-zone quantization based on coefficient positions and coefficient distributions of the transform coefficients to form quantization levels, wherein said step of adaptively performing the dead-zone quantization comprises the steps of:
- initially performing the dead-zone quantization by determining a preliminary quantization level using a fixed dead-zone/rounding control;
- and
- repeating the dead-zone quantization based on the preliminary quantization level and using a coefficient quantization level dependent dead-zone/rounding control;
- and
- de-quantizing the quantization levels to reconstructed levels, wherein a rounding parameter used for de-quantizing a quantization level of a transform coefficient is determined by the quantization level.
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