Motion video coding with adaptive precision for DC component coefficient quantization and variable length coding
AssigneeSony Corporation
InventorMotoki Kato
Life of this patent
Estimating the term…
Abstract
Direct current component coefficients resulting from an orthogonal transformation of a video signal are encoded with a precision, expressed in terms of quantization bits, which may be varied at each video sequence, group of pictures, picture, slice, macroblock or block portion of the video signal in accordance with a required picture quality. The encoded coefficients may be decoded in accordance with the precision used during encoding.
Claims29
A method of encoding a video signal having pixels represented by n bits, n being an integer, comprising the steps of:
- receiving a picture quality signal;
- selecting an encoding precision of n+m bits, m being a non-negative integer, in accordance with said picture quality signal;
- orthogonally transforming said video signal to produce direct current component coefficients and alternating current component coefficients;
- quantizing only said direct current component coefficients using the selected encoding precision;
- obtaining a difference between a first of said quantized direct current component coefficients and an initial value set in accordance with said selected encoding precision;
- and
- variable length encoding the differentiated direct current component coefficients using variable length coding tables, each of said coding tables having a length that is a function of said selected encoding precision.
An apparatus for encoding a video signal having pixels represented by n bits, n being an integer, comprising:
- means for receiving a picture quality signal;
- means for selecting an encoding precision of n+m bits, m being a non-negative integer, in accordance with said picture quality signal;
- means for orthogonally transforming said video signal to produce direct current component coefficients and alternating current component coefficients;
- means for quantizing only said direct current component coefficients using the selected encoding precision;
- means for obtaining a difference between a first of said quantized direct current component coefficients and an initial value set in accordance with said selected encoding precision;
- and
- means for variable length encoding the differentiated direct current component coefficients using variable length coding tables, each of said coding tables having a length that is a function of said selected encoding precision.
A method of decoding an encoded video signal corresponding to an original video signal having pixels represented by n bits, n being an integer, comprising the steps of:
- receiving a picture quality signal;
- selecting a decoding precision of n+m bits, m being a non-negative integer, in accordance with said picture quality signal;
- extracting encoded direct current component coefficients from said encoded video signal;
- variable length decoding only said encoded direct current component coefficients using variable length coding tables, each of said coding tables having a length that is a function of the selected decoding precision;
- obtaining an inverse difference between a first of the variable length decoded direct current component coefficients and an initial value set in accordance with the selected decoding precision;
- and
- inverse quantizing the inverse differentiated direct current component coefficients using the selected decoding precision.
An apparatus for decoding an encoded video signal corresponding to an original video signal having pixels represented by n bits, n being an integer, comprising:
- means for receiving a picture quality signal;
- means for selecting a decoding precision of n+m bits, m being a non-negative integer, in accordance with said picture quality signal;
- means for extracting encoded direct current component coefficients from said encoded video signal;
- means for variable length decoding only said encoded direct current component coefficients using variable length coding tables, each of said coding tables having a length that is a function of the selected decoding precision;
- means for obtaining an inverse difference between a first of the variable length decoded direct current component coefficients and an initial value set in accordance with the selected decoding precision;
- and
- means for inverse quantizing the inverse differentiated direct current component coefficients using the selected decoding precision.
Dependencies are inferred from the claim text.