Soft decision and iterative video coding for MPEG and H.264
AssigneeBlackBerry Limited
InventorsEn-hui Yang, Xiang Yu
Life of this patent
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Abstract
A method of encoding video data using soft decision quantization makes use of iterative encoding to provide the ability to optimize encoding across different functional elements in a hybrid video encoder. Iterative encoding is used to allow quantization step size, motion prediction and quantization levels to be optimized despite their interrelated nature.
Claims19
A method for obtaining an optimal sequence of quantized coefficients for a block of transform residuals from a video, for encoding the video in a video encoder, the method comprising:
- obtaining a sequence of quantized coefficients for the block of transform residuals;
- calculating for the obtained sequence a rate-distortion cost based on a distortion cost and on a rate cost based on a context-adaptive entropy encoder, wherein the context-adaptive entropy encoder encodes each quantized coefficient by selecting at least one context from a plurality of contexts by determining an index for a set of contexts based, at least in part, on a previous quantized coefficient in the sequence of quantized coefficients;
- and
- changing a value of one of said quantized coefficients of the obtained sequence to produce a new sequence of quantized coefficients, so that a resulting rate-distortion cost for the new sequence of quantized coefficients is smaller than a rate-distortion cost for the obtained sequence.
A video encoder for encoding a video by obtaining an optimal sequence of quantized coefficients for a block of transform residuals from the video, the video encoder comprising:
- a processor;
- memory;
- a video encoding application executable by the processor and which, when executed, configures the processor to:
- obtain a sequence of quantized coefficients for the block of transform residuals;
- calculate, for the obtained sequence, a rate-distortion cost based on a distortion cost and on a rate cost based on a context-adaptive entropy encoder, wherein the context-adaptive entropy encoder encodes each quantized coefficient by selecting at least one context from a plurality of contexts by determining an index for a set of contexts based, at least in part, on a previous quantized coefficient in the sequence of quantized coefficients;
- and
- change a value of one of said quantized coefficients of the obtained sequence to produce a new sequence of quantized coefficients, so that a resulting rate-distortion cost for the new sequence of quantized coefficients is smaller than a rate-distortion cost for the obtained sequence.
A non-transitory computer-readable medium storing processor-executable instructions, for obtaining an optimal sequence of quantized coefficients for a block of transform residuals from a video, wherein the instructions, when executed, configure one or more processors to:
- obtain a sequence of quantized coefficients for the block of transform residuals;
- calculate for the obtained sequence a rate-distortion cost based on a distortion cost and on a rate cost based on a context-adaptive entropy encoder, wherein the context-adaptive entropy encoder encodes each quantized coefficient by selecting at least one context from a plurality of contexts by determining an index for a set of contexts based, at least in part, on a previous quantized coefficient in the sequence of quantized coefficients;
- and
- change a value of one of said quantized coefficients of the obtained sequence to produce a new sequence of quantized coefficients, so that a resulting rate-distortion cost for the new sequence of quantized coefficients is smaller than a rate-distortion cost for the obtained sequence.
Dependencies are inferred from the claim text.