ESTIMATING RATE COSTS IN VIDEO ENCODING OPERATIONS USING ENTROPY ENCODING STATISTICS

摘要

A component of an entropy encoding stage of a block processing pipeline (e.g., a CABAC encoder) may, for a block of pixels in a video frame, accumulate counts indicating the number of times each of two possible symbols is used in encoding a syntax element bin. An empirical probability for each symbol, an estimated entropy, and an estimated rate cost for encoding the bin may be computed, dependent on the symbol counts. A pipeline stage that precedes the entropy encoding stage may, upon receiving another block of pixels for the video frame, calculate and use the estimated rate cost when making encoding decisions for the other block of pixels based on a cost function that includes a rate cost term. The symbol counts or empirical probabilities may be passed to the earlier pipeline stage or written to a shared memory, from which components of the earlier stage may obtain them.

主权项

1. An apparatus, comprising:
a block processing pipeline configured to process blocks of pixels from a video frame; and a memory accessible by respective processors in components at each of two or more stages of the block processing pipeline; wherein an entropy encoding stage of the block processing pipeline comprises a binary arithmetic coding component configured to encode syntax element bins that represent the blocks of pixels; wherein, for each of one or more of a plurality of syntax element bins for a given block of pixels, the binary arithmetic coding component is configured to:
code the syntax element bin using one or more symbols, each of which has one of two possible values;update, in the memory, at least one of: a count of symbols used in coding the syntax element bin having one of the two possible values or a count of symbols used in coding the syntax element bin having the other one of the two possible values; and wherein, when processing another block of pixels, a processor in a component at a stage of the block processing pipeline that precedes the entropy encoding stage is configured to:
access the count of symbols used in coding a given syntax element bin having the one of the two possible values and the count of symbols used in coding the given syntax element bin having the other one of the two possible values;compute, for the given syntax element bin, a current probability for each of the two possible values of the symbols used to encode the given syntax element bin, dependent on the accessed counts;compute an estimate of entropy for the given syntax element bin, dependent on the computed current probability for each of the two possible values; andcalculate an estimated rate cost for encoding the given syntax element bin for the other block of pixels, wherein the estimated rate cost is dependent on the computed estimate of entropy, and wherein the estimated rate cost represents an estimate of the amount of data needed to encode the given syntax element bin of the other block of pixels.