Video Encoder CABAC Bypass Coding Residual Coefficients
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Solution Overview
Problem
The existing video coding standards, such as H.264/MPEG-4 AVC, face challenges in achieving high compression efficiency when encoding residual coefficients, particularly at high resolutions or frame rates, due to limitations in the coding of residual data in the frequency domain.
Innovation Solution
The method involves a video encoder and decoder system that utilizes a transform unit (TU) with a quadtree structure, allowing for both square and non-square shapes, and employs context-adaptive binary arithmetic coding (CABAC) with bypass coding mode to efficiently encode and decode residual coefficients, enhancing throughput by reading multiple adjacent bins in parallel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If context-adaptive binary arithmetic coding (CABAC) is used to encode residual coefficients, then coding efficiency is improved, but processing complexity and time increase
Solution Approach 1:
The patent segments the encoding process by separating bypass-coded bins from context-modelled bins. Bypass-coded bins are processed independently and in parallel, while context-modelled bins use adaptive probability models. This segmentation allows the system to achieve high coding efficiency for bypass-coded regions without the full computational overhead of CABAC, thus resolving the contradiction between coding efficiency and processing complexity.
Solution Approach 2:
The patent applies partial CABAC by using bypass coding for certain bins that do not require context modeling. This partial application of the full CABAC process reduces processing complexity while maintaining sufficient coding efficiency for those specific bins, thereby resolving the contradiction between complete CABAC efficiency gains and the associated processing burden.
2Productivity
If multiple adjacent bins are read in parallel to increase throughput, then processing speed is improved, but synchronization and control complexity increase
Solution Approach 1:
The patent segments bins into bypass-coded and context-modelled categories, allowing bypass-coded bins to be read in parallel without requiring complex synchronization with context-modelled bins. This segmentation enables throughput improvement through parallel processing while minimizing synchronization complexity by isolating the parallel operations to specific bin types.
3Adaptability or versatility
If transform units are allowed to have non-square shapes, then adaptability to different block structures is improved, but decoding complexity increases
Solution Approach 1:
The patent applies different coding strategies to different regions of the transform unit based on its shape. For non-square TUs, specific scanning orders and coefficient encoding methods are applied locally to match the geometric structure, while square TUs use standard procedures. This local adaptation improves versatility without requiring complete redesign of the decoding process for all TU types.
Data Source
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AI summary
Disclosed is a method of coding image data into a bitstream, the method comprising: arithmetically coding flags each of which being for a different one of prediction units in a target coding unit into the bitstream, in a case where the target coding unit is divided into the prediction units, the flag indicating whether any of specific intra-prediction modes is used; bypass coding pieces of information each of which being for a different one of the prediction units in the target coding unit into the bitstream, each of the pieces of information being for designating one of intra-prediction modes; and coding the target coding unit into the bitstream using intra-prediction modes to be indicated by the flags and the pieces of information. In the bitstream, the pieces of information each of which being for a different one of the prediction units in the target coding unit are located posterior to the flags each of which being for a different one of the prediction units in the target coding unit.