CABAC Coefficient Coding Switch for High-Throughput HEVC
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Solution Overview
Problem
High bit-rate encoding and decoding in video coding standards like HEVC using CABAC face significant throughput performance issues, consuming substantial processing resources and time, especially with high bit-rate cases and large Absolute-3 values.
Innovation Solution
Implementing a method that involves arithmetic decoding and encoding of transform coefficients using k-th order Exp-Golomb coding, and dynamically switching between Golomb-Rice and Exponential-Golomb coding based on the magnitude of Absolute-3 values and block sizes to optimize throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If CABAC is used to compress TQCs without loss, then compression efficiency is improved, but processing complexity and time increase significantly
Solution Approach 1:
The patent segments the TQC encoding process into multiple stages: significance map generation, level value encoding, and sign encoding. Each stage uses simplified coding methods appropriate to its specific function, avoiding the need for complex context-adaptive probability models while maintaining good compression efficiency.
Solution Approach 2:
The patent employs simpler, computationally cheaper coding schemes (such as fixed-length or variable-length codes without complex probability adaptation) that can be quickly computed and discarded, replacing the need for expensive, time-consuming context-adaptive arithmetic coding while achieving acceptable compression ratios.
2Manufacturing precision
If CABAC is used for high bit-rate encoding, then compression accuracy is improved, but throughput performance deteriorates
Solution Approach 1:
The patent introduces dynamic switching between different coding modes (e.g., between simplified coding and more accurate coding schemes) based on local characteristics of the TQCs. This allows the system to achieve high compression accuracy when needed while maintaining high throughput when the data characteristics allow for simpler encoding.
Solution Approach 2:
The patent changes encoding parameters (such as code length, coding scheme type) based on the magnitude and distribution of TQC values. By adapting parameters to the actual data characteristics rather than using fixed complex models, the system achieves both good compression accuracy and high processing speed.
3Loss of information
If context-adaptive coding is used based on neighboring blocks, then compression efficiency is improved, but computational resources increase
Solution Approach 1:
The patent applies context-adaptive coding selectively to only those TQCs that benefit most from it (e.g., significant coefficients or those in specific spatial positions), while using simpler coding for the remainder. This partial application maintains good compression efficiency while dramatically reducing the computational burden of evaluating and updating context models for all coefficients.
Data Source
AI summary
A system utilizing a high throughput coding mode for CABAC in HEVC is described. The system may include an electronic device configured to obtain a block of data to be encoded using an arithmetic based encoder; to generate a sequence of syntax elements using the obtained block; to compare an Absolute-3 value of the sequence or a parameter associated with the Absolute-3 value to a preset value; and to convert the Absolute-3 value to a codeword using a first code or a second code that is different than the first code, according to a result of the comparison.