CABAC Bypass Bin Multiplexing for Higher Video Codec Throughput
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Solution Overview
Problem
CABAC is a throughput bottleneck in video codec implementations due to feedback loops, which limits parallelization and increases power consumption on battery-operated devices, especially for high-resolution and high-frame-rate videos.
Innovation Solution
Accelerate bypass bin processing by directly writing and reading bypass bins into and from the compressed video bit stream without encoding or decoding, using a multiplexing scheme to combine context-coded and bypass bins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If CABAC encoding with feedback loops is used, then compression efficiency is improved, but throughput is reduced and power consumption increases
Solution Approach 1:
The patent segments the binary symbols into two distinct categories: context-coded bins and bypass bins. This segmentation allows different processing paths to be applied to different types of data, enabling parallel processing of bypass bins while maintaining sequential processing of context-coded bins, thereby improving throughput without sacrificing compression efficiency.
Solution Approach 2:
The patent extracts bypass bins from the main CABAC processing pipeline and handles them separately through direct writing to the bit stream. This extraction removes the bottleneck caused by feedback loops for a significant portion of the data, enabling parallel processing and improving overall throughput while maintaining compression efficiency for the remaining context-coded bins.
2Loss of information
If CABAC encoding with feedback loops is used, then compression efficiency is improved, but device complexity is increased
Solution Approach 1:
The patent divides the processing logic into separate paths: one for context-coded bins that requires feedback loops and probability modeling, and another for bypass bins that uses simple direct writing. This segmentation reduces the complexity of each individual processing path while maintaining the overall compression efficiency through the combination of both paths.
3Use of energy by moving object
If voltage scaling is used to reduce power consumption, then power savings are achieved, but throughput is reduced
Solution Approach 1:
The patent segments processing into parallel paths, allowing bypass bins to be processed independently of context-coded bins. This enables the system to maintain higher throughput by processing bypass bins in parallel while using voltage scaling on the context-coded bin processing path, achieving better power-throughput trade-off.
Solution Approach 2:
The patent extracts bypass bin processing from the power-intensive CABAC pipeline and handles it through a simpler, parallel path. This extraction allows the main processing path to use voltage scaling for power savings while the extracted bypass path maintains high throughput through parallel execution.
Data Source
AI summary
A method for encoding a video sequence in a video encoder to generate a compressed video bit stream is provided that includes binarizing a plurality of syntax elements, wherein each binarized syntax element comprises a string of one or more binary symbols (bins), wherein a bin is one selected from a context-coded bin and bypass bin, encoding the context-coded bins of the binarized syntax elements using binary arithmetic encoding, and adding the bypass bins of the binarized syntax elements to the compressed video bit stream with no encoding.