CABAC Bin Coding Switch for High-Throughput Video Encoding
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Solution Overview
Problem
CABAC is a throughput bottleneck in video codec implementations due to feedback loops, making it difficult to achieve high throughput necessary for high resolution and frame-rate videos, particularly on battery-operated devices.
Innovation Solution
Implementing a method and apparatus for context adaptive binary arithmetic coding (CABAC) with scalable throughput by reducing the number of context-coded bins during entropy encoding and decoding, enabling high throughput mode to increase processing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If CABAC with context coding mode is used for all bins, then coding efficiency is improved, but throughput is reduced due to feedback loops
Solution Approach 1:
The patent segments the CABAC coding process into two distinct modes: context coding mode for the first N bins and bypass coding mode for subsequent bins. This segmentation allows the system to achieve high coding efficiency for the initial bins using context modeling while enabling high throughput for the remaining bins using the simpler bypass mode, thereby resolving the contradiction between coding efficiency and throughput.
Solution Approach 2:
The patent introduces dynamic switching between context coding mode and bypass coding mode based on the bin index. The coding mode changes dynamically during the encoding process, transitioning from context coding to bypass coding after a specified number of bins have been coded. This dynamic approach allows the system to optimize both coding efficiency and throughput at different stages of the encoding process.
2Loss of information
If CABAC is implemented on battery-operated devices, then video compression is achieved, but battery life is limited due to serial processing
Solution Approach 1:
The patent segments the coding process into context coding and bypass coding phases, allowing battery-operated devices to use the computationally intensive context coding only for the first N bins while using the simpler bypass coding for the remaining bins. This reduces overall computational load and power consumption, thereby extending battery life while maintaining video compression capability.
Solution Approach 2:
The patent changes the coding parameter (coding mode) based on the bin index and device capabilities. For battery-operated devices, the system can adjust the threshold N to balance between compression efficiency and power consumption, enabling flexible operation adapted to device-specific constraints.
3Measurement precision
If high resolution and frame-rate videos are processed, then video quality is improved, but throughput requirements increase making CABAC difficult to parallelize
Solution Approach 1:
The patent segments the coding process to allow parallel processing of bypass-coded bins while maintaining sequential context coding for the first N bins. This segmentation enables higher throughput for high resolution and frame-rate videos by allowing multiple bypass bins to be processed in parallel, while still achieving good video quality through the initial context coding phase.
Data Source
AI summary
A method for encoding a video sequence is provided that includes entropy encoding syntax elements representative of transform coefficients generated as the video sequence is processed, wherein entropy encoding syntax elements representative of a transform coefficient includes binarizing the syntax elements representative of the transform coefficient to generate a plurality of binary symbols (bins), coding a portion of the plurality of bins in context coding mode, and coding a remaining portion of the plurality of bins in bypass coding mode. The method further includes reducing the number of bins that are coded in context coding mode for each transform coefficient in a plurality of subsequent transform coefficients that are entropy encoded after a specified number of transform coefficients have been entropy encoded.