SAO Parameter Estimation Using Non-Deblock Pixels
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Solution Overview
Problem
Current video coding standards, such as HEVC, face challenges in reducing blocking artifacts and intensity shift due to the delay caused by waiting for deblock filtering to complete before estimating Sample Adaptive Offset (SAO) parameters, which restricts LCU-based processing and degrades performance.
Innovation Solution
Estimating SAO parameters using non-deblock-filtered reconstructed pixels to enable LCU-based processing without waiting for deblock filtering to finish, allowing SAO filtering to be applied to deblock-filtered pixels, thereby improving accuracy and reducing delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If SAO parameters are estimated using deblock-filtered reconstructed pixels, then the accuracy of SAO estimation is improved, but the encoding delay increases and LCU-based processing is restricted
Solution Approach 1:
The patent applies preliminary action by estimating SAO parameters using non-deblock-filtered reconstructed pixels before the deblocking filter is applied. This allows the SAO parameter estimation to proceed in parallel with the deblocking process rather than waiting for it to complete, thereby reducing encoding delay while maintaining LCU-based processing efficiency. The estimated parameters are then refined or adjusted after deblocking to maintain accuracy.
2Productivity
If SAO filtering is applied to non-deblock-filtered pixels, then processing speed is improved, but the quality of filtering is degraded
Solution Approach 1:
The patent performs preliminary SAO filtering on non-deblock-filtered pixels to enable parallel processing and improve speed. Subsequently, the SAO filter is applied again or adjusted using the deblock-filtered pixels to ensure high filtering quality. This two-stage approach allows the system to benefit from both fast preliminary processing and high-quality final filtering.
Solution Approach 2:
The patent uses the non-deblock-filtered pixels as an intermediary for initial SAO parameter estimation, which then serves as a basis for the final SAO filtering operation on deblock-filtered pixels. This intermediary step enables processing optimization while the final operation ensures quality, effectively using the intermediate result as a bridge between speed and quality requirements.
3Productivity
If LCU-based processing is enabled, then processing efficiency is improved, but it requires waiting for deblock filtering to complete which reduces efficiency
Solution Approach 1:
The patent enables LCU-based processing by performing preliminary SAO parameter estimation using non-deblock-filtered pixels within the LCU before the deblocking filter completes. This allows the LCU processing to proceed independently and in parallel with the deblocking operation, eliminating the waiting time that would otherwise bottleneck processing efficiency.
Data Source
AI summary
A method for sample adaptive offset (SAO) filtering in a video encoder is provided that includes estimating SAO parameters for color components of a largest coding unit (LCU) of a picture, wherein estimating SAO parameters includes using at least some non-deblock-filtered reconstructed pixels of the LCU to estimate the SAO parameters, performing SAO filtering on the reconstructed LCU according to the estimated SAO parameters, and entropy encoding SAO information for the LCU in a compressed video bit stream, wherein the SAO information signals the estimated SAO parameters for the LCU.