SAO Parameter Estimation Using Non-Deblocked LCU Pixels
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Solution Overview
Problem
The existing HEVC standard's sample adaptive offset (SAO) parameter estimation process is delayed due to the need for deblock-filtered pixels from neighboring LCUs, leading to restricted LCU-based processing and potential performance degradation.
Innovation Solution
The use of non-deblock-filtered pixels for SAO parameter estimation allows for LCU-based processing without delay, improving accuracy and efficiency by applying SAO filtering after deblock filtering is complete.
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 processing 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 advance without waiting for the deblocking process to complete, thereby reducing processing delay while maintaining LCU-based processing efficiency. The estimated parameters are then used after deblocking to guide the SAO filtering process.
2Loss of time
If SAO filtering is applied before deblock filtering, then processing delay is reduced, but the accuracy of SAO estimation deteriorates
Solution Approach 1:
The patent performs preliminary SAO parameter estimation using non-deblock-filtered pixels, then applies the deblocking filter, and finally uses the estimated parameters to guide SAO filtering on the deblock-filtered output. This sequence allows early parameter estimation without sacrificing final filtering accuracy, as the parameters are refined based on the actual deblock-filtered pixels.
Solution Approach 2:
The patent employs feedback by using the estimated SAO parameters to guide the SAO filtering process after deblocking is complete. The system iteratively refines the SAO parameters based on the actual deblock-filtered reconstructed pixels, ensuring that the final SAO filtering achieves optimal accuracy while maintaining processing efficiency.
3Productivity
If LCU-based processing is implemented, then processing efficiency is improved, but it requires waiting for deblock filtering to complete
Solution Approach 1:
The patent enables LCU-based processing by performing SAO parameter estimation preliminarily using non-deblock-filtered reconstructed pixels within each LCU. This preliminary estimation allows independent LCU processing to proceed without waiting for the deblocking filter to complete, thereby maintaining high processing efficiency and productivity while minimizing waiting time.
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.