Loop Filtering in Video Coding Systems
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Solution Overview
Problem
Conventional video encoding systems require iterative processes to determine the optimal loop filter level, leading to substantial computations, increased data access, and long latency, which is undesirable for efficient video encoding.
Innovation Solution
The method involves determining an initial loop filter level based on quality settings such as quantization parameter (QP), target bit rate, and frame characteristics, incorporating this information into the bitstream, and applying loop filtering to reconstructed frames without iterative testing, allowing for reduced computational burden and latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If iterative loop filter level determination is performed by trying out all filter candidates to maximize PSNR, then video quality is improved, but computational complexity increases substantially
Solution Approach 1:
The patent applies loop filtering to a partial frame (e.g., first N macroblocks) before completing encoding of the entire frame. This preliminary application allows the filter to be applied early based on available data, avoiding the need to wait for complete frame reconstruction and subsequent iterative testing of all filter candidates, thereby reducing computational complexity while maintaining acceptable video quality
Solution Approach 2:
Instead of applying loop filtering to the entire frame after complete encoding, the patent applies filtering to only a partial frame (partial or excessive action). This reduces the amount of data processing required and eliminates the need for iterative determination of filter levels across the whole frame, significantly reducing computational complexity while still providing quality improvement
2Measurement precision
If iterative loop filter level determination is performed across the entire frame, then filtering accuracy is improved, but encoding latency increases
Solution Approach 1:
The patent performs loop filtering as a preliminary action on partial frame data before the entire frame encoding is complete. This allows filtering to occur earlier in the encoding pipeline, reducing encoding latency while maintaining sufficient filtering accuracy on the processed portion of the frame
Solution Approach 2:
The patent skips the iterative process of determining filter levels for the entire frame by rushing through the filtering operation on available partial frame data. This eliminates time-consuming iterative calculations and reduces encoding latency while still applying beneficial filtering effects
3Measurement precision
If loop filtering is applied to the complete reconstructed frame, then video quality is improved, but data access requirements increase
Solution Approach 1:
The patent applies loop filtering to only a partial frame (e.g., first N macroblocks) rather than the complete reconstructed frame. This reduces the quantity of data that must be accessed and processed, lowering memory bandwidth requirements and data access overhead while still providing quality improvement on the filtered portion
Data Source
AI summary
A method and apparatus for encoding of video data incorporating loop filtering are disclosed. The method and apparatus according to an embodiment of the present invention determines an initial loop filter level for a frame of the video data according to quality setting of the frame. The information associated with the initial loop filter level is incorporated in the bitstream corresponding to compressed video data. The loop filtering is applied to a macroblock without the need to wait for the whole frame reconstruction to complete. In another embodiment according to the present invention, the initial loop filter level may be refined according to stability associated with the frame. In yet another embodiment according to the present invention, the method may include determining whether segment mode is on or off and determining a frame-level or segment-level initial loop filter level accordingly.