CDEF Video Filtering with Single-Pass Frame Parameter Reuse
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Solution Overview
Problem
The Constrained Directional Enhancement Filtering (CDEF) technique in video encoding requires a two-pass encoding process, which is costly due to increased bandwidth, storage, and latency requirements.
Innovation Solution
Implementing a single-pass processing method for CDEF by using frame-level filter parameters determined from previous frames to apply an in-loop filter during encoding, thereby eliminating the need for a global search and reducing hardware complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two-pass encoding process is used for CDEF, then filtering accuracy is improved, but bandwidth and storage requirements increase
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing filter parameters (strength values, directional information) during the first pass encoding. These pre-computed parameters are then reused in the second pass without requiring re-processing of the entire frame data, thus reducing bandwidth and storage needs while maintaining filtering accuracy.
Solution Approach 2:
The patent extracts only the essential filter parameters (strength, direction, block size) from the complete frame data during the first pass. By separating and storing only these critical parameters rather than the entire frame, the solution reduces bandwidth and storage requirements while preserving the capability to perform accurate filtering in the second pass.
2Manufacturing precision
If two-pass encoding process is used for CDEF, then filtering quality is improved, but processing latency increases
Solution Approach 1:
The patent performs preliminary analysis and parameter determination in the first pass, storing only the essential filter characteristics. This allows the second pass to apply filtering quickly using pre-determined parameters, significantly reducing the time penalty associated with two-pass processing while maintaining high filtering quality.
Solution Approach 2:
The patent segments the encoding process into parameter determination (first pass) and parameter application (second pass). By dividing the work this way and caching intermediate results, the system reduces overall latency compared to traditional two-pass methods that would require complete re-processing.
3Measurement precision
If global search is performed for CDEF parameters, then filtering precision is improved, but hardware complexity increases
Solution Approach 1:
The patent extracts and stores only the optimal filter parameters resulting from the global search, rather than implementing the complete global search mechanism in hardware. This extraction approach maintains filtering precision by preserving the search results while dramatically reducing hardware complexity by eliminating the need for complex search algorithms in the filtering stage.
Solution Approach 2:
The patent performs the computationally intensive global search parameter optimization in advance during the first pass, storing only the resulting parameter values. This preliminary optimization eliminates the need for complex real-time search hardware in the second pass, reducing hardware complexity while maintaining the precision benefits of global search.
Data Source
AI summary
A video to be encoded using a codec is received Pre-filter encoding of a specific frame of the video is performed. In a single-pass processing of the specific frame, frame-level filter parameters determined using a previous frame are used to apply an in-loop filter on blocks of the specific frame during encoding of the specific frame. Statistics for the specific frame are gathered for determining frame-level filter parameters to be used for a future frame of the video. Post-filter encoding of the specific frame of the video is performed.