Inter-Frame Mode Selection for Video Coding Complexity Reduction
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Solution Overview
Problem
The high calculation complexity of mode selection in video coding, particularly in HEVC, hinders real-time video coding applications and increases computational resources required, especially for inter-frame predictive frames which dominate video bitstreams.
Innovation Solution
An inter-frame mode selection method that skips or stops unnecessary calculations by determining if the coding overhead for a coding unit can be skipped, recursively dividing units, and comparing coding overheads to determine optimal modes, thereby reducing the complexity of mode selection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If comprehensive mode selection calculation is performed for all coding units in HEVC, then coding efficiency is optimized, but calculation complexity increases significantly
Solution Approach 1:
The patent segments the mode selection process into two distinct stages: a fast evaluation stage that quickly identifies promising coding modes using simplified criteria, and a detailed optimization stage that performs comprehensive rate-distortion optimization only on the segmented subset of candidate modes. This segmentation reduces the overall calculation complexity while maintaining coding efficiency.
Solution Approach 2:
The patent performs preliminary filtering of coding modes before the main optimization process. By pre-evaluating coding units using fast criteria (such as motion vector similarity, prediction mode compatibility, and early termination conditions), the system identifies and eliminates unpromising modes in advance, reducing the computational burden of subsequent detailed optimization.
2Manufacturing precision
If exhaustive mode selection is performed for inter-frame predictive frames, then video quality is maximized, but coding speed decreases
Solution Approach 1:
The patent applies partial action by performing exhaustive mode selection only on a selectively identified subset of coding units rather than all coding units. Fast evaluation criteria identify coding units that benefit most from detailed optimization, while others use simplified mode selection. This partial application of exhaustive search maintains video quality for critical regions while improving overall coding speed.
Solution Approach 2:
The patent implements skipping mechanisms that allow the encoder to bypass detailed mode selection for coding units that can be quickly evaluated. By rushing through the evaluation of certain coding units using fast criteria and only performing detailed optimization when necessary, the system maintains video quality while significantly improving coding speed.
3Loss of energy
If detailed rate-distortion optimization is performed for every coding unit, then compression efficiency is improved, but processing time increases
Solution Approach 1:
The patent performs preliminary evaluation of coding units using fast criteria before applying detailed rate-distortion optimization. By pre-identifying coding units that are likely to benefit from comprehensive optimization (based on factors like motion complexity, prediction mode diversity, and regional importance), the system avoids unnecessary processing time for coding units where detailed optimization would provide minimal gains.
Solution Approach 2:
The patent applies different optimization qualities to different regions of the video frame. Coding units in important regions (such as areas with high motion, edges, or semantic significance) receive detailed rate-distortion optimization, while coding units in less important regions use simplified evaluation. This local differentiation improves compression efficiency where needed while reducing overall processing time.
Data Source
AI summary
An initial value of a current depth Depth is 1, and an inter-frame mode selection method includes: S701: if calculation of a coding overhead of coding a coding unit CUDepth is to be skipped, invoking S703 to S705; and if the calculation is not to be skipped, invoking S702 to S705; S702: determining a current optimum coding mode and coding overhead of the coding unit CUDepth; S703: dividing the coding unit CUDepth into multiple coding subunits having a depth Depth+1, and recursively performing S701 to S705 until the depth of the coding subunit reaches a preset maximum depth or satisfies a division stopping condition; S704: comparing a sum of coding overheads of the multiple coding subunits with the current coding overhead of the coding unit CUDepth; and S705: determining that a mode corresponding to the smaller one in S704 is an optimum coding mode.