Macroblock Delta QP Decision via Cached Motion Estimation
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Solution Overview
Problem
Existing video encoding systems face challenges in efficiently selecting the optimal quantization parameter (QP) for macroblocks, leading to suboptimal bit rate and quality trade-offs, which affects the encoding speed and accuracy.
Innovation Solution
A system and method that includes a quantization module to select a range of QP values, determine the optimal QP for minimal distortion, and encode macroblocks using the determined parameter, incorporating techniques like caching motion estimation and restricting QP search ranges to enhance encoding speed and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a full range of quantization parameters is evaluated to find the optimal QP, then the quality of video encoding is improved, but the encoding time and computational complexity increase
Solution Approach 1:
The patent applies preliminary action by pre-calculating and caching motion estimation results for different QP values before the actual encoding process. This allows the encoder to quickly retrieve pre-computed motion vectors and compensation data instead of performing full motion estimation during encoding, significantly reducing encoding time while maintaining the ability to evaluate multiple QP values for optimal quality
Solution Approach 2:
The patent segments the QP evaluation process by dividing it into multiple candidate QP values that are evaluated separately. Instead of evaluating every possible QP value in the full range, the encoder focuses on a subset of promising candidates, reducing the computational burden while still finding near-optimal quality solutions
2Measurement precision
If motion estimation is performed for multiple QP values to ensure optimal quality, then the accuracy of quantization is improved, but the computational complexity and processing time increase
Solution Approach 1:
The patent performs motion estimation in advance for multiple QP candidates and caches the results. This preliminary computation separates the complex motion estimation task from the actual encoding decision process, allowing accurate QP selection without repeating expensive motion estimation operations during the critical encoding phase
Solution Approach 2:
The patent performs motion estimation for more QP candidates than would traditionally be evaluated, using cached results to enable this extended evaluation. This partial excessive action ensures that the optimal QP is found with high confidence, and the cached data prevents the computational complexity from increasing linearly with the number of candidates
3Measurement precision
If the encoder evaluates all possible quantization parameters to ensure optimal bit rate and quality trade-off, then the precision of bit rate control is improved, but the encoding speed decreases
Solution Approach 1:
The patent pre-computes rate-distortion metrics for multiple QP candidates and caches these results. This allows the encoder to quickly evaluate the bit rate and quality trade-offs for different QP values without performing full encoding simulations, maintaining precise bit rate control while preserving high encoding speed
Solution Approach 2:
The patent segments the bit rate evaluation process by focusing on candidate QP values that are most likely to achieve the target bit rate. Instead of evaluating all possible QP values, the encoder identifies and evaluates only the relevant subset, maintaining precision in bit rate control while significantly improving encoding speed
Data Source
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AI summary
A system and method for encoding multimedia video is described. As video is encoded a quantization parameter is selected for each macroblock. As described herein, the quantization parameter for each macroblock may be selected by limiting the universe of all possible quantization parameters to a particular range of possible quantization parameter values. This increases the speed of video encoding by reducing the number of quantization parameters that are tested for each video macroblock.