Macroblock Rate Control via Real MAD Feedback
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Solution Overview
Problem
Conventional video encoding systems face inaccuracies and latency in rate control due to reliance on prediction Mean Absolute Difference (MAD) without considering real MAD variances, especially when complexity varies within a video sequence.
Innovation Solution
A method and apparatus for rate control in the macroblock layer that calculates a real MAD of the current macroblock, adjusts the prediction MAD based on this real MAD, and uses the final MAD to determine a quantization parameter, ensuring more accurate rate control by reflecting actual data variances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If prediction MAD is used for rate control, then calculation speed is improved, but accuracy deteriorates due to inaccuracy and latency
Solution Approach 1:
The patent implements feedback by using the real MAD of the current MB to adjust the prediction MAD. The quantization parameter calculator receives the real MAD, compares it with the prediction MAD, and adjusts the quantization parameter accordingly. This closed-loop feedback mechanism corrects the inaccuracy and latency inherent in prediction-based methods, improving rate control accuracy while maintaining computational efficiency.
2Device complexity
If prediction MAD only is used, then device complexity is reduced, but reliability deteriorates under high complexity variances
Solution Approach 1:
The patent changes the parameter used for rate control from prediction MAD alone to a adjusted value that incorporates real MAD. The quantization parameter calculator modifies the quantization parameter based on the relationship between prediction MAD and real MAD, allowing the system to adapt to varying complexity in video sequences. This parameter adjustment enhances reliability under high complexity variances while keeping the overall algorithm relatively simple.
3Measurement precision
If real MAD is calculated and used for adjustment, then rate control accuracy is improved, but calculation time increases
Solution Approach 1:
The patent applies preliminary action by calculating the real MAD of the current MB before using it to adjust the quantization parameter. The quantization parameter calculator first obtains the real MAD, then uses it to refine the prediction MAD and determine the final quantization parameter. This preliminary calculation of real MAD enables more accurate rate control decisions to be made efficiently, balancing accuracy improvement with acceptable calculation time.
Data Source
AI summary
The invention introduces a method for rate control in an MB (macroblock) layer, including: calculating a prediction MAD (Mean Absolute Difference) of a current MB of a current frame according to a real MAD of a previous MB of a previous frame; calculating a real MAD of the current MB of the current frame; performing an adjustment procedure to adjust the prediction MAD of the current MB of the current frame according to the real MAD of the current MB of the current frame to obtain a final MAD of the current MB of the current frame; calculating a quantization parameter of the current MB of the current frame according to the final MAD of the current MB of the current frame; and outputting the quantization parameter of the current MB of the current frame to a quantizer.