Adaptive Intra Mode Prediction Threshold for Video Encoding
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Solution Overview
Problem
Current video encoding technologies face challenges in reducing computational complexity and data transfer needs for intra prediction, particularly in advanced standards like H.264, where computing the sum of absolute differences (SAD) for all macroblocks is computationally intensive and requires significant data transfer.
Innovation Solution
The approach involves computing intra mode SAD only for macroblocks with high inter mode SAD values, using a predetermined threshold calculated from previous frame statistics, and pipelining inter mode SAD computation to reduce unnecessary calculations and data transfer, thereby improving performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If intra mode SAD is computed for all macroblocks, then video quality is maintained, but computational complexity and data transfer increase significantly
Solution Approach 1:
The patent applies partial action by computing intra mode SAD only for a subset of macroblocks rather than all macroblocks. Specifically, intra mode prediction is performed only when inter mode SAD exceeds a threshold value, which reduces the number of SAD computations while maintaining acceptable video quality by focusing computational resources on macroblocks that benefit most from intra prediction.
Solution Approach 2:
The patent implements local quality by applying different prediction strategies to different macroblocks based on their specific characteristics. Each macroblock is evaluated individually using inter mode prediction first, and only those macroblocks with high inter mode SAD (indicating poor inter prediction quality) undergo intra mode prediction. This localized approach optimizes computational resources where they are most needed.
2Measurement precision
If intra mode SAD is computed for all macroblocks, then encoding accuracy is improved, but data transfer from external memory to hardware accelerator increases
Solution Approach 1:
The patent reduces data transfer by performing intra mode SAD computation only for a partial set of macroblocks. By using the inter mode SAD threshold criterion, the system avoids transferring and processing data for macroblocks that would not benefit from intra prediction, thereby reducing the quantity of data transferred from external memory to the hardware accelerator.
Solution Approach 2:
The patent applies preliminary action by first computing inter mode SAD for all macroblocks before deciding whether to perform intra mode prediction. This preliminary computation allows the system to identify which macroblocks require intra mode processing, enabling selective data transfer and computation only for those specific macroblocks, thus reducing overall data transfer requirements.
3Device complexity
If intra mode search is completely switched off, then computational complexity is reduced, but video quality artifacts increase
Solution Approach 1:
The patent avoids completely switching off intra mode search by implementing a selective intra mode prediction approach. Instead of eliminating intra prediction entirely, the system performs intra mode SAD computation only for macroblocks where inter mode prediction fails to achieve satisfactory quality (high inter mode SAD). This partial application maintains video quality for critical macroblocks while reducing overall computational complexity.
Solution Approach 2:
The patent changes the parameter of intra mode prediction application from universal (all macroblocks) to conditional (based on inter mode SAD threshold). By introducing a threshold-based selection criterion, the system dynamically adjusts which macroblocks undergo intra mode prediction, balancing computational complexity and video quality through parameter-based decision making.
Data Source
AI summary
This invention predicts that intra mode prediction is more effective for the macroblocks where motion estimation in inter mode prediction fails. This failure is indicated by a large value of the inter mode SAD. This invention performs intra mode prediction for only macro blocks have larger inter mode SADs. The definition of a large inter mode SAD differs for different content. This invention compares the inter mode SAD of a current macroblock with an adaptive threshold. This adaptive threshold depends on the average and variance of the SADs of the previous predicted frame. An adaptive threshold is calculated for each new predictive frame.