Intra Block Copy Cost Estimation for Screen Content Video
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Solution Overview
Problem
Current video coding standards face challenges in efficiently encoding screen content video, which often contains mixed content like natural video, text, and graphics, leading to high prediction error levels in intra-coded blocks.
Innovation Solution
The proposed solution involves methods and apparatus for video coding using intra block copy (IntraBC) estimation, which computes the activity of a block and selects the best encoding mode based on IntraBC coding costs estimated through one-dimensional or two-dimensional searches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If intra block copy (IntraBC) mode is used for encoding blocks in screen content video, then coding efficiency is improved through bit rate savings, but prediction error levels increase due to mixed content characteristics
Solution Approach 1:
The patent implements dynamic mode selection between IntraBC mode and conventional intra prediction modes based on block activity characteristics. The encoder adaptively switches between coding modes depending on the specific block content and activity level, allowing optimal coding efficiency while managing prediction errors through context-aware mode decision.
Solution Approach 2:
The patent modifies the IntraBC search range parameter dynamically based on block activity. When block activity is detected to be below a threshold, the search range is reduced, which changes the coding parameters to balance between coding efficiency and prediction accuracy for low-activity blocks.
2Measurement precision
If two-dimensional search is performed for IntraBC cost estimation, then coding accuracy is improved, but encoding complexity increases
Solution Approach 1:
The patent dynamically adjusts the search dimension (1D or 2D) based on block activity characteristics. For blocks with low activity, a computationally lighter 1D search is performed, while 2D search is applied only when necessary for blocks with higher activity, thus reducing overall encoding complexity while maintaining accuracy where needed.
Solution Approach 2:
The patent applies partial 2D search instead of full 2D search by using 1D search as a simplified alternative for low-activity blocks. This partial application of the more complex search algorithm only where necessary reduces computational burden while still achieving adequate coding accuracy for the majority of low-activity blocks.
3Productivity
If IntraBC cost estimation is performed for all blocks, then coding optimization is improved, but processing time increases
Solution Approach 1:
The patent performs IntraBC cost estimation partially by skipping the estimation process for blocks with low activity below a threshold. This selective application of cost estimation reduces processing time for the majority of low-activity blocks while still optimizing coding for blocks where IntraBC is likely to provide benefit.
Solution Approach 2:
The patent computes block activity as a preliminary step before performing IntraBC cost estimation. By pre-assessing block activity and using this information to guide subsequent processing decisions, the system avoids unnecessary cost estimation computations for low-activity blocks, thereby reducing overall processing time while maintaining optimization where needed.
Data Source
AI summary
A method for encoding video data is provided that includes determining whether or not a parent coding unit of a coding unit of the video data was predicted in intra-prediction block copy (IntraBC) mode and, when it is determined that the parent coding unit was not predicted in IntraBC mode: computing activity of the coding unit, determining an IntraBC coding cost of the coding unit by computing the IntraBC coding cost of the coding unit using a two dimensional (2D) search when the activity of the coding unit is not than an activity threshold, and computing the IntraBC coding cost of the coding unit using a one dimensional (1D) search when the activity of the coding unit is less than the activity threshold, using the IntraBC coding cost to select an encoding mode from one of a plurality of encoding modes, encoding the coding unit using the selected encoding mode.