Screen Content Video Encoder Motion Estimation Optimization
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Solution Overview
Problem
Current video codec standards, particularly the H.265/HEVC standard, face inefficiencies in encoder-side decisions regarding coding modes and options, especially for screen content video, leading to suboptimal motion estimation and encoding processes.
Innovation Solution
The method involves identifying appropriate starting points for motion estimation in different reference pictures, skipping certain encoding stages based on hash-based block matching results, and selectively evaluating intra-picture prediction modes, thereby optimizing encoding processes by terminating unnecessary computations and improving rate-distortion performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional motion estimation is performed for all candidate blocks in screen content video, then motion compensation accuracy is improved, but encoding time and computational complexity increase significantly
Solution Approach 1:
The patent applies preliminary action by performing hash-based block matching before traditional motion estimation to identify candidate blocks with high similarity. This preliminary step filters out unlikely candidates, so that full motion estimation is only performed on a reduced set of promising blocks, thereby maintaining accuracy while reducing encoding time
Solution Approach 2:
The patent segments the motion estimation process into multiple stages: first performing fast hash-based block matching to identify candidate blocks, then performing full motion estimation only on those candidates. This segmentation allows the system to process different blocks with different levels of detail based on their characteristics
2Manufacturing precision
If all coding modes and options are evaluated for every block, then encoding optimality is improved, but device complexity and processing load increase
Solution Approach 1:
The patent applies partial action by selectively evaluating coding modes and options based on block characteristics. Instead of evaluating all possible modes for every block, the system evaluates only the most relevant modes for each block type (e.g., intra-picture modes for screen content, inter-picture modes for natural video), reducing processing complexity while maintaining encoding optimality
Solution Approach 2:
The patent applies local quality by adapting the encoding evaluation process to the specific characteristics of each block. Different blocks receive different levels of evaluation based on their content type, with screen content blocks receiving different treatment compared to natural video blocks, thereby optimizing the balance between quality and complexity locally
3Productivity
If hash-based block matching is performed for all blocks, then encoding speed is improved, but loss of information increases due to approximate matching
Solution Approach 1:
The patent segments the block matching process into two stages: hash-based approximate matching for fast candidate identification, followed by precise motion estimation for final selection. This segmentation allows the system to use fast approximate methods where sufficient and precise methods where needed, balancing speed and accuracy
Solution Approach 2:
The patent uses hash-based block matching as an intermediary step between raw video data and final motion compensation. This intermediary performs a fast preliminary filter that identifies promising candidate blocks, which are then subjected to more rigorous evaluation, thus maintaining overall matching precision while improving speed
Data Source
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Figure 4a
AI summary
Innovations in encoder-side decisions for coding of screen content video or other video can speed up encoding in various ways. For example, some of the innovations relate to ways to speed up motion estimation by identifying appropriate starting points for the motion estimation in different reference pictures. Many of the encoder-side decisions speed up encoding by terminating encoding for a block or skipping the evaluation of certain modes or options when a condition is satisfied. For example, some of the innovations relate to ways to speed up encoding when hash-based block matching is used. Still other innovations relate to ways to identify when certain intra-picture prediction modes should or should not be evaluated during encoding. Other innovations relate to other aspects of encoding.