Fast Motion Estimation Using Scene Change Detection
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Solution Overview
Problem
Current video encoding technologies face high computational complexity and inefficiency in motion estimation when using multiple reference pictures, particularly in advanced standards like H.264, which slows down encoding speed and increases system costs.
Innovation Solution
A method for fast motion estimation in video encoders that employs scene detection to exclude reference pictures across scene changes and calculates motion vectors only for relevant reference pictures, reducing the computational burden by starting with the closest reference frame and terminating the process when sufficient prediction is achieved.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If motion estimation is performed for all reference pictures to achieve best prediction, then compression efficiency is improved, but computational complexity increases significantly
Solution Approach 1:
The patent segments the motion estimation process by dividing reference pictures into two groups: those before the scene change and those after the scene change. The encoder performs motion estimation only on reference pictures from the appropriate segment based on whether a scene change is detected, rather than exhaustively searching all reference pictures. This segmentation reduces computational complexity while maintaining prediction accuracy for the current picture.
Solution Approach 2:
The patent applies preliminary scene change detection before performing motion estimation. By detecting scene changes in advance and determining which reference pictures are relevant beforehand, the encoder avoids performing unnecessary motion estimation on irrelevant reference pictures. This preliminary action filters out unnecessary computations while ensuring that motion estimation is performed on the appropriate reference pictures that can provide accurate prediction.
2Reliability
If motion estimation is performed for all reference pictures, then prediction quality is improved, but encoding speed decreases
Solution Approach 1:
The patent segments the set of reference pictures based on scene change boundaries. By dividing reference pictures into relevant and irrelevant segments, the encoder performs motion estimation only on the relevant segment, thereby maintaining prediction quality while significantly improving encoding speed by eliminating unnecessary computations on irrelevant reference pictures.
Solution Approach 2:
The patent performs preliminary scene change detection and reference picture selection before motion estimation. This preliminary action identifies which reference pictures are suitable for motion estimation based on scene change information, allowing the encoder to proceed directly to motion estimation on the appropriate pictures without wasting time evaluating all reference pictures, thus improving encoding speed while preserving prediction quality.
3Reliability
If multiple reference pictures are used for motion estimation, then compression efficiency is improved, but system cost increases
Solution Approach 1:
The patent segments the motion estimation process to operate only on relevant reference pictures identified through scene change detection. This segmentation allows the system to utilize multiple reference pictures for improved compression efficiency while avoiding the need to process all available reference pictures, thereby reducing the computational resources and system cost required compared to exhaustive multi-reference picture processing.
4Device complexity
If fast-search algorithms are used to reduce complexity, then computational complexity is reduced, but prediction accuracy deteriorates due to local minima trapping
Solution Approach 1:
The patent applies preliminary scene change detection to identify the relevant segment of reference pictures before performing motion estimation. This preliminary action narrows the search space to only those reference pictures that can provide accurate prediction, allowing fast-search algorithms to operate effectively without trapping in local minima, as the search is confined to the relevant segment where accurate motion vectors are likely to be found.
Data Source
AI summary
An apparatus and corresponding method for fast motion estimation with multiple reference pictures are provided, where an exemplary video encoder for encoding video signal data for an image block relative to multiple reference pictures includes a fast motion estimator for providing motion vectors corresponding to one of the reference pictures, including a scene detection portion for performing fast motion estimation while excluding reference pictures that fall across a scene change; and where a corresponding method for encoding video signal data for an image block having multiple reference pictures includes receiving a substantially uncompressed image block, detecting a scene change, excluding reference pictures that fall across the scene change, and computing motion vectors corresponding to a difference between the image block and one of the plurality of reference pictures.