Intra Prediction Mode Search Scheme for Video Encoding
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Solution Overview
Problem
Current video compression methods, such as those in the H.264 standard, face high computational expenses in selecting the optimal intra prediction mode for each block within a macroblock, particularly due to the need to evaluate multiple possible prediction modes for 4×4, 16×16, and 8×8 blocks.
Innovation Solution
A method is introduced to reduce computational complexity by determining a most probable intra prediction mode and using a search order lookup table to evaluate intra prediction modes in order of probability, limiting the number of modes evaluated while maintaining compression quality, thereby reducing the number of iterations required for each block.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all possible intra prediction modes are evaluated to ensure optimal compression quality, then compression quality is improved, but computational complexity increases significantly
Solution Approach 1:
The patent computes a most probable intra prediction mode in advance using a simplified method (such as using neighboring block modes or gradient calculations) before evaluating all possible modes. This preliminary computation guides the subsequent exhaustive search by providing a starting point or ordering criterion, reducing the effective search space while maintaining the ability to find the optimal mode if needed.
Solution Approach 2:
The patent implements a two-stage evaluation process where only a limited number of modes (e.g., 3-5 modes) are fully evaluated in detail, while other modes are either skipped or given less thorough evaluation. This partial action approach achieves acceptable compression quality for most cases without the full computational burden of evaluating all modes exhaustively.
2Productivity
If the number of intra prediction modes evaluated is reduced to decrease computational cost, then processing efficiency is improved, but compression quality may deteriorate
Solution Approach 1:
The patent changes the evaluation parameter from a fixed exhaustive search of all modes to a dynamic selection process where the number and ordering of modes to evaluate are determined by the computed most probable mode. This parameter change allows the system to adapt the evaluation depth and scope based on local image characteristics, maintaining quality when the most probable mode is accurate while improving efficiency when it provides a good approximation.
Solution Approach 2:
The patent uses feedback from the most probable mode computation to guide the selection and ordering of modes for detailed evaluation. The most probable mode serves as feedback that informs which other modes are worth evaluating and in what order, creating a feedback loop that improves processing efficiency while preserving compression quality through intelligent mode selection.
3Ease of manufacture
If a fixed search order is used for evaluating intra prediction modes, then implementation is simplified, but adaptability to different image content is reduced
Solution Approach 1:
The patent transforms the static fixed search order into a dynamic search order that adapts to different image content. The most probable mode computation (using neighboring block information, gradients, or other local features) produces a dynamic ordering criterion that changes based on the local image characteristics, allowing the system to adapt to different content types while maintaining a systematic evaluation framework.
Solution Approach 2:
The patent performs a preliminary analysis of the local image content (computing the most probable mode) before establishing the search order for mode evaluation. This preliminary action creates an adaptive search strategy where the evaluation order is tailored to the specific image content being processed, improving adaptability while keeping the overall implementation structure relatively simple through the use of lookup tables or predefined ordering rules.
Data Source
AI summary
The following embodiments describe an approach for selecting an intra prediction mode for video encoding, such as occurs in the H.264 standard. One embodiment describes a method of selecting an optimum intra prediction mode. This method involves selecting a first intra prediction mode, which is used to determine a search order for a number of intra prediction modes. These intra prediction modes are then evaluated in order to identify the optimum intra prediction mode.