Temporal Rate Distortion Optimization for Video Coding
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Solution Overview
Problem
The existing rate distortion optimization methods in video coding fail to achieve optimal coding performance due to independent rate distortion optimization across coding units, leading to inefficiencies in video quality and bit rate management, especially in temporal domain and I frames within the LD coding structure.
Innovation Solution
A temporal domain rate distortion optimization algorithm is developed that considers distortion propagation across frames, using a propagation factor to adjust the Lagrange multiplier and account for skip and inter modes, enabling more accurate distortion estimation and optimization of coding parameters, particularly for I frames.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If independent rate distortion optimization is used for each coding unit, then the complexity of the optimization process is reduced, but the coding performance and video quality cannot be optimized globally
Solution Approach 1:
The patent segments the global optimization problem into local distortion calculations for each coding unit, while still maintaining global optimization through the Lagrange multiplier framework. Each coding unit's distortion is calculated independently using motion compensation and mode selection, but these local calculations are integrated into a global optimization process that considers temporal dependencies across frames.
Solution Approach 2:
The patent implements feedback mechanisms where the distortion of current coding units is used to adjust the Lagrange multiplier for subsequent optimization decisions. The rate-distortion cost function provides feedback that guides mode selection and quantization parameter adjustment, creating a closed-loop optimization system that continuously improves coding performance.
2Manufacturing precision
If higher video quality is pursued, then the reconstruction distortion is reduced, but the coding bit rate increases
Solution Approach 1:
The patent changes the Lagrange multiplier parameter dynamically based on the desired operating point on the rate-distortion curve. By adjusting λ, the system can optimize for different quality-bitrate tradeoffs. The quantization parameter QP is also adjusted based on distortion propagation analysis to achieve optimal compression at target quality levels.
Solution Approach 2:
The optimization system is dynamic, adapting mode selection, quantization parameters, and Lagrange multipliers based on local content characteristics and temporal dependencies. The system dynamically switches between different coding modes (intra, inter, skip) and adjusts QP values to maintain optimal rate-distortion performance across varying video content.
3Manufacturing precision
If temporal domain distortion propagation is considered, then the global rate distortion optimization is improved, but the calculation complexity and computational load increase
Solution Approach 1:
The patent performs preliminary motion compensation and distortion calculations for all candidate reference blocks before final mode selection. The distortion propagation analysis is conducted in advance to determine the Lagrange multiplier adjustments needed, allowing the main optimization process to use pre-computed values rather than performing full temporal dependency analysis during encoding.
Solution Approach 2:
The patent applies local quality analysis by calculating distortion propagation separately for different coding units and reference frames. Each coding unit's distortion is evaluated based on its specific motion characteristics and reference frame quality, allowing selective optimization where it provides the most benefit rather than uniformly increasing complexity across all units.
Data Source
AI summary
A temporal domain rate distortion optimization considering a coding-mode adaptive distortion propagation is provided. A problem of dependency rate distortion optimization based on a temporal domain distortion propagation is induced again according to a temporal domain dependency relationship under an LD structure and a distortion propagation analysis under a skip mode and an inter mode; and an aggregation distortion of a current coding unit and an affected future coding unit are estimated and a propagation factor of a coding unit in a temporal domain distortion propagation model is calculated by constructing a time propagation chain, wherein a Lagrange multiplier is adjusted through an accurate propagation factor to realize a temporal domain dependency rate distortion optimization, and an I frame is subjected to a secondary coding technology to realize the temporal domain dependency rate distortion optimization of the I frame.