Adaptive Transform Windows for Low-Delay Signal Coding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing transform-based coding techniques require interleaved windows for transition, limiting the independence of analysis windows and resulting in poor frequency resolution and high discontinuity, which affects coding quality and introduces delay in interactive communications.
Innovation Solution
A method allowing independent choice of analysis and synthesis windows with rising and falling edges, enabling direct transition between window types without restrictions, adapting to signal characteristics for improved coding gain and reduced delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If interleaved windows are used for transition between analysis windows, then perfect reconstruction is ensured, but window independence is limited and frequency resolution deteriorates
Solution Approach 1:
The transition between analysis windows is segmented into two independent stages: first transitioning from window type A to window type B for analysis, then separately transitioning from window type B to window type C for synthesis. This segmentation allows each transition to be optimized independently, achieving both perfect reconstruction and high frequency resolution without the constraints of interleaved windows.
Solution Approach 2:
A third window type B is introduced as an intermediary between window types A and C. This intermediary window enables independent optimization of the analysis transition (A→B) and synthesis transition (B→C), allowing each to achieve optimal frequency resolution while maintaining perfect reconstruction through the coordinated two-stage process.
2Ease of manufacture
If identical windows are used for analysis and synthesis, then implementation is simplified, but adaptability to signal characteristics is reduced
Solution Approach 1:
Different window types are assigned to different functional stages: window type A is optimized for analysis with characteristics suited for energy compaction, while window type C is optimized for synthesis with characteristics suited for noise shaping. This local optimization of window properties at each stage enables superior overall system performance compared to using identical windows throughout.
Solution Approach 2:
The system dynamically selects different window types based on the signal processing stage (analysis vs. synthesis) rather than using a fixed identical window. This dynamic adaptation allows the window characteristics to be optimized for each specific processing requirement, improving both signal adaptation and implementation efficiency.
3Stability of the object's composition
If fixed window transitions are used, then coding stability is maintained, but coding gain is reduced due to inability to adapt to signal changes
Solution Approach 1:
The window type selection is made dynamic and adaptive based on signal characteristics detected at each processing stage. The analysis window type is selected based on incoming signal properties, and the synthesis window type is selected based on the transformed signal properties. This dynamic adaptation maintains coding stability through systematic selection while maximizing coding gain by matching window characteristics to signal characteristics.
Solution Approach 2:
The system uses feedback from signal characteristic analysis to dynamically select appropriate window types. The analysis stage provides feedback about signal properties that informs the selection of the synthesis window type, creating a closed-loop adaptive system that maintains stability through consistent selection criteria while maximizing coding gain through signal-specific optimization.
Data Source
AI summary
The present invention provides coding/decoding a digital signal, in particular using a transform with overlap employing weighting windows. In the invention, two consecutive and equal-size blocks of samples of the signal may be weighted by respective different successive windows. These two windows may be chosen independently of each other according to a criterion specific to the characteristics of the signal (entropy, data rate/distortion, etc.) that are determined for each of the two blocks.