Adaptive Transform Windows for Low Latency Signal Coding
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Solution Overview
Problem
Existing digital signal coding techniques face challenges in adapting transform windows over time without intermediate constraints, leading to suboptimal coding gain and increased decoding delay, particularly in interactive communications where low latency is crucial.
Innovation Solution
The method involves using independent analysis and synthesis windows with rising and falling edges that can change freely between consecutive blocks, allowing direct transitions without intermediate windows, and incorporating all-zero coefficients to reduce decoding delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If intermediate windows are used to ensure perfect reconstruction during transform transitions, then reconstruction quality is improved, but decoding delay increases
Solution Approach 1:
The patent extracts and removes the intermediate window constraint from the transform coding system. By allowing direct transitions between analysis windows without requiring intermediate windows for perfect reconstruction, the system eliminates the time delay associated with these intermediate steps while maintaining acceptable reconstruction quality through alternative means.
Solution Approach 2:
The patent applies preliminary action by pre-calculating and storing correction factors that compensate for the absence of intermediate windows. These correction factors are computed in advance and applied during decoding to maintain reconstruction quality without requiring the time-consuming intermediate window transitions.
2Productivity
If transform windows are adapted freely between consecutive blocks, then coding gain is improved, but transition constraints increase complexity
Solution Approach 1:
The patent changes the parameters of the transform windows by allowing their shape, length, and other characteristics to vary freely between consecutive blocks. This adaptation to signal properties maximizes coding gain while the use of correction factors manages the complexity of these transitions.
Solution Approach 2:
The patent introduces dynamics by making the transform windows adaptive and variable rather than fixed. The windows can change their properties between blocks based on signal characteristics, allowing the system to optimize coding performance for different signal conditions while maintaining manageable complexity through predefined correction mechanisms.
3Ease of operation
If fixed transform windows are used, then decoding complexity is reduced, but adaptability to signal properties deteriorates
Solution Approach 1:
The patent makes the transform windows dynamic and adaptive rather than fixed. The windows can adjust their properties between consecutive blocks to match signal characteristics, improving adaptability while the use of correction factors and precomputed parameters keeps decoding complexity manageable.
Solution Approach 2:
The patent enables parameter changes in the transform windows by allowing their characteristics to vary based on signal properties. This adaptability is achieved while controlling decoding complexity through the use of correction factors that compensate for the variability without requiring complex real-time adjustments.
Data Source
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AI summary
Transform-based coding/decoding, with adaptive windows. The present invention pertains to the coding/decoding of a digital signal, in particular based on a transform with overlap using weighting windows. In the sense of the invention, two consecutive and equal-sized blocks of samples of the signal may be weighted respectively by two different successive windows. These two windows may be chosen independently of one another, according to a criterion specific to the characteristics of the signal (entropy, data rate/distortion, or the like) which are determined on each of the two blocks. Abstract figure: 10 A