Auxiliary Window Decoding for Low-Delay Transient Signal Frames
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Solution Overview
Problem
Existing audio and image signal processing technologies face challenges in efficiently encoding and decoding signals with transients, leading to pre-echo noise and inefficiencies in low-delay communication applications.
Innovation Solution
The proposed solution involves an apparatus and method for generating and decoding audio or image signals using a multi-overlap region with three overlapping window functions, which reduces the delay for transient look-ahead and adapts overlap widths and transform lengths based on transient locations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If asymmetric transition windows are used for block switching between long and short transforms, then transient coding quality is improved, but encoder look-ahead delay increases
Solution Approach 1:
The patent applies preliminary action by performing transient detection and window type selection in advance during the encoding process. The encoder determines the appropriate window type (first, second, or third window) based on transient characteristics detected ahead of time, allowing smooth transitions between long and short transforms without requiring excessive look-ahead delay.
Solution Approach 2:
The patent implements dynamics by making the window function dynamically adaptable based on signal characteristics. The encoder selectively switches between different window types (first window with first overlap, second window with second overlap, third window with third overlap) depending on the detected transient properties, enabling optimal transient coding while minimizing fixed look-ahead requirements.
2Manufacturing precision
If reduced overlap width is used for non-stationary signals, then temporal extension of transform is limited, but coding flexibility is reduced
Solution Approach 1:
The patent applies dynamics by providing multiple overlap width options (first overlap, second overlap, third overlap) that can be dynamically selected based on signal characteristics. The encoder chooses the appropriate overlap width depending on whether the signal is stationary or non-stationary, maintaining both temporal error localization and coding flexibility.
Solution Approach 2:
The patent implements parameter changes by varying the overlap width parameter according to signal conditions. The encoder adjusts the overlap parameter between different window types to optimize performance for different signal characteristics, allowing reduced overlap for non-stationary signals while maintaining flexibility for stationary signals.
3Manufacturing precision
If multiple window types with different overlaps are used, then transient coding is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the window function selection into distinct, well-defined types (first window, second window, third window) with specific characteristics. Each window type is associated with particular transient conditions, making the selection process more manageable and less complex than arbitrary window design.
Solution Approach 2:
The patent implements parameter changes by systematically varying key parameters (overlap width, window shape) across the different window types. This structured approach to parameter variation simplifies the management of multiple window types compared to fully custom window designs, as the parameters follow predictable patterns based on transient characteristics.
Data Source
AI summary
An apparatus processing an encoded signal to acquire first and second frames comprising spectral values and an aliasing portion; applying a transform to the first frame using a first window function to acquire a first block of samples, applying another transform to a first portion of the second frame using a second window function, and applying another one or more transforms to a second portion of the second frame using one or more third window functions to acquire a second block of samples; and post-processing the second block of samples using a folding-out operation to acquire a post-processed second block of samples comprising a portion of the second block of samples overlapping with the first block of samples in a multi-overlap region, windowing the post-processed second block of samples using an auxiliary window function, and overlap-adding a windowed post-processed second block of samples and the first block of samples.