Lapped Transform Signal Reconstruction with Adaptive Resampling
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Solution Overview
Problem
Lapped transform representations in audio compression techniques face challenges with sample rate changes, as aliasing issues arise at the overlapping regions of retransforms, leading to discontinuities and inefficiencies in coding efficiency across varying transmission bitrates.
Innovation Solution
An information signal reconstructor is configured to perform aliasing cancellation by resampling and retransforming overlapping regions using a retransformer, resampler, and combiner, allowing for adaptive sample rate changes without disrupting the lapped transform representation, enabling efficient coding across different environmental conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If lapped transform representation is used for audio compression, then coding efficiency is improved, but aliasing issues arise at overlapping regions during sample rate changes
Solution Approach 1:
The patent converts the harmful aliasing effect into a beneficial tool by designing the lapped transform to intentionally create controlled aliasing in overlapping regions. This aliasing is then systematically canceled through the retransformer-resampler-combiner structure, allowing continuous representation across sample rate changes while maintaining high coding efficiency.
Solution Approach 2:
The patent introduces intermediate processing stages (retransformer and resampler) between the lapped transform and the final reconstruction. These intermediaries handle the aliasing cancellation and sample rate adaptation, mediating between the efficient but discontinuous lapped transform representation and the continuous output signal.
2Adaptability or versatility
If sample rate changes are implemented to adapt to varying transmission bitrate, then adaptability is improved, but discontinuities occur at the border between regions
Solution Approach 1:
The patent implements dynamic sample rate adaptation by allowing the sample rate to change between different time regions based on transmission conditions. The border region between different sample rates is handled dynamically through resampling and aliasing cancellation, enabling the system to adapt to varying bitrate requirements while maintaining signal continuity.
Solution Approach 2:
The patent changes the sample rate parameter adaptively between different time regions to match transmission conditions. By modifying this fundamental parameter and using aliasing cancellation techniques at the transition borders, the system achieves both adaptability to different bitrates and continuity of the reconstructed signal.
3Reliability
If aliasing cancellation is performed using overlapping regions, then signal continuity is maintained, but processing complexity increases
Solution Approach 1:
The patent segments the signal processing into distinct functional blocks: lapped transform stage, retransformer stage, resampler stage, and combiner stage. Each segment handles a specific aspect of the aliasing cancellation process, making the overall complex operation more manageable and implementable through modular processing steps.
Data Source
AI summary
An information signal reconstructor is configured to reconstruct, using aliasing cancellation, an information signal from a lapped transform representation of the information signal including, for each of consecutive, overlapping regions of the information signal, a transform of a windowed version of the respective region, wherein the information signal reconstructor is configured to reconstruct the information signal at a sample rate which changes at a border between a preceding region and a succeeding region of the information signal.