TCX LTP Decoding for Smooth Audio Error Concealment
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Solution Overview
Problem
Current audio signal encoding and decoding technologies face challenges in effectively managing signal fade-out during error concealment in switched audio coding systems, particularly in maintaining spectral shape and background noise levels during packet losses.
Innovation Solution
The proposed solution involves a method for decoding audio signals that employs a TCX LTP feedback loop decoupling and fading the TCX LTP gain to zero, while using noise level tracing to reconstruct audio signals based on comfort noise levels, ensuring a smooth transition to a background noise envelope during burst packet losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the TCX LTP feedback loop is maintained during error concealment, then the spectral shape and signal characteristics are preserved, but unwanted tonal components and background noise artifacts are introduced
Solution Approach 1:
The patent extracts and removes the harmful tonal components and background noise artifacts that are generated when the TCX LTP feedback loop is maintained during error concealment, while preserving the beneficial spectral shape characteristics
Solution Approach 2:
The patent changes the gain parameter of the TCX LTP feedback loop, fading it to zero during error concealment to eliminate unwanted tonal components while maintaining spectral shape through noise level tracing
2Object-generated harmful factors
If the TCX LTP gain is faded to zero during error concealment, then unwanted tonal components are eliminated, but the transition to background noise may become abrupt
Solution Approach 1:
The patent implements dynamic control of the TCX LTP gain parameter, fading it smoothly to zero during error concealment based on the duration of the error burst, thereby eliminating tonal components while maintaining a stable and pleasant transition to background noise
Solution Approach 2:
The patent uses noise level tracing as a feedback mechanism to monitor the background noise characteristics and adjust the TCX LTP gain fading accordingly, ensuring a smooth and natural transition to the background noise envelope
3Reliability
If noise level tracing is used to reconstruct audio signals during packet losses, then comfort noise characteristics are maintained, but the system complexity increases
Solution Approach 1:
The patent implements a universal noise level tracing mechanism that serves multiple functions: tracking background noise characteristics, guiding the TCX LTP gain fading process, and reconstructing comfort noise during packet losses, thereby maintaining reliability without proportionally increasing complexity
Data Source
AI summary
An apparatus for decoding an encoded audio signal to obtain a reconstructed audio signal is provided. The apparatus includes a receiving interface, a delay buffer and a sample processor for processing the selected audio signal samples to obtain reconstructed audio signal samples of the reconstructed audio signal. The sample selector is configured to select, if a current frame is received by the receiving interface and if the current frame being received by the receiving interface is not corrupted, the plurality of selected audio signal samples from the audio signal samples being stored in the delay buffer depending on a pitch lag information being included by the current frame.