Error Concealment via Segmented LPC Representations
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Solution Overview
Problem
Conventional audio coding technologies face challenges in precisely controlling energy during frame loss in audio signals, particularly in fading out noisy parts to background noise while maintaining tonal parts' spectral properties, due to limitations in controlling LPC coefficients and codebook gains.
Innovation Solution
The solution involves generating separate LPC representations for tonal and noisy parts of the signal, using adaptive and fixed codebooks, and applying gain compensation to maintain the signal's amplitude and spectral properties during error concealment, allowing for independent control of energy levels and spectral shaping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single set of LPC coefficients is repeated or interpolated during frame loss, then the concealment process is simple, but the ability to precisely control energy and spectral properties is limited
Solution Approach 1:
The patent divides the single LPC coefficient set into multiple separate LPC coefficient sets, each associated with different codebooks (adaptive codebook, fixed codebook, noise codebook). This segmentation allows independent control of spectral properties for different signal components, enabling precise energy control while maintaining manageable complexity through modular structure.
2Reliability
If LPC coefficients are extrapolated using conventional methods, then the concealment can be performed, but the spectral properties of tonal parts cannot be maintained while fading noisy parts to background noise
Solution Approach 1:
The patent applies different LPC coefficient sets to different codebooks, where each codebook handles specific signal characteristics (tonal, noisy, background). This local quality approach allows the adaptive codebook to maintain tonal spectral properties while the noise codebook fades noisy parts to background noise, achieving both reliability and spectral control flexibility simultaneously.
3Use of energy by moving object
If codebook gains are controlled during concealment, then energy levels can be adjusted, but independent control of spectral shaping for different signal parts is not achieved
Solution Approach 1:
The patent segments the spectral control function by creating separate LPC coefficient sets for different codebooks. This allows energy level control through codebook gains while simultaneously achieving independent spectral shaping for each signal component, resolving the contradiction between energy control and spectral control structure complexity.
Data Source
AI summary
An apparatus for generating an error concealment signal includes an LPC (linear prediction coding) representation generator for generating a first replacement LPC representation and a different second replacement LPC representation; an LPC synthesizer for filtering a first codebook information using the first replacement representation to obtain a first replacement signal and for filtering a different second codebook information using the second replacement LPC representation to obtain a second replacement signal; and a replacement signal combiner for combining the first replacement signal and the second replacement signal to obtain the error concealment signal.