LC3 Decoder Concealment for Tonal Frame Loss Recovery
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Transform-based audio codecs face challenges in frame loss concealment, particularly in reconstructing audio signals when spectral lines are missing, as existing techniques often result in artefacts due to inadequate error concealment methods.
Innovation Solution
A decoder and decoding method that implement error concealment by reconstructing audio signals based on spectral lines with frequencies above a threshold, and adjust error concealment strategies depending on whether the previous frame contains tonal or harmonic signal components, using techniques like sign flipping and non-linear attenuation to preserve tonality and reduce artefacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If error concealment is applied to all spectral lines, then audio quality during frame loss is improved, but artefacts are introduced due to inadequate concealment methods
Solution Approach 1:
The patent applies different error concealment strategies to different frequency regions. Specifically, it identifies tonal spectral lines and applies targeted concealment methods (such as sign flipping or amplitude adjustment) only to those lines, rather than uniformly to all spectral lines. This local differentiation preserves tonal characteristics while avoiding artefacts that would result from blanket application of concealment algorithms.
Solution Approach 2:
The patent dynamically adjusts concealment parameters based on the detected tonality of spectral lines. For tonal lines, it modifies parameters such as sign inversion probability or amplitude scaling factors to maintain the perceived pitch and harmonic structure. This parameter adaptation allows effective concealment that respects the local spectral characteristics, reducing artefacts while maintaining audio quality.
2Reliability
If error concealment is applied to maintain tonality, then audio quality is improved, but device complexity increases due to additional processing requirements
Solution Approach 1:
The patent segments the spectrum into tonal and non-tonal regions by analyzing spectral line characteristics. This segmentation allows the system to apply complex tonality-preserving concealment only where needed (to tonal lines), while using simpler methods for non-tonal lines. The segmentation approach breaks down the complex problem into manageable parts, reducing overall processing complexity while maintaining audio quality.
Solution Approach 2:
The patent applies full tonality-preserving error concealment processing only to the subset of spectral lines that are identified as tonal, rather than to all spectral lines. This partial action approach maintains audio quality for the critical tonal components while avoiding the unnecessary processing complexity that would result from applying the same sophisticated algorithms to all spectral lines uniformly.
Data Source
AI summary
FIG. 1 illustrates a decoder for decoding a current frame to reconstruct an audio signal according to an embodiment. The audio signal is encoded within the current frame. The current frame includes a current bitstream payload. The current bitstream payload includes a plurality of payload bits. The plurality of payload bits encodes a plurality of spectral lines of a spectrum of the audio signal. Each of the payload bits exhibits a position within the current bitstream payload. The decoder includes a decoding module and an output interface. The decoding module is configured to reconstruct the audio signal. The output interface is configured to output the audio signal.