Signal Decoding with Sub-Band Noise Filling for Low-Bitrate Audio
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing frequency domain codec algorithms face challenges in decoding signals due to insufficient bit allocation, leading to poor decoding quality, especially when bit rates are low, resulting in 'empty' or 'water-like' audio outputs as less important spectral coefficients are not encoded, affecting auditory quality.
Innovation Solution
A method and device for decoding signals that classify sub-bands into saturated and unsaturated bit allocation categories, performing noise filling on spectral coefficients with insufficient bits to reconstruct missing coefficients using harmonic parameters, improving decoding quality by differentially applying noise filling based on spectral characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If bits are allocated only to relatively important spectral coefficients during encoding, then the encoding efficiency is improved, but the decoding quality deteriorates because less important spectral coefficients are not encoded and cause 'empty' or 'water-like' audio outputs
Solution Approach 1:
The patent converts the harmful effect of missing spectral coefficients (causing 'empty' or 'water-like' audio) into a benefit by applying noise filling techniques. The noise filling process generates artificial spectral coefficients to replace missing ones, transforming the degradation caused by bit allocation constraints into an acceptable or even improved auditory quality through perceptual masking principles.
Solution Approach 2:
The patent changes the parameter of spectral coefficient representation by introducing noise filling values. Instead of using only originally encoded spectral coefficients, the system modifies the spectral domain parameters by inserting synthesized noise coefficients in frequencies where no bits were allocated, thereby changing the audio signal characteristics to improve perceived quality.
2Manufacturing precision
If noise filling is performed on all spectral coefficients without differentiation, then the decoding quality is improved, but errors in noise filling occur affecting auditory quality
Solution Approach 1:
The patent applies local quality by differentiating noise filling application across different spectral regions. Instead of uniformly applying noise filling to all spectral coefficients, the system selectively applies noise filling based on local spectral characteristics, such as identifying which frequency bands actually require filling and applying appropriate noise levels and types to each region, thereby avoiding errors in regions where noise filling is unnecessary or harmful.
Solution Approach 2:
The patent segments the spectral coefficients into different categories (those requiring noise filling and those that don't) based on bit allocation patterns and spectral characteristics. This segmentation allows the system to apply different processing strategies to different portions of the spectrum, improving overall reliability by avoiding inappropriate noise filling operations.
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
Embodiments of the present invention provide a method and device for decoding a signal. The method for decoding a signal includes: obtaining spectral coefficients of sub-bands from a received bitstream by means of decoding; classifying sub-bands in which the spectral coefficients are located into a sub-band with saturated bit allocation and a sub-band with unsaturated bit allocation; performing noise filling on a spectral coefficient that has not been obtained by means of decoding and is in the sub-band with unsaturated bit allocation, so as to restore the spectral coefficient that has not been obtained by means of decoding; and obtaining a frequency domain signal according to the spectral coefficients obtained by means of decoding and the restored spectral coefficient. In the foregoing embodiments of the present invention, a sub-band with unsaturated bit allocation in a frequency domain signal may be obtained by classification, and a spectral coefficient that has not been obtained by means of decoding and is in the sub-band with unsaturated bit allocation may be restored, thereby improving signal decoding quality.