LSF Coefficient Quantization via Warped Domain Gain-Shape Coding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for quantizing Line Spectral Frequency (LSF) coefficients in speech and audio encoding are computationally costly and inefficient, particularly due to the use of large codebooks and exhaustive searches in legacy algorithms.
Innovation Solution
A method involving the determination of LSF residual coefficients, transformation into a warped domain, and application of gain-shape coding schemes with different trade-offs in gain and shape resolution, reducing computational complexity and improving compression efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If legacy methods use large stored codebooks or several medium sized codebooks in multistage vector quantization, then LSF coefficient quantization quality is improved, but computational complexity and storage requirements increase significantly
Solution Approach 1:
The LSF coefficient vector is divided into multiple sub-vectors, each of which is quantized separately using smaller codebooks. This segmentation approach maintains quantization quality while reducing the size of individual codebooks and the computational complexity of exhaustive searches, as each sub-vector is processed independently with reduced dimensionality.
Solution Approach 2:
The patent transforms the quantization problem from the original LSF coefficient domain to a warped domain using a transformation matrix. This dimensional transformation allows the use of more efficient codebook structures and search algorithms in the transformed space, reducing computational complexity while preserving reconstruction quality.
2Device complexity
If algorithmic VQ with structured lattice is used, then storage requirements and search complexity are reduced, but quantization flexibility and quality may be compromised
Solution Approach 1:
The structured lattice VQ is applied to segmented sub-vectors rather than the entire LSF coefficient vector. This allows the algorithmic efficiency of structured lattices to be realized while maintaining quantization flexibility through separate processing of multiple sub-vectors, balancing computational efficiency with reconstruction quality.
Solution Approach 2:
The patent combines multiple quantization techniques: structured lattice VQ for efficient coding, transformation to warped domain for better conditioning, and segmentation for reduced complexity. This composite approach integrates the advantages of different methods while mitigating their individual limitations, achieving both efficiency and quality.
3Productivity
If Trellis Coded Quantization is employed, then computational efficiency is improved, but adaptability to different resolution requirements is reduced
Solution Approach 1:
The patent employs dynamic selection of quantization parameters including variable codebook sizes, adjustable transformation matrices, and flexible segmentation strategies. This dynamic approach allows the system to adapt to different resolution requirements and computational constraints, maintaining versatility while achieving computational efficiency through optimized processing.
Data Source
AI summary
A method and apparatus for handling input Line Spectral Frequency, LSF, coefficients. The method comprises determining LSF residual coefficients as first compressed LSF coefficients subtracted from the input LSF coefficients, and transforming the LSF residual coefficients into a warped domain. One of a plurality of gain-shape coding schemes is applied on the transformed LSF residual coefficients in order to achieve gain-shape coded LSF residual coefficients, where the plurality of gain-shape coding schemes have mutually different trade-offs in one or more of gain resolution and shape resolution for one or more of the transformed LSF residual coefficients. A representation of the first compressed LSF coefficients, the gain-shape coded LSF residual coefficients, and information on the applied gain-shape coding scheme are transmitted over a communication channel to a decoder.