Multi-channel audio coding bridging parametric and matrixed methods
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing multi-channel audio coding methods face challenges in achieving efficient coding while maintaining backwards compatibility with stereo devices, with matrixed-surround methods offering limited quality and parametric methods requiring high bit-rates, leading to unacceptably high audio quality loss.
Innovation Solution
A method that dynamically adjusts the representation of multi-channel audio signals by using high-quality spatial audio parameters for critical portions and matrix-based solutions for less vital portions, allowing for flexible bit-rate and quality adjustment, and eliminating unnecessary side-information to reduce overall bit-rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If matrixed-surround methods are used for multi-channel audio coding, then backwards compatibility with stereo devices is maintained, but audio quality is limited
Solution Approach 1:
The audio signal is divided into different frequency bands (parameter bands), with each band processed independently using appropriate coding methods. This segmentation allows selective application of high-quality parametric coding where needed while maintaining compatibility elsewhere.
Solution Approach 2:
Different coding approaches are applied to different portions of the audio signal based on local requirements. Critical frequency bands receive full parametric coding for high quality, while less critical bands use matrixed-surround methods, optimizing the balance between quality and compatibility.
2Manufacturing precision
If fully parametric methods are used for multi-channel audio coding, then audio quality is improved, but bit-rate increases to unacceptable levels
Solution Approach 1:
The audio spectrum is segmented into multiple parameter bands, and parametric coding is selectively applied only to bands where it provides necessary quality improvement. This reduces the overall bit-rate requirement compared to applying parametric coding to the entire spectrum.
Solution Approach 2:
Instead of applying full parametric coding to all frequency bands, the method applies parametric coding partially - only to the extent necessary for achieving acceptable quality. Less critical bands are handled with simpler matrixed-surround methods, reducing total bit-rate consumption.
3Manufacturing precision
If parametric coding with side-information is used, then multi-channel reconstruction quality is improved, but transmission bandwidth increases
Solution Approach 1:
Side-information is generated and transmitted selectively for different frequency bands rather than for the entire audio spectrum. This segmentation of side-information transmission reduces the total bandwidth requirement while maintaining reconstruction quality where it matters most.
Solution Approach 2:
Side-information is provided locally only for frequency bands where it is necessary to achieve the desired reconstruction quality. Bands with sufficient inherent information or lower quality requirements receive no additional side-information, optimizing bandwidth utilization.
4Manufacturing precision
If high bit-rate parametric coding is used, then audio quality is maintained, but efficiency of coding is reduced
Solution Approach 1:
High-quality parametric coding is applied partially only to frequency bands where it is necessary, rather than to the entire audio signal. This partial application maintains audio quality for critical bands while significantly improving overall coding efficiency by avoiding redundant high-bit-rate encoding of less critical bands.
Data Source
Figure 1
Figure 2
Figure 2A
AI summary
The purpose of the invention is to bridge the gap between parametric multi-channel audio coding and matrixed-surround multi-channel coding by gradually improving the sound of an up-mix signal while raising the bit-rate consumed by the side-information starting from 0 up to the bit-rates of the parametric methods. More specifically, it provides a method of flexibly choosing an "operating point" somewhere between matrixed-surround (no side-information, limited audio quality) and fully parametric reconstruction (full side-information rate required, good quality). This operating point can be chosen dynamically (i.e. varying over time) and in response to the permissible side-information rate, as it is dictated by the individual application.