Parametric Multi-Channel Audio Coding Matrixing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for multi-channel audio reconstruction, such as matrixing techniques and parameter-controlled up-mix, face challenges in achieving high-quality reconstruction independent of the available decoder, particularly due to the modification of the stereo down-mix signal which can degrade 5-channel reconstruction.
Innovation Solution
A method that processes a stereo signal by applying specific complex functions based on spatial parameters to the stereo signals, ensuring that the energy difference between modified signals is greater than or equal to the energy sum, allowing for front/back steering and enabling matrix decoding without degrading parametric multi-channel reconstruction. This involves adding and modifying signals with functions that are dependent on spatial parameters, allowing for invertible matrixing and decoder-independent quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If matrixing techniques are applied to reduce bandwidth, then transmission efficiency is improved, but reconstruction quality deteriorates
Solution Approach 1:
The patent applies parameter-controlled up-mix where the encoder transmits spatial parameters (azimuth, elevation, distance) that control the up-mix process in the decoder. This allows the reconstruction quality to be adjusted via parameters while maintaining transmission efficiency through 2-channel down-mix.
2Manufacturing precision
If all individual channels are encoded without matrixing, then reconstruction quality is improved, but transmission bandwidth increases
Solution Approach 1:
The patent segments the 5-channel audio signal into a 2-channel down-mix signal for transmission and separate spatial parameters. This segmentation allows efficient 2-channel transmission while preserving the information needed for high-quality 5-channel reconstruction through parameter-controlled up-mix.
3Adaptability or versatility
If the stereo down-mix signal is modified for matrix decoding, then compatibility with matrix decoders is improved, but parametric multi-channel reconstruction quality deteriorates
Solution Approach 1:
The patent introduces spatial parameters as an intermediary that mediates between the 2-channel down-mix and the 5-channel reconstruction. These parameters carry the necessary spatial information without requiring modification of the down-mix signal itself, thus preserving reconstruction quality while enabling compatibility with different decoder types.
4Manufacturing precision
If spatial parameters are transmitted for up-mix control, then reconstruction quality is improved, but bit rate increases
Solution Approach 1:
The patent transmits only the essential spatial parameters (azimuth, elevation, distance) needed for perceptually accurate reconstruction, rather than transmitting complete channel information. This partial transmission approach achieves high reconstruction quality while keeping the bit rate increase minimal compared to full multi-channel transmission.
Data Source
AI summary
Techniques are described for combining parametric multi-channel audio coding with matrixing, reconstructing a full-quality multi-channel, independent of the decoder. A stereo signal is obtained from encoding an N-channel audio signal into spatial parameters and a stereo down-mix signal having first and second stereo signals, including adding a first signal and a third signal to obtain a first output signal, the first signal having the first stereo signal modified by a first complex function, the third signal having the second stereo signal modified by a third complex function. A second signal and fourth signal are similarly added to obtain a second output signal. Complex functions are chosen such that an energy value of the difference between first signal and the second signals (fourth signal and third signals) is larger than or equal to the energy value of the sum of the first and the second signal (fourth signal and third signal).