Multi-Channel Audio Encoding With Down-Mix Level Compensation
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Solution Overview
Problem
Existing methods for encoding and decoding multi-channel audio signals often result in signal level attenuation during down-mixing, leading to signal distortion and quality deterioration due to the offset of channel levels, which cannot be fully addressed by varying energy levels in predetermined frequency domains.
Innovation Solution
The proposed solution involves calculating a compensation parameter based on the multi-channel audio signal and down-mix signal to compensate for level attenuation, which is then encoded and used to generate a bitstream that includes spatial information, allowing for accurate restoration of the original multi-channel audio signal during decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a multi-channel audio signal is down-mixed into a mono or stereo signal, then the encoding complexity is reduced, but signal level attenuation occurs causing distortion and quality deterioration
Solution Approach 1:
The patent calculates compensation parameters before the down-mixing process, storing these parameters for later use during decoding. This preliminary calculation of compensation values based on original channel levels allows the system to pre-compensate for the attenuation that will occur during down-mixing, thereby maintaining signal level accuracy while still achieving encoding complexity reduction through down-mixing.
Solution Approach 2:
The patent introduces compensation parameters that modify the encoding process by storing information about the original channel levels and their relationships. These parameters are used during decoding to adjust the reconstructed signal levels, effectively changing the parameter space to include compensation data that counteracts the level attenuation caused by down-mixing operations.
2Productivity
If channel signals are added up during down-mixing, then the down-mix signal is generated, but level attenuation occurs because channels offset each other
Solution Approach 1:
The patent implements a feedback mechanism where compensation parameters are calculated based on the original multi-channel signal characteristics and the resulting down-mixed signal. These parameters are stored and fed back into the decoding process, where they guide the reconstruction of channel levels to match the original signal characteristics, thereby compensating for the attenuation that occurred during the down-mixing addition process.
3Adaptability or versatility
If spatial information is used to restore the original multi-channel audio signal, then the multi-channel structure is recovered, but signal distortion occurs due to level attenuation in the down-mix signal
Solution Approach 1:
The patent combines spatial information with compensation parameters to create a composite decoding approach. The spatial information provides the structural framework for reconstructing the multi-channel signal, while the compensation parameters provide the level correction data needed to maintain signal quality. This composite approach allows simultaneous achievement of multi-channel restoration capability and signal quality preservation.
Data Source
AI summary
Methods and apparatuses for encoding and decoding a multi-channel audio signal are provided. In the encoding method, spatial information is calculated based on a multi-channel audio signal and a down-mix signal, and a compensation parameter that compensates for the down-mix signal is calculated based on the multi-channel audio signal and the down-mix signal. Thereafter, a bitstream is generated by encoding the spatial information, the compensation parameter, and the down-mix signal and combining the results of the encoding. Therefore, it is possible to prevent deterioration of the quality of sound regarding a multi-channel audio signal by compensating for the multi-channel audio signal using a compensation parameter that compensates for a down-mix signal.