Multichannel Signal Processing Using OTT Boxes for Compression
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Solution Overview
Problem
Current multichannel signal processing technologies, such as MPEG Surround (MPS), face challenges in maintaining sound quality while compressing signals with an increasing number of channels, leading to excessive data reduction and limitations in backward compatibility.
Innovation Solution
A method and apparatus that process multichannel signals using an N-N/2-N configuration, where an N/2-channel downmix signal is identified and transformed into an N-channel output signal using one-to-two (OTT) boxes, decorrelators, and mix matrices, allowing for efficient compression and expansion of multichannel signals beyond the MPS standard.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a multichannel signal with a large number of channels is compressed using traditional MPS, then the compression ratio is high, but the sound quality degrades significantly
Solution Approach 1:
The patent segments the multichannel signal processing into multiple stages: downmixing N channels to N/2 channels, encoding with MPS, then upmixing back to N channels using OTT boxes. This segmentation allows compression at intermediate stages while preserving quality through controlled expansion, resolving the contradiction between high compression ratio and maintained sound quality
Solution Approach 2:
The patent implements a nested structure where the N-N/2-N configuration contains multiple levels of processing: the outer layer performs downmixing to N/2 channels, the middle layer applies MPS compression, and the inner layer uses OTT boxes for upmixing. This nested approach enables progressive compression and expansion while maintaining signal fidelity and achieving both high compression ratios and preserved sound quality
2Adaptability or versatility
If the number of channels in the multichannel signal exceeds MPS standard limits, then more channels are supported, but backward compatibility is lost
Solution Approach 1:
The patent makes the encoding system universal by implementing the N-N/2-N configuration that can handle both standard MPS channel configurations and extended configurations beyond MPS limits. The OTT boxes enable the system to universally support various channel numbers while maintaining compatibility with existing MPS decoders through the intermediate N/2 channel representation
Solution Approach 2:
The patent introduces an intermediary N/2 channel downmix signal that acts as a bridge between the original N channel input and the MPS-compressed output. This intermediary representation maintains backward compatibility with MPS standards while enabling support for extended channel configurations, as the compressed bitstream can be decoded by existing MPS decoders yet still represent extended channel information
3Productivity
If compression is applied to maintain bandwidth efficiency, then data transmission is efficient, but sound quality deteriorates
Solution Approach 1:
The patent applies dynamic processing through the OTT boxes that adaptively reconstruct N channel signals from N/2 channel downmix signals. The dynamic upmixing process adjusts signal distribution across channels based on the compressed representation, enabling efficient transmission while dynamically recovering sound quality at the decoder side
Solution Approach 2:
The patent changes key parameters in the signal processing chain: transforming from N channels to N/2 channels for compression, then using OTT boxes to change the parameter distribution back to N channels. This parameter transformation approach enables efficient compression at the N/2 stage while recovering full channel quality through controlled parameter changes during upmixing
Data Source
AI summary
Provided are an encoding method of a multichannel signal, an encoding apparatus to perform the encoding method, a multichannel signal processing method, and a decoding apparatus to perform the decoding method. The decoding method may include identifying an N/2-channel downmix signal derived from an N-channel input signal; and generating an N-channel output signal from the identified N/2-channel downmix signal using a plurality of one-to-two (OTT) boxes. If a low frequency effect (LFE) channel is absent in the output signal, the number of OTT boxes may be equal to N/2 where N/2 denotes the number of channels of the downmix signal.