Multi-Channel Audio Decoding Center Channel Cancellation
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Solution Overview
Problem
Conventional multi-channel audio decoding techniques, such as BCC and intensity stereo, face limitations in reconstructing high-quality multi-channel audio signals due to the introduction of artifacts and reduced auditory image width, particularly in signals with independent channels and wide sound images.
Innovation Solution
A method involving a cancellation channel calculator and combiner to reduce the influence of the center channel in both transmission channels, allowing for improved reconstruction of output channels by combining the cancellation channel with the transmitted channels and using parametric side information to enhance sound perception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional multi-channel decoding techniques (BCC or intensity stereo) are used, then bandwidth reduction is achieved, but auditory image width is reduced and artifacts are introduced
Solution Approach 1:
The patent introduces a center channel cancellation component as an intermediary element that processes the decoded center channel signal and subtracts it from the surround channels. This mediator eliminates the harmful influence of the center channel leakage while preserving the beneficial bandwidth reduction of joint stereo coding.
Solution Approach 2:
The patent extracts and isolates the center channel component from the decoded transmission channels, then removes it from the surround channels through subtraction. This extraction approach separates the problematic center channel influence from the surround channel signals, restoring auditory image width.
2Productivity
If joint stereo techniques are used to reduce data transmission, then transmission efficiency is improved, but channel independence is lost
Solution Approach 1:
The patent employs a feedback mechanism where the decoded center channel signal is fed back through a cancellation component that subtracts it from the surround channels. This feedback loop restores channel independence by actively removing the coupled center channel influence while maintaining the efficiency of joint stereo transmission.
Solution Approach 2:
The patent dynamically adjusts the channel characteristics by selectively canceling the center channel component only in the surround channels, while preserving the center channel in its original form. This dynamic processing restores channel independence where needed without affecting overall transmission efficiency.
3Adaptability or versatility
If center channel is introduced in both transmission channels for downmix operation, then stereo compatibility is achieved, but channel separation is reduced
Solution Approach 1:
The center channel cancellation component acts as an intermediary that selectively removes the center channel influence from surround channels while leaving the center channel intact in both transmission channels, thus maintaining stereo compatibility while restoring channel separation.
Solution Approach 2:
The patent applies local quality modification by selectively canceling the center channel component only in specific channels (surround channels) where it causes interference, while preserving the center channel in its original form in both transmission channels to maintain stereo compatibility.
Data Source
AI summary
An apparatus for generating a multi-channel output signal performs a center channel cancellation to obtain improved base channels for reconstructing left-side output channels or right-side output channels. In particular, the apparatus includes a cancellation channel calculator for calculating a cancellation channel using information related to the original center channel available at the decoder. The device furthermore includes a combiner for combining a transmission channel with the cancellation channel. Finally, the apparatus includes a reconstructor for generating the multi-channel output signal. Due to the center channel cancellation, the channel reconstructor not only uses a different base channel for reconstructing the center channel but also uses base channels different from the transmission channels for reconstructing left and right output channels which have a reduced or even completely cancelled influence of the original center channel.