Audio Encoder Inter-Channel Correlation Mode Selection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The EVS codec does not support stereo signals, leading to a deterioration in sound quality when processing stereo signals using a multimode monaural codec, as different coding modes may be applied to the left and right channels, causing abnormal sound and distortion in stereo reproduction.
Innovation Solution
An encoder is configured to calculate the inter-channel correlation between the left and right channels of a stereo signal and encode them using a common coding mode if the correlation is above a threshold, or individually determined modes if the correlation is below the threshold, to maintain sound quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a stereo signal is encoded by using a multi-mode monaural codec that performs encoding by switching among a plurality of coding modes, then the codec can be used in a stereo rendering system, but different coding modes may be used for the left channel and the right channel, causing deterioration in sound quality in stereo reproduction
Solution Approach 1:
The patent applies local quality by making the coding mode selection dependent on the inter-channel correlation value. When correlation is high, a common coding mode is applied to both channels; when correlation is low, independent coding modes are used. This localized adaptation to signal characteristics resolves the contradiction between codec versatility and sound quality consistency.
Solution Approach 2:
The patent implements dynamics by dynamically switching between common coding mode and independent coding mode based on the calculated inter-channel correlation. The coding strategy is not fixed but adapts in real-time according to the signal characteristics, allowing the system to maintain sound quality while supporting stereo rendering.
2Adaptability or versatility
If each of the right channel and left channel of a stereo signal is processed by using the mono encoding of the EVS codec, then the EVS codec can be used in a stereo rendering system, but different coding modes may be used for the left channel and the right channel, causing deterioration in sound quality
Solution Approach 1:
The patent applies local quality by making the coding mode selection dependent on the inter-channel correlation value. When correlation is high, a common coding mode is applied to both channels; when correlation is low, independent coding modes are used. This localized adaptation to signal characteristics resolves the contradiction between codec versatility and sound quality consistency.
Solution Approach 2:
The patent implements feedback by calculating the inter-channel correlation and using this information to control the coding mode selection. The system continuously monitors the relationship between channels and adjusts the coding strategy accordingly, ensuring reliable stereo reproduction while maintaining EVS codec compatibility.
Data Source
AI summary
An inter-channel correlation calculation unit calculates an inter-channel correlation between a left channel and a right channel by using a left channel signal and a right channel signal that constitute a stereo signal. A DMA stereo encoding unit and a DM stereo encoding unit encode the left channel signal and the right channel signal by using a common coding mode when the inter-channel correlation is greater than a threshold value, and individually encode the left channel signal and the right channel signal by using a coding mode determined for each of the left channel signal and the right channel signal when the inter-channel correlation is less than or equal to the threshold value.