Stereo Codec Mode Selection for Uncorrelated Audio and Cross-Talk
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Solution Overview
Problem
Existing stereo sound coding technologies face challenges in efficiently encoding uncorrelated stereo content and detecting cross-talk, leading to increased bitrates and compromised sound quality, especially in complex audio scenes with multiple speakers.
Innovation Solution
A method and device for classifying uncorrelated stereo content and detecting cross-talk in stereo sound signals using features extracted from the left and right channels, employing a Logistic Regression model to switch between LRTD and DFT stereo modes based on correlation and cross-talk detection, optimizing coding efficiency and quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If stereo coding is applied to transmit stereo information, then sound quality is improved, but bitrate is doubled
Solution Approach 1:
The patent combines left and right channels into a single coded stream using stereo coding techniques. The encoder processes both channels simultaneously, extracting common information and representing it efficiently, thereby transmitting stereo audio at approximately half the bitrate of separate mono coding while maintaining sound quality.
Solution Approach 2:
The stereo codec is designed to handle multiple scenarios universally - it can process correlated stereo content, uncorrelated stereo content, and even mono content. The system adapts its coding strategy based on the input characteristics, making it suitable for various audio applications from music to speech.
2Quantity of substance
If low bitrate is used for each channel to maintain reasonable overall bitrate, then bitrate is reduced, but sound quality is affected
Solution Approach 1:
By merging the coding of left and right channels into a unified stereo coding process, the system exploits inter-channel redundancy. Common information present in both channels is encoded once and shared, allowing efficient representation at low bitrates while preserving sound quality through intelligent use of available bits.
Solution Approach 2:
The stereo codec dynamically adjusts coding parameters based on the correlation between channels. When channels are highly correlated, more aggressive compression is applied; when less correlated, the system allocates more bits to preserve quality. This adaptive parameter adjustment maintains sound quality across varying bitrate conditions.
3Quantity of substance
If parametric stereo coding is used, then bitrate efficiency is improved, but complexity of detecting and measuring increases
Solution Approach 1:
The parametric stereo coding process is divided into distinct stages: down-mixing left and right channels to mono, computing stereo parameters from the down-mixed signal and original channels, quantizing these parameters, and transmitting them. This segmentation allows efficient processing at each stage while maintaining overall bitrate efficiency.
Solution Approach 2:
The down-mixed mono signal serves as an intermediary in the parametric stereo coding process. It facilitates the computation of stereo parameters by providing a common reference that captures the essential information from both channels, simplifying the extraction of inter-channel cues while maintaining bitrate efficiency.
4Manufacturing precision
If stereo mode is selected for complex audio scenes with multiple speakers, then sound quality is improved, but bitrate increases
Solution Approach 1:
The stereo codec employs dynamic mode selection that adapts to the characteristics of the audio scene. It continuously analyzes the input signal to determine whether stereo coding or mono coding is more appropriate, dynamically switching between modes to optimize the balance between sound quality and bitrate for complex scenarios with multiple speakers.
Solution Approach 2:
The system changes coding parameters based on scene complexity detection. When multiple speakers or uncorrelated sources are detected, the codec adjusts its parameters to allocate bits more effectively, using techniques such as independent channel coding or enhanced stereo parameter representation to maintain quality while controlling bitrate increase.
Data Source
AI summary
A method and device selecting one of a first stereo mode and a second stereo mode for coding a stereo sound signal including a left channel and a right channel, comprises producing a first output indicative of a presence or absence of uncorrelated stereo content in the stereo sound signal, producing a second output indicative of a presence or absence of cross-talk in the stereo sound signal, calculating auxiliary parameters for use in selecting the stereo mode for coding a stereo sound signal, and selecting the stereo mode for coding a stereo sound signal in response to the first output, the second output and the auxiliary parameters.