Codec Signal Selection and Gain Control for Low-Noise Audio Mixing
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Solution Overview
Problem
In audio signal processing, there are challenges with volume control delays and signal-to-noise ratio degradation due to limitations in transmitting gain control signals and noise management across different signal paths in audio reproduction systems, particularly in scenarios where high-quality audio is mixed with alerts or additional content.
Innovation Solution
An audio signal processing module with a controller that compares and selects between input signals based on similarity, amplitude, and spectral analysis, applying variable gain to ensure optimal noise performance and content fidelity without external control signals, using a module with input nodes, a variable gain stage, and a selector to manage signal paths and gain settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If volume control signals are transmitted from the applications processor to the codec component, then volume control functionality is achieved, but transmission delays of approximately 300 milliseconds occur
Solution Approach 1:
The patent introduces an intermediary mechanism by having the codec component autonomously determine gain settings based on local analysis of incoming audio signals. Instead of relying on external volume control commands from the applications processor, the codec acts as an intelligent intermediary that automatically adjusts its gain to prevent clipping while maintaining audio quality, thereby eliminating the 300ms transmission delay.
Solution Approach 2:
The codec component is designed to be self-sufficient by incorporating built-in intelligence to analyze incoming audio signals and autonomously determine appropriate gain settings. This self-service capability allows the codec to independently manage volume control without requiring external commands, thereby eliminating transmission delays and improving real-time audio processing.
2Adaptability or versatility
If the audio signal path includes multiple processing stages, then signal conditioning operations can be performed, but audio artifacts such as noise, distortion, and truncation are introduced
Solution Approach 1:
The patent extracts the essential function of volume control from complex multi-stage processing chains and implements it as a dedicated gain determination mechanism within the codec. By separating the gain control function from other signal processing operations and placing it at the appropriate location in the signal path, the system achieves necessary signal conditioning while minimizing the introduction of audio artifacts like noise and distortion.
Solution Approach 2:
The system performs preliminary gain determination by analyzing the incoming audio signal characteristics before the signal undergoes further processing. By pre-determining the appropriate gain setting based on signal analysis, the system prepares the signal in advance to avoid clipping and reduces the need for subsequent corrective processing stages that would introduce artifacts.
3Ease of operation
If gain control is implemented in the applications processor, then volume control is achieved, but control signal transmission to the codec is delayed
Solution Approach 1:
The patent transforms the codec from a passive signal processing component into an active intermediary that autonomously determines gain settings. This intermediary role allows the codec to receive audio signals directly and independently adjust gain without waiting for control signals from the applications processor, thereby eliminating the transmission delay while maintaining volume control functionality.
Solution Approach 2:
The codec is equipped with self-service capabilities to autonomously analyze incoming audio signals and determine appropriate gain settings without external intervention. This self-determination mechanism eliminates dependency on applications processor commands, thereby removing the 300ms transmission delay and enabling real-time volume control.
Data Source
AI summary
This application relates to methods and apparatus for audio signal processing, for example by a codec. An audio signal processing module has at least one input for receiving first and second input signals and an output path for outputting an output audio signal. The first and second input signals may be supplied by a first audio component and may correspond to the same source audio data. A controller is configured to compare the first and second input signals and to select one of the first or second input signals as the basis for a signal to be supplied to said output path based on the comparison. The controller may determine a measure of similarity in content between the first and second input signals.