Stereo Volume Control Using L-R Spatial Signal Protection
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Solution Overview
Problem
Television viewers experience discomfort due to sudden and dramatic volume changes during channel changes or between program and commercial broadcasts, primarily caused by lack of level control at the broadcast point and excessive spatial processing, leading to inconsistent audio levels.
Innovation Solution
A dynamic volume control system that maintains a perceived constant volume level by using a combination of dynamic volume control, excessive spatial processing protection, and program change detection, which adjusts the audio signals to minimize level changes and enhance audio quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple spatial processing is applied to enhance surround effects in two-channel systems, then spatial audio quality is improved, but perceived volume level becomes unstable and center image intelligibility deteriorates
Solution Approach 1:
The system employs feedback mechanisms where the processed audio signals are monitored and fed back to the processing stage. The center channel extractor continuously analyzes the L-R signal and adjusts processing parameters based on detected spatial content levels, creating a closed-loop control system that maintains stable perceived volume while preserving spatial enhancement effects.
Solution Approach 2:
The patent dynamically changes processing parameters based on the detected spatial content characteristics. When excessive spatial processing is detected, the system adjusts the gain applied to the L-R signal, modifies the center channel extraction parameters, and varies the contour filter characteristics in real-time, allowing the system to adapt to different program material and maintain consistent volume perception.
2Object-affected harmful factors
If dynamic volume control is implemented to maintain consistent volume levels, then listener comfort is improved, but device complexity increases
Solution Approach 1:
The volume control system is segmented into distinct functional modules: a center channel extractor that separates L-R from L+R signals, a spatial content detector that analyzes the extracted center channel, a gain controller that adjusts levels based on detection results, and contour filters that shape the frequency response. This modular segmentation allows each component to perform a specific function, simplifying the overall design and implementation while achieving effective volume control.
Solution Approach 2:
The patent introduces a center channel extraction process as an intermediary between the input stereo signals and the volume control mechanism. By extracting and analyzing the L-R signal through this intermediate stage, the system can detect spatial content without directly processing the full stereo signals, reducing computational complexity while maintaining effective control over perceived volume levels.
3Stability of the object's composition
If program change detection is used to anticipate volume changes, then volume consistency is improved, but response time delays occur
Solution Approach 1:
The system performs preliminary action by continuously monitoring and detecting program changes in advance of actual volume shifts. The center channel extractor and spatial content detector operate continuously to identify upcoming program transitions, allowing the gain controller to pre-adjust volume levels before significant changes occur, thereby maintaining consistency while minimizing perceived delays.
Solution Approach 2:
The patent implements dynamic response characteristics where the detection and control parameters adapt based on the detected program state. The system adjusts its sensitivity and response thresholds dynamically, allowing faster response to sudden program changes while maintaining stability during normal playback, thus reducing effective response time without sacrificing volume consistency.
Data Source
AI summary
A disclosed system and method dynamically controls the perceived volume of a stereo audio program including left and right channel signals. The system comprises: a dynamic volume control configured and arranged so as to maintain a perceived constant volume level of the stereo audio program; and an excessive spatial processing protection processor configured and arranged for controlling the level of a difference signal, created as a function of the right channel signal subtracted from the left channel signal (L−R), relative to the level of a sum signal, created as a function of the right channel signal plus the left channel signal; wherein the excessive spatial processing protection processor processes the audio signals so as to control the difference (L−R) signal relative to the sum (L+R) signal. A system and method are also provided for dynamically controlling the perceived volume of a stereo audio program including left and right channel signals, comprising: a dynamic volume control configured and arranged so as to maintain a perceived constant volume level of the stereo audio program; and a program change detector configured and arranged to provide a program change signal indicating that the volume of the left and right channel signals has dropped below a threshold level for at least a threshold time period so as to anticipate a possible change in the sound level of the left and right channel signals; wherein the dynamic volume control is responsive to the program change signal.