Variable Exponent Averaging Detection for Dynamic Range Control
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Solution Overview
Problem
Existing dynamic range controllers in audio and video signal processing struggle to separately control DC, static, and dynamic actions, leading to limited artistic control over signal dynamics and poor handling of complex waveforms, resulting in issues like distortion, clipping, and loss of signal details.
Innovation Solution
The Variable Exponent Averaging (VEA) Detector and Dynamic Range Controller (DRC) use a VEA Processor with one or more VEA Detectors to evaluate signal samples by taking the X root of the average of signal values raised to the same power, incorporating antilog processing in a log domain circuit, allowing for more accurate RMS and root mean X value calculations, enabling better control over signal dynamics through adjustable exponent values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If first-order linear filters are used in dynamic range controllers, then the device complexity is reduced and ease of operation is improved, but the ability to separately control DC, static, and dynamic actions is lost and dynamic control capability is severely limited
Solution Approach 1:
The patent segments the dynamic range control into three independent filter circuits: a first filter for DC control, a second filter for static control, and a third filter for dynamic control. Each filter processes the same input signal but with different time constants and gain settings, allowing independent adjustment of each control aspect without interfering with the others. This segmentation resolves the contradiction by maintaining relative simplicity while enabling comprehensive adaptability.
Solution Approach 2:
The patent implements dynamic control by making the filter characteristics adjustable and signal-dependent. The third filter specifically provides dynamic control with variable time constants that adapt to changing signal conditions. This allows the system to transition between different control modes dynamically, resolving the limitation of fixed first-order filters while maintaining manageable complexity.
2Device complexity
If RMS detection is used in dynamic range controllers, then the measurement of average signal level is simplified, but the accuracy of perceived loudness measurement deteriorates and artistic control over signal dynamics is limited
Solution Approach 1:
The patent changes the detection parameter from simple RMS to a more sophisticated measurement that incorporates multiple filter outputs with different time constants. By combining DC, static, and dynamic filter measurements, the system achieves more accurate perceived loudness measurement that better reflects human auditory perception while maintaining reasonable computational complexity.
3Adaptability or versatility
If non-linear or time-variant filters are imposed on the signal envelope, then dynamic signal changes can be controlled, but the static performance of the dynamic range controller changes and control over DC and static actions is lost
Solution Approach 1:
The patent segments the control function into three independent filter circuits, each dedicated to a specific control aspect (DC, static, dynamic). This segmentation allows non-linear and time-variant processing in the dynamic filter without affecting the stability and linearity of the DC and static filters, thereby maintaining static performance while enabling dynamic control flexibility.
Solution Approach 2:
The patent uses the three-filter architecture as an intermediary structure that decouples the interaction between DC, static, and dynamic control. Each filter acts as an independent intermediary processing stage, allowing complex dynamic control to be implemented without directly interfering with the simpler DC and static control paths, thus maintaining overall system reliability.
4Adaptability or versatility
If prior art detectors and DRCs perform signal detection and processing in the log domain, then the dynamic range handling is improved, but the performance is not noticeably better than analog devices or native digital signal processing
Solution Approach 1:
The patent segments the log domain processing into three distinct filter circuits with different characteristics, allowing each to optimize for its specific control function. This segmentation enables better utilization of the log domain's dynamic range handling capabilities while achieving more accurate signal measurement through the combined output of multiple specialized processing paths.
Data Source
AI summary
The VEA Detector and Dynamic Range Controller of the invention more accurately measure constant or non-constant, periodic or aperiodic, signals and the use of such measurements to control the upstream and/or downstream processing of program signals, including without limitation audio, video, and power program signals. The invention uses an antilog module acting within the context of a log domain circuit such that the “averaging” at an integrator is linear, not logarithmic. However, since the detection is within the log domain, the dynamic range of the VEA Detector is exponentially larger.