Dual Microphone Audio Level Estimation for Clipping Prevention
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Solution Overview
Problem
Digital cameras in outdoor and sports environments often capture audio signals that exceed the capabilities of microphones, leading to clipped audio with a lower signal-to-noise ratio, which diminishes the quality of captured audio and user experience.
Innovation Solution
A camera system with multiple microphones, including dual membrane microphones where one microphone has a higher gain than the other, and a microphone controller that selects the appropriate microphone based on audio signal levels to prevent clipping, using a level estimation module to determine the gain difference and amplify the selected audio signal seamlessly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single microphone is used to capture audio in outdoor and sports environments, then the device complexity is low, but the audio signal level exceeds the microphone's capabilities causing clipping and reduced signal-to-noise ratio
Solution Approach 1:
The audio capture system is segmented into multiple independent microphone channels with different sensitivity levels. Instead of using a single microphone, the patent employs a first microphone and a second microphone, each capturing audio signals at different gain levels, allowing the system to handle a broader range of audio signal levels without clipping.
Solution Approach 2:
The system dynamically selects between different microphone channels based on the detected audio signal level. The audio signal level detection mechanism enables real-time switching between the first microphone (for lower volume events) and the second microphone (for higher volume events), optimizing audio capture reliability across varying acoustic conditions.
2Adaptability or versatility
If the microphone gain is increased to capture louder sounds, then the dynamic range is improved, but the signal-to-noise ratio deteriorates due to clipping
Solution Approach 1:
Different microphones are assigned different gain characteristics to suit specific audio scenarios. The first microphone is optimized for capturing lower volume audio events with higher signal-to-noise ratio, while the second microphone is optimized for capturing higher volume audio events. This local optimization of gain characteristics allows the system to maintain high signal-to-noise ratio across the entire dynamic range.
Solution Approach 2:
The system dynamically adjusts the audio capture path by selecting appropriate microphone channels based on detected signal levels. This dynamic adaptation enables the system to maintain optimal signal-to-noise ratio across varying audio volumes, effectively expanding the usable dynamic range without sacrificing audio quality.
3Adaptability or versatility
If multiple microphones with different gains are used to increase dynamic range, then the audio capture capability is improved, but the device complexity increases
Solution Approach 1:
The audio system is segmented into distinct microphone channels, each with specific gain characteristics. This segmentation allows the system to handle diverse audio scenarios by selecting the appropriate channel, effectively expanding dynamic range while maintaining manageable complexity through modular architecture.
Solution Approach 2:
The multiple microphone system serves multiple functions: capturing both low-volume and high-volume audio events with optimal signal-to-noise ratio. By making the microphone system multi-functional, the patent achieves expanded dynamic range without proportionally increasing complexity, as each microphone serves a specific purpose in the overall audio capture strategy.
Data Source
AI summary
A camera system includes a first microphone, a second microphone, and a microphone controller. The first microphone and the second microphone are configured to capture audio over a time interval to produce a first captured audio signal and a second captured audio signal, respectively. The second captured audio signal is dampened relative to the first captured audio signal by a dampening factor. The microphone controller is configured to store the first captured audio signal in response to a determination that the first captured audio signal does not clip. In response to a determination that the first captured audio signal clips, the microphone controller is configured to identify a gain between the first captured audio signal and the second captured audio signal representative of the dampening factor, amplify the second captured audio signal based on the identified gain, and store the amplified second captured audio signal.