Audio Output Hardware Volume Control Without Fixed-Point Distortion
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Solution Overview
Problem
Existing audio systems experience latency and audio distortion when performing volume adjustments due to the difference in digital audio processing formats between audio source and output devices, particularly when using floating-point and fixed-point processing.
Innovation Solution
An audio system that applies dynamic range compression and inverse volume adjustments at the audio source device to ensure that volume adjustments are immediate and do not exceed the output capabilities of the audio output device, converting audio signals from floating-point to fixed-point format.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If volume adjustment is performed at the audio output device using fixed-point processing, then immediate volume control is achieved, but audio distortion occurs when signal levels exceed 0 dBFS
Solution Approach 1:
The audio source device performs preliminary dynamic range compression on the audio signal before transmission, ensuring that the signal levels are pre-adjusted to accommodate subsequent volume changes at the output device without exceeding 0 dBFS and causing distortion
Solution Approach 2:
The system uses feedback by transmitting volume adjustment information from the audio output device back to the audio source device, enabling the source device to apply corresponding volume adjustments and dynamic range compression to maintain signal integrity
2Reliability
If dynamic range compression is applied at the audio source device, then audio distortion is prevented, but processing complexity increases
Solution Approach 1:
The patent introduces an intermediary processing stage at the audio source device that applies dynamic range compression and volume adjustments before transmission, acting as a mediator that prepares the signal to work harmoniously with the fixed-point processing at the output device
Solution Approach 2:
The system dynamically changes audio signal parameters including applying dynamic range compression with adjustable thresholds and ratios, and transmitting volume adjustment parameters to coordinate processing between source and output devices
Data Source
AI summary
A method performed by an audio source device that is communicatively coupled with an audio output device, the method includes obtaining an audio signal; receiving a volume adjustment; applying the volume adjustment to the audio signal; applying dynamic range compression on the volume adjusted audio signal; and applying an inverse volume adjustment to the compressed audio signal, where the inverse volume adjusted audio signal is to be transmitted to the audio output device.