Audio Frame Compensation Circuit for Bluetooth Pop Noise
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Solution Overview
Problem
In Bluetooth SCO/eSCO connections, especially in complex electromagnetic environments like those with widespread 2.4 GHz band WIFI, lost audio frames lead to annoying 'pop' sounds during calls due to the lack of effective frame compensation.
Innovation Solution
A circuit and method that identify a reference audio segment, search for a similar segment in a cached audio segment using cross-correlation, adjust the amplitude of a subsequent segment to match the lost frame, and output it as a compensated audio frame, ensuring smooth transitions and minimizing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If audio frames are transmitted in complex electromagnetic environments, then real-time voice communication can be achieved, but lost audio frames occur causing 'pop' sounds
Solution Approach 1:
The patent caches audio segments before transmission so that when frames are lost, similar segments can be retrieved from the cache to compensate for the loss. This preliminary caching action enables recovery from transmission failures without causing audible artifacts.
Solution Approach 2:
The patent creates a copy of the audio signal by finding similar segments in the cached audio data. When an audio frame is lost, the system copies a similar segment from the cache to replace the missing frame, thereby maintaining audio continuity and eliminating pop sounds.
2Reliability
If audio segments are cached and searched using cross-correlation, then lost frames can be compensated, but device complexity increases
Solution Approach 1:
The patent extracts only the essential similar segment from the cached audio data using cross-correlation search, rather than processing or storing multiple candidate segments. This extraction approach provides effective compensation while keeping the circuit complexity manageable.
Data Source
AI summary
A circuit to compensate for a lost audio frame, comprising: an identifier configured to identify a reference audio segment with a first length followed by the lost audio frame with a second length; a searcher coupled to the identifier and configured to search for a first audio segment similar to the reference audio segment in a cached audio segment followed by the reference audio segment by utilizing a cross-correlation search; the identifier further configured to identify a second audio segment subsequent to the first audio segment as a pre-compensated audio frame; an adjustor coupled to the identifier and configured to adjust an amplitude of the second audio segment based on a scale factor; and an output coupled to the adjustor to output the adjusted second audio segment as a compensated audio frame.