Sometimes audio quality is poor on Android, but it happens always when proximity sensor turns off the screen during call.
Udating Opus to the latest version might give slight improvemnt as well as trying to build it with floats disabled. Increasing priority of audio encoding thread may also help which was abandoned at some point - not sure when and why, maybe by mistake.
(Issue migrated from https://trac.jitsi.org/ticket/1237)
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