[pulseaudio-discuss] Sound recording/routing issues on Librem5
tanuk at iki.fi
Mon Dec 2 16:57:11 UTC 2019
On Mon, 2019-12-02 at 08:49 -0700, Angus Ainslie wrote:
> So this was a weird one. The modem and codec are fixed at a 48K sample
> rate ( the codec can do other rates but the clocks are currently set for
> 48k). On the devkit we added an alternate rate of 44.1K to deal with
> call audio. Pulse audio was using the alternate rate instead of the
> default rate and it was setting up the codec for 44.1K and one of the
> rates got set to a sample rate of 47999 Hz
> In one of the tests I also saw a rate of 43KHz but I don't seem to have
> captured any debug for that one.
> Dropping the alternate rate caused pulse audio to use 48K which allowed
> the sound to flow through the loopbacks and the latency disappeared at
> the same time.
> Thanks for your help.
Great that you got it behaving! Regarding the weird rates: it's normal
that the loopback sink input has a rate that is slightly different from
the normal rate. It's part of the logic that adapts to clock drift
between the source and sink. If the rate changes a lot, however, that
can be an indication that the hardware isn't working properly (it's
producing or consuming audio too fast or too slow).
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