[pulseaudio-tickets] [Bug 87814] Microphone has loud static/distortion when volume is not 100%

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=87814

--- Comment #4 from Radics Péter <mitchnull at gmail.com> ---
I have a similar issue but I can also reproduce the extreme loud sound with a
simple playback (with aplay).  The playback gets extreme loud if the
per-application sound volume is not exactly 100% (or 0, which mutes it).  The
error seem to happen only to mono sound (that's why I think it's the same
issue: the mic input is also mono).

I first noticed it with non-kde notifications on a kde desktop (the
notification was coming from thunderbird)

Then it happened with pidgin voice call.

Then I traced the issue to mono playback. The sample I used was:
test.wav: RIFF (little-endian) data, WAVE audio, Microsoft PCM, 16 bit, mono
16000 Hz. I also tested this on a non-kde (simple openbox) desktop, with
pavucontrol.  (under kde I tested this using both pavucontrol and kmix to
change the per-stream volume).

I've tried different settings for resamnple-method (in daemon.conf)
(speex-float-1, trivial, ffmpeg), they all produced the same behavior.

On another laptop we could reproduce the extreme loud sound by changing the
sound level of a paused music player (audacious) while playing the mono sample
with aplay (that is: the mono sample's sound settings were not touched, that
was the only actively playing sound and it got extremely loud just by changing
the sound volume of another application).  On this particular laptop the
threshold for the "loudness" seems to be around 40% instead of 100% (setting
the volume below 40% results in extreme loudness).

I first noticed the issue with pulseaudio-5.0, too.

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