If i have one stream at 100%, i have a volume level range from the master volume from 100% t0 20%. Because PulseAudio sets Alsa Master Volume to 0% at 20%. This gets worse if i set this one particular stream to ~3%, then i have an range from 75% to 100% on the master volume. Because Pulse set Alsa master to 0% at 75%. I consider this as a bug because, it is in impossible with this behavior to control the volumes in low levels. If you play just a little around with different stream volumes this can get much worse. And you have set unexpected the cut to a different point. The cut off point can so to speak unexpectedly jump from 20% to 75% an shrink your volume range extremely! Using Sabayon Linux with PulseAudio 3.0 3.7.8-gentoo x86_64 AMD A8-3500M APU
This most likely is a bug in alsa, not in pulseaudio. Alsa gives pulseaudio information about the gain in decibels for each volume level in the alsa mixer. In your case, the lowest level should be -infinity dB (i.e. muted), but apparently alsa reports something else. This makes pulseaudio think that the lowest level is does not mean mute, so it's ok to select it even when pulseaudio volume is not 0%. You can confirm this by checking what dB gain alsa reports when the mixer is set to the lowest level. If you're using alsamixer to monitor/edit the alsa volume levels, it shows the dB gain in the upper left corner.
I'm marking this not our bug for tracking. Please feel free drop comments here if you'd like more help figuring this out, though.
This problem is also observed on C-Media USB soundcard. I've filed a bug report on https://bugzilla.kernel.org/show_bug.cgi?id=196669 If your card is a different brand, you might as well try to file a bug report.
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