On Mon, Apr 27, 2009 at 06:43:08PM +0200, Lennart Poettering wrote: > > I'm observing strange audio artefacts with my audio driver which seem to > > be related to audio material overamplification. IOW, the effect is only > > audible at waveform peaks. When I attenuate the playback volume > > pavucontrol, things get a lot worse - horrible distortion all over > > the place, even in more quite audio sections. > > > > Also, when comparing the audio output of 'aplay -Dpulse foo.wav' with > > 'aplay -Dplughw foo.wav', it is clearly audible that PA adds some kind > > of amplification to the material (I would guess ~3dB), even though all > > GUI accessible levels are set to 100%. > > > > The driver I'm working on does not have any volume control features, > > hence this must be done in software. > > > > Has that been encountered before? > > Please try to reproduce this, then do "ls" in pacmd and paste it > somehere. This should show if PA does digital amplification for any of > the active streams. It's always reproducable, here is the output: http://caiaq.de/download/tmp/pacmd-distortion.txt Let me know if I can provide more details. Thanks, Daniel
