Created attachment 66151 [details] x = alsamixer pecentage for the PCM control. y = corresponding volume in dB. I have an ASUS P5KPL-1600 motherboard with a VIA VT1708B 8-Ch chip managed by snd-hda-intel. The volume control in pavucontrol, Gnome's sound preferences and all apps with flat-volume enabled is too non-lineal and just plain wrong. alsamixer has two useful controls for output volume: PCM: goes from -40.25dB in 0% through 0dB in 53% to 14dB (*with clipping*) in 100%. (This is not linear at all, see graph.png, attached.) Master: goes from 0dB in 0% (very quiet output) to 6.75dB (without any clipping, loud and clear) in 100% with 0.25dB = 3.75% increments. When, in PulseAudio 2.1, I set the volume in 100% it maxes out both PCM and Master, so I get a quite distorted sound. This is expected, but the scale is wrong: 100% is 0dB but it should be 14dB. The base should be at -14dB, or 58%, when PCM is at 0dB (53%) and Master at 6.75dB (100%), but it is at -20.75dB (45%), with Master and PCM at 0dB, with very quiet output. The difference in sound pressure between 45% and 53% is very large. Between -20.75dB (45%) and -68dB (7%) the volume does not change at all. All controls in alsamixer remain the same. Between -68dB (7%) and -108.24dB (2%) the PCM control goes down to zero, and any less than that results in muted output. This behaviour is quite strange and I don't know how much of it is pulseaudio's fault, how much is the alsa driver's and how much is mine. Thanks.
you have to provide pulseaudio verbose log to show how pulseaidiot caluclate dB when request volume from 100% to 0% Aug 2 19:08:44 encke pulseaudio[2207]: ( 9.204| 9.204) [pulseaudio] protocol-native.c: Client indicator-sound-service changes volume of sink alsa_output.pci-0000_00_1b.0.analog-stereo. Aug 2 19:08:44 encke pulseaudio[2207]: ( 9.205| 0.000) [alsa-sink] alsa-sink.c: Requested volume: 0: 99% 1: 99% Aug 2 19:08:44 encke pulseaudio[2207]: ( 9.205| 0.000) [alsa-sink] alsa-sink.c: in dB: 0: -0.18 dB 1: -0.18 dB Aug 2 19:08:44 encke pulseaudio[2207]: ( 9.205| 0.000) [alsa-sink] alsa-sink.c: Got hardware volume: 0: 100% 1: 100% Aug 2 19:08:44 encke pulseaudio[2207]: ( 9.205| 0.000) [alsa-sink] alsa-sink.c: in dB: 0: 0.00 dB 1: 0.00 dB Aug 2 19:08:44 encke pulseaudio[2207]: ( 9.205| 0.000) [alsa-sink] alsa-sink.c: Calculated software volume: 0: 99% 1: 99% (accurate-enough=yes) Aug 2 19:08:44 encke pulseaudio[2207]: ( 9.205| 0.000) [alsa-sink] alsa-sink.c: in dB: 0: -0.18 dB 1: -0.18 dB
Thanks for taking a look at this, it has been fixed (perhaps inadvertently) since I reported it. Have a good day.
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