2010/6/7 Colin Guthrie <gmane@xxxxxxxxxxxxxx> > 'Twas brillig, and Raymond Yau at 06/06/10 01:12 did gyre and gimble: > > 2010/5/28 Colin Guthrie <gmane@xxxxxxxxxxxxxx> > > > >> 'Twas brillig, and Colin Guthrie at 27/05/10 15:43 did gyre and gimble: > >>> PA should play nice with the softvol plugin so I don't think this is > the > >>> bit that is at fault. > >>> > >>> I strongly suspect that the reason has already been correctly > identified > >>> a while ago, which is that this card considers -48dB silent where as PA > >>> assumes this level is -200dB. I believe it was Raymond who pointed out > >>> the -48dB level in the HDA spec before on this list. > >>> > >> > > > > if floating point 0.0 is -inf dB , and 1.0 is 0dB , > > > > 0.5 is -6dB , 0.25 is -12 dB , 0.125 is -24dB and 0.0625 is -48dB > > This is just a pure mapping from dB->linear, but as this linear mapping > is generally not "natural" there are several different approaches to > presenting this to users. In PA, a cubic mapping is used on top of this > basic conversion, to map to the percentage scale (0.0 to 1.0 if you like). > > So I'm not sure what point you're making by providing these numbers. Can > you explain? > > > how can PA master volume control at 10~15% equivalent to HDA 's -48dB ? > > Not sure what you mean here, but I suspect it's the cubic mapping that > is confusing you. > >> FWIW, I've got the same/similar h/w with a cutoff at 14% in PA as you have. According to your email , you mention than your hardware has a cutoff at 14% in PA the mixer application programmer can select any kind of scaling in the slider do you mean 14% in pavucontrol or Master volume control of "pulse" device ? but pavucontrol did not provide any dB value at any point _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
