2010/6/7 Colin Guthrie gmane@colin.guthr.ie
'Twas brillig, and Raymond Yau at 06/06/10 01:12 did gyre and gimble:
2010/5/28 Colin Guthrie gmane@colin.guthr.ie
'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