[alsa-devel] wrong decibel data?

Raymond Yau superquad.vortex2 at gmail.com
Wed Apr 21 04:32:24 CEST 2010

2010/4/17 Colin Guthrie <gmane at colin.guthr.ie>

> 'Twas brillig, and Raymond Yau at 16/04/10 14:48 did gyre and gimble:
> > 2010/4/3 Colin Guthrie <gmane at colin.guthr.ie>
> Sorry for the top post but....
> Raymond. Your replies are often very disjoint. I see no relevance to my
> message here and why you're replying here is beyond me.
> It's totally unclear what point you are making and which parts of this
> message are your comments and which are Lennart's original comments
> that's you've just pasted in.
> What are you trying to say?
> Col


>> Basically, if the signal is completely cut off, then the attenuation is
-inf dB.

you have to sum the dB gain of  the SPL of the speaker/headphone when you
want to calculate the dB ( sound pressure and the distance )

>> FWIW, I've got the same/similar h/w with a cutoff at 14% in PA as you
have. I've been meaning to get this fixed for a while, but I'm
incredibly lazy with certain things that don't bother me practically, so
haven't followed it up yet.

>> If any specific debug is needed here, feel free to ask.

Just reply since you still have similar problem , but it seem that you are
unwilling to provide info to debug your case , at least you have to provide
output of alsa-info.sh even when you have the same/similar h/w  ,

do your laptop has the volume knob ?


If pulseaudio provide per-application volume control, why the PA community
propose to throw away the volume slider of the application. (i.e. why only
allow pavucontrol to change the per-application volume ?


>> Making the application volume sliders control the device volume isn't
good either, because if an application has a volume slider, the natural
assumption made by users is that the slider controls only that application's

>> Solution: throw away volume sliders in applications, and promote centralized volume management with volume applets and hardware controls.

I suggest PA should provide the pre-application volume control for the
application too since from the viewpoint of PA when PA have to control all
the volume , it is better not allow application to control alsa master
volume control. but there is no reason to remove the volume sliders in


The per-application volume control is quite similar to the per voice
volume control of those hardware mixing sound cards ,
although there are some differences

 the per voice volume control of hardware mixing sound card provide digital
gain/atten by the DSP ( not those gain/atten of  DAC )


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