[alsa-devel] wrong decibel data?

Raymond Yau superquad.vortex2 at gmail.com
Tue Jun 22 17:29:08 CEST 2010

2010/6/22 Colin Guthrie <gmane at colin.guthr.ie>

> 'Twas brillig, and Raymond Yau at 22/06/10 03:31 did gyre and gimble:
> > 2010/6/14 Colin Guthrie <gmane at colin.guthr.ie>
> >> I've made this change on my system and while previously my UI had no
> >> "Base Volume" displayed (because all my "h/w" (I include softvol in
> >> that) controls had their dB value >0.
> >>
> >
> > as your card has no h/w gain,  > 0dB , but the gain in softvol plugin is
> a
> > software gain (i.e. in the red region in PA "s volume scale
> >
> > how can base_volume display in gnome volume control (unamplified) ?
> >
> > BTW ,  -46.5dB to 0dB of softvol plugin is software atten ( not h/w atten
> )
> As I said above, anything that comes from alsa is considered h/w
> amplification for the purposes of PA's volume scale. It's not practical
> to differentiate them

Software gain is different from hardware gain.

Clipping due to software gain +12dB cannot compensated by -12dB by hardware

> Does any card actually configure softvol, by default, to provide any
> gain, > 0dB for outputs? If so, then this is IMO a bad idea.

-51dB to 0dB is also software atten of softvol plugin

if PA did not want to differeniate hardware/software gain/atten
Just  set this softvol PCM to 0dB and use PA 's own software gain/atten or
don't use front device for HDA

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