[alsa-devel] Verifying mixer dB data/Invalid dB data from USB cards, especially Aureon 5.1 MkII

Raymond Yau superquad.vortex2 at gmail.com
Sat Mar 20 08:58:03 CET 2010

2010/2/17 James Courtier-Dutton <james.dutton at gmail.com>

> On 16 February 2010 23:56, Lennart Poettering <mznyfn at 0pointer.de> wrote:
> >
> > The reason I was asking how Jaroslav chose the 0dB position for his
> > measurements was purely because I wanted to do my own measurements for
> > that Aureon card. The dbmeasure tool I wrote for stuff like that puts
> > 0dB at max amplification, however Jaroslav didn't, so I was wondering
> > how he chose 0dB then.
> >
> > Lennart
> >
> I think the digital side is clear. So I will not go into that.

The problem is at the digital side , The range between -inf dB and -48dB /
-96dB software atten is lost during the conversion of the floating format
format to S16_LE or S32_LE ( native format supported by hardware driver )

i.e. the bottom part of the pulseaudio volume control cannot be used

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