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

[Lennart Poettering]

On Tue, 16.02.10 22:39, Mark Brown (broonie at opensource.wolfsonmicro.com) wrote:

> 
> On Tue, Feb 16, 2010 at 10:07:03PM +0100, Lennart Poettering wrote:
> > On Tue, 16.02.10 17:29, Jaroslav Kysela (perex at perex.cz) wrote:
> 
> > > Basically, if I remember correctly the discussion, 0dB on all elements 
> > > should main unchanged volume, <0dB attenuation and >0dB gain.
> 
> > But you need some kind of "anchor" for that. What you write above
> > applies only for elements that have some kind of analog input and
> > output. But the most interesting components are probably the DAC and
> > ADC (i.e. the "innermost" elements), and it's not clear what level they
> > output, so the "anchor" for the relative dB values is missing...
> 
> Typically the DACs and ADCs will have a full scale signal at line
> reference level - it should generally be a good approximation with
> nothing else to go on.

"line reference level"? What is that?

Lennart

-- 
Lennart Poettering                        Red Hat, Inc.
lennart [at] poettering [dot] net
http://0pointer.net/lennart/           GnuPG 0x1A015CC4