Re: [Alsa-user] RME AES-32 questions

[John S. <lin...@fr...>]

James Courtier-Dutton wrote:

> Some time ago, there was no way to tell, from user space, if 100%
> or 50% was 0db, -50dB or +50dB. As a result, the safest value to
> use was the minimum value being either 0% or mute. That has changed
> with alsa 1.0.16, as dB gain information is now available.

I'm not sure where user space fits in. I'm talking about the
sound/pci/rme9652/hdspm.c driver which mutes every channel at
initialization by calling

   all_in_all_mixer(hdspm, 0);

cf. http://lxr.linux.no/linux/sound/pci/rme9652/hdspm.c#L3396

AFAIU, the driver "knows" what level corresponds to 0 db.

> But the value of 50% does not correspond to 0 dB for all sound
> cards.

I'm not discussing all sound cards, I'm discussing the sound cards
driven by hdspm. Is it safe to assume that, for the cards driven by
hdspm, level 32768 corresponds to 0 dB?

Regards.