On Wed, Feb 17, 2010 at 11:55:17AM +0000, James Courtier-Dutton wrote: > On 16 February 2010 23:56, Lennart Poettering <mznyfn@xxxxxxxxxxx> 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. > > I think we need to separate the analogue side into a number of categories: > 1) Standard consumer line-out levels. > 2) Standard pro line-out levels. > 3) Consumer line-in levels. > 4) Pro line-in levels. > 5) Consumer mic levels. > 6) Pro mic levels. > 7) Consumer speaker levels. > 8) Pro speaker levels. There's also headphones there, though for both speakers and headphones it's questionable if we want to do anything. > On the analogue side, I believe the 0dB gain point is intended to be > the point at which one can be fairly sure that the distortion will be > low for a sensible full scale input. Generally 0dB is pass through (which does also tend to be the optimal performance point). Actual expected gain levels will vary depending on application - for example, a microphone input will usually need an amplifier with fairly high gain in the path to get the signal to a level usable by the rest of the system. _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
