On 16 February 2010 23:56, Lennart Poettering mznyfn@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.
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.
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. I think we can get better definition on items 1 to 4. To this end, I think ALSA needs a new control type so the user can set what line out voltages will occur using standard full scale digital inputs. http://en.wikipedia.org/wiki/Decibel