----- Original Message -----
  From: "Zixns" <alexduthil(a)gmail.com>
 ok, last questions on the software mixer. On my linux distribution, i
 have
 alsa with pulseaudio. i know that pulseaudio is doing software
 mixing. If I
 remove pulseaudio, I can still do software mixing : which lib /
 program in
 alsa is doing it ? 
your alsa setup surely uses dmix:
http://www.alsa-project.org/main/index.php/Asoundrc#dmix