On Sun, Aug 12, 2012 at 12:31 AM, Fons Adriaensen <fons@linuxaudio.org> wrote:
First, PA has no visibility on whatever internal volume control an app provides. It just doesn't know about it. All it gets is the output from the app.
This is not correct. If the app has proper PA support (such as all KDE apps, and probably all gnome apps), then PA does the app specific mixing, not the app itself. Moreover, if only one app is playing sound then PA does no mixing at all, but passes it all directly to ALSA (and sets ALSA's controls of course).
Second, PA has no way to know how to correctly use the soundcard controls, or even to know what exactly they control and how they do it. On some cards the 'master' is digital scaling before the D/A converter. On some others it controls an analog gain stage after the converter. The correct way to use those is completely different.
If I understand correctly ALSA provides lots of meta-information about the controllers to PA. Before PA this meta information was ignored, and it is due to bugs in that that PA had a bad reputation in the beginning. PA has heuristics to try to do the best it can with the information provided to it. Are you saying that an unqualified user is likely to get a better result than these heuristics? It seems that what you are saying should mean that ALAS is clearly not good enough, and that we need something more, such as PA to deal with getting the mixing right, as it is too hard for users. -t