Am Sun, 29 Jan 2012 11:03:13 -0400 schrieb Norbert Zeh <nzeh@cs.dal.ca>:
Let me chime in here to add an important point to this discussion. The whole discussion so far sounds as if PA works great with non-pro cards and breaks only on pro cards. That's not the case: PA has problems even with what is probably the lowest end of chips: built-in audio chips on all my motherboards. And the behaviour I observed is exactly what Heiko and Ralf observed too: everything works great with ALSA and starts to act up when using PA.
Things I observed (on Ubuntu, Mint, openSUSE, Arch...so it's not distro-specific) were way too low input (mic) and output volumes even when setting the volume controls to 100%.
That's not the point with pro-audio hardware. The problem with ice1712 chips is that those chips aren't stereo or surround sound chips. Those cards have instead separate lines for in- and output. They can of course be mixed as normal stereo, but they can mixed however you want. Those cards don't have a master volume control or an amplifier, they only have attenuators. So those cards can't be handled like those consumer sound cards, and they need a special mixer and patch bay. ALSA delivers one in the package alsa-tools called envy24control. PA just knows pure stereo and maybe surround sound. PA wants to have a master volume control. PA doesn't have a mixer and patch bay for those cards. And the PA developers blame ALSA for this and just think crippling down those cards to pure stereo cards with an ominous ALSA configuration. Of course, this is a very dirty workaround to get those cards somehow working with PA, but with this configuration you disable all the other functionality of those cards. That is the problem. Well, it's not a problem as long as PA stays just optional so that people who like the features of PA and just use a consumer sound card can use PA and the pro-audio users don't need to use it. So the problem is that PA is made more and more as a standard by several up- and downstreams. That is what worries me.
I really wanted to use PA because it offers something ALSA does not: simultaneous audio streams from different applications (i.e., when firing up Windows in a VirtualBox, it does not hog my audio).
Simultaneous audio streams from different applications are mixed together by ALSA's dmix which is activated by default since years. I haven't tested sound from VirtualBox, yet. Heiko