ALSA is the kernel level sound mixer, it manages your sound card directly. ALSA is a crap (seriously) and it can handle a few (sometimes just one) channel. PulseAudio is a software mixer, on top of the userland (like you'd run an app). When it runs, it uses Alsa's channel and manages EVERY mixing stuff, devices, network devices, everything by itself. (It's like one more unneeded layer) Actually you can run only ALSA, but you might get mixing problems and Ubuntu comes with PA support/PA dependence. (Some apps are hard coded to use PulseAudio, with custom patches and so on.) (PulseAudio also consumes much more CPU than OSS or ALSA.)
Whats the point? People say for networking it is good, and it solves the multi-channel misery, easy to develop apps for PA, easy to select new devices, to control volume by app, etc etc. However, in my opinion there is no point in PulseAudio. Okay, networking is OK. But for a simple user, its just an insane fat stuff on the system. It adds latency, it runs NOT in the kernel (Okay I won't list all the problems with it). They should write an ALSA2 (Pick out the solutions from PA and add the essential ones into Alsa). OSS solves the problem, however its not GPL, they don't like it. (The open source ...uhm... 'leaders'..) That's why they say (game developers, app developers) that they hate writing apps for Linux because the whole sound system is a messy hell.
Illustration:
Typical sound system nowadays, like Ubuntu:
KERNEL:{alsa} -> {alsa-channel} -> user:{pulseaudio} -> user:app1,app2,app3
Simple ALSA:
KERNEL:{alsa} -> dmix (it "runs in the kernel") -> user:app1,app2,app3
OSS:
KERNEL:{OSS(module)} -> user: app1,app2,app3
van
http://superuser.com/questions/144648/how-do-alsa-and-pulseaudio-relate Er zullen wel meer links te vinden zijn, maar dit vond ik wel een aardig antwoord. Ik ben zelf het meest gecharmeerd van ALSA. Maar ik ben dan ook van de oude garde.
