An Introduction to Linux Audio (O'Reilly)

Posted Aug 3, 2007 19:47 UTC (Fri) by drag (subscriber, #31333) [Link]

Actually nowadays dmix is enabled by default. There is no longer any need for a typical end user to muck around with their asoundrc.

The only time Linux, generally, users are forced to deal with Alsa now is when faced by Artsd (which is easy since it can be configured to use alsa) or with OSS-only applications which can't typically use dmix.

Your behind the times by a year or so. :)

Arts is effectively dead. But Pulseaudio has replaced ESD and is API/ABI compatable while being much superior. (esd has always sounded like utter crap..)

If you have need for networked sound I strongly suggest looking at pulseaudio. It supports all sorts of fancy features... For example Zeroconf so that the services will automatically be declared over a network and be picked up by things like Avahi or other pulseaudio software.Also it can be setup to follow X. So if your accessing remote X and there is sound involved then you can use pulseaudio to automatically follow it.

Also there is a 'pulse' plugin for Alsa. This way anything that supports Alsa can be used over the network via pulseaudio.

Jack is very nice for audio work.

It's special feature is that it is low-latency. This makes it suitable for realtime audio editing with multiple audio streams and multiple applications.

This gives Linux a unique advantage with applications that support jack they and route and re-route audio and midi between applications. Software synths, recording applications, midi controllers, LADSPA plugins etc etc. It'll work with internal and external midi stuff and allow you to easily control the I/O on your sound card, both digital and analog for setting up things like monitoring audio channels and playback/record stuff.

You can connect all these things to create very sophisticated super-applications. Sort of like you can string awk, sed, cat, and other things together to make sophisticated text handling applications.

In comparison with typical proprietary Windows or OS X setup your depending on one or another company's flagship product and your options are much more limited.

Combined with special low-latency patches like Ingor Molnar's realtime-preempt this allows a Linux PC to work as a REAL audio workstation and be suitable for studio, dj, and live audio work. Whatever you want. There are currently people selling Linux-based audio workstations for professional/studio-level work.

I think that the difference between desktop audio and network audio is enough that there is enough room for Jack, Alsa, and Pulseaudio to exist besides each other.

Also keep in mind that it's possible to get Jack and Pulseaudio to work together. There are also Jack and Pulse plugins for Alsa applications to use.

For arranging your applications to work through Pulseaudio take a look at:
http://www.pulseaudio.org/wiki/PerfectSetup

Posted Aug 3, 2007 19:55 UTC (Fri) by johnkarp (subscriber, #39285) [Link]

Say you are using a computer to do audio recording in a studio. With Jack,
you could route inputs from various audio interfaces into various effects
plugins, send some to a multitrack recorder, and also combine them all
into a mix for the musicians, so they can play off the effects. During the
recording session, you can easily reroute the signals from a central
patchbay.

You could probably hack together a workalike with other Linux audio
technologies, but it would be unusable because of the latencies. (Its
difficult to play an instrument well when you can only hear what you were
playing 0.3 seconds ago.)

I don't think Jack will become the standard general-purpose audio API
though, because each user on a system requires a separate Jack daemon that
has to run with realtime priviledges.