[SGVLUG] Linux ProAudio

[Dustin]

Hi, Macie.  This is Dustin, who bought the hub and SCSI drives from you on
Sunday.  I hooked up the hub and it works fine.  I haven't had time to 
open up the PII and test the drives yet.

You were interested in the Linux ProAudio tools.  I'm going to kill two
birds with one stone and write up a little mini-article and forward it on
to the local LUG mailing list as well, so it's longer than I'd have
written otherwise.  We are going to have a Linux Audio meeting sometime
soon; let me know if you're interested I'll make sure you hear about the
details.

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The only hard-disk recorder that has any pretensions to professional use
(i.e. comparable to ProTools, Nuendo, et al) on Linux (and I am quite sure
the only open-source tool of that kind on any platform) is Ardour:

http://ardour.org/

it is under heavy development at the moment, working up to a 1.0 release, 
so AFAICT most serious people are actually running one of the nightly 
builds and re-building frequently.  #ardour on freenode is kind of the 
center of development and the principal author is there most of the time, 
and the answer to *many* questions is "that was fixed in CVS three days 
ago. :-)  Having the developers so accessible is a big plus, of course.

If you visit #ardour you might see me there, so say hi.  My username is 
'laurence'.

There are plenty of other neat tools, but Ardour is the biggie.

The biggest hurdle for newbies to using Ardour, besides maybe not having 
used something like ProTools before, is the fact that it won't even run 
until you get Jack working:

http://ardour.org/jack.php

but it's worth it, because the architecture is very nice.  I don't think
the page explains Jack that well--think of it as unix pipes for audio, on
steroids, written for super-low latency.  Jack-aware tools (meaning just 
about all the serious professional tools on Linux) basically route all 
data through jack, which provides enormous flexibility at the cost of some 
complexity.

Running jack usually forces you to face the fact that the standard Linux
kernel is built for overall throughput, not low latency, because you get
xruns (missed audio frames) all over the place.  At the minimum you want a
preemptible, realtime-enabled kernel.  You can rebuild it yourself (I did)  
to add the realtime-lsm patch (I'm talking most 2.6 kernels except maybe
the most recent one or so, 2.4 can be excellent but it's much more complex
to make it realtime and I have not done it) with fair results, but most
people download an already-tuned multimedia kernel from various places.  
I have a bunch of saved links on what you need if you build yourself; just
googling gets quite confusing because most of the info on the web is quite
out-of-date and the current pages don't seem to rank that highly in 
google's page rank algorithm.

The other cool thing about the Linux pro-audio architecture, besides Jack, 
is the LADSPA plug-in architecture:

http://hans.fugal.net:2500/linuxaudio/show/LADSPA+Plugins

since just about everything that has plugins uses this standard, you can 
use the same plugins on all the tools.

Most people seem to use one of a few multimedia packages that go on top of
a standard distro that wrap up a multimedia-tuned kernel and recent
versions of all these audio packages.  Apparently in most cases with the
exception of Gentoo, the release cycles and the general-purpose nature of
regular distros makes them less than ideal for digital audio work even
though all the software you need may be present.

The most popular is probably Planet CCRMA

http://ccrma.stanford.edu/planetccrma/software/

which runs on top of Fedore Core.  This appears to be the simplest way to
get good results for most people.  As a guess, the next most common is
probably Demudi

http://demudi.agnula.org/

which runs as a Custom Debian Distribution on top of Debian.  There are
other choices, in order of how common I seem to have seen them mentioned
(which may or may not reflect either popularity or how good an option they
are):

Gentoo.  There is no separate multimedia package for Gentoo, but the 
malleable design of Gentoo seems to be able to turn it into a rather good 
multimedia setup without creating a separate subdistro.  I'm not sure 
exactly what CFLAGS, USE flags, kernel, and whatnot that people use for 
this, though I may have to find out if/when I switch back to Gentoo.

Slackware plus the Audioslack packages:

http://www.audioslack.com/

Thac's RPMs.  They were for Mandrake so that's what is mostly on the page,
but apparently very recently he's switched to PCLinuxOS:

http://rpm.nyvalls.se/

That's more than enough for now.

Dustin