LPC: The past, present, and future of Linux audio [LWN.net]

LPC: The past, present, and future of Linux audio

Posted Oct 7, 2009 18:32 UTC (Wed) by drag (guest, #31333)
In reply to: LPC: The past, present, and future of Linux audio by cventers
Parent article: LPC: The past, present, and future of Linux audio

Well the fact is that OS X does not use a Microkernel and never did. It was a lie. To keep the Apple reality distortion bubble from popping people have created the concept of 'hybrid microkernel' to describe the OS X kernel as if that was some sort of CS concept.

Which all that it means is that Apple copied the NT kernel design approach by incorporating some features of microkernels into what ends up being fundamentally a monolithic design.

But as far as audio stuff goes I am told that Apple's CoreAudio is actually a compelling feature over what is available in other operating systems. It's designed with music production in mind.

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To get the best out of Linux it is still very tedious and highly technical.

It involves:

* Installing and configuring Jack
* Configuring your applications to use Jack
* Purchasing a audio card with good performance characteristics. (Intel-HDA, while it is fine for music playback, is not designed for low-latency performance regardless of what drivers you use on it)
* Installing a custom OS kernel with *-rt patches.

And a great deal of learning the ins and outs of how to manage all the above.

Generally the biggest difference between the the actual workflows of Linux vs Windows is that instead of using big music production apps with plugins you use a lot of smaller applications chained together through Jack.

Now keep in mind that it has been a _long_ time since I mucked around with this stuff.

But I have a simple piano-style M-audio midi controller. It connects to the PC using a USB connection.

So the workflow went like this:

USB Controller -(jack midi routing)-> Software Synth (I forget which) -(pcm audio routing)-> Alsa Modular Synth (for effects processing) -(pcm audio routing)-> volume controls -(pcm audio routing)-> digital out on my sound card --> digital receiver --> speakers.

All in all I got the system to reliably operate to the point were I could not notice a delay from when I press a key to when I heard the sound.

Of course this required a couple hours of mucking around and setup. Debian by default could barely do software synth on it's own before I started customising it.

The situation has improved somewhat with the introduction of custom Linux variants in the form of 64Studio and Ubuntu Studio and things of that nature. So at least the software setup is mostly taken care of.

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LPC: The past, present, and future of Linux audio

Posted Oct 7, 2009 18:57 UTC (Wed) by cventers (guest, #31465) [Link]

Perhaps not, I don't remember all of the technical details, but I do remember the funnel lock. That was enough to keep me away from it at the time.

And you're absolutely right about the tedious nature of setup on Linux. I too have a MIDI USB controller from M-Audio, and I too got it working under Linux (actually even patched into reFX Vanguard courtesy of dssi-vst). But what I found is that when musical inspiration hits, I want to spend the least amount of time possible getting into working music software, because it generally doesn't survive having to debug some arcane software issue.

LPC: The past, present, and future of Linux audio

Posted Oct 7, 2009 18:58 UTC (Wed) by jebba (guest, #4439) [Link] (1 responses)

I appreciate that it may be pretty hard to get jack/rt going using some approaches (e.g. older debian). But a fedora(ish) install with planetccrma packages (including kernel) make it quite easy. I have repeatedly read that Intel HDA can't be used with realtime, but I have used it successfully on various EeePCs and my thinkpad. It seems that the package defaults are more reasonable now--with F11 and the thinkpad I basically just installed the ccrma packages, started up qjackctl and it "just worked".

LPC: The past, present, and future of Linux audio

Posted Oct 7, 2009 19:20 UTC (Wed) by drag (guest, #31333) [Link]

It's gotten better.

But for best performance you still need to patch and recompile your kernel as well learn the in-and-outs of dealing with the multiple Linux user interfaces.

With my setup I was getting pretty reliable sub-10msec latencies with Jack's settings with no xruns, although I usually let things slide to 60-70 just so I could have more responsive system.

The other thing that sucks about Intel HDA (besides the low quality of digital-analog conversion chips and relative high buffer requirements) as far audio creation stuff is concerned is just the lack of I/O options. This is the biggest real difference between 'profesional' and 'consumer' audio hardware. My old M-Audio Audiophile 24/96 has Analog stereo in, stereo out, digital in, digital out, and midi in and midi out. It also has nice-quality D-A/A-D conversion and the difference is enough that a with a quiet room and nice headphones pretty much anybody can tell the difference.

But, of course, that's PCI.

Otherwise I have no problems with using Intel-HDA for anything. It's the sound card I use the most since that is what is on my laptops. For music playback and doing some recording stuff it's perfectly fine and unless you are in a quiet area with high quality headphones the chances of anybody being able to the the difference is very unlikely.