• From: Bleeding Kansas
  • Registered: 2009-11-09
  • Posts: 178

Topic: #! and the RT kernel.

Hey all I wanted to give a quick and dirty rundown of setting up #! as a Real Time studio environment with the jaunty or hardy rt kernels depending on which version of #! you're running. This will also work with other distros if they have a RT kernel patch.

1. Get the RT (Real Time) kernel. Go into synaptic and search "linux-rt", get everything associated with the RT kernel. Install it and then.......

2. Modify your /etc/security/limits.conf file. This is the important stuff and why many people run into installing the right Kernel, but it still won't record with Real Time rights.

 sudo gedit /etc/security/limits.conf

   Once in add these 3 lines

@audio          -       rtprio          99
@audio          -       memlock         unlimited
@audio          -       nice            -19

This will effectively add an audio group, but not all distributions have an audio group by default.

*Note* I personally run my rtprio at 100, because that's what I saw in Dyne:Bolic's config file and it runs great. Also, I've seen where "nice" may or may not really matter all that much, but I leave it just in case. Any of these numbers can be changed per your preference, but this should get anyone up and running pretty quickly.

3. Modify your Users and Groups. For #! go Menu>System>Users>Groups. Unlock it with your admin password and click "Manage Groups". From there click "Add Group" name it "audio" (it is case sensitive so make sure it matches what's in the limits.conf file) and check box your name as a user in that group.

That's it! Now you should be able to run Real Time applications with Real Time priority.

Okay you got it now what do you do with it?

Check out the repos and start with qjackctl, ardour, hydrogen or just install the ubuntu studio meta for audio and plugins, but that installs a lot of stuff. I also highly recommend a program called Traverso, but don't get it from the repositories. I recommend compiling it. The newer version has some features that are minute, but important. Check it out www.traverso-daw.org and read the site it has some good info on it and it has a current pdf manual for the program.

There are some more things that you can do to tune your system, but this should get you going. I hope this helped someone out or peaked someones interest. If there's something I missed or you have any questions let me know.

*IMPORTANT NOTE* When you're recording or doing audio work with the RT kernel and Jack etc. turn off you networking abilities. Being hooked up to the internet, wired or wireless, will cause xruns, audio blurbs and an overall bad recording day.

*ANOTHER NOTE* Jack needs to be setup to read your card, latencies, channels and more. It's really powerful and awesome, but it can seem overwhelming. Honestly, I'd do my best to give a tutorial on it too, but there are a lot of variables involved and it wouldn't work for everyone. Any card recognized by Alsa will work and there are enough things on google about Jack that it's just a matter of painting by numbers. If there's enough interest here for a Jack tutorial I'll do my best, but I can't make many promises. smile

|My Band: 12 Honest Men| |My Screenshot Gallery on Minus|
  • Registered: 2010-05-14
  • Posts: 31

Re: #! and the RT kernel.

Forgive me for being a thread necromancer, but this is a really great guide. I would love to see one updated for Statler and Debian sources.

identi.ca | blog | dj mixes

shazbot's Website

  • pvsage
  • Internal Affairs
  • Offline
  • From: Section Six
  • Registered: 2009-10-18
  • Posts: 6,009

Re: #! and the RT kernel.

^ I've checked the Debian repos; it doesn't look like there is a rtkernel available for Debian Squeeze.  (It seems there was one back when Etch was stable.)  There's a rt-tests package, but not the kernel or headers.

If you find the rtkernel available as a .deb, feel free to try it with Statler and let us know how it goes.

while ( ! ( succeed = try() ) );
  • Registered: 2010-05-14
  • Posts: 31

Re: #! and the RT kernel.

I had noticed the same. I have never built and installed my own kernel before, but if I have the time to research it and back up my data I might try it. I don't even know if it's possible to do what I want right now. It looks like Ubuntu Studio has one by default but all my previous experiences with that distro leave me loathe to return.

I'm fairly new to the Debian way of doing things. As Squeeze matures into stable, are they likely to add the RT kernel as an option at some point?

identi.ca | blog | dj mixes

shazbot's Website

  • pvsage
  • Internal Affairs
  • Offline
  • From: Section Six
  • Registered: 2009-10-18
  • Posts: 6,009

Re: #! and the RT kernel.

This looks promising, at least at first glance:
http://www.pengutronix.de/software/linu … an_en.html

while ( ! ( succeed = try() ) );
  • Registered: 2011-01-16
  • Posts: 7

Re: #! and the RT kernel.

pvsage wrote:

This looks promising, at least at first glance:
http://www.pengutronix.de/software/linu … an_en.html

I installed this  from synaptic  (after manually updating sources.list) - it certainly works  a treat on my system (Dell Inspiron 1525 laptop).

At the moment I'm trying to out liquorix (non-RT) kernel just for comparison. That seems to be running well too.

  • From: 127.0.0.1
  • Registered: 2010-07-02
  • Posts: 1,274

Re: #! and the RT kernel.

FYI there is a dedicated audio/graphic design workstation distro that is debian based called AVlinux. http://www.bandshed.net/AVLinux.html Version 4.2 comes preconfigured with a RT enabled liquorix kernel. It also has some really nice wine configurations built in for running windows VSTi in ardour or inside a seperate wrapper, out of the box firewire compatability, and tons of other cool stuff. I installed it on my laptop that I use for audio stuff and crunchbangified it. I got my Native Instruments Audio 4 DJ working perfectly with it at 24bit/96khz. So far mixxx appears to work perfectly, even at those settings while broadcasting via shoutcast/icecast. Overall I'm pretty amazed with how well it runs on a non-hyperthreading 2.2 ghz duo core with 3 gb ram, I mean I only paid $300 for this laptop and that was brand new a year or two ago. I can't get anywhere near those settings in Windows 7 without getting pops and clicks. Next month when my timecode vinyls come in the mail I'll be able to put it to the test. Here's a couple pics:
http://img84.imageshack.us/img84/1894/myscreenshot1.th.pnghttp://img153.imageshack.us/img153/6258/myscreenshot2.th.png

Last edited by mynis01 (2011-01-17 01:55:06)

  • pvsage
  • Internal Affairs
  • Offline
  • From: Section Six
  • Registered: 2009-10-18
  • Posts: 6,009

Re: #! and the RT kernel.

@stephenirwin:  Anonymous will probably chide you for resurrecting this old thread; I personally see nothing wrong with it.  Please keep us apprised!

@mynis01:  Thanks for pointing out AVLinux!  The closest I had been able to find to that (aside from *buntuStudio and 64 Studio) was some "Linux for Musicians" distro, and the support website was all in Portuguese or something. roll

while ( ! ( succeed = try() ) );
  • Registered: 2010-12-30
  • Posts: 17

Re: #! and the RT kernel.

*IMPORTANT NOTE* When you're recording or doing audio work with the RT kernel and Jack etc. turn off you networking abilities. Being hooked up to the internet, wired or wireless, will cause xruns, audio blurbs and an overall bad recording day.

Not possible when you're doing IDJC and Skype for a talk radio broadcast.  That is all about connecting to the Internet.

  • Registered: 2009-09-08
  • Posts: 139

Re: #! and the RT kernel.

Hi

mynis01 wrote:

I installed it on my laptop that I use for audio stuff and crunchbangified it.

Could you pls. be so kind as to elaborate a little bit how you "crunchbangified" it?
Can you see any chance getting the Hercules "DJ Control MP3 e2" play well together with mixxx?

Last edited by tonyoptical (2011-01-17 13:57:01)

  • From: 127.0.0.1
  • Registered: 2010-07-02
  • Posts: 1,274

Re: #! and the RT kernel.

tonyoptical wrote:

Could you pls. be so kind as to elaborate a little bit how you "crunchbangified" it?

Well since AVlinux is also primarily based on debian squeeze, most of the modifications I had to make to "crunchbangify" were just gui related. I tried using the built in openbox install first but since the default desktop uses a hybrid of openbox and lxde I found it easier to just use xfce, disable the xfce panel and desktop icons, install conky terminator and tint2, enable the right click menu to open applications, make hotketys, etc. I basically just made it more lightweight, since my whole intent was solely to use it to run mixxx for the most part. I should note that the built in libflashsupport-jack plugin that allows you to route flash video output from your browser into jack was a welcome addition. One thing I haven't figured out how to do yet is to use shift+alt+<-- and shift+alt+--> to send windows to the left and right desktops. The hotkeys I set to boot applications were made in the gui tool supplied in the xfce settings menu.

tonyoptical wrote:

Can you see any chance getting the Hercules "DJ Control MP3 e2" play well together with mixxx?

There are patches available to do just that, and apparently they work great except that scratching with the jog wheel isn't working as well as it could be. It works, but the problem is that the degree to which it adjusts the speed varies depending on what point you are at in the playback of the track. But if you don't use jog wheels to scratch then you should be golden. IMO, and I mean this with all due respect, if you want to scratch, get some real vinyl tongue You can read more about mixxx in conjunction with the hercules console here: http://www.mixxx.org/forums/viewtopic.p … p;start=20

Last edited by mynis01 (2011-01-17 15:25:38)

  • From: 127.0.0.1
  • Registered: 2010-07-02
  • Posts: 1,274

Re: #! and the RT kernel.

honeyradiance wrote:

*IMPORTANT NOTE* When you're recording or doing audio work with the RT kernel and Jack etc. turn off you networking abilities. Being hooked up to the internet, wired or wireless, will cause xruns, audio blurbs and an overall bad recording day.

Not possible when you're doing IDJC and Skype for a talk radio broadcast.  That is all about connecting to the Internet.

Also I should note that the new mixxx 1.9.0 beta has a built in functionality to send audio to a shoutcast or icecast server, I haven't really tested it out yet though.