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--- wiki:intel_hda_realtime_howto [2012/01/18 01:27] – quinn_adams
+++ wiki:intel_hda_realtime_howto [2013/06/02 15:45] – external edit 127.0.0.1
@@ Line 1: / Line 1: @@
-The paragon of udnesrtadnnig these issues is right here!
+[[http://lists.linuxaudio.org/pipermail/linux-audio-user/2008-November/056243.html|Based on this mail on LAU by Nathanael Anderson]]
+~~META:title=Intel-HDA JACK low latency howto~~
+~~META:desc=How to get Intel-HDA cards working with low latency, in duplex operation~~
-[[http://e-writer.org/|essay writer]]
+====== Intel-HDA JACK low latency howto ======
+I've seen asked many times on the list how to get intel-hda cards working with low latency, in duplex operation. Here is a full, step by step, on how I got 4ms latency. I'm using a Dell M90 with a Quadro fx 1500, attached to a docking station with a Maudio Delta 66 pci card (secondary card) in it, the binary Nvidia drivers and Compiz. So if you were wondering, it is possible. :)
+===== Kernel =====
+(I'm not going to walk you through how to compile a kernel)
+the last kernel before the big kernel lock regression
+  wget http://www.kernel.org/pub/linux/kernel/v2.6/linux-2.6.24.7.tar.bz2
+  tar xvjf linux-2.6.24.7.tar.bz2
+  cd linux-2.6.24.7.tar.bz2
+  wget http://www.kernel.org/pub/linux/kernel/projects/rt/patch-2.6.24.7-rt21.bz2
+if you don't see it here look in the [[http://www.kernel.org/pub/linux/kernel/projects/rt/older/|projects/rt/older/]] directory
+  bzcat ../patch-2.6.24.7-rt21.bz2
+Download this config: {{:wiki:config-intel-hda.txt}}
+  mv config-intel-hda.txt .config.old
+  make oldconfig
+build and install your kernel
+===== Module Options =====
+Add the following line to the file your distribution has its module options in
+(in ubuntu it is /etc/modules.d/alsa-base)
+  options snd-hda-intel model=ref position_fix=1 enable=1 index=0
+===== Mixer Options (VERY IMPORTANT ! ! !) =====
+enable capture/record elements in mixer
+**without this jack can't play nicely with intel-hda cards**
+===== RT Permissions =====
+In most modern distros /etc/security/limits.conf is where realtime permissions are set, I added these 3 lines to it, and added myself to the @audio group in /etc/group
+  @audio          -       memlock         1024000
+  @audio          -       nice            -10
+  @audio          -       rtprio          99
+===== Jack options =====
+I use qjackctl to set these
+  * put a check in Realtime
+  * Priority 89
+  * Frames/Period 64
+  * Sample Rate 48000
+  * Periods/Buffer 3
+===== Comments =====
+Please comment here if this guide worked for you or what you had to do to get it working:
+!-- Comments end here --!
+{{tag>Sound_Cards_and_Drivers jack howtos_and_faqs}}