An 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. :)

(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 projects/rt/older/ directory)

bzcat ../patch-2.6.24.7-rt21.bz2

wget http://pastebin.com/pastebin.php?dl=f6ad31838
mv pastebin.php\?dl\=f6ad31838 .config.old
make oldconfig

(build and install your kernel)

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

enable capture/record elements in mixer

without this jack can't play nicely with intel-hda cards

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

I use qjackctl to set these

• put a check in Realtime
• Priority 89
• Frames/Period 64
• Sample Rate 48000
• Periods/Buffer 3

Please comment here if this guide worked for you or what you had to do to get it working:

!– Comments end here –!