Hi there, I have just bought a PreSonus Firebox (on advice from this forum) and have got it working with my Ubuntu Feisty Faun system. I can now listen to audio I have recorded in Ardour and it sounds pretty darn good!
The trouble is latency. To even start Jack using FreeBoB without getting XRun errors whilst not doing anything I have to set up with:
But even with that setup, I hear a lot of pops during playback. I even hear pops with Frames/Period set to 256 (23.2ms latency). My system is as follows:
AMD 64 3800+
2GB RAM
PreSonus Firebox
2 x 250GB SATA HDDs (not using RAID) with the following partitions:
sda1 - Ubuntu 7.04 on
sda2 - Personal docs
Backed up data & Windows Vista (going to bin it) on sdb
This situation doesn’t seem right with my specs. Perhaps I am wrong?
Anyways, I am wondering what I can do to improve this situation. I am open to installing a different distro as I havn’t been using Ubuntu for long enough to mind wiping and starting again! Will using hdds in RAID help? Any advice would be greatly appreciated.
I have not made any changes to the kernel since installing Ubuntu (not the studio version). So certainly no preemptive kernel.
I am not running Jack in realtime, it won’t let me do that (after trying several things I still can’t figure that one) and I can’t even get it to run nice with frames/period = 128 and nperiods = 2.
I have just downloaded Ubuntu Studio and shall be installing that when I get a minute and have figured out the best way to install on my drives with audio in mind. Any advice on partitioning and installation that will help with latency (2 x 250GB SATA hdds)?
first things first: are you running JACK in realtime mode (-R, or the “realtime” option in the QJackctl setup dialog) ?
btw, frames/period = 64 is a very, very ambitious setting for a system you haven’t been using very much. its unlikely to work without a full tuned system and an RT-kernel. its true that using num_periods = 4 helps, but you’d likely be better with frames/period = 128 and nperiods = 2. but not until you’ve got the rest of the system properly tuned up.
Hey, Ya something is weird. I have lesser hardware and can achieve a stable 1.3ms latency (48khz, 64 frames/period, Periods/buffer 2)
I do have a different interface tho… A delta 44… The question I have for you is: Are you running a fully preemptive (RT) kernel. A low latency desktop kernel just doesn’t cut it… Not for me anyway. If you’re not sure type “uname -a” at the command line… You should see something similar to this --> 2.6.20-16-realtime #2 SMP PREEMPT
I am running Ubuntu Studio, which to my surprise, did/does not come with the fully preemptive RT kernel. I had to add a repository and install it.
Here’s the link --> https://wiki.ubuntu.com/RealTime
With just the rt kernel running (no other optimizations) I am able to achieve great performance. Although I have added a few optimizations.
When I was running the low latency desktop kernel I could never do better than 5.x ms without xruns. Thats why I’m wondering.
Hopefully someone else can help you out if the above is not the case.
Installed Ubuntu Studio and the RT Kernel you showed me and I am now running in realtime without XRuns at frames/period = 64 and nperiods = 2 (latency 2.9ms).
As far as the partitioning, I guess it’s a bit late to respond… Don’t really have any suggestions anyway though… I just did the default root and swap on my ide drive and I’m getting by with it.
In the future I plan on getting 2 sata drives. One dedicated to digital audio/ardour and the other will have the root/swap/home partitions… So then I can isolate disk access for doing recording.
Anyway, thats awesome. Glad things are working well. Happy recording
