[PD] latency solutions... and then some

Pierre Massat pimassat at gmail.com
Sun Feb 7 11:25:09 CET 2010

I totally agree with Michal about the OS. I haven't tried MacOS but i know
for sure that XP can't beat a good rt Linux kernel.
That being said, I personnally spent about 6 months trying various Linux
distros before i found a good match with my hardware. Although I have had
very little luck with Ubuntu, you should probably start with this OS, and
then try other options (Pure:Dyne, Fedora with Planet CCRMA, 64 Studio...).
Most of these come with a live version which you can try without installing
Here's what I'd advise you to do everytime you install a new distro:
1) Install it or run the live cd (of course)
2) Run QJAckCtl or Jack Control to try the audio server first (google it to
find the proper settings for realtime use). If you don't get a decent
latency without any Xruns (shouldn't be higher than 6 ms on your hardware),
then you can either try another distro OR install the rt-kernel for your OS
(in case the standard install did not include it).
3) Once you are sure that JACK is working fine with a low latency and no
Xruns, you can try your Pd patches.

Hope this helps.


2010/2/7 Michal Seta <mis at artengine.ca>

> On Wed, Feb 3, 2010 at 9:22 PM, Jeffrey Concepcion
> <jeffreyconcepcion at gmail.com> wrote:
> > Thanks for the suggestions, i'll deffinately be looking into your
> > suggestions (i'm not familiar with some of the terms ). For now i must
> deal
> > with what i have at home, which is an acer netbook w/ windows Xp @ 1.6
> GHz,
> > 1GB RAM btw! No external soundcard as of yet. i should get (in theory) a
> > similar result to Pierre's so i'll be trying that approach for now
> Don't be fooled by the processor Hz count. First of all, different
> operating systems deal with system resources in different ways.
> Whether you can get reliable, low latency performance from XP on a
> netbook is beyond my experience but AFAIK, Windows and MacOS are not
> as transparent and easily tuned as *NIX are.  I still use very lean
> and small window manager when I want to be sure to have clean audio
> without dropouts in low latency.
> Beyond that, the hardware performance has a lot to do with latency.
> The cheap audio interfaces that are bundled with today's computers,
> especially netbooks, are not necessarily useful for for real-time, low
> latency work.  They will usually require a relatively large buffers to
> convert analog<->digital without hick-ups and that will add up to the
> buffers needed by the audio driver, pd, CPU's workload etc.
> That said, you may want to look at this thread (and/or google similar):
> http://linuxaudio.org/mailarchive/lau/2009/5/6/154392
> There are some people using linux on netbooks for realtime processing
> and therefore it is possible.  YYMV, depending on your needs, your
> perception of "real time" and the hardware/software configuration.
> Note, that if you want to give linux a try you can grab pure:dyne or
> ubuntu and install it on a USB stick or HD and take it from there
> until you decide which OS works best for your particular needs.
> pure:dyne will give you immediate access to media applications
> (including pd) and realtime kernel.
> I am actually working these days with an Acer netbook (aspire one)
> running ubuntu 9.10.  Using a rt kernel improves audio performance
> somewhat.  I just used a stock rt build, I could probably roll my own,
> tuned to my liking but I think I am getting too old for that :).
> However, the hardware cannot really keep up with very low latencies.
> My focus is not on getting lowest possible latency right now so I do
> not have any better advice at the moment.
> half a cent from yours truly.
> ./MiS
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