hey hey!

probably my problems with pd's audio latency are easy to explain and eliminate, but by now i didn't make it by myself.

basically i am trying to create a looping-module for some simple live overdubbing. i already supposed that i have to factor in the latency for precise timing, but the presetted 50ms doesn't bring correct results. so i measured the latency with this latency.pd patch, using jack to create the feedback, it shows me a latency of about 24.6ms. is this latency constant? and what does the 50ms-preset mean?

and by the way, what are the first steps to optimize (minimize) the latency?

i am using ubuntu studio, pd-extended and right now the built-in sound card of my ibm think pad t41.

thank you!

Try sticking some subpatchs in your patch this should reduce the latency

@andymc2011 said:

Try sticking some subpatchs in your patch this should reduce the latency

that doesn't change anything and also doesn't help me understanding this latency thing

Without knowing exactly what you've already done to achieve lower latency, I'll cover the basics.

Latency is is controlled by several factors:

The Kernel: while you don't need a low latency kernel getting one or using Ubuntu Studio can help. There have been some incompatibilities with graphics drivers from nvidia in the past so YMMV

Kernel configuration: If you haven't read this page, read it - all of it - and do the tweaks that pertain to you. https://help.ubuntu.com/community/UbuntuStudioPreparation

Kernel Sound drivers: you are either going to use ALSA (through jack) or ffado for a firewire audio device. Pulseaudio is not an option here. Pulseaudio is not the devil, it's just not made for low latency work. refer to the link about on how to deal with it.

Jack Configuration once you've tweaked everything above then you can lower your frames/period and period/buffere settings as low as they will go without Xruns

Your soundcard not all soundcards can get down to 2ms latency in Jack, and considering you are using just the builtin audio you may have to consider a external usb audio device. Something like these would work:

Behringer UCA202

Cakewalk UA-1G