[PD] midi latency pd -> alsa / jackd

Rob Bothof rbothof at xs4all.nl
Sat Jul 14 21:09:06 CEST 2012

Dear List,

I'm working on a diy midi-controller and running into some latency problems,
the controller is a 'scratch disk' with with a pic microcontroller with usb.

i've build an absolute encoder for it and i'm sending the data or angle 
as pitchbend data (for high resolution)
the speed with which i'm sending the data is way beyond midi-standards, 
i know...

now when i set up pd to use alsa audio (internal soundcard) and alsa 
midi, the device works perfect, very smooth..
when i choose jackd as a soundcard, i'm getting getting latency on the 
midi input..midi input is falling behind,
then picking up instantly, falling behind again and so on...like a 
sawtooth shape..

the settings i choose for jackd have no effect on this..either when i'm 
using the internal soundcard via jackd -> alsa,
or a firewire device via freebob...the latency problem is the 
same...also with higher audiobuffer settings there is no change
in the latency

I disabled alsa sequencer support in jack so midi is running straight to 

i know i'm working out of midi standards, but any help to where the 
problem might be,
or simular experiences, would be greatly appreciated...

Rob Bothof

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