[PD] Is this a MidiYoke or a PD bug?

matteo sisti sette matteosistisette at gmail.com
Tue Nov 20 10:44:23 CET 2007


The subject line of this message may recall another similar one I
posted recently, but this is actually a different question (different

The attached patch periodically sends a burst of N midi control
changes with a random value, control number 1 and channel 1. Let T be
the time period, i.e. right input to the [metro]; N is set through the
message box in the patch.

Now, I select MidiYoke 1 as the output midi port, and I open another
instance of PD with MidiYoke 1 as the input port. In this second
instance of PD I create a simple patch with just a [ctlin] and three
number boxes connected to its outlet to see what it receives.

With reasonable values of N and T, all works fine, and on the receiving side I
always get 1 as the control number and channel, and a random control value.

But if I set T to very small values and N>1, namely when N/T>4, every
once in a while on the receiving side I get a control change with
"103" as the control number, and 0 as the value (still channel 1).

I have been playing around with N and T and I seem to get coherent
results, in that the errors happen when the ratio N/T is greater than
a certain threshold, in my case 4. For example, N=4 and T=1, or N=8
and T=2, will trigger the bug.

Has anyone ever experienced a similar issue? Do you know whether it is
a bug in MidiYoke or in PD?

Obviously I recognize that sending more than 4 midi messages per
millisecond fron an application to another one is too much, and I
don't expect to be able to do that as an average rate for a long
period of time. However, suppose I send midi events at a fairly
reasonable *average* rate but every once in a while I may get a burst:
it's a serious issue if in those cases you can get unpredictable and
undetected errors.


Matteo Sisti Sette
matteosistisette at gmail.com
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