Re: [Jack-Devel] Dispersing MIDI messages: one to multiple

On Thu, Jan 29, 2015 at 10:08 AM, Marjan Mrak <marjan.mrak@gmail.comwrote:
> I have developed JACK MIDI client, which grabs midi messages from MIDI
> keyboard on one port, and disperses it according to:
Hey,

> It works, but if I am using it, totaly at random sound output "hangs" for
> like 10th of second.
I'm not sure why it would "hang", and I'm not sure quite what you mean
with that: are notes not passed through at all, or is it that certain
notes are skipped?

> I suspect my code is the problem. I would just like someone to examine it -
> perhaps I am doiung something wrong here.
I hope its the latter.. because there's a little bug hiding in the
MIDI get code from JACK. It attempts to read *one* event, for every
"nframe" that is available. The following code snippet is taken from
the JACK example-clients - midisine.c

jack_midi_event_t in_event;
jack_nframes_t event_index = 0;
jack_nframes_t event_count = jack_midi_get_event_count(port_buf);

if(event_count 1)
{
   printf(" midisine: have %d events\n", event_count);
   for(i=0; i<event_count; i++)
   {
      jack_midi_event_get(&in_event, port_buf, i);
      printf(" event %d time is %d. 1st byte is 0x%x\n", i,
in_event.time, *(in_event.buffer));
   }
}

I'm not sure if your code is "production ready" - printf locks a
mutex, a big no-no in RT code. Since MIDI handling and audio are in
the same real-time thread, its not wise to printf in production code.
It could cause xruns in JACK if the printf decides to lock and wait
too long.

Hope the above helps the issue, cheers, -Harry

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