[LAD] making sense of Jack MIDI; or, is this an appropriate use for Jack?

M Donalies ingeniousnebbish at cox.net
Fri Feb 15 18:33:48 UTC 2013

On Friday 15 February 2013 11:12:04 Paul Davis wrote:
> JACK does not provide sequencing facilities. It simply transports MIDI
> between ports.
> > If I wanted to do the sequencing myself, what would be involved?
> a lot.

Does that mean:
Don't even think about it unless you're a systems programmer because there's 
1000 low-level subtleties involved.

Or is it just the tedium of turning all the midi events into binary and making 
sure all the events are in order to be processed by the target (fluidsynth or 
soundcard or whatever)?

I can handle the latter, but certainly not the former. My idiot-level 
algorithm is kind of like writing realtime midi to a port and looks something 
1) My app has a buffer of the binary midi data. Jack is running and I've 
created a midi out port.

2) Jack let's me know what time it is through a callback.

3) To play, I record the current time as my starting time. Then write some 
events to the port.

4) Wait for another callback and write more data.

Ok, you can stop banging your head on or desk, exclaiming "How does this idiot 
even know how to post a message to the list!" I have the feeling this is the 
equivalent of the car question, "Now tell me again, why do I have to use this 
icky motor oil stuff? Pouring water in the reservoir fills it just the same and 
it's far less messy."


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