Re: [LAD] Deciphering jack-smf-utils -- Jack MIDI stuff

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To: <linux-audio-dev@...>
Date: Monday, February 18, 2013 - 1:56 pm

This question arises from jack-keyboard rather than jack-smf-utils. The basic
framework is very similar, but jack-keyboard gets input from a gui rather than
from a smf.

So the idea is that you press a key on the keyboard and an event handler gets
called. The event handler calls queue_new_message(int, int, int), which
creates a midi event ev on the stack. Then it calls queue_message(&ev).

queue_message() copies ev to a ringbuffer. Okay, so far, so good.
queue_new_message() exits and ev goes out of scope, so only the copy on the
ringbuffer remains.

The next process cycle process_callback() is invoked. It calls
process_midi_output(), which takes data from the ringbuffer and moves it to
output_port's buffer.

Is this what's happening?

Now for receiving timing info from Jack. Where's a good place to look for code
that explains how to get (and display in a gui widget) the current time while
transport is rolling? There's QJackCtl of course. Is there something simpler,
more of an example program?

--
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Messages in current thread:
[LAD] Deciphering jack-smf-utils -- Jack MIDI stuff, M Donalies, (Sun Feb 17, 3:06 am)
Re: [LAD] Deciphering jack-smf-utils -- Jack MIDI stuff, M Donalies, (Mon Feb 18, 1:56 pm)
Re: [LAD] Deciphering jack-smf-utils -- Jack MIDI stuff, Paul Coccoli, (Sun Feb 17, 1:21 pm)