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

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To: <linux-audio-dev@...>
Date: Sunday, February 17, 2013 - 3:06 am

I haven't really looked at the recorder program, but the player is pretty
cool.

To make it easier for me to understand, I simplified the code somewhat (got rid
of lash stuff, reduced output to a single port, etc) so my code excerpts below
don't match up exactly with the original code.

The first question is a rather stupid one: How long is a Jack frame? If we're
running at 44.1 kHz, is a frame 1/44100 sec? Or is it some multiple? Or is it
something else? And does the process callback get called at each frame while
transport is rolling?

process_callback() calls process_midi_output(), wherein we find:
port_buffer = jack_port_get_buffer(output_port, nframes);
Why the nframes parameter? Is there a separate buffer area for each frame?

A little later in the same function we have:
last_frame_time = jack_last_frame_time(jack_client);
Is this the time of the end of the last process cycle?

--
7:8
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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, Paul Coccoli, (Sun Feb 17, 1:21 pm)