[LAD] Deciphering jack-smf-utils -- Jack MIDI stuff
paul at linuxaudiosystems.com
Mon Feb 18 13:33:16 UTC 2013
On Mon, Feb 18, 2013 at 8:35 AM, M Donalies <ingeniousnebbish at cox.net>wrote:
> On Sunday 17 February 2013 08:21:51 Paul Coccoli wrote:
> > On Sat, Feb 16, 2013 at 10:33 PM, M Donalies <ingeniousnebbish at cox.net>
> > > 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?
> > There's a separate buffer for each port.
> Yes, and that's the output_port arg, but what's with nframes? Why isn't the
> function simply: jack_port_get_buffer(output_port) ?
because the client may not want to get all the data at once.
ardour, for example, breaks up the process() cycle internally to deal with
"global" scheduled events. so it may ask for the first N frames, then
another M, then another P frames until everything is done.
there was another reason at one time too, but the internally engineering of
JACK has eliminated that one.
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