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

M Donalies ingeniousnebbish at cox.net
Mon Feb 18 13:35:32 UTC 2013


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> 
wrote:
> > 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) ?

> > 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?
> 
> Not sure about this one.  The docs say: "the precise time at the start
> of the current process cycle" which should be the same time as the
> start of the current process cycle, I would think.

Oh, I get it. I was reading "last" as "previous" as in currentCycle - 1.

-- 
7:8


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