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

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