example-clients/midiseq.c

/*
    Copyright (C) 2004 Ian Esten
    
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include <jack/jack.h>
#include <jack/midiport.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

jack_client_t *client;
jack_port_t *output_port;

unsigned char* note_frqs;
jack_nframes_t* note_starts;
jack_nframes_t* note_lengths;
jack_nframes_t num_notes;
jack_nframes_t loop_nsamp;
jack_nframes_t loop_index;

void usage()
{
	fprintf(stderr, "usage: jack_midiseq name nsamp [startindex note nsamp] ...... [startindex note nsamp]\n");
	fprintf(stderr, "eg: jack_midiseq Sequencer 24000 0 60 8000 12000 63 8000\n");
	fprintf(stderr, "will play a 1/2 sec loop (if srate is 48khz) with a c4 note at the start of the loop\n");
	fprintf(stderr, "that lasts for 12000 samples, then a d4# that starts at 1/4 sec that lasts for 800 samples\n");
}

int process(jack_nframes_t nframes, void *arg)
{
	int i,j;
	void* port_buf = jack_port_get_buffer(output_port, nframes);
	unsigned char* buffer;
	jack_midi_clear_buffer(port_buf);
	/*memset(buffer, 0, nframes*sizeof(jack_default_audio_sample_t));*/

	for(i=0; i<nframes; i++)
	{
		for(j=0; j<num_notes; j++)
		{
			if(note_starts[j] == loop_index)
			{
				buffer = jack_midi_event_reserve(port_buf, i, 3);
/*				printf("wrote a note on, port buffer = 0x%x, event buffer = 0x%x\n", port_buf, buffer);*/
				buffer[2] = 64;		/* velocity */
				buffer[1] = note_frqs[j];
				buffer[0] = 0x90;	/* note on */
			}
			else if(note_starts[j] + note_lengths[j] == loop_index)
			{
				buffer = jack_midi_event_reserve(port_buf, i, 3);
/*				printf("wrote a note off, port buffer = 0x%x, event buffer = 0x%x\n", port_buf, buffer);*/
				buffer[2] = 64;		/* velocity */
				buffer[1] = note_frqs[j];
				buffer[0] = 0x80;	/* note off */
			}
		}
		loop_index = loop_index+1 >= loop_nsamp ? 0 : loop_index+1;
	}
	return 0;
}

int main(int narg, char **args)
{
	int i;
	jack_nframes_t nframes;
	if((narg<6) || ((narg-3)%3 !=0))
	{
		usage();
		exit(1);
	}
	if((client = jack_client_open (args[1], JackNullOption, NULL)) == 0)
	{
		fprintf (stderr, "jack server not running?\n");
		return 1;
	}
	jack_set_process_callback (client, process, 0);
	output_port = jack_port_register (client, "out", JACK_DEFAULT_MIDI_TYPE, JackPortIsOutput, 0);
	nframes = jack_get_buffer_size(client);
	loop_index = 0;
	num_notes = (narg - 3)/3;
	note_frqs = malloc(num_notes*sizeof(unsigned char));
	note_starts = malloc(num_notes*sizeof(jack_nframes_t));
	note_lengths = malloc(num_notes*sizeof(jack_nframes_t));
	loop_nsamp = atoi(args[2]);
	for(i=0; i<num_notes; i++)
	{
		note_starts[i] = atoi(args[3 + 3*i]);
		note_frqs[i] = atoi(args[4 + 3*i]);
		note_lengths[i] = atoi(args[5 + 3*i]);
	}

	if (jack_activate(client))
	{
		fprintf (stderr, "cannot activate client");
		return 1;
	}

	while (1)
	{
		sleep(1);
	};
	
}