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/*
* intime.c -- JACK internal timebase master example client.
*
* To run: first start `jackd', then `jack_load intime intime 6/8,180bpm'.
*/
/* Copyright (C) 2003 Jack O'Quin.
*
* 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 <inttypes.h>
#include <stdio.h>
#include <string.h>
#include <jack/jack.h>
/* Time and tempo variables, global to the entire transport timeline.
* There is no attempt to keep a true tempo map. The default time
* signature is "march time": 4/4, 120bpm
*/
float time_beats_per_bar = 4.0;
float time_beat_type = 4.0;
double time_ticks_per_beat = 1920.0;
double time_beats_per_minute = 120.0;
/* BBT timebase callback.
*
* Runs in the process thread. Realtime, must not wait.
*/
void
timebbt (jack_transport_state_t state, jack_nframes_t nframes,
jack_position_t *pos, int new_pos, void *arg)
{
double min; /* minutes since frame 0 */
long abs_tick; /* ticks since frame 0 */
long abs_beat; /* beats since frame 0 */
if (new_pos) {
pos->valid = JackPositionBBT;
pos->beats_per_bar = time_beats_per_bar;
pos->beat_type = time_beat_type;
pos->ticks_per_beat = time_ticks_per_beat;
pos->beats_per_minute = time_beats_per_minute;
/* Compute BBT info from frame number. This is
* relatively simple here, but would become complex if
* we supported tempo or time signature changes at
* specific locations in the transport timeline. I
* make no claims for the numerical accuracy or
* efficiency of these calculations. */
min = pos->frame / ((double) pos->frame_rate * 60.0);
abs_tick = min * pos->beats_per_minute * pos->ticks_per_beat;
abs_beat = abs_tick / pos->ticks_per_beat;
pos->bar = abs_beat / pos->beats_per_bar;
pos->beat = abs_beat - (pos->bar * pos->beats_per_bar) + 1;
pos->tick = abs_tick - (abs_beat * pos->ticks_per_beat);
pos->bar_start_tick = pos->bar * pos->beats_per_bar *
pos->ticks_per_beat;
pos->bar++; /* adjust start to bar 1 */
/* some debug code... */
fprintf(stderr, "\nnew position: %" PRIu32 "\tBBT: %3"
PRIi32 "|%" PRIi32 "|%04" PRIi32 "\n",
pos->frame, pos->bar, pos->beat, pos->tick);
} else {
/* Compute BBT info based on previous period. */
pos->tick += (nframes * pos->ticks_per_beat *
pos->beats_per_minute / (pos->frame_rate * 60));
while (pos->tick >= pos->ticks_per_beat) {
pos->tick -= pos->ticks_per_beat;
if (++pos->beat > pos->beats_per_bar) {
pos->beat = 1;
++pos->bar;
pos->bar_start_tick += (pos->beats_per_bar *
pos->ticks_per_beat);
}
}
}
}
/* experimental timecode callback
*
* Fill in extended timecode fields using the trivial assumption that
* we are running at nominal speed, hence with no drift.
*
* It would probably be faster to compute frame_time without the
* conditional expression. But, this demonstrates the invariant:
* next_time[i] == frame_time[i+1], unless a reposition occurs.
*
* Runs in the process thread. Realtime, must not wait.
*/
void
timecode (jack_transport_state_t state, jack_nframes_t nframes,
jack_position_t *pos, int new_pos, void *arg)
{
/* nominal transport speed */
double seconds_per_frame = 1.0 / (double) pos->frame_rate;
pos->valid = JackPositionTimecode;
pos->frame_time = (new_pos?
pos->frame * seconds_per_frame:
pos->next_time);
pos->next_time = (pos->frame + nframes) * seconds_per_frame;
}
/* after internal client loaded */
JACK_LIB_EXPORT
int
jack_initialize (jack_client_t *client, const char *load_init)
{
JackTimebaseCallback callback = timebbt;
int rc = sscanf(load_init, " %f/%f, %lf bpm ", &time_beats_per_bar,
&time_beat_type, &time_beats_per_minute);
if (rc > 0) {
fprintf (stderr, "counting %.1f/%.1f at %.2f bpm\n",
time_beats_per_bar, time_beat_type,
time_beats_per_minute);
} else {
int len = strlen(load_init);
if ((len > 0) && (strncmp(load_init, "timecode", len) == 0))
callback = timecode;
}
if (jack_set_timebase_callback(client, 0, callback, NULL) != 0) {
fprintf (stderr, "Unable to take over timebase.\n");
return 1; /* terminate */
}
fprintf (stderr, "Internal timebase master defined.\n");
jack_activate (client);
return 0; /* success */
}
/* before unloading */
JACK_LIB_EXPORT
void
jack_finish (void *arg)
{
fprintf (stderr, "Internal timebase client exiting.\n");
}
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