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triggerbox: given no other info, assume a clip is 1,2,4,8 or 16 bars at 4/4 

this solves the oft-recurring problem where we assign
 a beat-count of '3' or '7' because minipm  mis-detected the tempo,
 and that situation is vanishingly rare.  it's better to assume 4 or 8

the user always has the option to change the number of beats (and
 therefore the detected tempo) manually, for those clips that are
 in a different time signature.  but minibpm cannot be expected
 to help us there.

NOTE: this is a fallback to make things 'just work' lacking any other context.

* if the tempo is detected in the filename, we use that instead
* clips that were recorded to the timeline use that bpm+timesig
* in the future we can use file-metadata (acidized wave?) instead
* this is audio-only: midi files can have an embedded timesignature

but... given no other information, experience says the vast majority
of downloaded/purchased clips will be 1,2 or 4 bars at 4/4.
This commit is contained in:
Ben Loftis 2022-05-14 14:12:24 -05:00
parent be5c64f737
commit 0cfbc64e54
1 changed files with 18 additions and 10 deletions
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28
libs/ardour/triggerbox.cc
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@ -1612,18 +1612,10 @@ AudioTrigger::estimate_tempo ()
}
}
/* We don't have too many good choices here. Triggers can fire at any
* time, so there's no special place on the tempo map that we can use
* to get the meter from and thus compute an estimated bar count for
* this region. Our solution for now: just use the first meter.
*/
if (text_tempo < 0) {
breakfastquay::MiniBPM mbpm (_box.session().sample_rate());
mbpm.setBPMRange (metric.tempo().quarter_notes_per_minute () * 0.75, metric.tempo().quarter_notes_per_minute() * 1.5);
_estimated_tempo = mbpm.estimateTempoOfSamples (data[0], data.length);
//cerr << name() << "MiniBPM Estimated: " << _estimated_tempo << " bpm from " << (double) data.length / _box.session().sample_rate() << " seconds\n";
@ -1642,6 +1634,24 @@ AudioTrigger::estimate_tempo ()
/* fractional beatcnt */
double maybe_beats = (seconds / 60.) * _estimated_tempo;
double beatcount = round (maybe_beats);
/* the vast majority of third-party clips are 1,2,4,8, or 16-bar 'beats'.
* Given no other metadata, it makes things 'just work' if we assume 4/4 time signature, and power-of-2 bars (1,2,4,8 or 16)
* TODO: someday we could provide a widget for users who have unlabeled, un-metadata'd, clips that they *know* are 3/4 or 5/4 or 11/4 */
{
double barcount = round (beatcount/4);
if (barcount <= 18) { /* why not 16 here? fuzzy logic allows minibpm to misjudge the clip a bit */
for (int pwr = 0; pwr <= 4; pwr++) {
float bc = pow(2,pwr);
if (barcount <= bc) {
barcount = bc;
break;
}
}
}
beatcount = round(barcount * 4);
}
double est = _estimated_tempo;
_estimated_tempo = beatcount / (seconds/60.);
DEBUG_TRACE (DEBUG::Triggers, string_compose ("given original estimated tempo %1, rounded beatcnt is %2 : resulting in working bpm = %3\n", est, _beatcnt, _estimated_tempo));
@ -1650,8 +1660,6 @@ AudioTrigger::estimate_tempo ()
set_follow_length(Temporal::BBT_Offset( 0, rint(beatcount), 0));
}
/* use initial tempo in map (assumed for now to be the only one */
#if 0
cerr << "estimated tempo: " << _estimated_tempo << endl;
const samplecnt_t one_beat = tm->bbt_duration_at (timepos_t (AudioTime), BBT_Offset (0, 1, 0)).samples();