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Slightly simpler implementation of framewalk_to_beats.

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git-svn-id: svn://localhost/ardour2/branches/3.0@10967 d708f5d6-7413-0410-9779-e7cbd77b26cf
This commit is contained in:
Carl Hetherington
2011-12-10 16:06:29 +00:00
parent 6b27595c4e
commit 6e211e27e2
2 changed files with 30 additions and 83 deletions
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2
libs/ardour/ardour/tempo.h
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@@ -249,7 +249,7 @@ class TempoMap : public PBD::StatefulDestructible
framepos_t framepos_plus_bbt (framepos_t pos, Timecode::BBT_Time b) const;
framepos_t framepos_plus_beats (framepos_t, Evoral::MusicalTime) const;
double framewalk_to_beats (framepos_t pos, framecnt_t distance) const;
Evoral::MusicalTime framewalk_to_beats (framepos_t pos, framecnt_t distance) const;
void change_existing_tempo_at (framepos_t, double bpm, double note_type);
void change_initial_tempo (double bpm, double note_type);

111
libs/ardour/tempo.cc
View File

@@ -2135,29 +2135,15 @@ TempoMap::framepos_plus_bbt (framepos_t pos, BBT_Time op) const
return pos;
}
/** Count the number of beats that are equivalent to distance when starting at pos */
double
Evoral::MusicalTime
TempoMap::framewalk_to_beats (framepos_t pos, framecnt_t distance) const
{
Metrics::const_iterator i;
double beats = 0;
const MeterSection* meter;
const MeterSection* m;
const TempoSection* tempo;
const TempoSection* t;
double frames_per_beat;
double ddist = distance;
double dpos = pos;
meter = &first_meter ();
tempo = &first_tempo ();
assert (meter);
assert (tempo);
/* find the starting metrics for tempo & meter */
const MeterSection* meter;
/* Find the starting metrics for tempo & meter */
for (i = metrics->begin(); i != metrics->end(); ++i) {
@@ -2165,6 +2151,9 @@ TempoMap::framewalk_to_beats (framepos_t pos, framecnt_t distance) const
break;
}
const TempoSection* t;
const MeterSection* m;
if ((t = dynamic_cast<const TempoSection*>(*i)) != 0) {
tempo = t;
} else if ((m = dynamic_cast<const MeterSection*>(*i)) != 0) {
@@ -2179,83 +2168,41 @@ TempoMap::framewalk_to_beats (framepos_t pos, framecnt_t distance) const
i -> for first new metric after "pos", possibly metrics->end()
*/
/* now comes the complicated part. we have to add one beat a time,
checking for a new metric on every beat.
*/
Evoral::MusicalTime beats = 0;
frames_per_beat = tempo->frames_per_beat (_frame_rate, *meter);
while (distance) {
double last_dpos = 0;
/* End of this section */
framepos_t const end = i == metrics->end() ? max_framepos : (*i)->frame ();
while (ddist > 0) {
/* Distance to the end in frames */
framecnt_t const distance_to_end = end - pos;
/* if we're nearly at the end, but have a fractional beat left,
compute the fraction and then its all over
*/
/* Amount to subtract this time */
double const sub = min (distance, distance_to_end);
if (ddist < frames_per_beat) {
beats += ddist / frames_per_beat;
break;
}
/* Update */
distance -= sub;
beats += sub / tempo->frames_per_beat (_frame_rate, *meter);
/* walk one beat */
last_dpos = dpos;
ddist -= frames_per_beat;
dpos += frames_per_beat;
beats += 1.0;
/* check if we need to use a new metric section: has adding frames moved us
to or after the start of the next metric section? in which case, use it.
*/
if (i != metrics->end()) {
double const f = (*i)->frame ();
if (f <= (framepos_t) dpos) {
/* We just went past a tempo/meter section start at (*i)->frame(),
which will be on a beat.
So what we have is
(*i)->frame() [f]
beat beat beat beat
| | | |
| | | |
^ ^
| |
| new
| dpos [q]
last
dpos [p]
We need to go back to last_dpos (1 beat ago) and re-add
(f - p) beats using the old frames per beat and (q - f) beats
using the new.
*/
beats -= 1;
beats += (f - last_dpos) / frames_per_beat;
if ((t = dynamic_cast<const TempoSection*>(*i)) != 0) {
tempo = t;
} else if ((m = dynamic_cast<const MeterSection*>(*i)) != 0) {
meter = m;
}
++i;
frames_per_beat = tempo->frames_per_beat (_frame_rate, *meter);
beats += (dpos - f) / frames_per_beat;
/* Move on if there's anything to move to */
if (i != metrics->end ()) {
const TempoSection* t;
const MeterSection* m;
if ((t = dynamic_cast<const TempoSection*>(*i)) != 0) {
tempo = t;
} else if ((m = dynamic_cast<const MeterSection*>(*i)) != 0) {
meter = m;
}
++i;
}
}
return beats;
}
/** Compare the time of this with that of another MetricSection.
* @param with_bbt True to compare using start(), false to use frame().
* @return -1 for less than, 0 for equal, 1 for greater than.