nframes_t pos = 0;
int avail = 0;
- // note: this_time_fraction is a ratio of original length. 1.0 = no change,
- // 0.5 is half as long, 2.0 is twice as long, etc.
+ cerr << "RBEffect: source region: position = " << region->position()
+ << ", start = " << region->start()
+ << ", length = " << region->length()
+ << ", ancestral_start = " << region->ancestral_start()
+ << ", ancestral_length = " << region->ancestral_length()
+ << ", stretch " << region->stretch()
+ << ", shift " << region->shift() << endl;
+
+ /*
+ We have two cases to consider:
+
+ 1. The region has not been stretched before.
+
+ In this case, we just want to read region->length() frames
+ from region->start().
+
+ We will create a new region of region->length() *
+ tsr.time_fraction frames. The new region will have its
+ start set to 0 (because it has a new audio file that begins
+ at the start of the stretched area) and its ancestral_start
+ set to region->start() (so that we know where to begin
+ reading if we want to stretch it again).
+
+ 2. The region has been stretched before.
+
+ The region starts at region->start() frames into its
+ (possibly previously stretched) source file. But we don't
+ want to read from its source file; we want to read from the
+ file it was originally stretched from.
+
+ The region's source begins at region->ancestral_start()
+ frames into its master source file. Thus, we need to start
+ reading at region->ancestral_start() + (region->start() /
+ region->stretch()) frames into the master source. This
+ value will also become the ancestral_start for the new
+ region.
+
+ We cannot use region->ancestral_length() to establish how
+ many frames to read, because it won't be up to date if the
+ region has been trimmed since it was last stretched. We
+ must read region->length() / region->stretch() frames and
+ stretch them by tsr.time_fraction * region->stretch(), for
+ a new region of region->length() * tsr.time_fraction
+ frames.
+
+ Case 1 is of course a special case of 2, where
+ region->ancestral_start() == 0 and region->stretch() == 1.
+
+ When we ask to read from a region, we supply a position on
+ the global timeline. The read function calculates the
+ offset into the source as (position - region->position()) +
+ region->start(). This calculation is used regardless of
+ whether we are reading from a master or
+ previously-stretched region. In order to read from a point
+ n frames into the master source, we need to provide n -
+ region->start() + region->position() as our position
+ argument to master_read_at().
+
+ Note that region->ancestral_length() is not used.
+
+ I hope this is clear.
+ */
+
+ double stretch = region->stretch() * tsr.time_fraction;
+ double shift = region->shift() * tsr.pitch_fraction;
+
+ nframes_t read_start = region->ancestral_start() +
+ nframes_t(region->start() / (double)region->stretch());
- double this_time_fraction = tsr.time_fraction * region->stretch ();
- double this_pitch_fraction = tsr.pitch_fraction * region->shift ();
+ nframes_t read_duration =
+ nframes_t(region->length() / (double)region->stretch());
- RubberBandStretcher stretcher (session.frame_rate(), region->n_channels(),
- (RubberBandStretcher::Options) tsr.opts,
- this_time_fraction, this_pitch_fraction);
+ uint32_t channels = region->n_channels();
+
+ RubberBandStretcher stretcher
+ (session.frame_rate(), channels,
+ (RubberBandStretcher::Options) tsr.opts, stretch, shift);
tsr.progress = 0.0f;
tsr.done = false;
- uint32_t channels = region->n_channels();
- nframes_t duration = region->ancestral_length();
-
- stretcher.setExpectedInputDuration(duration);
+ stretcher.setExpectedInputDuration(read_duration);
stretcher.setDebugLevel(1);
/* the name doesn't need to be super-precise, but allow for 2 fractional
digits just to disambiguate close but not identical FX
*/
- if (this_time_fraction == 1.0) {
- snprintf (suffix, sizeof (suffix), "@%d", (int) floor (this_pitch_fraction * 100.0f));
- } else if (this_pitch_fraction == 1.0) {
- snprintf (suffix, sizeof (suffix), "@%d", (int) floor (this_time_fraction * 100.0f));
+ if (stretch == 1.0) {
+ snprintf (suffix, sizeof (suffix), "@%d", (int) floor (shift * 100.0f));
+ } else if (shift == 1.0) {
+ snprintf (suffix, sizeof (suffix), "@%d", (int) floor (stretch * 100.0f));
} else {
snprintf (suffix, sizeof (suffix), "@%d-%d",
- (int) floor (this_time_fraction * 100.0f),
- (int) floor (this_pitch_fraction * 100.0f));
+ (int) floor (stretch * 100.0f),
+ (int) floor (shift * 100.0f));
}
/* create new sources */
done = 0;
try {
- while (pos < duration && !tsr.cancel) {
+ while (pos < read_duration && !tsr.cancel) {
nframes_t this_read = 0;
for (uint32_t i = 0; i < channels; ++i) {
this_read = 0;
+
nframes_t this_time;
+ this_time = min(bufsize, read_duration - pos);
- this_time = min(bufsize, duration - pos);
-
+ nframes_t this_position;
+ this_position = read_start + pos -
+ region->start() + region->position();
+
this_read = region->master_read_at
(buffers[i],
buffers[i],
gain_buffer,
- pos + region->position(),
+ this_position,
this_time,
i);
pos += this_read;
done += this_read;
- tsr.progress = ((float) done / duration) * 0.25;
+ tsr.progress = ((float) done / read_duration) * 0.25;
- stretcher.study(buffers, this_read, pos == duration);
+ stretcher.study(buffers, this_read, pos == read_duration);
}
done = 0;
pos = 0;
- while (pos < duration && !tsr.cancel) {
+ while (pos < read_duration && !tsr.cancel) {
nframes_t this_read = 0;
this_read = 0;
nframes_t this_time;
-
- this_time = min(bufsize, duration - pos);
+ this_time = min(bufsize, read_duration - pos);
+
+ nframes_t this_position;
+ this_position = read_start + pos -
+ region->start() + region->position();
this_read = region->master_read_at
(buffers[i],
buffers[i],
gain_buffer,
- pos + region->position(),
+ this_position,
this_time,
i);
pos += this_read;
done += this_read;
- tsr.progress = 0.25 + ((float) done / duration) * 0.75;
+ tsr.progress = 0.25 + ((float) done / read_duration) * 0.75;
- stretcher.process(buffers, this_read, pos == duration);
+ stretcher.process(buffers, this_read, pos == read_duration);
int avail = 0;
for (vector<boost::shared_ptr<AudioRegion> >::iterator x = results.begin(); x != results.end(); ++x) {
- (*x)->set_ancestral_data (region->ancestral_start(),
- region->ancestral_length(),
- this_time_fraction,
- this_pitch_fraction );
+ (*x)->set_ancestral_data (read_start,
+ read_duration,
+ stretch,
+ shift);
(*x)->set_master_sources (region->get_master_sources());
}
projects / ardour.git / commitdiff