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authorHans Baier <hansfbaier@googlemail.com>2009-06-10 00:03:47 +0000
committerHans Baier <hansfbaier@googlemail.com>2009-06-10 00:03:47 +0000
commit43340cd37ce91752f80b776d905e1b0d103c89ef (patch)
treea4aa17688238e96d686ba7435e88eccfa4000ff9 /libs/ardour/interpolation.cc
parentf284d28d5306114e9badc9077835683e541420e0 (diff)
* Refactor varispeed playback into own class, replace fixed-point arithmetic by double, fix unit tests for libardour
git-svn-id: svn://localhost/ardour2/branches/3.0@5145 d708f5d6-7413-0410-9779-e7cbd77b26cf
Diffstat (limited to 'libs/ardour/interpolation.cc')
-rw-r--r--libs/ardour/interpolation.cc46
1 files changed, 22 insertions, 24 deletions
diff --git a/libs/ardour/interpolation.cc b/libs/ardour/interpolation.cc
index 7aece6453c..066507283b 100644
--- a/libs/ardour/interpolation.cc
+++ b/libs/ardour/interpolation.cc
@@ -1,43 +1,41 @@
#include <stdint.h>
#include "ardour/interpolation.h"
+using namespace ARDOUR;
+
nframes_t
LinearInterpolation::interpolate (nframes_t nframes, Sample *input, Sample *output)
{
- // the idea behind phase is that when the speed is not 1.0, we have to
+ // the idea is that when the speed is not 1.0, we have to
// interpolate between samples and then we have to store where we thought we were.
// rather than being at sample N or N+1, we were at N+0.8792922
- // so the "phase" element, if you want to think about this way,
- // varies from 0 to 1, representing the "offset" between samples
- uint64_t phase = last_phase;
-
- // acceleration
- int64_t phi_delta;
-
- // phi = fixed point speed
- if (phi != target_phi) {
- phi_delta = ((int64_t)(target_phi - phi)) / nframes;
- } else {
- phi_delta = 0;
- }
// index in the input buffers
nframes_t i = 0;
+
+ double acceleration;
+ double distance = 0.0;
+
+ if (_speed != _target_speed) {
+ acceleration = _target_speed - _speed;
+ } else {
+ acceleration = 0.0;
+ }
for (nframes_t outsample = 0; outsample < nframes; ++outsample) {
- i = phase >> 24;
- Sample fractional_phase_part = (phase & fractional_part_mask) / binary_scaling_factor;
+ i = distance;
+ Sample fractional_phase_part = distance - i;
- // Linearly interpolate into the output buffer
- // using fixed point math
- output[outsample] =
- input[i] * (1.0f - fractional_phase_part) +
- input[i+1] * fractional_phase_part;
- phase += phi + phi_delta;
+ if (input && output) {
+ // Linearly interpolate into the output buffer
+ output[outsample] =
+ input[i] * (1.0f - fractional_phase_part) +
+ input[i+1] * fractional_phase_part;
+ }
+ distance += _speed + acceleration;
}
-
- last_phase = (phase & fractional_part_mask);
+ i = (distance + 0.5L);
// playback distance
return i;
}