#include <stdint.h>
+#include <cstdio>
#include "ardour/interpolation.h"
using namespace ARDOUR;
-LibSamplerateInterpolation::LibSamplerateInterpolation() : _speed (1.0L), state (0)
-{
-}
-LibSamplerateInterpolation::~LibSamplerateInterpolation()
+framecnt_t
+LinearInterpolation::interpolate (int channel, framecnt_t nframes, Sample *input, Sample *output)
{
- for (int i = 0; i < state.size(); i++) {
- state[i] = src_delete (state[i]);
- }
-}
+ // index in the input buffers
+ framecnt_t i = 0;
+
+ double acceleration;
+ double distance = 0.0;
-void
-LibSamplerateInterpolation::set_speed (double new_speed)
-{
- _speed = new_speed;
- for (int i = 0; i < state.size(); i++) {
- src_set_ratio (state[i], 1.0/_speed);
+ if (_speed != _target_speed) {
+ acceleration = _target_speed - _speed;
+ } else {
+ acceleration = 0.0;
}
-}
-void
-LibSamplerateInterpolation::reset_state ()
-{
- printf("INTERPOLATION: reset_state()\n");
- for (int i = 0; i < state.size(); i++) {
- if (state[i]) {
- src_reset (state[i]);
- } else {
- state[i] = src_new (SRC_SINC_FASTEST, 1, &error);
+ distance = phase[channel];
+ for (framecnt_t outsample = 0; outsample < nframes; ++outsample) {
+ i = floor(distance);
+ Sample fractional_phase_part = distance - i;
+ if (fractional_phase_part >= 1.0) {
+ fractional_phase_part -= 1.0;
+ i++;
}
+
+ 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;
}
-}
-void
-LibSamplerateInterpolation::add_channel_to (int input_buffer_size, int output_buffer_size)
-{
- SRC_DATA* newdata = new SRC_DATA;
-
- /* Set up sample rate converter info. */
- newdata->end_of_input = 0 ;
-
- newdata->input_frames = input_buffer_size;
- newdata->output_frames = output_buffer_size;
-
- newdata->input_frames_used = 0 ;
- newdata->output_frames_gen = 0 ;
-
- newdata->src_ratio = 1.0/_speed;
-
- data.push_back (newdata);
- state.push_back (0);
-
- reset_state ();
+ i = floor(distance);
+ phase[channel] = distance - floor(distance);
+
+ return i;
}
-void
-LibSamplerateInterpolation::remove_channel_from ()
+framecnt_t
+CubicInterpolation::interpolate (int channel, framecnt_t nframes, Sample *input, Sample *output)
{
- delete data.back ();
- data.pop_back ();
- delete state.back ();
- state.pop_back ();
- reset_state ();
-}
+ // index in the input buffers
+ framecnt_t i = 0;
-nframes_t
-LibSamplerateInterpolation::interpolate (int channel, nframes_t nframes, Sample *input, Sample *output)
-{
- if (!data.size ()) {
- printf ("ERROR: trying to interpolate with no channels\n");
- return 0;
- }
-
- data[channel]->data_in = input;
- data[channel]->data_out = output;
-
- data[channel]->input_frames = nframes * _speed;
- data[channel]->output_frames = nframes;
- data[channel]->src_ratio = 1.0/_speed;
-
- if ((error = src_process (state[channel], data[channel]))) {
- printf ("\nError : %s\n\n", src_strerror (error));
- exit (1);
- }
-
- //printf("INTERPOLATION: channel %d input_frames_used: %d\n", channel, data[channel]->input_frames_used);
-
- return data[channel]->input_frames_used;
+ double acceleration;
+ double distance = 0.0;
+
+ if (_speed != _target_speed) {
+ acceleration = _target_speed - _speed;
+ } else {
+ acceleration = 0.0;
+ }
+
+ distance = phase[channel];
+
+ if (nframes < 3) {
+ /* no interpolation possible */
+
+ for (i = 0; i < nframes; ++i) {
+ output[i] = input[i];
+ }
+
+ return nframes;
+ }
+
+ /* keep this condition out of the inner loop */
+
+ if (input && output) {
+
+ Sample inm1;
+
+ if (floor (distance) == 0.0) {
+ /* best guess for the fake point we have to add to be able to interpolate at i == 0:
+ .... maintain slope of first actual segment ...
+ */
+ inm1 = input[i] - (input[i+1] - input[i]);
+ } else {
+ inm1 = input[i-1];
+ }
+
+ for (framecnt_t outsample = 0; outsample < nframes; ++outsample) {
+
+ float f = floor (distance);
+ float fractional_phase_part = distance - f;
+
+ /* get the index into the input we should start with */
+
+ i = lrintf (f);
+
+ /* fractional_phase_part only reaches 1.0 thanks to float imprecision. In theory
+ it should always be < 1.0. If it ever >= 1.0, then bump the index we use
+ and back it off. This is the point where we "skip" an entire sample in the
+ input, because the phase part has accumulated so much error that we should
+ really be closer to the next sample. or something like that ...
+ */
+
+ if (fractional_phase_part >= 1.0) {
+ fractional_phase_part -= 1.0;
+ ++i;
+ }
+
+ // Cubically interpolate into the output buffer: keep this inlined for speed and rely on compiler
+ // optimization to take care of the rest
+ // shamelessly ripped from Steve Harris' swh-plugins (ladspa-util.h)
+
+ output[outsample] = input[i] + 0.5f * fractional_phase_part * (input[i+1] - inm1 +
+ fractional_phase_part * (4.0f * input[i+1] + 2.0f * inm1 - 5.0f * input[i] - input[i+2] +
+ fractional_phase_part * (3.0f * (input[i] - input[i+1]) - inm1 + input[i+2])));
+
+ distance += _speed + acceleration;
+ inm1 = input[i];
+ }
+
+ } else {
+
+ /* not sure that this is ever utilized - it implies that one of the input/output buffers is missing */
+
+ for (framecnt_t outsample = 0; outsample < nframes; ++outsample) {
+ distance += _speed + acceleration;
+ }
+ }
+
+ i = floor(distance);
+ phase[channel] = distance - floor(distance);
+
+ return i;
}
projects / ardour.git / blobdiff