X-Git-Url: https://main.carlh.net/gitweb/?a=blobdiff_plain;f=libs%2Fardour%2Finterpolation.cc;h=3ba9253dee7016045c92108f2c9f1454fe2a331f;hb=9bf40bde3aed831791108bfccc4b1e10b071afdc;hp=79ec82b482099ee6c801b18ffa6c59bf99196b43;hpb=bb9cc45cd22af67ac275a5e73accbe14fee664d8;p=ardour.git diff --git a/libs/ardour/interpolation.cc b/libs/ardour/interpolation.cc index 79ec82b482..3ba9253dee 100644 --- a/libs/ardour/interpolation.cc +++ b/libs/ardour/interpolation.cc @@ -1,83 +1,227 @@ -#include +/* + Copyright (C) 2012 Paul Davis + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 2 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; if not, write to the Free Software + Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + +*/ + +#include #include +#include + #include "ardour/interpolation.h" +#include "ardour/midi_buffer.h" using namespace ARDOUR; +using std::cerr; +using std::endl; - -nframes_t -LinearInterpolation::interpolate (int channel, nframes_t nframes, Sample *input, Sample *output) +CubicInterpolation::CubicInterpolation () + : valid_z_bits (0) { - // index in the input buffers - nframes_t i = 0; +} - double acceleration; - double distance = 0.0; +samplecnt_t +CubicInterpolation::interpolate (int channel, samplecnt_t input_samples, Sample *input, samplecnt_t & output_samples, Sample *output) +{ + assert (input_samples > 0); + assert (output_samples > 0); + assert (input); + assert (output); + assert (phase.size () > channel); + + _speed = fabs (_speed); + + if (invalid (0)) { + + /* z[0] not set. Two possibilities + * + * 1) we have just been constructed or ::reset() + * + * 2) we were only given 1 sample after construction or + * ::reset, and stored it in z[1] + */ + + if (invalid (1)) { + + /* first call after construction or after ::reset */ + + switch (input_samples) { + case 1: + /* store one sample for use next time. We don't + * have enough points to interpolate or even + * compute the first z[0] value, but keep z[1] + * around. + */ + z[1] = input[0]; validate (1); + output_samples = 0; + return 0; + case 2: + /* store two samples for use next time, and + * compute a value for z[0] that will maintain + * the slope of the first actual segment. We + * still don't have enough samples to interpolate. + */ + z[0] = input[0] - (input[1] - input[0]); validate (0); + z[1] = input[0]; validate (1); + z[2] = input[1]; validate (2); + output_samples = 0; + return 0; + default: + /* We have enough samples to interpolate this time, + * but don't have a valid z[0] value because this is the + * first call after construction or ::reset. + * + * First point is based on a requirement to maintain + * the slope of the first actual segment + */ + z[0] = input[0] - (input[1] - input[0]); validate (0); + break; + } + } else { + + /* at least one call since construction or + * after::reset, since we have z[1] set + * + * we can now compute z[0] as required + */ + + z[0] = z[1] - (input[0] - z[1]); validate (0); + + /* we'll check the number of samples we've been given + in the next switch() statement below, and either + just save some more samples or actual interpolate + */ + } - if (_speed != _target_speed) { - acceleration = _target_speed - _speed; - } else { - acceleration = 0.0; + assert (is_valid (0)); } - distance = phase[channel]; - for (nframes_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++; + switch (input_samples) { + case 1: + /* one more sample of input. find the right vX to store + it in, and decide if we're ready to interpolate + */ + if (invalid (1)) { + z[1] = input[0]; validate (1); + /* still not ready to interpolate */ + output_samples = 0; + return 0; + } else if (invalid (2)) { + /* still not ready to interpolate */ + z[2] = input[0]; validate (2); + output_samples = 0; + return 0; + } else if (invalid (3)) { + z[3] = input[0]; validate (3); + /* ready to interpolate */ } - - if (input && output) { - // Linearly interpolate into the output buffer - output[outsample] = - input[i] * (1.0f - fractional_phase_part) + - input[i+1] * fractional_phase_part; + break; + case 2: + /* two more samples of input. find the right vX to store + them in, and decide if we're ready to interpolate + */ + if (invalid (1)) { + z[1] = input[0]; validate (1); + z[2] = input[1]; validate (2); + /* still not ready to interpolate */ + output_samples = 0; + return 0; + } else if (invalid (2)) { + z[2] = input[0]; validate (2); + z[3] = input[1]; validate (3); + /* ready to interpolate */ + } else if (invalid (3)) { + z[3] = input[0]; validate (3); + /* ready to interpolate */ } - distance += _speed + acceleration; + break; + + default: + /* caller has given us at least enough samples to interpolate a + single value. + */ + z[1] = input[0]; validate (1); + z[2] = input[1]; validate (2); + z[3] = input[2]; validate (3); } - i = floor(distance); - phase[channel] = distance - floor(distance); + /* ready to interpolate using z[0], z[1], z[2] and z[3] */ + + assert (is_valid (0)); + assert (is_valid (1)); + assert (is_valid (2)); + assert (is_valid (3)); + + /* we can use up to (input_samples - 2) of the input, so compute the + * maximum number of output samples that represents. + * + * Remember that the expected common case here is to be given + * input_samples that is substantially larger than output_samples, + * thus allowing us to always compute output_samples in one call. + */ - return i; + const samplecnt_t output_from_input = floor ((input_samples - 2) / _speed); + + /* limit output to either the caller's requested number or the number + * determined by the input size. + */ + + const samplecnt_t limit = std::min (output_samples, output_from_input); + + samplecnt_t outsample = 0; + double distance = phase[channel]; + samplecnt_t used = floor (distance); + samplecnt_t i = 0; + + while (outsample < limit) { + + i = floor (distance); + + /* this call may stop the loop from being vectorized */ + float fractional_phase_part = fmod (distance, 1.0); + + /* Cubically interpolate into the output buffer */ + output[outsample++] = z[1] + 0.5f * fractional_phase_part * + (z[2] - z[0] + fractional_phase_part * (4.0f * z[2] + 2.0f * z[0] - 5.0f * z[1] - z[3] + + fractional_phase_part * (3.0f * (z[1] - z[2]) - z[0] + z[3]))); + + distance += _speed; + + z[0] = z[1]; + z[1] = input[i]; + z[2] = input[i+1]; + z[3] = input[i+2]; + } + + output_samples = outsample; + phase[channel] = fmod (distance, 1.0); + return i - used; +} + +void +CubicInterpolation::reset () +{ + Interpolation::reset (); + valid_z_bits = 0; } -nframes_t -CubicInterpolation::interpolate (int channel, nframes_t nframes, Sample *input, Sample *output) +samplecnt_t +CubicInterpolation::distance (samplecnt_t nsamples) { - // 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; - } - - distance = phase[channel]; - for (nframes_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) { - // Cubically interpolate into the output buffer - output[outsample] = cube_interp(fractional_phase_part, input[i-1], input[i], input[i+1], input[i+2]); - } - distance += _speed + acceleration; - } - - i = floor(distance); - phase[channel] = distance - floor(distance); - - return i; + assert (phase.size () > 0); + return floor (floor (phase[0]) + (_speed * nsamples)); }