X-Git-Url: https://main.carlh.net/gitweb/?a=blobdiff_plain;f=libs%2Fardour%2Finterpolation.cc;h=286030c26db487cb8d825d0bd712119d3be9116a;hb=4bdbe77414b956e27f2c1631e67189c70409a3d1;hp=9a45d560c0b0ef5813dba8bd3e0f79a50816ff23;hpb=16b964020fdf9deda6262e7dd9048e36acc0912e;p=ardour.git diff --git a/libs/ardour/interpolation.cc b/libs/ardour/interpolation.cc index 9a45d560c0..286030c26d 100644 --- a/libs/ardour/interpolation.cc +++ b/libs/ardour/interpolation.cc @@ -1,83 +1,190 @@ +/* + 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 "ardour/interpolation.h" +#include "ardour/midi_buffer.h" using namespace ARDOUR; -nframes_t -LinearInterpolation::interpolate (int channel, nframes_t nframes, Sample *input, Sample *output) +framecnt_t +LinearInterpolation::interpolate (int channel, framecnt_t nframes, Sample *input, Sample *output) { // index in the input buffers - nframes_t i = 0; - - double acceleration; - double distance = 0.0; - + framecnt_t i = 0; + + double acceleration = 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; + + for (framecnt_t outsample = 0; outsample < nframes; ++outsample) { + double const d = phase[channel] + outsample * (_speed + acceleration); + i = floor(d); + Sample fractional_phase_part = d - i; if (fractional_phase_part >= 1.0) { fractional_phase_part -= 1.0; i++; } - + if (input && output) { - // Linearly interpolate into the output buffer - output[outsample] = + // Linearly interpolate into the output buffer + output[outsample] = input[i] * (1.0f - fractional_phase_part) + input[i+1] * fractional_phase_part; } - distance += _speed + acceleration; } - + + double const distance = phase[channel] + nframes * (_speed + acceleration); i = floor(distance); - phase[channel] = distance - floor(distance); - + phase[channel] = distance - i; + return i; +} + +framecnt_t +CubicInterpolation::interpolate (int channel, framecnt_t nframes, Sample *input, Sample *output) +{ + // index in the input buffers + framecnt_t i = 0; + + 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 */ + + if (input && output) { + 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]; + } + + i = floor(distance); + phase[channel] = distance - floor(distance); + + } else { + /* used to calculate play-distance with acceleration (silent roll) + * (use same algorithm as real playback for identical rounding/floor'ing) + */ + for (framecnt_t outsample = 0; outsample < nframes; ++outsample) { + distance += _speed + acceleration; + } + i = floor(distance); + } + return i; } -nframes_t -CubicInterpolation::interpolate (int channel, nframes_t nframes, Sample *input, Sample *output) +framecnt_t +CubicMidiInterpolation::distance (framecnt_t nframes, bool roll) { - // 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() == 1); + + framecnt_t i = 0; + + double acceleration; + double distance = 0.0; + + if (nframes < 3) { + return nframes; + } + + if (_speed != _target_speed) { + acceleration = _target_speed - _speed; + } else { + acceleration = 0.0; + } + + distance = phase[0]; + + for (framecnt_t outsample = 0; outsample < nframes; ++outsample) { + distance += _speed + acceleration; + } + + if (roll) { + phase[0] = distance - floor(distance); + } + + i = floor(distance); + + return i; }