X-Git-Url: https://main.carlh.net/gitweb/?a=blobdiff_plain;f=libs%2Fardour%2Finterpolation.cc;h=286030c26db487cb8d825d0bd712119d3be9116a;hb=66163305317e8acf20c4a16b9709fc809d6a0ff9;hp=20ab584885e7f19dd6bd348c2648b5d429c08c1b;hpb=a473d630eb165272992e90f8d854b1d66ec0be63;p=ardour.git diff --git a/libs/ardour/interpolation.cc b/libs/ardour/interpolation.cc index 20ab584885..286030c26d 100644 --- a/libs/ardour/interpolation.cc +++ b/libs/ardour/interpolation.cc @@ -1,7 +1,27 @@ +/* + 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; @@ -10,127 +30,161 @@ framecnt_t LinearInterpolation::interpolate (int channel, framecnt_t nframes, Sample *input, Sample *output) { // index in the input buffers - framecnt_t i = 0; + framecnt_t i = 0; - double acceleration; - double distance = 0.0; + double acceleration = 0; if (_speed != _target_speed) { acceleration = _target_speed - _speed; - } else { - acceleration = 0.0; } - distance = phase[channel]; for (framecnt_t outsample = 0; outsample < nframes; ++outsample) { - i = floor(distance); - Sample fractional_phase_part = distance - i; + 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 + // 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; + // 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; + } - double acceleration; - double distance = 0.0; + /* keep this condition out of the inner loop */ - if (_speed != _target_speed) { - acceleration = _target_speed - _speed; - } else { - acceleration = 0.0; - } + if (input && output) { - distance = phase[channel]; + Sample inm1; - if (nframes < 3) { - /* no interpolation possible */ + 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 (i = 0; i < nframes; ++i) { - output[i] = input[i]; - } + for (framecnt_t outsample = 0; outsample < nframes; ++outsample) { - return nframes; - } + float f = floor (distance); + float fractional_phase_part = distance - f; - /* keep this condition out of the inner loop */ + /* get the index into the input we should start with */ - if (input && output) { + i = lrintf (f); - Sample inm1; + /* 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 (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]; - } + if (fractional_phase_part >= 1.0) { + fractional_phase_part -= 1.0; + ++i; + } - for (framecnt_t outsample = 0; outsample < nframes; ++outsample) { + // 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) - float f = floor (distance); - float fractional_phase_part = distance - f; + 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]))); - /* get the index into the input we should start with */ + distance += _speed + acceleration; + inm1 = input[i]; + } - i = lrintf (f); + i = floor(distance); + phase[channel] = distance - floor(distance); - /* 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 ... - */ + } 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; +} + +framecnt_t +CubicMidiInterpolation::distance (framecnt_t nframes, bool roll) +{ + assert(phase.size() == 1); - if (fractional_phase_part >= 1.0) { - fractional_phase_part -= 1.0; - ++i; - } + framecnt_t i = 0; - // 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) + double acceleration; + double distance = 0.0; - 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]))); + if (nframes < 3) { + return nframes; + } - distance += _speed + acceleration; - inm1 = input[i]; - } + if (_speed != _target_speed) { + acceleration = _target_speed - _speed; + } else { + acceleration = 0.0; + } - } else { + distance = phase[0]; - /* 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; + } - for (framecnt_t outsample = 0; outsample < nframes; ++outsample) { - distance += _speed + acceleration; - } - } + if (roll) { + phase[0] = distance - floor(distance); + } - i = floor(distance); - phase[channel] = distance - floor(distance); + i = floor(distance); - return i; + return i; }