X-Git-Url: https://main.carlh.net/gitweb/?a=blobdiff_plain;ds=sidebyside;f=libs%2Fardour%2Finterpolation.cc;h=9eee53cc232da7925a4961c89cecbc52e3512656;hb=1399ef391de5b05888ea2e13e6ff80f14b6e84d9;hp=be4967b521ab151fb41eadf4a69e878b7a36f584;hpb=9b2898c533686e18a8134eeba8237402f837f8f8;p=ardour.git diff --git a/libs/ardour/interpolation.cc b/libs/ardour/interpolation.cc index be4967b521..9eee53cc23 100644 --- a/libs/ardour/interpolation.cc +++ b/libs/ardour/interpolation.cc @@ -1,5 +1,5 @@ /* - Copyright (C) 2012 Paul Davis + 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 @@ -48,7 +48,7 @@ LinearInterpolation::interpolate (int channel, framecnt_t nframes, Sample *input } 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; @@ -64,107 +64,89 @@ LinearInterpolation::interpolate (int channel, framecnt_t nframes, Sample *input 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) { + // index in the input buffers + framecnt_t i = 0; - Sample inm1; + double acceleration; + double distance = phase[channel]; - 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 (_speed != _target_speed) { + acceleration = _target_speed - _speed; + } else { + acceleration = 0.0; + } - for (framecnt_t outsample = 0; outsample < nframes; ++outsample) { + if (nframes < 3) { + /* no interpolation possible */ - float f = floor (distance); - float fractional_phase_part = distance - f; + if (input && output) { + for (i = 0; i < nframes; ++i) { + output[i] = input[i]; + } + } - /* get the index into the input we should start with */ + phase[channel] = 0; + return nframes; + } - i = lrintf (f); + /* keep this condition out of the inner loop */ - /* 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 (input && output) { + /* best guess for the fake point we have to add to be able to interpolate at i == 0: + * .... maintain slope of first actual segment ... + */ + Sample inm1 = input[i] - (input[i+1] - input[i]); - if (fractional_phase_part >= 1.0) { - fractional_phase_part -= 1.0; - ++i; - } + for (framecnt_t outsample = 0; outsample < nframes; ++outsample) { + /* get the index into the input we should start with */ + i = floor (distance); + float fractional_phase_part = fmod (distance, 1.0); - // 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) + // 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]))); + 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]; - } + distance += _speed + acceleration; + inm1 = input[i]; + } - i = floor(distance); - phase[channel] = distance - floor(distance); + i = floor (distance); + phase[channel] = fmod (distance, 1.0); - } 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); - } + } 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); + phase[channel] = fmod (distance, 1.0); + } - return i; + return i; } +/* CubicMidiInterpolation::distance is identical to + * return CubicInterpolation::interpolate (0, nframes, NULL, NULL); + */ framecnt_t -CubicMidiInterpolation::distance (framecnt_t nframes, bool roll) +CubicMidiInterpolation::distance (framecnt_t nframes, bool /*roll*/) { - assert(phase.size() == 1); + assert (phase.size () == 1); framecnt_t i = 0; double acceleration; - double distance = 0.0; + double distance = phase[0]; if (nframes < 3) { + /* no interpolation possible */ + phase[0] = 0; return nframes; } @@ -174,17 +156,12 @@ CubicMidiInterpolation::distance (framecnt_t nframes, bool roll) 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); + i = floor (distance); + phase[0] = fmod (distance, 1.0); return i; }