X-Git-Url: https://main.carlh.net/gitweb/?a=blobdiff_plain;f=libs%2Fardour%2Finterpolation.cc;h=1393d8aae81e659c1e4c87b9954307e44c5ce8b3;hb=8f59346592b8232e910ce0bbdc247cf8cecde4dd;hp=3d2f754da9c59a7785788874061ea02e4f09ebe0;hpb=47e56905523cb9269a19300d2b468118dda3a161;p=ardour.git diff --git a/libs/ardour/interpolation.cc b/libs/ardour/interpolation.cc index 3d2f754da9..1393d8aae8 100644 --- a/libs/ardour/interpolation.cc +++ b/libs/ardour/interpolation.cc @@ -1,95 +1,136 @@ #include +#include #include "ardour/interpolation.h" using namespace ARDOUR; -LibSamplerateInterpolation::LibSamplerateInterpolation() : _speed (1.0L), state (0) -{ -} -LibSamplerateInterpolation::~LibSamplerateInterpolation() +nframes_t +LinearInterpolation::interpolate (int channel, nframes_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 + nframes_t i = 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); + double acceleration; + double distance = 0.0; + + 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 (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) { + // 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); -void -LibSamplerateInterpolation::remove_channel_from () -{ - delete data.back (); - data.pop_back (); - delete state.back (); - state.pop_back (); - reset_state (); + return i; } 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; +CubicInterpolation::interpolate (int channel, nframes_t nframes, Sample *input, Sample *output) +{ + // 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]; + + 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 (nframes_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 (nframes_t outsample = 0; outsample < nframes; ++outsample) { + distance += _speed + acceleration; + } + } + + i = floor(distance); + phase[channel] = distance - floor(distance); + + return i; }