65 lines
2.2 KiB
C++
65 lines
2.2 KiB
C++
// See ../doc/synth.html for commentary
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#include <memory.h>
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#include <iostream>
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#include <sndfile.h>
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#include <gaborator/gaborator.h>
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int main(int argc, char **argv) {
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if (argc < 2) {
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std::cerr << "usage: synth output.wav\n";
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exit(1);
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}
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double fs = 44100;
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gaborator::log_fq_scale scale(12, 20.0 / fs, 8.18 / fs);
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gaborator::parameters params(scale);
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params.phase = gaborator::coef_phase::global;
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gaborator::analyzer<float> analyzer(params);
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static int pentatonic[] = { 57, 60, 62, 64, 67 };
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int n_notes = 64;
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double tempo = 120.0;
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double beat_duration = 60.0 / tempo;
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float volume = 0.2;
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gaborator::coefs<float> coefs(analyzer);
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for (int i = 0; i < n_notes; i++) {
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int midi_note = pentatonic[rand() % 5];
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double note_start_time = beat_duration * i;
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double note_end_time = note_start_time + 3.0;
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int band = analyzer.band_ref() - midi_note;
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fill([&](int, int64_t t, std::complex<float> &coef) {
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float amplitude =
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volume * expf(-2.0f * (float)(t / fs - note_start_time));
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coef += std::complex<float>(amplitude, 0.0f);
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},
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band, band + 1,
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note_start_time * fs, note_end_time * fs,
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coefs);
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}
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double audio_start_time = -0.5;
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double audio_end_time = beat_duration * n_notes + 5.0;
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int64_t start_frame = audio_start_time * fs;
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int64_t end_frame = audio_end_time * fs;
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size_t n_frames = end_frame - start_frame;
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std::vector<float> audio(n_frames);
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analyzer.synthesize(coefs, start_frame, end_frame, audio.data());
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SF_INFO sfinfo;
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memset(&sfinfo, 0, sizeof(sfinfo));
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sfinfo.samplerate = fs;
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sfinfo.channels = 1;
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sfinfo.format = SF_FORMAT_WAV | SF_FORMAT_PCM_16;
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SNDFILE *sf_out = sf_open(argv[1], SFM_WRITE, &sfinfo);
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if (! sf_out) {
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std::cerr << "could not open output audio file: "
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<< sf_strerror(sf_out) << "\n";
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exit(1);
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}
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sf_command(sf_out, SFC_SET_CLIPPING, NULL, SF_TRUE);
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sf_count_t n_written = sf_writef_float(sf_out, audio.data(), n_frames);
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if (n_written != n_frames) {
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std::cerr << "write error\n";
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exit(1);
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}
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sf_close(sf_out);
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return 0;
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}
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