mirror of
https://github.com/libretro/cpp-cheat.git
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301 lines
9.7 KiB
C
301 lines
9.7 KiB
C
/*
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http://stackoverflow.com/a/36510894/895245
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TODO
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- smooth transition between sines without tic sound. Needs a phase change I imagine.
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- ADSR https://en.wikipedia.org/wiki/Synthesizer#Attack_Decay_Sustain_Release_.28ADSR.29_envelope
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Currently, hitting the same not twice sounds the same as hitting it once for double the time,
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(except for the tic of phase, which is a bug as well...)
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- drum / percurssion synth
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- siren sound TODO Mechanical: https://www.youtube.com/watch?v=uckkpr2b8U8
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*/
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#include <math.h>
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#include <stdarg.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <stdint.h>
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typedef uint16_t point_type;
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#define WRITE(name, func) \
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f = fopen("tmp." name ".raw", "wb"); \
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for (t = 0; t < NSAMPLES; ++t) { \
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func; \
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write_ampl(f, ampl); \
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} \
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fclose(f);
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double PI2;
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void write_ampl(FILE *f, point_type ampl) {
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uint8_t bytes[2];
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bytes[0] = ampl >> 8;
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bytes[1] = ampl & 8;
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fwrite(bytes, 2, sizeof(uint8_t), f);
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}
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/* https://en.wikipedia.org/wiki/Piano_key_frequencies */
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double piano_freq(unsigned int i) {
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return 440.0 * pow(2, (i - 49.0) / 12.0);
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}
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/* Chord formed by the nth note of the piano. */
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point_type piano_sum(unsigned int max_ampl, unsigned int time,
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double sample_freq, unsigned int nargs, unsigned int *notes) {
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double freq;
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unsigned int i;
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double sum = 0;
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for (i = 0 ; i < nargs; ++i)
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sum += sin(PI2 * time * piano_freq(notes[i]) / sample_freq);
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return max_ampl * 0.5 * (nargs + sum) / nargs;
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}
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enum notes {
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A0 = 1, AS0, B0,
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C1, C1S, D1, D1S, E1, F1, F1S, G1, G1S, A1, A1S, B1,
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C2, C2S, D2, D2S, E2, F2, F2S, G2, G2S, A2, A2S, B2,
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C3, C3S, D3, D3S, E3, F3, F3S, G3, G3S, A3, A3S, B3,
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C4, C4S, D4, D4S, E4, F4, F4S, G4, G4S, A4, A4S, B4,
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C5, C5S, D5, D5S, E5, F5, F5S, G5, G5S, A5, A5S, B5,
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C6, C6S, D6, D6S, E6, F6, F6S, G6, G6S, A6, A6S, B6,
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C7, C7S, D7, D7S, E7, F7, F7S, G7, G7S, A7, A7S, B7,
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C8,
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};
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int main(void) {
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FILE *f;
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PI2 = 2 * acos(-1.0);
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const double SAMPLE_FREQ = 44100;
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const unsigned int NSAMPLES = 4 * SAMPLE_FREQ;
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double freq;
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point_type ampl;
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point_type max_ampl = UINT16_MAX;
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unsigned int t;
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WRITE("1000", (ampl = max_ampl * 0.5 * (1.0 + sin(PI2 * t * 1000.0 / SAMPLE_FREQ))));
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/* Maximum and minimum of human audition. TODO explain their weird sound. */
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WRITE("20", (ampl = max_ampl * 0.5 * (1.0 + sin(PI2 * t * 20.0 / SAMPLE_FREQ))));
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WRITE("2000", (ampl = max_ampl * 0.5 * (1.0 + sin(PI2 * t * 2000.0 / SAMPLE_FREQ))));
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/* Out of human range. TODO explain outcome. */
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WRITE("10", (ampl = max_ampl * 0.5 * (1.0 + sin(PI2 * t * 10.0 / SAMPLE_FREQ))));
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WRITE("40000", (ampl = max_ampl * 0.5 * (1.0 + sin(PI2 * t * 40000.0 / SAMPLE_FREQ))));
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/* Smaller amplitude: less loud. */
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WRITE("half", (ampl = max_ampl * 0.25 * (1.0 + sin(PI2 * t * 1000.0 / SAMPLE_FREQ))));
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/* Constant amplitude: produces only 2 quick ticks at start and end,
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* when the speaker's membrane moves. */
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WRITE("const", (ampl = max_ampl));
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/* TODO: why does this produces only two ticks, and not a bunch of ticks? */
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f = fopen("tmp.max_min.raw", "wb");
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for (t = 0; t < NSAMPLES; ++t) {
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if (t % 2 == 0) {
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ampl = 0;
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} else {
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ampl = max_ampl;
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}
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write_ampl(f, ampl);
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}
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fclose(f);
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/*
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Dual channel, one sin per channel.
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Play with ffmpeg -ac 2.
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Get microphones. Each phone gives a different frequency.
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*/
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f = fopen("tmp.dual.raw", "wb");
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for (t = 0; t < NSAMPLES; ++t) {
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ampl = max_ampl * 0.5 * (1.0 + sin(PI2 * t * 100.0 / SAMPLE_FREQ));
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write_ampl(f, ampl);
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ampl = max_ampl * 0.5 * (1.0 + sin(PI2 * t * 2000.0 / SAMPLE_FREQ));
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write_ampl(f, ampl);
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}
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fclose(f);
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/*
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Sum of sinuses with different frequencies and same amplitude.
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AKA chord.
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*/
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f = fopen("tmp.sum.raw", "wb");
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for (t = 0; t < NSAMPLES; ++t) {
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ampl = max_ampl * 0.25 * (
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2.0 +
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sin(PI2 * t * 1000.0 / SAMPLE_FREQ) +
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sin(PI2 * t * 2000.0 / SAMPLE_FREQ)
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);
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write_ampl(f, ampl);
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}
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fclose(f);
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/*
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Sum of sinuses with different frequencies, and different amplitudes.
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*/
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f = fopen("tmp.sum_ampl.raw", "wb");
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for (t = 0; t < NSAMPLES; ++t) {
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ampl = max_ampl * (1.0 / 12.0) * (
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6.0 +
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sin(PI2 * t * 1000.0 / SAMPLE_FREQ) * 5.0 +
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sin(PI2 * t * 2000.0 / SAMPLE_FREQ)
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);
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write_ampl(f, ampl);
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}
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fclose(f);
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/*
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See how a phase shift sounds like. No difference?
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But obviously in some cases there must be a difference, e.g. canceling waves.
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http://www.silcom.com/~aludwig/Phase_audibility.htm
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*/
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f = fopen("tmp.sum_phase.raw", "wb");
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for (t = 0; t < NSAMPLES; ++t) {
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ampl = max_ampl * 0.25 * (
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2.0 +
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sin(PI2 * t * 500.0 / SAMPLE_FREQ) +
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sin((PI2 * t * 2000.0 / SAMPLE_FREQ) + (PI2 / 4.0))
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);
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write_ampl(f, ampl);
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}
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fclose(f);
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/*
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https://en.wikipedia.org/wiki/Chirp
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Linearly varying instanteneous frequency.
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http://math.stackexchange.com/questions/85388/does-the-phrase-instantaneous-frequency-make-sense
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TODO understand intuitively why if we remove the 2.0 divisor from the frequency
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then it goes first up and then down.
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Yes, I know that mathematically it comes from the derivative.
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*/
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f = fopen("tmp.chirp.raw", "wb");
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for (t = 0; t < NSAMPLES; ++t) {
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freq = 20.0 + 19980.0 * t / ((double)NSAMPLES * 2.0);
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ampl = max_ampl * 0.5 * (1.0 + sin(PI2 * t * freq / SAMPLE_FREQ));
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write_ampl(f, ampl);
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}
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fclose(f);
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/*
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Saw tooth
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https://www.youtube.com/watch?v=uIuJTWS2uvY mentions that high frequency saws
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and sines are more similar than low frequency. This is because
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humans don't hear the higher harmonics, and the lower one dominates.
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*/
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f = fopen("tmp.saw.raw", "wb");
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for (t = 0; t < NSAMPLES; ++t) {
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freq = 1000;
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ampl = max_ampl * fabs(1.0 - 2.0 * (t % (int)(SAMPLE_FREQ / freq)) / (SAMPLE_FREQ / freq));
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write_ampl(f, ampl);
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}
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fclose(f);
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f = fopen("tmp.tune.raw", "wb");
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for (t = 0; t < NSAMPLES; ++t) {
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if (t < NSAMPLES / 4) {
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freq = piano_freq(C4);
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} else if (t < NSAMPLES / 2) {
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freq = piano_freq(E4);
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} else if (t < 3 * NSAMPLES / 4) {
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freq = piano_freq(G4);
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} else {
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freq = piano_freq(C5);
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}
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ampl = max_ampl * 0.5 * (1.0 + sin(PI2 * t * freq / SAMPLE_FREQ));
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write_ampl(f, ampl);
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}
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fclose(f);
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f = fopen("tmp.chord.raw", "wb");
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for (t = 0; t < NSAMPLES; ++t) {
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ampl = piano_sum(max_ampl, t, SAMPLE_FREQ, 4, (unsigned int[]){C4, E4, G4, B4});
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write_ampl(f, ampl);
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}
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fclose(f);
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/*
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# Pianola
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# Canon
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https://en.wikipedia.org/wiki/Player_piano
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http://www.8notes.com/scores/420.asp After where I've stopped,
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that score gets weird, maybe find another one.
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*/
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{
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unsigned int i;
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unsigned int samples_per_unit = SAMPLE_FREQ * 0.375;
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unsigned int *ip[] = {
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(unsigned int[]){4, 2, C3, E4},
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(unsigned int[]){4, 2, G3, D4},
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(unsigned int[]){4, 2, A3, C4},
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(unsigned int[]){4, 2, E3, B3},
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(unsigned int[]){4, 2, F3, A3},
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(unsigned int[]){4, 2, C3, G3},
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(unsigned int[]){4, 2, F3, A3},
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(unsigned int[]){4, 2, G3, B3},
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(unsigned int[]){4, 3, C3, G4, E5},
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(unsigned int[]){4, 3, G3, B4, D5},
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(unsigned int[]){4, 2, A3, C5},
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(unsigned int[]){4, 3, E3, G4, B4},
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(unsigned int[]){4, 3, F3, C4, A4},
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(unsigned int[]){4, 3, C3, G4, G4},
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(unsigned int[]){4, 3, F3, F4, A4},
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(unsigned int[]){4, 3, G3, D4, B4},
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(unsigned int[]){2, 3, C4, E4, C5},
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(unsigned int[]){2, 3, C4, E4, C5},
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(unsigned int[]){2, 3, G3, D4, D5},
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(unsigned int[]){2, 3, G3, D4, B4},
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(unsigned int[]){2, 3, A3, C4, C5},
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(unsigned int[]){2, 3, A3, C4, E5},
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(unsigned int[]){2, 2, E3, G5},
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(unsigned int[]){2, 2, E3, G4},
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(unsigned int[]){2, 3, F3, A3, A4},
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(unsigned int[]){2, 3, F3, A3, F4},
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(unsigned int[]){2, 3, C3, E4},
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(unsigned int[]){2, 3, C3, G4},
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(unsigned int[]){2, 3, F3, A3, F4},
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(unsigned int[]){2, 3, F3, A3, C5},
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(unsigned int[]){2, 3, G3, B3, B4},
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(unsigned int[]){2, 3, G3, B3, G4},
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(unsigned int[]){2, 3, C4, E4, C5},
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(unsigned int[]){1, 3, C4, E4, E5},
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(unsigned int[]){1, 3, C4, E4, G5},
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(unsigned int[]){1, 2, G3, G5},
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(unsigned int[]){1, 2, G3, A5},
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(unsigned int[]){1, 2, G3, G5},
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(unsigned int[]){1, 2, G3, F5},
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(unsigned int[]){3, 3, A3, C4, E5},
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(unsigned int[]){1, 3, A3, C4, E5},
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(unsigned int[]){1, 3, E3, G3, E5},
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(unsigned int[]){1, 3, E3, G3, F5},
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(unsigned int[]){1, 3, E3, G3, E5},
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(unsigned int[]){1, 3, E3, G3, D5},
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};
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f = fopen("tmp.canon.raw", "wb");
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for (i = 0; i < sizeof(ip) / sizeof(int*); ++i) {
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unsigned int *cur = ip[i];
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unsigned int total = samples_per_unit * cur[0];
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for (t = 0; t < total; ++t) {
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ampl = piano_sum(max_ampl, t, SAMPLE_FREQ, cur[1], &cur[2]);
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write_ampl(f, ampl);
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}
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}
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fclose(f);
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}
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return EXIT_SUCCESS;
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}
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