音频倍速播放之sonic

/* Sonic library Copyright 2010 Bill Cox This file is part of the Sonic Library. This file is licensed under the Apache 2.0 license, and also placed into the public domain. Use it either way, at your option. */ #include <stdio.h> #include <stdlib.h> #include <string.h> #include <stdarg.h> #include <limits.h> #include <math.h> #include "sonic.h" #ifndef M_PI #define M_PI 3.14159265358979323846 #endif /* The following code was used to generate the following sinc lookup table. #include <math.h> #include <limits.h> #include <stdio.h> double findHannWeight(int N, double x) { return 0.5*(1.0 - cos(2*M_PI*x/N)); } double findSincCoefficient(int N, double x) { double hannWindowWeight = findHannWeight(N, x); double sincWeight; x -= N/2.0; if (x > 1e-9 || x < -1e-9) { sincWeight = sin(M_PI*x)/(M_PI*x); } else { sincWeight = 1.0; } return hannWindowWeight*sincWeight; } int main() { double x; int i; int N = 12; for (i = 0, x = 0.0; x <= N; x += 0.02, i++) { printf("%u %d\n", i, (int)(SHRT_MAX*findSincCoefficient(N, x))); } return 0; } */ /* The number of points to use in the sinc FIR filter for resampling. */ #define SINC_FILTER_POINTS 12 /* I am not able to hear improvement with higher N. */ #define SINC_TABLE_SIZE 601 /* Lookup table for windowed sinc function of SINC_FILTER_POINTS points. */ static short sincTable[SINC_TABLE_SIZE] = { 0, 0, 0, 0, 0, 0, 0, -1, -1, -2, -2, -3, -4, -6, -7, -9, -10, -12, -14, -17, -19, -21, -24, -26, -29, -32, -34, -37, -40, -42, -44, -47, -48, -50, -51, -52, -53, -53, -53, -52, -50, -48, -46, -43, -39, -34, -29, -22, -16, -8, 0, 9, 19, 29, 41, 53, 65, 79, 92, 107, 121, 137, 152, 168, 184, 200, 215, 231, 247, 262, 276, 291, 304, 317, 328, 339, 348, 357, 363, 369, 372, 374, 375, 373, 369, 363, 355, 345, 332, 318, 300, 281, 259, 234, 208, 178, 147, 113, 77, 39, 0, -41, -85, -130, -177, -225, -274, -324, -375, -426, -478, -530, -581, -632, -682, -731, -779, -825, -870, -912, -951, -989, -1023, -1053, -1080, -1104, -1123, -1138, -1149, -1154, -1155, -1151, -1141, -1125, -1105, -1078, -1046, -1007, -963, -913, -857, -796, -728, -655, -576, -492, -403, -309, -210, -107, 0, 111, 225, 342, 462, 584, 708, 833, 958, 1084, 1209, 1333, 1455, 1575, 1693, 1807, 1916, 2022, 2122, 2216, 2304, 2384, 2457, 2522, 2579, 2625, 2663, 2689, 2706, 2711, 2705, 2687, 2657, 2614, 2559, 2491, 2411, 2317, 2211, 2092, 1960, 1815, 1658, 1489, 1308, 1115, 912, 698, 474, 241, 0, -249, -506, -769, -1037, -1310, -1586, -1864, -2144, -2424, -2703, -2980, -3254, -3523, -3787, -4043, -4291, -4529, -4757, -4972, -5174, -5360, -5531, -5685, -5819, -5935, -6029, -6101, -6150, -6175, -6175, -6149, -6096, -6015, -5905, -5767, -5599, -5401, -5172, -4912, -4621, -4298, -3944, -3558, -3141, -2693, -2214, -1705, -1166, -597, 0, 625, 1277, 1955, 2658, 3386, 4135, 4906, 5697, 6506, 7332, 8173, 9027, 9893, 10769, 11654, 12544, 13439, 14335, 15232, 16128, 17019, 17904, 18782, 19649, 20504, 21345, 22170, 22977, 23763, 24527, 25268, 25982, 26669, 27327, 27953, 28547, 29107, 29632, 30119, 30569, 30979, 31349, 31678, 31964, 32208, 32408, 32565, 32677, 32744, 32767, 32744, 32677, 32565, 32408, 32208, 31964, 31678, 31349, 30979, 30569, 30119, 29632, 29107, 28547, 27953, 27327, 26669, 25982, 25268, 24527, 23763, 22977, 22170, 21345, 20504, 19649, 18782, 17904, 17019, 16128, 15232, 14335, 13439, 12544, 11654, 10769, 9893, 9027, 8173, 7332, 6506, 5697, 4906, 4135, 3386, 2658, 1955, 1277, 625, 0, -597, -1166, -1705, -2214, -2693, -3141, -3558, -3944, -4298, -4621, -4912, -5172, -5401, -5599, -5767, -5905, -6015, -6096, -6149, -6175, -6175, -6150, -6101, -6029, -5935, -5819, -5685, -5531, -5360, -5174, -4972, -4757, -4529, -4291, -4043, -3787, -3523, -3254, -2980, -2703, -2424, -2144, -1864, -1586, -1310, -1037, -769, -506, -249, 0, 241, 474, 698, 912, 1115, 1308, 1489, 1658, 1815, 1960, 2092, 2211, 2317, 2411, 2491, 2559, 2614, 2657, 2687, 2705, 2711, 2706, 2689, 2663, 2625, 2579, 2522, 2457, 2384, 2304, 2216, 2122, 2022, 1916, 1807, 1693, 1575, 1455, 1333, 1209, 1084, 958, 833, 708, 584, 462, 342, 225, 111, 0, -107, -210, -309, -403, -492, -576, -655, -728, -796, -857, -913, -963, -1007, -1046, -1078, -1105, -1125, -1141, -1151, -1155, -1154, -1149, -1138, -1123, -1104, -1080, -1053, -1023, -989, -951, -912, -870, -825, -779, -731, -682, -632, -581, -530, -478, -426, -375, -324, -274, -225, -177, -130, -85, -41, 0, 39, 77, 113, 147, 178, 208, 234, 259, 281, 300, 318, 332, 345, 355, 363, 369, 373, 375, 374, 372, 369, 363, 357, 348, 339, 328, 317, 304, 291, 276, 262, 247, 231, 215, 200, 184, 168, 152, 137, 121, 107, 92, 79, 65, 53, 41, 29, 19, 9, 0, -8, -16, -22, -29, -34, -39, -43, -46, -48, -50, -52, -53, -53, -53, -52, -51, -50, -48, -47, -44, -42, -40, -37, -34, -32, -29, -26, -24, -21, -19, -17, -14, -12, -10, -9, -7, -6, -4, -3, -2, -2, -1, -1, 0, 0, 0, 0, 0, 0, 0 }; struct sonicStreamStruct { short *inputBuffer; short *outputBuffer; short *pitchBuffer; short *downSampleBuffer; float speed; float volume; float pitch; float rate; int oldRatePosition; int newRatePosition; int useChordPitch; int quality; int numChannels; int inputBufferSize; int pitchBufferSize; int outputBufferSize; int numInputSamples; int numOutputSamples; int numPitchSamples; int minPeriod; int maxPeriod; int maxRequired; int remainingInputToCopy; int sampleRate; int prevPeriod; int prevMinDiff; float avePower; }; /* Scale the samples by the factor. */ static void scaleSamples( short *samples, int numSamples, float volume) { int fixedPointVolume = volume*4096.0f; int value; while(numSamples--) { value = (*samples*fixedPointVolume) >> 12; if(value > 32767) { value = 32767; } else if(value < -32767) { value = -32767; } *samples++ = value; } } /* Get the speed of the stream. */ float sonicGetSpeed( sonicStream stream) { return stream->speed; } /* Set the speed of the stream. */ void sonicSetSpeed( sonicStream stream, float speed) { stream->speed = speed; } /* Get the pitch of the stream. */ float sonicGetPitch( sonicStream stream) { return stream->pitch; } /* Set the pitch of the stream. */ void sonicSetPitch( sonicStream stream, float pitch) { stream->pitch = pitch; } /* Get the rate of the stream. */ float sonicGetRate( sonicStream stream) { return stream->rate; } /* Set the playback rate of the stream. This scales pitch and speed at the same time. */ void sonicSetRate( sonicStream stream, float rate) { stream->rate = rate; stream->oldRatePosition = 0; stream->newRatePosition = 0; } /* Get the vocal chord pitch setting. */ int sonicGetChordPitch( sonicStream stream) { return stream->useChordPitch; } /* Set the vocal chord mode for pitch computation. Default is off. */ void sonicSetChordPitch( sonicStream stream, int useChordPitch) { stream->useChordPitch = useChordPitch; } /* Get the quality setting. */ int sonicGetQuality( sonicStream stream) { return stream->quality; } /* Set the "quality". Default 0 is virtually as good as 1, but very much faster. */ void sonicSetQuality( sonicStream stream, int quality) { stream->quality = quality; } /* Get