ref: d04e5193e35696ba1b3de26d4a3070c281c6cbea
dir: /libfaad/dither.c/
/* This program is licensed under the GNU Library General Public License, version 2, * a copy of which is included with this program (with filename LICENSE.LGPL). * * (c) 2002 John Edwards * mostly lifted from work by Frank Klemm * random functions for dithering. * * last modified: * $Id: dither.c,v 1.7 2002/12/05 19:28:22 menno Exp $ */ #include "common.h" #ifndef FIXED_POINT #include <string.h> #include "dither.h" #include "common.h" double Random_Equi ( double mult ) // gives a equal distributed random number { // between -2^31*mult and +2^31*mult return mult * (int) random_int (); } double Random_Triangular ( double mult ) // gives a triangular distributed random number { // between -2^32*mult and +2^32*mult return mult * ( (double) (int) random_int () + (double) (int) random_int () ); } /*********************************************************************************************************************/ static const float32_t F44_0 [16 + 32] = { (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0, (float)0 }; static const float32_t F44_1 [16 + 32] = { /* SNR(w) = 4.843163 dB, SNR = -3.192134 dB */ (float) 0.85018292704024355931, (float) 0.29089597350995344721, (float)-0.05021866022121039450, (float)-0.23545456294599161833, (float)-0.58362726442227032096, (float)-0.67038978965193036429, (float)-0.38566861572833459221, (float)-0.15218663390367969967, (float)-0.02577543084864530676, (float) 0.14119295297688728127, (float) 0.22398848581628781612, (float) 0.15401727203382084116, (float) 0.05216161232906000929, (float)-0.00282237820999675451, (float)-0.03042794608323867363, (float)-0.03109780942998826024, (float) 0.85018292704024355931, (float) 0.29089597350995344721, (float)-0.05021866022121039450, (float)-0.23545456294599161833, (float)-0.58362726442227032096, (float)-0.67038978965193036429, (float)-0.38566861572833459221, (float)-0.15218663390367969967, (float)-0.02577543084864530676, (float) 0.14119295297688728127, (float) 0.22398848581628781612, (float) 0.15401727203382084116, (float) 0.05216161232906000929, (float)-0.00282237820999675451, (float)-0.03042794608323867363, (float)-0.03109780942998826024, (float) 0.85018292704024355931, (float) 0.29089597350995344721, (float)-0.05021866022121039450, (float)-0.23545456294599161833, (float)-0.58362726442227032096, (float)-0.67038978965193036429, (float)-0.38566861572833459221, (float)-0.15218663390367969967, (float)-0.02577543084864530676, (float) 0.14119295297688728127, (float) 0.22398848581628781612, (float) 0.15401727203382084116, (float) 0.05216161232906000929, (float)-0.00282237820999675451, (float)-0.03042794608323867363, (float)-0.03109780942998826024, }; static const float32_t F44_2 [16 + 32] = { /* SNR(w) = 10.060213 dB, SNR = -12.766730 dB */ (float) 1.78827593892108555290, (float) 0.95508210637394326553, (float)-0.18447626783899924429, (float)-0.44198126506275016437, (float)-0.88404052492547413497, (float)-1.42218907262407452967, (float)-1.02037566838362314995, (float)-0.34861755756425577264, (float)-0.11490230170431934434, (float) 0.12498899339968611803, (float) 0.38065885268563131927, (float) 0.31883491321310506562, (float) 0.10486838686563442765, (float)-0.03105361685110374845, (float)-0.06450524884075370758, (float)-0.02939198261121969816, (float) 1.78827593892108555290, (float) 0.95508210637394326553, (float)-0.18447626783899924429, (float)-0.44198126506275016437, (float)-0.88404052492547413497, (float)-1.42218907262407452967, (float)-1.02037566838362314995, (float)-0.34861755756425577264, (float)-0.11490230170431934434, (float) 0.12498899339968611803, (float) 0.38065885268563131927, (float) 0.31883491321310506562, (float) 0.10486838686563442765, (float)-0.03105361685110374845, (float)-0.06450524884075370758, (float)-0.02939198261121969816, (float) 1.78827593892108555290, (float) 0.95508210637394326553, (float)-0.18447626783899924429, (float)-0.44198126506275016437, (float)-0.88404052492547413497, (float)-1.42218907262407452967, (float)-1.02037566838362314995, (float)-0.34861755756425577264, (float)-0.11490230170431934434, (float) 0.12498899339968611803, (float) 0.38065885268563131927, (float) 0.31883491321310506562, (float) 0.10486838686563442765, (float)-0.03105361685110374845, (float)-0.06450524884075370758, (float)-0.02939198261121969816, }; static const float32_t F44_3 [16 + 32] = { /* SNR(w) = 15.382598 dB, SNR = -29.402334 dB */ (float) 2.89072132015058161445, (float) 2.68932810943698754106, (float) 0.21083359339410251227, (float)-0.98385073324997617515, (float)-1.11047823227097316719, (float)-2.18954076314139673147, (float)-2.36498032881953056225, (float)-0.95484132880101140785, (float)-0.23924057925542965158, (float)-0.13865235703915925642, (float) 0.43587843191057992846, (float) 0.65903257226026665927, (float) 0.24361815372443152787, (float)-0.00235974960154720097, (float) 0.01844166574603346289, (float) 0.01722945988740875099, (float) 2.89072132015058161445, (float) 2.68932810943698754106, (float) 0.21083359339410251227, (float)-0.98385073324997617515, (float)-1.11047823227097316719, (float)-2.18954076314139673147, (float)-2.36498032881953056225, (float)-0.95484132880101140785, (float)-0.23924057925542965158, (float)-0.13865235703915925642, (float) 0.43587843191057992846, (float) 0.65903257226026665927, (float) 0.24361815372443152787, (float)-0.00235974960154720097, (float) 0.01844166574603346289, (float) 0.01722945988740875099, (float) 2.89072132015058161445, (float) 2.68932810943698754106, (float) 0.21083359339410251227, (float)-0.98385073324997617515, (float)-1.11047823227097316719, (float)-2.18954076314139673147, (float)-2.36498032881953056225, (float)-0.95484132880101140785, (float)-0.23924057925542965158, (float)-0.13865235703915925642, (float) 0.43587843191057992846, (float) 0.65903257226026665927, (float) 0.24361815372443152787, (float)-0.00235974960154720097, (float) 0.01844166574603346289, (float) 0.01722945988740875099 }; double scalar16 ( const float32_t* x, const float32_t* y ) { return x[ 0]*y[ 0] + x[ 1]*y[ 1] + x[ 2]*y[ 2] + x[ 3]*y[ 3] + x[ 4]*y[ 4] + x[ 5]*y[ 5] + x[ 6]*y[ 6] + x[ 7]*y[ 7] + x[ 8]*y[ 8] + x[ 9]*y[ 9] + x[10]*y[10] + x[11]*y[11] + x[12]*y[12] + x[13]*y[13] + x[14]*y[14] + x[15]*y[15]; } void Init_Dither ( unsigned char bits, unsigned char shapingtype ) { static uint8_t default_dither [] = { 92, 92, 88, 84, 81, 78, 74, 67, 0, 0 }; static const float32_t* F [] = { F44_0, F44_1, F44_2, F44_3 }; uint8_t index; if (shapingtype < 0) shapingtype = 0; if (shapingtype > 3) shapingtype = 3; index = bits - 11 - shapingtype; if (index < 0) index = 0; if (index > 9) index = 9; memset ( Dither.ErrorHistory , 0, sizeof (Dither.ErrorHistory ) ); memset ( Dither.DitherHistory, 0, sizeof (Dither.DitherHistory) ); Dither.FilterCoeff = F [shapingtype]; Dither.Mask = ((uint64_t)-1) << (32 - bits); Dither.Add = 0.5 * ((1L << (32 - bits)) - 1); Dither.Dither = 0.01*default_dither[index] / (((int64_t)1) << bits); } #endif