ref: a2a56b3ea59188e2e2b60b69a0a8f77aa3093144
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 1.4 2002/09/13 13:08:45 menno Exp $
*/
#include "common.h"
#ifndef FIXED_POINT
#include <memory.h>
#include "dither.h"
static const uint8_t Parity [256] = { // parity
0,1,1,0,1,0,0,1,1,0,0,1,0,1,1,0,1,0,0,1,0,1,1,0,0,1,1,0,1,0,0,1,
1,0,0,1,0,1,1,0,0,1,1,0,1,0,0,1,0,1,1,0,1,0,0,1,1,0,0,1,0,1,1,0,
1,0,0,1,0,1,1,0,0,1,1,0,1,0,0,1,0,1,1,0,1,0,0,1,1,0,0,1,0,1,1,0,
0,1,1,0,1,0,0,1,1,0,0,1,0,1,1,0,1,0,0,1,0,1,1,0,0,1,1,0,1,0,0,1,
1,0,0,1,0,1,1,0,0,1,1,0,1,0,0,1,0,1,1,0,1,0,0,1,1,0,0,1,0,1,1,0,
0,1,1,0,1,0,0,1,1,0,0,1,0,1,1,0,1,0,0,1,0,1,1,0,0,1,1,0,1,0,0,1,
0,1,1,0,1,0,0,1,1,0,0,1,0,1,1,0,1,0,0,1,0,1,1,0,0,1,1,0,1,0,0,1,
1,0,0,1,0,1,1,0,0,1,1,0,1,0,0,1,0,1,1,0,1,0,0,1,1,0,0,1,0,1,1,0
};
static uint32_t __r1 = 1;
static uint32_t __r2 = 1;
/*
* This is a simple random number generator with good quality for audio purposes.
* It consists of two polycounters with opposite rotation direction and different
* periods. The periods are coprime, so the total period is the product of both.
*
* -------------------------------------------------------------------------------------------------
* +-> |31:30:29:28:27:26:25:24:23:22:21:20:19:18:17:16:15:14:13:12:11:10: 9: 8: 7: 6: 5: 4: 3: 2: 1: 0|
* | -------------------------------------------------------------------------------------------------
* | | | | | | |
* | +--+--+--+-XOR-+--------+
* | |
* +--------------------------------------------------------------------------------------+
*
* -------------------------------------------------------------------------------------------------
* |31:30:29:28:27:26:25:24:23:22:21:20:19:18:17:16:15:14:13:12:11:10: 9: 8: 7: 6: 5: 4: 3: 2: 1: 0| <-+
* ------------------------------------------------------------------------------------------------- |
* | | | | |
* +--+----XOR----+--+ |
* | |
* +----------------------------------------------------------------------------------------+
*
*
* The first has an period of 3*5*17*257*65537, the second of 7*47*73*178481,
* which gives a period of 18.410.713.077.675.721.215. The result is the
* XORed values of both generators.
*/
uint32_t
random_int ( void )
{
uint32_t t1, t2, t3, t4;
t3 = t1 = __r1; t4 = t2 = __r2; // Parity calculation is done via table lookup, this is also available
t1 &= 0xF5; t2 >>= 25; // on CPUs without parity, can be implemented in C and avoid unpredictable
t1 = Parity [t1]; t2 &= 0x63; // jumps and slow rotate through the carry flag operations.
t1 <<= 31; t2 = Parity [t2];
return (__r1 = (t3 >> 1) | t1 ) ^ (__r2 = (t4 + t4) | t2 );
}
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