1/* plugin_common - Routines common to several plugins 2 * Copyright (C) 2002,2003,2004,2005,2006,2007 Josh Coalson 3 * 4 * dithering routine derived from (other GPLed source): 5 * mad - MPEG audio decoder 6 * Copyright (C) 2000-2001 Robert Leslie 7 * 8 * This program is free software; you can redistribute it and/or 9 * modify it under the terms of the GNU General Public License 10 * as published by the Free Software Foundation; either version 2 11 * of the License, or (at your option) any later version. 12 * 13 * This program is distributed in the hope that it will be useful, 14 * but WITHOUT ANY WARRANTY; without even the implied warranty of 15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 * GNU General Public License for more details. 17 * 18 * You should have received a copy of the GNU General Public License 19 * along with this program; if not, write to the Free Software 20 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. 21 */ 22 23#if HAVE_CONFIG_H 24# include <config.h> 25#endif 26 27#include "dither.h" 28#include "FLAC/assert.h" 29 30#ifdef max 31#undef max 32#endif 33#define max(a,b) ((a)>(b)?(a):(b)) 34 35#ifndef FLaC__INLINE 36#define FLaC__INLINE 37#endif 38 39 40/* 32-bit pseudo-random number generator 41 * 42 * @@@ According to Miroslav, this one is poor quality, the one from the 43 * @@@ original replaygain code is much better 44 */ 45static FLaC__INLINE FLAC__uint32 prng(FLAC__uint32 state) 46{ 47 return (state * 0x0019660dL + 0x3c6ef35fL) & 0xffffffffL; 48} 49 50/* dither routine derived from MAD winamp plugin */ 51 52typedef struct { 53 FLAC__int32 error[3]; 54 FLAC__int32 random; 55} dither_state; 56 57static FLaC__INLINE FLAC__int32 linear_dither(unsigned source_bps, unsigned target_bps, FLAC__int32 sample, dither_state *dither, const FLAC__int32 MIN, const FLAC__int32 MAX) 58{ 59 unsigned scalebits; 60 FLAC__int32 output, mask, random; 61 62 FLAC__ASSERT(source_bps < 32); 63 FLAC__ASSERT(target_bps <= 24); 64 FLAC__ASSERT(target_bps <= source_bps); 65 66 /* noise shape */ 67 sample += dither->error[0] - dither->error[1] + dither->error[2]; 68 69 dither->error[2] = dither->error[1]; 70 dither->error[1] = dither->error[0] / 2; 71 72 /* bias */ 73 output = sample + (1L << (source_bps - target_bps - 1)); 74 75 scalebits = source_bps - target_bps; 76 mask = (1L << scalebits) - 1; 77 78 /* dither */ 79 random = (FLAC__int32)prng(dither->random); 80 output += (random & mask) - (dither->random & mask); 81 82 dither->random = random; 83 84 /* clip */ 85 if(output > MAX) { 86 output = MAX; 87 88 if(sample > MAX) 89 sample = MAX; 90 } 91 else if(output < MIN) { 92 output = MIN; 93 94 if(sample < MIN) 95 sample = MIN; 96 } 97 98 /* quantize */ 99 output &= ~mask; 100 101 /* error feedback */ 102 dither->error[0] = sample - output; 103 104 /* scale */ 105 return output >> scalebits; 106} 107 108size_t FLAC__plugin_common__pack_pcm_signed_big_endian(FLAC__byte *data, const FLAC__int32 * const input[], unsigned wide_samples, unsigned channels, unsigned source_bps, unsigned target_bps) 109{ 110 static dither_state dither[FLAC_PLUGIN__MAX_SUPPORTED_CHANNELS]; 111 FLAC__byte * const start = data; 112 FLAC__int32 sample; 113 const FLAC__int32 *input_; 114 unsigned samples, channel; 115 const unsigned bytes_per_sample = target_bps / 8; 116 const unsigned incr = bytes_per_sample * channels; 117 118 FLAC__ASSERT(channels > 0 && channels <= FLAC_PLUGIN__MAX_SUPPORTED_CHANNELS); 119 FLAC__ASSERT(source_bps < 32); 120 FLAC__ASSERT(target_bps <= 24); 121 FLAC__ASSERT(target_bps <= source_bps); 122 FLAC__ASSERT((source_bps & 7) == 0); 123 FLAC__ASSERT((target_bps & 7) == 0); 124 125 if(source_bps != target_bps) { 126 const FLAC__int32 MIN = -(1L << (source_bps - 1)); 127 const FLAC__int32 MAX = ~MIN; /*(1L << (source_bps-1)) - 1 */ 128 129 for(channel = 0; channel < channels; channel++) { 130 131 samples = wide_samples; 132 data = start + bytes_per_sample * channel; 133 input_ = input[channel]; 134 135 while(samples--) { 136 sample = linear_dither(source_bps, target_bps, *input_++, &dither[channel], MIN, MAX); 137 138 switch(target_bps) { 139 case 8: 140 data[0] = sample ^ 0x80; 141 break; 142 case 16: 143 data[0] = (FLAC__byte)(sample >> 8); 144 data[1] = (FLAC__byte)sample; 145 break; 146 case 24: 147 data[0] = (FLAC__byte)(sample >> 16); 148 data[1] = (FLAC__byte)(sample >> 8); 149 data[2] = (FLAC__byte)sample; 150 break; 151 } 152 153 data += incr; 154 } 155 } 156 } 157 else { 158 for(channel = 0; channel < channels; channel++) { 159 samples = wide_samples; 160 data = start + bytes_per_sample * channel; 161 input_ = input[channel]; 162 163 while(samples--) { 164 sample = *input_++; 165 166 switch(target_bps) { 167 case 8: 168 data[0] = sample ^ 0x80; 169 break; 170 case 16: 171 data[0] = (FLAC__byte)(sample >> 8); 172 data[1] = (FLAC__byte)sample; 173 break; 174 case 24: 175 data[0] = (FLAC__byte)(sample >> 16); 176 data[1] = (FLAC__byte)(sample >> 8); 177 data[2] = (FLAC__byte)sample; 178 break; 179 } 180 181 data += incr; 182 } 183 } 184 } 185 186 return wide_samples * channels * (target_bps/8); 187} 188 189size_t FLAC__plugin_common__pack_pcm_signed_little_endian(FLAC__byte *data, const FLAC__int32 * const input[], unsigned wide_samples, unsigned channels, unsigned source_bps, unsigned target_bps) 190{ 191 static dither_state dither[FLAC_PLUGIN__MAX_SUPPORTED_CHANNELS]; 192 FLAC__byte * const start = data; 193 FLAC__int32 sample; 194 const FLAC__int32 *input_; 195 unsigned samples, channel; 196 const unsigned bytes_per_sample = target_bps / 8; 197 const unsigned incr = bytes_per_sample * channels; 198 199 FLAC__ASSERT(channels > 0 && channels <= FLAC_PLUGIN__MAX_SUPPORTED_CHANNELS); 200 FLAC__ASSERT(source_bps < 32); 201 FLAC__ASSERT(target_bps <= 24); 202 FLAC__ASSERT(target_bps <= source_bps); 203 FLAC__ASSERT((source_bps & 7) == 0); 204 FLAC__ASSERT((target_bps & 7) == 0); 205 206 if(source_bps != target_bps) { 207 const FLAC__int32 MIN = -(1L << (source_bps - 1)); 208 const FLAC__int32 MAX = ~MIN; /*(1L << (source_bps-1)) - 1 */ 209 210 for(channel = 0; channel < channels; channel++) { 211 212 samples = wide_samples; 213 data = start + bytes_per_sample * channel; 214 input_ = input[channel]; 215 216 while(samples--) { 217 sample = linear_dither(source_bps, target_bps, *input_++, &dither[channel], MIN, MAX); 218 219 switch(target_bps) { 220 case 8: 221 data[0] = sample ^ 0x80; 222 break; 223 case 24: 224 data[2] = (FLAC__byte)(sample >> 16); 225 /* fall through */ 226 case 16: 227 data[1] = (FLAC__byte)(sample >> 8); 228 data[0] = (FLAC__byte)sample; 229 } 230 231 data += incr; 232 } 233 } 234 } 235 else { 236 for(channel = 0; channel < channels; channel++) { 237 samples = wide_samples; 238 data = start + bytes_per_sample * channel; 239 input_ = input[channel]; 240 241 while(samples--) { 242 sample = *input_++; 243 244 switch(target_bps) { 245 case 8: 246 data[0] = sample ^ 0x80; 247 break; 248 case 24: 249 data[2] = (FLAC__byte)(sample >> 16); 250 /* fall through */ 251 case 16: 252 data[1] = (FLAC__byte)(sample >> 8); 253 data[0] = (FLAC__byte)sample; 254 } 255 256 data += incr; 257 } 258 } 259 } 260 261 return wide_samples * channels * (target_bps/8); 262} 263