1 /* plugin_common - Routines common to several plugins
2 * Copyright (C) 2002,2003 Josh Coalson
4 * dithering routine derived from (other GPLed source):
5 * mad - MPEG audio decoder
6 * Copyright (C) 2000-2001 Robert Leslie
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.
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.
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.
24 #include "FLAC/assert.h"
29 #define max(a,b) ((a)>(b)?(a):(b))
33 #define FLAC__INLINE __inline
38 /* 32-bit pseudo-random number generator
40 * @@@ According to Miroslav, this one is poor quality, the one from the
41 * @@@ original replaygain code is much better
43 static FLAC__INLINE FLAC__uint32 prng(FLAC__uint32 state)
45 return (state * 0x0019660dL + 0x3c6ef35fL) & 0xffffffffL;
48 /* dither routine derived from MAD winamp plugin */
55 static 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 FLAC__int32 output, mask, random;
60 FLAC__ASSERT(source_bps < 32);
61 FLAC__ASSERT(target_bps <= 24);
62 FLAC__ASSERT(target_bps <= source_bps);
65 sample += dither->error[0] - dither->error[1] + dither->error[2];
67 dither->error[2] = dither->error[1];
68 dither->error[1] = dither->error[0] / 2;
71 output = sample + (1L << (source_bps - target_bps - 1));
73 scalebits = source_bps - target_bps;
74 mask = (1L << scalebits) - 1;
77 random = (FLAC__int32)prng(dither->random);
78 output += (random & mask) - (dither->random & mask);
80 dither->random = random;
89 else if(output < MIN) {
100 dither->error[0] = sample - output;
103 return output >> scalebits;
106 unsigned 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)
108 static dither_state dither[FLAC_PLUGIN__MAX_SUPPORTED_CHANNELS];
109 FLAC__byte * const start = data;
111 const FLAC__int32 *input_;
112 unsigned samples, channel;
113 const unsigned bytes_per_sample = target_bps / 8;
114 unsigned inc = bytes_per_sample * channels;
116 FLAC__ASSERT(channels > 0 && channels <= FLAC_PLUGIN__MAX_SUPPORTED_CHANNELS);
117 FLAC__ASSERT(source_bps < 32);
118 FLAC__ASSERT(target_bps <= 24);
119 FLAC__ASSERT(target_bps <= source_bps);
120 FLAC__ASSERT((source_bps & 7) == 0);
121 FLAC__ASSERT((target_bps & 7) == 0);
123 if(source_bps != target_bps) {
124 const FLAC__int32 MIN = -(1L << (source_bps - 1));
125 const FLAC__int32 MAX = ~MIN; /*(1L << (source_bps-1)) - 1 */
127 for(channel = 0; channel < channels; channel++) {
129 samples = wide_samples;
130 data = start + bytes_per_sample * channel;
131 input_ = input[channel];
134 sample = linear_dither(source_bps, target_bps, *input_++, &dither[channel], MIN, MAX);
138 data[0] = sample ^ 0x80;
141 data[0] = (FLAC__byte)(sample >> 8);
142 data[1] = (FLAC__byte)sample;
145 data[0] = (FLAC__byte)(sample >> 16);
146 data[1] = (FLAC__byte)(sample >> 8);
147 data[2] = (FLAC__byte)sample;
156 for(channel = 0; channel < channels; channel++) {
157 samples = wide_samples;
158 data = start + bytes_per_sample * channel;
159 input_ = input[channel];
166 data[0] = sample ^ 0x80;
169 data[0] = (FLAC__byte)(sample >> 8);
170 data[1] = (FLAC__byte)sample;
173 data[0] = (FLAC__byte)(sample >> 16);
174 data[1] = (FLAC__byte)(sample >> 8);
175 data[2] = (FLAC__byte)sample;
187 unsigned 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)
189 static dither_state dither[FLAC_PLUGIN__MAX_SUPPORTED_CHANNELS];
190 FLAC__byte * const start = data;
192 const FLAC__int32 *input_;
193 unsigned samples, channel;
194 const unsigned bytes_per_sample = target_bps / 8;
195 unsigned inc = bytes_per_sample * channels;
197 FLAC__ASSERT(channels > 0 && channels <= FLAC_PLUGIN__MAX_SUPPORTED_CHANNELS);
198 FLAC__ASSERT(source_bps < 32);
199 FLAC__ASSERT(target_bps <= 24);
200 FLAC__ASSERT(target_bps <= source_bps);
201 FLAC__ASSERT((source_bps & 7) == 0);
202 FLAC__ASSERT((target_bps & 7) == 0);
204 if(source_bps != target_bps) {
205 const FLAC__int32 MIN = -(1L << (source_bps - 1));
206 const FLAC__int32 MAX = ~MIN; /*(1L << (source_bps-1)) - 1 */
208 for(channel = 0; channel < channels; channel++) {
210 samples = wide_samples;
211 data = start + bytes_per_sample * channel;
212 input_ = input[channel];
215 sample = linear_dither(source_bps, target_bps, *input_++, &dither[channel], MIN, MAX);
219 data[0] = sample ^ 0x80;
222 data[2] = (FLAC__byte)(sample >> 16);
225 data[1] = (FLAC__byte)(sample >> 8);
226 data[0] = (FLAC__byte)sample;
234 for(channel = 0; channel < channels; channel++) {
235 samples = wide_samples;
236 data = start + bytes_per_sample * channel;
237 input_ = input[channel];
244 data[0] = sample ^ 0x80;
247 data[2] = (FLAC__byte)(sample >> 16);
250 data[1] = (FLAC__byte)(sample >> 8);
251 data[0] = (FLAC__byte)sample;