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Diffstat (limited to 'lib/rbcodec/dsp/compressor.c')
-rw-r--r-- | lib/rbcodec/dsp/compressor.c | 363 |
1 files changed, 363 insertions, 0 deletions
diff --git a/lib/rbcodec/dsp/compressor.c b/lib/rbcodec/dsp/compressor.c new file mode 100644 index 0000000000..3a8d52e4da --- /dev/null +++ b/lib/rbcodec/dsp/compressor.c | |||
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1 | /*************************************************************************** | ||
2 | * __________ __ ___. | ||
3 | * Open \______ \ ____ ____ | | _\_ |__ _______ ___ | ||
4 | * Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ / | ||
5 | * Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < < | ||
6 | * Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \ | ||
7 | * \/ \/ \/ \/ \/ | ||
8 | * $Id$ | ||
9 | * | ||
10 | * Copyright (C) 2009 Jeffrey Goode | ||
11 | * | ||
12 | * This program is free software; you can redistribute it and/or | ||
13 | * modify it under the terms of the GNU General Public License | ||
14 | * as published by the Free Software Foundation; either version 2 | ||
15 | * of the License, or (at your option) any later version. | ||
16 | * | ||
17 | * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY | ||
18 | * KIND, either express or implied. | ||
19 | * | ||
20 | ****************************************************************************/ | ||
21 | #include "config.h" | ||
22 | #include "fixedpoint.h" | ||
23 | #include "fracmul.h" | ||
24 | #include "settings.h" | ||
25 | #include "dsp.h" | ||
26 | #include "compressor.h" | ||
27 | |||
28 | /* Define LOGF_ENABLE to enable logf output in this file */ | ||
29 | /*#define LOGF_ENABLE*/ | ||
30 | #include "logf.h" | ||
31 | |||
32 | static int32_t comp_rel_slope IBSS_ATTR; /* S7.24 format */ | ||
33 | static int32_t comp_makeup_gain IBSS_ATTR; /* S7.24 format */ | ||
34 | static int32_t comp_curve[66] IBSS_ATTR; /* S7.24 format */ | ||
35 | static int32_t release_gain IBSS_ATTR; /* S7.24 format */ | ||
36 | |||
37 | #define UNITY (1L << 24) /* unity gain in S7.24 format */ | ||
38 | |||
39 | /** COMPRESSOR UPDATE | ||
40 | * Called via the menu system to configure the compressor process */ | ||
41 | bool compressor_update(void) | ||
42 | { | ||
43 | static int curr_set[5]; | ||
44 | int new_set[5] = { | ||
45 | global_settings.compressor_threshold, | ||
46 | global_settings.compressor_makeup_gain, | ||
47 | global_settings.compressor_ratio, | ||
48 | global_settings.compressor_knee, | ||
49 | global_settings.compressor_release_time}; | ||
50 | |||
51 | /* make menu values useful */ | ||
52 | int threshold = new_set[0]; | ||
53 | bool auto_gain = (new_set[1] == 1); | ||
54 | const int comp_ratios[] = {2, 4, 6, 10, 0}; | ||
55 | int ratio = comp_ratios[new_set[2]]; | ||
56 | bool soft_knee = (new_set[3] == 1); | ||
57 | int release = new_set[4] * NATIVE_FREQUENCY / 1000; | ||
58 | |||
59 | bool changed = false; | ||
60 | bool active = (threshold < 0); | ||
61 | |||
62 | for (int i = 0; i < 5; i++) | ||
63 | { | ||
64 | if (curr_set[i] != new_set[i]) | ||
65 | { | ||
66 | changed = true; | ||
67 | curr_set[i] = new_set[i]; | ||
68 | |||
69 | #if defined(ROCKBOX_HAS_LOGF) && defined(LOGF_ENABLE) | ||
70 | switch (i) | ||
71 | { | ||
72 | case 0: | ||
73 | logf(" Compressor Threshold: %d dB\tEnabled: %s", | ||
74 | threshold, active ? "Yes" : "No"); | ||
75 | break; | ||
76 | case 1: | ||
77 | logf(" Compressor Makeup Gain: %s", | ||
78 | auto_gain ? "Auto" : "Off"); | ||
79 | break; | ||
80 | case 2: | ||
81 | if (ratio) | ||
82 | { logf(" Compressor Ratio: %d:1", ratio); } | ||
83 | else | ||
84 | { logf(" Compressor Ratio: Limit"); } | ||
85 | break; | ||
86 | case 3: | ||
87 | logf(" Compressor Knee: %s", soft_knee?"Soft":"Hard"); | ||
88 | break; | ||
89 | case 4: | ||
90 | logf(" Compressor Release: %d", release); | ||
91 | break; | ||
92 | } | ||
93 | #endif | ||
94 | } | ||
95 | } | ||
96 | |||
97 | if (changed && active) | ||
98 | { | ||
99 | /* configure variables for compressor operation */ | ||
100 | static const int32_t db[] = { | ||
101 | /* positive db equivalents in S15.16 format */ | ||
102 | 0x000000, 0x241FA4, 0x1E1A5E, 0x1A94C8, | ||
103 | 0x181518, 0x1624EA, 0x148F82, 0x1338BD, | ||
104 | 0x120FD2, 0x1109EB, 0x101FA4, 0x0F4BB6, | ||
105 | 0x0E8A3C, 0x0DD840, 0x0D3377, 0x0C9A0E, | ||
106 | 0x0C0A8C, 0x0B83BE, 0x0B04A5, 0x0A8C6C, | ||
107 | 0x0A1A5E, 0x09ADE1, 0x094670, 0x08E398, | ||
108 | 0x0884F6, 0x082A30, 0x07D2FA, 0x077F0F, | ||
109 | 0x072E31, 0x06E02A, 0x0694C8, 0x064BDF, | ||
110 | 0x060546, 0x05C0DA, 0x057E78, 0x053E03, | ||
111 | 0x04FF5F, 0x04C273, 0x048726, 0x044D64, | ||
112 | 0x041518, 0x03DE30, 0x03A89B, 0x037448, | ||
113 | 0x03412A, 0x030F32, 0x02DE52, 0x02AE80, | ||
114 | 0x027FB0, 0x0251D6, 0x0224EA, 0x01F8E2, | ||
115 | 0x01CDB4, 0x01A359, 0x0179C9, 0x0150FC, | ||
116 | 0x0128EB, 0x010190, 0x00DAE4, 0x00B4E1, | ||
117 | 0x008F82, 0x006AC1, 0x004699, 0x002305}; | ||
118 | |||
119 | struct curve_point | ||
120 | { | ||
121 | int32_t db; /* S15.16 format */ | ||
122 | int32_t offset; /* S15.16 format */ | ||
123 | } db_curve[5]; | ||
124 | |||
125 | /** Set up the shape of the compression curve first as decibel | ||
126 | values */ | ||
127 | /* db_curve[0] = bottom of knee | ||
128 | [1] = threshold | ||
129 | [2] = top of knee | ||
130 | [3] = 0 db input | ||
131 | [4] = ~+12db input (2 bits clipping overhead) */ | ||
132 | |||
133 | db_curve[1].db = threshold << 16; | ||
134 | if (soft_knee) | ||
135 | { | ||
136 | /* bottom of knee is 3dB below the threshold for soft knee*/ | ||
137 | db_curve[0].db = db_curve[1].db - (3 << 16); | ||
138 | /* top of knee is 3dB above the threshold for soft knee */ | ||
139 | db_curve[2].db = db_curve[1].db + (3 << 16); | ||
140 | if (ratio) | ||
141 | /* offset = -3db * (ratio - 1) / ratio */ | ||
142 | db_curve[2].offset = (int32_t)((long long)(-3 << 16) | ||
143 | * (ratio - 1) / ratio); | ||
144 | else | ||
145 | /* offset = -3db for hard limit */ | ||
146 | db_curve[2].offset = (-3 << 16); | ||
147 | } | ||
148 | else | ||
149 | { | ||
150 | /* bottom of knee is at the threshold for hard knee */ | ||
151 | db_curve[0].db = threshold << 16; | ||
152 | /* top of knee is at the threshold for hard knee */ | ||
153 | db_curve[2].db = threshold << 16; | ||
154 | db_curve[2].offset = 0; | ||
155 | } | ||
156 | |||
157 | /* Calculate 0db and ~+12db offsets */ | ||
158 | db_curve[4].db = 0xC0A8C; /* db of 2 bits clipping */ | ||
159 | if (ratio) | ||
160 | { | ||
161 | /* offset = threshold * (ratio - 1) / ratio */ | ||
162 | db_curve[3].offset = (int32_t)((long long)(threshold << 16) | ||
163 | * (ratio - 1) / ratio); | ||
164 | db_curve[4].offset = (int32_t)((long long)-db_curve[4].db | ||
165 | * (ratio - 1) / ratio) + db_curve[3].offset; | ||
166 | } | ||
167 | else | ||
168 | { | ||
169 | /* offset = threshold for hard limit */ | ||
170 | db_curve[3].offset = (threshold << 16); | ||
171 | db_curve[4].offset = -db_curve[4].db + db_curve[3].offset; | ||
172 | } | ||
173 | |||
174 | /** Now set up the comp_curve table with compression offsets in the | ||
175 | form of gain factors in S7.24 format */ | ||
176 | /* comp_curve[0] is 0 (-infinity db) input */ | ||
177 | comp_curve[0] = UNITY; | ||
178 | /* comp_curve[1 to 63] are intermediate compression values | ||
179 | corresponding to the 6 MSB of the input values of a non-clipped | ||
180 | signal */ | ||
181 | for (int i = 1; i < 64; i++) | ||
182 | { | ||
183 | /* db constants are stored as positive numbers; | ||
184 | make them negative here */ | ||
185 | int32_t this_db = -db[i]; | ||
186 | |||
187 | /* no compression below the knee */ | ||
188 | if (this_db <= db_curve[0].db) | ||
189 | comp_curve[i] = UNITY; | ||
190 | |||
191 | /* if soft knee and below top of knee, | ||
192 | interpolate along soft knee slope */ | ||
193 | else if (soft_knee && (this_db <= db_curve[2].db)) | ||
194 | comp_curve[i] = fp_factor(fp_mul( | ||
195 | ((this_db - db_curve[0].db) / 6), | ||
196 | db_curve[2].offset, 16), 16) << 8; | ||
197 | |||
198 | /* interpolate along ratio slope above the knee */ | ||
199 | else | ||
200 | comp_curve[i] = fp_factor(fp_mul( | ||
201 | fp_div((db_curve[1].db - this_db), db_curve[1].db, 16), | ||
202 | db_curve[3].offset, 16), 16) << 8; | ||
203 | } | ||
204 | /* comp_curve[64] is the compression level of a maximum level, | ||
205 | non-clipped signal */ | ||
206 | comp_curve[64] = fp_factor(db_curve[3].offset, 16) << 8; | ||
207 | |||
208 | /* comp_curve[65] is the compression level of a maximum level, | ||
209 | clipped signal */ | ||
210 | comp_curve[65] = fp_factor(db_curve[4].offset, 16) << 8; | ||
211 | |||
212 | #if defined(ROCKBOX_HAS_LOGF) && defined(LOGF_ENABLE) | ||
213 | logf("\n *** Compression Offsets ***"); | ||
214 | /* some settings for display only, not used in calculations */ | ||
215 | db_curve[0].offset = 0; | ||
216 | db_curve[1].offset = 0; | ||
217 | db_curve[3].db = 0; | ||
218 | |||
219 | for (int i = 0; i <= 4; i++) | ||
220 | { | ||
221 | logf("Curve[%d]: db: % 6.2f\toffset: % 6.2f", i, | ||
222 | (float)db_curve[i].db / (1 << 16), | ||
223 | (float)db_curve[i].offset / (1 << 16)); | ||
224 | } | ||
225 | |||
226 | logf("\nGain factors:"); | ||
227 | for (int i = 1; i <= 65; i++) | ||
228 | { | ||
229 | debugf("%02d: %.6f ", i, (float)comp_curve[i] / UNITY); | ||
230 | if (i % 4 == 0) debugf("\n"); | ||
231 | } | ||
232 | debugf("\n"); | ||
233 | #endif | ||
234 | |||
235 | /* if using auto peak, then makeup gain is max offset - | ||
236 | .1dB headroom */ | ||
237 | comp_makeup_gain = auto_gain ? | ||
238 | fp_factor(-(db_curve[3].offset) - 0x199A, 16) << 8 : UNITY; | ||
239 | logf("Makeup gain:\t%.6f", (float)comp_makeup_gain / UNITY); | ||
240 | |||
241 | /* calculate per-sample gain change a rate of 10db over release time | ||
242 | */ | ||
243 | comp_rel_slope = 0xAF0BB2 / release; | ||
244 | logf("Release slope:\t%.6f", (float)comp_rel_slope / UNITY); | ||
245 | |||
246 | release_gain = UNITY; | ||
247 | } | ||
248 | |||
249 | return active; | ||
250 | } | ||
251 | |||
252 | /** GET COMPRESSION GAIN | ||
253 | * Returns the required gain factor in S7.24 format in order to compress the | ||
254 | * sample in accordance with the compression curve. Always 1 or less. | ||
255 | */ | ||
256 | static inline int32_t get_compression_gain(struct dsp_data *data, | ||
257 | int32_t sample) | ||
258 | { | ||
259 | const int frac_bits_offset = data->frac_bits - 15; | ||
260 | |||
261 | /* sample must be positive */ | ||
262 | if (sample < 0) | ||
263 | sample = -(sample + 1); | ||
264 | |||
265 | /* shift sample into 15 frac bit range */ | ||
266 | if (frac_bits_offset > 0) | ||
267 | sample >>= frac_bits_offset; | ||
268 | if (frac_bits_offset < 0) | ||
269 | sample <<= -frac_bits_offset; | ||
270 | |||
271 | /* normal case: sample isn't clipped */ | ||
272 | if (sample < (1 << 15)) | ||
273 | { | ||
274 | /* index is 6 MSB, rem is 9 LSB */ | ||
275 | int index = sample >> 9; | ||
276 | int32_t rem = (sample & 0x1FF) << 22; | ||
277 | |||
278 | /* interpolate from the compression curve: | ||
279 | higher gain - ((rem / (1 << 31)) * (higher gain - lower gain)) */ | ||
280 | return comp_curve[index] - (FRACMUL(rem, | ||
281 | (comp_curve[index] - comp_curve[index + 1]))); | ||
282 | } | ||
283 | /* sample is somewhat clipped, up to 2 bits of overhead */ | ||
284 | if (sample < (1 << 17)) | ||
285 | { | ||
286 | /* straight interpolation: | ||
287 | higher gain - ((clipped portion of sample * 4/3 | ||
288 | / (1 << 31)) * (higher gain - lower gain)) */ | ||
289 | return comp_curve[64] - (FRACMUL(((sample - (1 << 15)) / 3) << 16, | ||
290 | (comp_curve[64] - comp_curve[65]))); | ||
291 | } | ||
292 | |||
293 | /* sample is too clipped, return invalid value */ | ||
294 | return -1; | ||
295 | } | ||
296 | |||
297 | /** COMPRESSOR PROCESS | ||
298 | * Changes the gain of the samples according to the compressor curve | ||
299 | */ | ||
300 | void compressor_process(int count, struct dsp_data *data, int32_t *buf[]) | ||
301 | { | ||
302 | const int num_chan = data->num_channels; | ||
303 | int32_t *in_buf[2] = {buf[0], buf[1]}; | ||
304 | |||
305 | while (count-- > 0) | ||
306 | { | ||
307 | int ch; | ||
308 | /* use lowest (most compressed) gain factor of the output buffer | ||
309 | sample pair for both samples (mono is also handled correctly here) | ||
310 | */ | ||
311 | int32_t sample_gain = UNITY; | ||
312 | for (ch = 0; ch < num_chan; ch++) | ||
313 | { | ||
314 | int32_t this_gain = get_compression_gain(data, *in_buf[ch]); | ||
315 | if (this_gain < sample_gain) | ||
316 | sample_gain = this_gain; | ||
317 | } | ||
318 | |||
319 | /* perform release slope; skip if no compression and no release slope | ||
320 | */ | ||
321 | if ((sample_gain != UNITY) || (release_gain != UNITY)) | ||
322 | { | ||
323 | /* if larger offset than previous slope, start new release slope | ||
324 | */ | ||
325 | if ((sample_gain <= release_gain) && (sample_gain > 0)) | ||
326 | { | ||
327 | release_gain = sample_gain; | ||
328 | } | ||
329 | else | ||
330 | /* keep sloping towards unity gain (and ignore invalid value) */ | ||
331 | { | ||
332 | release_gain += comp_rel_slope; | ||
333 | if (release_gain > UNITY) | ||
334 | { | ||
335 | release_gain = UNITY; | ||
336 | } | ||
337 | } | ||
338 | } | ||
339 | |||
340 | /* total gain factor is the product of release gain and makeup gain, | ||
341 | but avoid computation if possible */ | ||
342 | int32_t total_gain = ((release_gain == UNITY) ? comp_makeup_gain : | ||
343 | (comp_makeup_gain == UNITY) ? release_gain : | ||
344 | FRACMUL_SHL(release_gain, comp_makeup_gain, 7)); | ||
345 | |||
346 | /* Implement the compressor: apply total gain factor (if any) to the | ||
347 | output buffer sample pair/mono sample */ | ||
348 | if (total_gain != UNITY) | ||
349 | { | ||
350 | for (ch = 0; ch < num_chan; ch++) | ||
351 | { | ||
352 | *in_buf[ch] = FRACMUL_SHL(total_gain, *in_buf[ch], 7); | ||
353 | } | ||
354 | } | ||
355 | in_buf[0]++; | ||
356 | in_buf[1]++; | ||
357 | } | ||
358 | } | ||
359 | |||
360 | void compressor_reset(void) | ||
361 | { | ||
362 | release_gain = UNITY; | ||
363 | } | ||