code.delx.au - pulseaudio/blob - src/pulse/volume.c

   1 /***
   2   This file is part of PulseAudio.
   3
   4   Copyright 2004-2006 Lennart Poettering
   5
   6   PulseAudio is free software; you can redistribute it and/or modify
   7   it under the terms of the GNU Lesser General Public License as published
   8   by the Free Software Foundation; either version 2.1 of the License,
   9   or (at your option) any later version.
  10
  11   PulseAudio is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with PulseAudio; if not, write to the Free Software
  18   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
  19   USA.
  20 ***/
  21
  22 #ifdef HAVE_CONFIG_H
  23 #include <config.h>
  24 #endif
  25
  26 #include <stdio.h>
  27 #include <string.h>
  28
  29 #include <pulse/i18n.h>
  30
  31 #include <pulsecore/core-util.h>
  32 #include <pulsecore/macro.h>
  33 #include <pulsecore/sample-util.h>
  34
  35 #include "volume.h"
  36
  37 int pa_cvolume_equal(const pa_cvolume *a, const pa_cvolume *b) {
  38     int i;
  39     pa_assert(a);
  40     pa_assert(b);
  41
  42     pa_return_val_if_fail(pa_cvolume_valid(a), 0);
  43     pa_return_val_if_fail(pa_cvolume_valid(b), 0);
  44
  45     if (a->channels != b->channels)
  46         return 0;
  47
  48     for (i = 0; i < a->channels; i++)
  49         if (a->values[i] != b->values[i])
  50             return 0;
  51
  52     return 1;
  53 }
  54
  55 pa_cvolume* pa_cvolume_init(pa_cvolume *a) {
  56     unsigned c;
  57
  58     pa_assert(a);
  59
  60     a->channels = 0;
  61
  62     for (c = 0; c < PA_CHANNELS_MAX; c++)
  63         a->values[c] = (pa_volume_t) -1;
  64
  65     return a;
  66 }
  67
  68 pa_cvolume* pa_cvolume_set(pa_cvolume *a, unsigned channels, pa_volume_t v) {
  69     int i;
  70
  71     pa_assert(a);
  72     pa_assert(channels > 0);
  73     pa_assert(channels <= PA_CHANNELS_MAX);
  74
  75     a->channels = (uint8_t) channels;
  76
  77     for (i = 0; i < a->channels; i++)
  78         a->values[i] = v;
  79
  80     return a;
  81 }
  82
  83 pa_volume_t pa_cvolume_avg(const pa_cvolume *a) {
  84     uint64_t sum = 0;
  85     unsigned c;
  86
  87     pa_assert(a);
  88     pa_return_val_if_fail(pa_cvolume_valid(a), PA_VOLUME_MUTED);
  89
  90     for (c = 0; c < a->channels; c++)
  91         sum += a->values[c];
  92
  93     sum /= a->channels;
  94
  95     return (pa_volume_t) sum;
  96 }
  97
  98 pa_volume_t pa_cvolume_avg_mask(const pa_cvolume *a, const pa_channel_map *cm, pa_channel_position_mask_t mask) {
  99     uint64_t sum = 0;
 100     unsigned c, n;
 101
 102     pa_assert(a);
 103
 104     if (!cm)
 105         return pa_cvolume_avg(a);
 106
 107     pa_return_val_if_fail(pa_cvolume_compatible_with_channel_map(a, cm), PA_VOLUME_MUTED);
 108
 109     for (c = n = 0; c < a->channels; c++) {
 110
 111         if (!(PA_CHANNEL_POSITION_MASK(cm->map[c]) & mask))
 112             continue;
 113
 114         sum += a->values[c];
 115         n ++;
 116     }
 117
 118     if (n > 0)
 119         sum /= n;
 120
 121     return (pa_volume_t) sum;
 122 }
 123
 124 pa_volume_t pa_cvolume_max(const pa_cvolume *a) {
 125     pa_volume_t m = 0;
 126     unsigned c;
 127
 128     pa_assert(a);
 129     pa_return_val_if_fail(pa_cvolume_valid(a), PA_VOLUME_MUTED);
 130
 131     for (c = 0; c < a->channels; c++)
 132         if (a->values[c] > m)
 133             m = a->values[c];
 134
 135     return m;
 136 }
 137
 138 pa_volume_t pa_cvolume_max_mask(const pa_cvolume *a, const pa_channel_map *cm, pa_channel_position_mask_t mask) {
 139     pa_volume_t m = 0;
 140     unsigned c, n;
 141
 142     pa_assert(a);
 143
 144     if (!cm)
 145         return pa_cvolume_max(a);
 146
 147     pa_return_val_if_fail(pa_cvolume_compatible_with_channel_map(a, cm), PA_VOLUME_MUTED);
 148
 149     for (c = n = 0; c < a->channels; c++) {
 150
 151         if (!(PA_CHANNEL_POSITION_MASK(cm->map[c]) & mask))
 152             continue;
 153
 154         if (a->values[c] > m)
 155             m = a->values[c];
 156     }
 157
 158     return m;
 159 }
 160
 161 pa_volume_t pa_sw_volume_multiply(pa_volume_t a, pa_volume_t b) {
 162     return pa_sw_volume_from_linear(pa_sw_volume_to_linear(a) * pa_sw_volume_to_linear(b));
 163 }
 164
 165 pa_volume_t pa_sw_volume_divide(pa_volume_t a, pa_volume_t b) {
 166     double v = pa_sw_volume_to_linear(b);
 167
 168     if (v <= 0)
 169         return 0;
 170
 171     return pa_sw_volume_from_linear(pa_sw_volume_to_linear(a) / v);
 172 }
 173
 174 /* Amplitude, not power */
 175 static double linear_to_dB(double v) {
 176     return 20.0 * log10(v);
 177 }
 178
 179 static double dB_to_linear(double v) {
 180     return pow(10.0, v / 20.0);
 181 }
 182
 183 pa_volume_t pa_sw_volume_from_dB(double dB) {
 184     if (isinf(dB) < 0 || dB <= PA_DECIBEL_MININFTY)
 185         return PA_VOLUME_MUTED;
 186
 187     return pa_sw_volume_from_linear(dB_to_linear(dB));
 188 }
 189
 190 double pa_sw_volume_to_dB(pa_volume_t v) {
 191
 192     if (v <= PA_VOLUME_MUTED)
 193         return PA_DECIBEL_MININFTY;
 194
 195     return linear_to_dB(pa_sw_volume_to_linear(v));
 196 }
 197
 198 pa_volume_t pa_sw_volume_from_linear(double v) {
 199
 200     if (v <= 0.0)
 201         return PA_VOLUME_MUTED;
 202
 203     /*
 204      * We use a cubic mapping here, as suggested and discussed here:
 205      *
 206      * http://www.robotplanet.dk/audio/audio_gui_design/
 207      * http://lists.linuxaudio.org/pipermail/linux-audio-dev/2009-May/thread.html#23151
 208      */
 209
 210     return (pa_volume_t) (cbrt(v) * PA_VOLUME_NORM);
 211 }
 212
 213 double pa_sw_volume_to_linear(pa_volume_t v) {
 214     double f;
 215
 216     if (v <= PA_VOLUME_MUTED)
 217         return 0.0;
 218
 219     if (v == PA_VOLUME_NORM)
 220         return 1.0;
 221
 222     f = ((double) v / PA_VOLUME_NORM);
 223
 224     return f*f*f;
 225 }
 226
 227 char *pa_cvolume_snprint(char *s, size_t l, const pa_cvolume *c) {
 228     unsigned channel;
 229     pa_bool_t first = TRUE;
 230     char *e;
 231
 232     pa_assert(s);
 233     pa_assert(l > 0);
 234     pa_assert(c);
 235
 236     pa_init_i18n();
 237
 238     if (!pa_cvolume_valid(c)) {
 239         pa_snprintf(s, l, _("(invalid)"));
 240         return s;
 241     }
 242
 243     *(e = s) = 0;
 244
 245     for (channel = 0; channel < c->channels && l > 1; channel++) {
 246         l -= pa_snprintf(e, l, "%s%u: %3u%%",
 247                       first ? "" : " ",
 248                       channel,
 249                       (c->values[channel]*100)/PA_VOLUME_NORM);
 250
 251         e = strchr(e, 0);
 252         first = FALSE;
 253     }
 254
 255     return s;
 256 }
 257
 258 char *pa_volume_snprint(char *s, size_t l, pa_volume_t v) {
 259     pa_assert(s);
 260     pa_assert(l > 0);
 261
 262     pa_init_i18n();
 263
 264     if (v == (pa_volume_t) -1) {
 265         pa_snprintf(s, l, _("(invalid)"));
 266         return s;
 267     }
 268
 269     pa_snprintf(s, l, "%3u%%", (v*100)/PA_VOLUME_NORM);
 270     return s;
 271 }
 272
 273 char *pa_sw_cvolume_snprint_dB(char *s, size_t l, const pa_cvolume *c) {
 274     unsigned channel;
 275     pa_bool_t first = TRUE;
 276     char *e;
 277
 278     pa_assert(s);
 279     pa_assert(l > 0);
 280     pa_assert(c);
 281
 282     pa_init_i18n();
 283
 284     if (!pa_cvolume_valid(c)) {
 285         pa_snprintf(s, l, _("(invalid)"));
 286         return s;
 287     }
 288
 289     *(e = s) = 0;
 290
 291     for (channel = 0; channel < c->channels && l > 1; channel++) {
 292         double f = pa_sw_volume_to_dB(c->values[channel]);
 293
 294         l -= pa_snprintf(e, l, "%s%u: %0.2f dB",
 295                          first ? "" : " ",
 296                          channel,
 297                          isinf(f) < 0 || f <= PA_DECIBEL_MININFTY ? -INFINITY : f);
 298
 299         e = strchr(e, 0);
 300         first = FALSE;
 301     }
 302
 303     return s;
 304 }
 305
 306 char *pa_sw_volume_snprint_dB(char *s, size_t l, pa_volume_t v) {
 307     double f;
 308
 309     pa_assert(s);
 310     pa_assert(l > 0);
 311
 312     pa_init_i18n();
 313
 314     if (v == (pa_volume_t) -1) {
 315         pa_snprintf(s, l, _("(invalid)"));
 316         return s;
 317     }
 318
 319     f = pa_sw_volume_to_dB(v);
 320     pa_snprintf(s, l, "%0.2f dB",
 321                 isinf(f) < 0 || f <= PA_DECIBEL_MININFTY ?  -INFINITY : f);
 322
 323     return s;
 324 }
 325
 326 int pa_cvolume_channels_equal_to(const pa_cvolume *a, pa_volume_t v) {
 327     unsigned c;
 328     pa_assert(a);
 329
 330     pa_return_val_if_fail(pa_cvolume_valid(a), 0);
 331
 332     for (c = 0; c < a->channels; c++)
 333         if (a->values[c] != v)
 334             return 0;
 335
 336     return 1;
 337 }
 338
 339 pa_cvolume *pa_sw_cvolume_multiply(pa_cvolume *dest, const pa_cvolume *a, const pa_cvolume *b) {
 340     unsigned i;
 341
 342     pa_assert(dest);
 343     pa_assert(a);
 344     pa_assert(b);
 345
 346     pa_return_val_if_fail(pa_cvolume_valid(a), NULL);
 347     pa_return_val_if_fail(pa_cvolume_valid(b), NULL);
 348
 349     for (i = 0; i < a->channels && i < b->channels; i++)
 350         dest->values[i] = pa_sw_volume_multiply(a->values[i], b->values[i]);
 351
 352     dest->channels = (uint8_t) i;
 353
 354     return dest;
 355 }
 356
 357 pa_cvolume *pa_sw_cvolume_multiply_scalar(pa_cvolume *dest, const pa_cvolume *a, pa_volume_t b) {
 358     unsigned i;
 359
 360     pa_assert(dest);
 361     pa_assert(a);
 362
 363     pa_return_val_if_fail(pa_cvolume_valid(a), NULL);
 364
 365     for (i = 0; i < a->channels; i++)
 366         dest->values[i] = pa_sw_volume_multiply(a->values[i], b);
 367
 368     dest->channels = (uint8_t) i;
 369
 370     return dest;
 371 }
 372
 373 pa_cvolume *pa_sw_cvolume_divide(pa_cvolume *dest, const pa_cvolume *a, const pa_cvolume *b) {
 374     unsigned i;
 375
 376     pa_assert(dest);
 377     pa_assert(a);
 378     pa_assert(b);
 379
 380     pa_return_val_if_fail(pa_cvolume_valid(a), NULL);
 381     pa_return_val_if_fail(pa_cvolume_valid(b), NULL);
 382
 383     for (i = 0; i < a->channels && i < b->channels; i++)
 384         dest->values[i] = pa_sw_volume_divide(a->values[i], b->values[i]);
 385
 386     dest->channels = (uint8_t) i;
 387
 388     return dest;
 389 }
 390
 391 pa_cvolume *pa_sw_cvolume_divide_scalar(pa_cvolume *dest, const pa_cvolume *a, pa_volume_t b) {
 392     unsigned i;
 393
 394     pa_assert(dest);
 395     pa_assert(a);
 396
 397     pa_return_val_if_fail(pa_cvolume_valid(a), NULL);
 398
 399     for (i = 0; i < a->channels; i++)
 400         dest->values[i] = pa_sw_volume_divide(a->values[i], b);
 401
 402     dest->channels = (uint8_t) i;
 403
 404     return dest;
 405 }
 406
 407 int pa_cvolume_valid(const pa_cvolume *v) {
 408     unsigned c;
 409
 410     pa_assert(v);
 411
 412     if (v->channels <= 0 || v->channels > PA_CHANNELS_MAX)
 413         return 0;
 414
 415     for (c = 0; c < v->channels; c++)
 416         if (v->values[c] == (pa_volume_t) -1)
 417             return 0;
 418
 419     return 1;
 420 }
 421
 422 static pa_bool_t on_left(pa_channel_position_t p) {
 423     return !!(PA_CHANNEL_POSITION_MASK(p) & PA_CHANNEL_POSITION_MASK_LEFT);
 424 }
 425
 426 static pa_bool_t on_right(pa_channel_position_t p) {
 427     return !!(PA_CHANNEL_POSITION_MASK(p) & PA_CHANNEL_POSITION_MASK_RIGHT);
 428 }
 429
 430 static pa_bool_t on_center(pa_channel_position_t p) {
 431     return !!(PA_CHANNEL_POSITION_MASK(p) & PA_CHANNEL_POSITION_MASK_CENTER);
 432 }
 433
 434 static pa_bool_t on_lfe(pa_channel_position_t p) {
 435     return p == PA_CHANNEL_POSITION_LFE;
 436 }
 437
 438 static pa_bool_t on_front(pa_channel_position_t p) {
 439     return !!(PA_CHANNEL_POSITION_MASK(p) & PA_CHANNEL_POSITION_MASK_FRONT);
 440 }
 441
 442 static pa_bool_t on_rear(pa_channel_position_t p) {
 443     return !!(PA_CHANNEL_POSITION_MASK(p) & PA_CHANNEL_POSITION_MASK_REAR);
 444 }
 445
 446 pa_cvolume *pa_cvolume_remap(pa_cvolume *v, const pa_channel_map *from, const pa_channel_map *to) {
 447     int a, b;
 448     pa_cvolume result;
 449
 450     pa_assert(v);
 451     pa_assert(from);
 452     pa_assert(to);
 453
 454     pa_return_val_if_fail(pa_cvolume_valid(v), NULL);
 455     pa_return_val_if_fail(pa_channel_map_valid(from), NULL);
 456     pa_return_val_if_fail(pa_channel_map_valid(to), NULL);
 457     pa_return_val_if_fail(pa_cvolume_compatible_with_channel_map(v, from), NULL);
 458
 459     if (pa_channel_map_equal(from, to))
 460         return v;
 461
 462     result.channels = to->channels;
 463
 464     for (b = 0; b < to->channels; b++) {
 465         pa_volume_t k = 0;
 466         int n = 0;
 467
 468         for (a = 0; a < from->channels; a++)
 469             if (from->map[a] == to->map[b]) {
 470                 k += v->values[a];
 471                 n ++;
 472             }
 473
 474         if (n <= 0) {
 475             for (a = 0; a < from->channels; a++)
 476                 if ((on_left(from->map[a]) && on_left(to->map[b])) ||
 477                     (on_right(from->map[a]) && on_right(to->map[b])) ||
 478                     (on_center(from->map[a]) && on_center(to->map[b])) ||
 479                     (on_lfe(from->map[a]) && on_lfe(to->map[b]))) {
 480
 481                     k += v->values[a];
 482                     n ++;
 483                 }
 484         }
 485
 486         if (n <= 0)
 487             k = pa_cvolume_avg(v);
 488         else
 489             k /= n;
 490
 491         result.values[b] = k;
 492     }
 493
 494     *v = result;
 495     return v;
 496 }
 497
 498 int pa_cvolume_compatible(const pa_cvolume *v, const pa_sample_spec *ss) {
 499
 500     pa_assert(v);
 501     pa_assert(ss);
 502
 503     pa_return_val_if_fail(pa_cvolume_valid(v), 0);
 504     pa_return_val_if_fail(pa_sample_spec_valid(ss), 0);
 505
 506     return v->channels == ss->channels;
 507 }
 508
 509 int pa_cvolume_compatible_with_channel_map(const pa_cvolume *v, const pa_channel_map *cm) {
 510     pa_assert(v);
 511     pa_assert(cm);
 512
 513     pa_return_val_if_fail(pa_cvolume_valid(v), 0);
 514     pa_return_val_if_fail(pa_channel_map_valid(cm), 0);
 515
 516     return v->channels == cm->channels;
 517 }
 518
 519 static void get_avg_lr(const pa_channel_map *map, const pa_cvolume *v, pa_volume_t *l, pa_volume_t *r) {
 520     int c;
 521     pa_volume_t left = 0, right = 0;
 522     unsigned n_left = 0, n_right = 0;
 523
 524     pa_assert(v);
 525     pa_assert(map);
 526     pa_assert(map->channels == v->channels);
 527     pa_assert(l);
 528     pa_assert(r);
 529
 530     for (c = 0; c < map->channels; c++) {
 531         if (on_left(map->map[c])) {
 532             left += v->values[c];
 533             n_left++;
 534         } else if (on_right(map->map[c])) {
 535             right += v->values[c];
 536             n_right++;
 537         }
 538     }
 539
 540     if (n_left <= 0)
 541         *l = PA_VOLUME_NORM;
 542     else
 543         *l = left / n_left;
 544
 545     if (n_right <= 0)
 546         *r = PA_VOLUME_NORM;
 547     else
 548         *r = right / n_right;
 549 }
 550
 551 float pa_cvolume_get_balance(const pa_cvolume *v, const pa_channel_map *map) {
 552     pa_volume_t left, right;
 553
 554     pa_assert(v);
 555     pa_assert(map);
 556
 557     pa_return_val_if_fail(pa_cvolume_valid(v), 0.0f);
 558     pa_return_val_if_fail(pa_channel_map_valid(map), 0.0f);
 559     pa_return_val_if_fail(pa_cvolume_compatible_with_channel_map(v, map), 0.0f);
 560
 561     if (!pa_channel_map_can_balance(map))
 562         return 0.0f;
 563
 564     get_avg_lr(map, v, &left, &right);
 565
 566     if (left == right)
 567         return 0.0f;
 568
 569     /*   1.0,  0.0  =>  -1.0
 570          0.0,  1.0  =>   1.0
 571          0.0,  0.0  =>   0.0
 572          0.5,  0.5  =>   0.0
 573          1.0,  0.5  =>  -0.5
 574          1.0,  0.25 => -0.75
 575          0.75, 0.25 => -0.66
 576          0.5,  0.25 => -0.5   */
 577
 578     if (left > right)
 579         return -1.0f + ((float) right / (float) left);
 580     else
 581         return 1.0f - ((float) left / (float) right);
 582 }
 583
 584 pa_cvolume* pa_cvolume_set_balance(pa_cvolume *v, const pa_channel_map *map, float new_balance) {
 585     pa_volume_t left, nleft, right, nright, m;
 586     unsigned c;
 587
 588     pa_assert(map);
 589     pa_assert(v);
 590     pa_assert(new_balance >= -1.0f);
 591     pa_assert(new_balance <= 1.0f);
 592
 593     pa_return_val_if_fail(pa_cvolume_valid(v), NULL);
 594     pa_return_val_if_fail(pa_channel_map_valid(map), NULL);
 595     pa_return_val_if_fail(pa_cvolume_compatible_with_channel_map(v, map), NULL);
 596
 597     if (!pa_channel_map_can_balance(map))
 598         return v;
 599
 600     get_avg_lr(map, v, &left, &right);
 601
 602     m = PA_MAX(left, right);
 603
 604     if (new_balance <= 0) {
 605         nright  = (new_balance + 1.0f) * m;
 606         nleft = m;
 607     } else  {
 608         nleft = (1.0f - new_balance) * m;
 609         nright = m;
 610     }
 611
 612     for (c = 0; c < map->channels; c++) {
 613         if (on_left(map->map[c])) {
 614             if (left == 0)
 615                 v->values[c] = nleft;
 616             else
 617                 v->values[c] = (pa_volume_t) (((uint64_t) v->values[c] * (uint64_t) nleft) / (uint64_t) left);
 618         } else if (on_right(map->map[c])) {
 619             if (right == 0)
 620                 v->values[c] = nright;
 621             else
 622                 v->values[c] = (pa_volume_t) (((uint64_t) v->values[c] * (uint64_t) nright) / (uint64_t) right);
 623         }
 624     }
 625
 626     return v;
 627 }
 628
 629 pa_cvolume* pa_cvolume_scale(pa_cvolume *v, pa_volume_t max) {
 630     unsigned c;
 631     pa_volume_t t = 0;
 632
 633     pa_assert(v);
 634
 635     pa_return_val_if_fail(pa_cvolume_valid(v), NULL);
 636     pa_return_val_if_fail(max != (pa_volume_t) -1, NULL);
 637
 638     t = pa_cvolume_max(v);
 639
 640     if (t <= PA_VOLUME_MUTED)
 641         return pa_cvolume_set(v, v->channels, max);
 642
 643     for (c = 0; c < v->channels; c++)
 644         v->values[c] = (pa_volume_t) (((uint64_t)  v->values[c] * (uint64_t) max) / (uint64_t) t);
 645
 646     return v;
 647 }
 648
 649 pa_cvolume* pa_cvolume_scale_mask(pa_cvolume *v, pa_volume_t max, pa_channel_map *cm, pa_channel_position_mask_t mask) {
 650     unsigned c;
 651     pa_volume_t t = 0;
 652
 653     pa_assert(v);
 654
 655     pa_return_val_if_fail(pa_cvolume_valid(v), NULL);
 656     pa_return_val_if_fail(max != (pa_volume_t) -1, NULL);
 657
 658     t = pa_cvolume_max_mask(v, cm, mask);
 659
 660     if (t <= PA_VOLUME_MUTED)
 661         return pa_cvolume_set(v, v->channels, max);
 662
 663     for (c = 0; c < v->channels; c++)
 664         v->values[c] = (pa_volume_t) (((uint64_t)  v->values[c] * (uint64_t) max) / (uint64_t) t);
 665
 666     return v;
 667 }
 668
 669 static void get_avg_fr(const pa_channel_map *map, const pa_cvolume *v, pa_volume_t *f, pa_volume_t *r) {
 670     int c;
 671     pa_volume_t front = 0, rear = 0;
 672     unsigned n_front = 0, n_rear = 0;
 673
 674     pa_assert(v);
 675     pa_assert(map);
 676     pa_assert(map->channels == v->channels);
 677     pa_assert(f);
 678     pa_assert(r);
 679
 680     for (c = 0; c < map->channels; c++) {
 681         if (on_front(map->map[c])) {
 682             front += v->values[c];
 683             n_front++;
 684         } else if (on_rear(map->map[c])) {
 685             rear += v->values[c];
 686             n_rear++;
 687         }
 688     }
 689
 690     if (n_front <= 0)
 691         *f = PA_VOLUME_NORM;
 692     else
 693         *f = front / n_front;
 694
 695     if (n_rear <= 0)
 696         *r = PA_VOLUME_NORM;
 697     else
 698         *r = rear / n_rear;
 699 }
 700
 701 float pa_cvolume_get_fade(const pa_cvolume *v, const pa_channel_map *map) {
 702     pa_volume_t front, rear;
 703
 704     pa_assert(v);
 705     pa_assert(map);
 706
 707     pa_return_val_if_fail(pa_cvolume_valid(v), 0.0f);
 708     pa_return_val_if_fail(pa_channel_map_valid(map), 0.0f);
 709     pa_return_val_if_fail(pa_cvolume_compatible_with_channel_map(v, map), 0.0f);
 710
 711     if (!pa_channel_map_can_fade(map))
 712         return 0.0f;
 713
 714     get_avg_fr(map, v, &front, &rear);
 715
 716     if (front == rear)
 717         return 0.0f;
 718
 719     if (rear > front)
 720         return -1.0f + ((float) front / (float) rear);
 721     else
 722         return 1.0f - ((float) rear / (float) front);
 723 }
 724
 725 pa_cvolume* pa_cvolume_set_fade(pa_cvolume *v, const pa_channel_map *map, float new_fade) {
 726     pa_volume_t front, nfront, rear, nrear, m;
 727     unsigned c;
 728
 729     pa_assert(map);
 730     pa_assert(v);
 731     pa_assert(new_fade >= -1.0f);
 732     pa_assert(new_fade <= 1.0f);
 733
 734     pa_return_val_if_fail(pa_cvolume_valid(v), NULL);
 735     pa_return_val_if_fail(pa_channel_map_valid(map), NULL);
 736     pa_return_val_if_fail(pa_cvolume_compatible_with_channel_map(v, map), NULL);
 737
 738     if (!pa_channel_map_can_fade(map))
 739         return v;
 740
 741     get_avg_fr(map, v, &front, &rear);
 742
 743     m = PA_MAX(front, rear);
 744
 745     if (new_fade <= 0) {
 746         nfront  = (new_fade + 1.0f) * m;
 747         nrear = m;
 748     } else  {
 749         nrear = (1.0f - new_fade) * m;
 750         nfront = m;
 751     }
 752
 753     for (c = 0; c < map->channels; c++) {
 754         if (on_front(map->map[c])) {
 755             if (front == 0)
 756                 v->values[c] = nfront;
 757             else
 758                 v->values[c] = (pa_volume_t) (((uint64_t) v->values[c] * (uint64_t) nfront) / (uint64_t) front);
 759         } else if (on_rear(map->map[c])) {
 760             if (rear == 0)
 761                 v->values[c] = nrear;
 762             else
 763                 v->values[c] = (pa_volume_t) (((uint64_t) v->values[c] * (uint64_t) nrear) / (uint64_t) rear);
 764         }
 765     }
 766
 767     return v;
 768 }
 769
 770 pa_cvolume* pa_cvolume_set_position(
 771         pa_cvolume *cv,
 772         const pa_channel_map *map,
 773         pa_channel_position_t t,
 774         pa_volume_t v) {
 775
 776     unsigned c;
 777     pa_bool_t good = FALSE;
 778
 779     pa_assert(cv);
 780     pa_assert(map);
 781
 782     pa_return_val_if_fail(pa_cvolume_compatible_with_channel_map(cv, map), NULL);
 783     pa_return_val_if_fail(t < PA_CHANNEL_POSITION_MAX, NULL);
 784
 785     for (c = 0; c < map->channels; c++)
 786         if (map->map[c] == t) {
 787             cv->values[c] = v;
 788             good = TRUE;
 789         }
 790
 791     return good ? cv : NULL;
 792 }
 793
 794 pa_volume_t pa_cvolume_get_position(
 795         pa_cvolume *cv,
 796         const pa_channel_map *map,
 797         pa_channel_position_t t) {
 798
 799     unsigned c;
 800     pa_volume_t v = PA_VOLUME_MUTED;
 801
 802     pa_assert(cv);
 803     pa_assert(map);
 804
 805     pa_return_val_if_fail(pa_cvolume_compatible_with_channel_map(cv, map), PA_VOLUME_MUTED);
 806     pa_return_val_if_fail(t < PA_CHANNEL_POSITION_MAX, PA_VOLUME_MUTED);
 807
 808     for (c = 0; c < map->channels; c++)
 809         if (map->map[c] == t)
 810             if (cv->values[c] > v)
 811                 v = cv->values[c];
 812
 813     return v;
 814 }