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      * We make sure that the conversion to linear and back yields the
 210      * same volume value! That's why we need the lround() below!
 211      */
 212
 213     return (pa_volume_t) lround(cbrt(v) * PA_VOLUME_NORM);
 214 }
 215
 216 double pa_sw_volume_to_linear(pa_volume_t v) {
 217     double f;
 218
 219     if (v <= PA_VOLUME_MUTED)
 220         return 0.0;
 221
 222     if (v == PA_VOLUME_NORM)
 223         return 1.0;
 224
 225     f = ((double) v / PA_VOLUME_NORM);
 226
 227     return f*f*f;
 228 }
 229
 230 char *pa_cvolume_snprint(char *s, size_t l, const pa_cvolume *c) {
 231     unsigned channel;
 232     pa_bool_t first = TRUE;
 233     char *e;
 234
 235     pa_assert(s);
 236     pa_assert(l > 0);
 237     pa_assert(c);
 238
 239     pa_init_i18n();
 240
 241     if (!pa_cvolume_valid(c)) {
 242         pa_snprintf(s, l, _("(invalid)"));
 243         return s;
 244     }
 245
 246     *(e = s) = 0;
 247
 248     for (channel = 0; channel < c->channels && l > 1; channel++) {
 249         l -= pa_snprintf(e, l, "%s%u: %3u%%",
 250                       first ? "" : " ",
 251                       channel,
 252                       (c->values[channel]*100)/PA_VOLUME_NORM);
 253
 254         e = strchr(e, 0);
 255         first = FALSE;
 256     }
 257
 258     return s;
 259 }
 260
 261 char *pa_volume_snprint(char *s, size_t l, pa_volume_t v) {
 262     pa_assert(s);
 263     pa_assert(l > 0);
 264
 265     pa_init_i18n();
 266
 267     if (v == (pa_volume_t) -1) {
 268         pa_snprintf(s, l, _("(invalid)"));
 269         return s;
 270     }
 271
 272     pa_snprintf(s, l, "%3u%%", (v*100)/PA_VOLUME_NORM);
 273     return s;
 274 }
 275
 276 char *pa_sw_cvolume_snprint_dB(char *s, size_t l, const pa_cvolume *c) {
 277     unsigned channel;
 278     pa_bool_t first = TRUE;
 279     char *e;
 280
 281     pa_assert(s);
 282     pa_assert(l > 0);
 283     pa_assert(c);
 284
 285     pa_init_i18n();
 286
 287     if (!pa_cvolume_valid(c)) {
 288         pa_snprintf(s, l, _("(invalid)"));
 289         return s;
 290     }
 291
 292     *(e = s) = 0;
 293
 294     for (channel = 0; channel < c->channels && l > 1; channel++) {
 295         double f = pa_sw_volume_to_dB(c->values[channel]);
 296
 297         l -= pa_snprintf(e, l, "%s%u: %0.2f dB",
 298                          first ? "" : " ",
 299                          channel,
 300                          isinf(f) < 0 || f <= PA_DECIBEL_MININFTY ? -INFINITY : f);
 301
 302         e = strchr(e, 0);
 303         first = FALSE;
 304     }
 305
 306     return s;
 307 }
 308
 309 char *pa_sw_volume_snprint_dB(char *s, size_t l, pa_volume_t v) {
 310     double f;
 311
 312     pa_assert(s);
 313     pa_assert(l > 0);
 314
 315     pa_init_i18n();
 316
 317     if (v == (pa_volume_t) -1) {
 318         pa_snprintf(s, l, _("(invalid)"));
 319         return s;
 320     }
 321
 322     f = pa_sw_volume_to_dB(v);
 323     pa_snprintf(s, l, "%0.2f dB",
 324                 isinf(f) < 0 || f <= PA_DECIBEL_MININFTY ?  -INFINITY : f);
 325
 326     return s;
 327 }
 328
 329 int pa_cvolume_channels_equal_to(const pa_cvolume *a, pa_volume_t v) {
 330     unsigned c;
 331     pa_assert(a);
 332
 333     pa_return_val_if_fail(pa_cvolume_valid(a), 0);
 334
 335     for (c = 0; c < a->channels; c++)
 336         if (a->values[c] != v)
 337             return 0;
 338
 339     return 1;
 340 }
 341
 342 pa_cvolume *pa_sw_cvolume_multiply(pa_cvolume *dest, const pa_cvolume *a, const pa_cvolume *b) {
 343     unsigned i;
 344
 345     pa_assert(dest);
 346     pa_assert(a);
 347     pa_assert(b);
 348
 349     pa_return_val_if_fail(pa_cvolume_valid(a), NULL);
 350     pa_return_val_if_fail(pa_cvolume_valid(b), NULL);
 351
 352     for (i = 0; i < a->channels && i < b->channels; i++)
 353         dest->values[i] = pa_sw_volume_multiply(a->values[i], b->values[i]);
 354
 355     dest->channels = (uint8_t) i;
 356
 357     return dest;
 358 }
 359
 360 pa_cvolume *pa_sw_cvolume_multiply_scalar(pa_cvolume *dest, const pa_cvolume *a, pa_volume_t b) {
 361     unsigned i;
 362
 363     pa_assert(dest);
 364     pa_assert(a);
 365
 366     pa_return_val_if_fail(pa_cvolume_valid(a), NULL);
 367
 368     for (i = 0; i < a->channels; i++)
 369         dest->values[i] = pa_sw_volume_multiply(a->values[i], b);
 370
 371     dest->channels = (uint8_t) i;
 372
 373     return dest;
 374 }
 375
 376 pa_cvolume *pa_sw_cvolume_divide(pa_cvolume *dest, const pa_cvolume *a, const pa_cvolume *b) {
 377     unsigned i;
 378
 379     pa_assert(dest);
 380     pa_assert(a);
 381     pa_assert(b);
 382
 383     pa_return_val_if_fail(pa_cvolume_valid(a), NULL);
 384     pa_return_val_if_fail(pa_cvolume_valid(b), NULL);
 385
 386     for (i = 0; i < a->channels && i < b->channels; i++)
 387         dest->values[i] = pa_sw_volume_divide(a->values[i], b->values[i]);
 388
 389     dest->channels = (uint8_t) i;
 390
 391     return dest;
 392 }
 393
 394 pa_cvolume *pa_sw_cvolume_divide_scalar(pa_cvolume *dest, const pa_cvolume *a, pa_volume_t b) {
 395     unsigned i;
 396
 397     pa_assert(dest);
 398     pa_assert(a);
 399
 400     pa_return_val_if_fail(pa_cvolume_valid(a), NULL);
 401
 402     for (i = 0; i < a->channels; i++)
 403         dest->values[i] = pa_sw_volume_divide(a->values[i], b);
 404
 405     dest->channels = (uint8_t) i;
 406
 407     return dest;
 408 }
 409
 410 int pa_cvolume_valid(const pa_cvolume *v) {
 411     unsigned c;
 412
 413     pa_assert(v);
 414
 415     if (v->channels <= 0 || v->channels > PA_CHANNELS_MAX)
 416         return 0;
 417
 418     for (c = 0; c < v->channels; c++)
 419         if (v->values[c] == (pa_volume_t) -1)
 420             return 0;
 421
 422     return 1;
 423 }
 424
 425 static pa_bool_t on_left(pa_channel_position_t p) {
 426     return !!(PA_CHANNEL_POSITION_MASK(p) & PA_CHANNEL_POSITION_MASK_LEFT);
 427 }
 428
 429 static pa_bool_t on_right(pa_channel_position_t p) {
 430     return !!(PA_CHANNEL_POSITION_MASK(p) & PA_CHANNEL_POSITION_MASK_RIGHT);
 431 }
 432
 433 static pa_bool_t on_center(pa_channel_position_t p) {
 434     return !!(PA_CHANNEL_POSITION_MASK(p) & PA_CHANNEL_POSITION_MASK_CENTER);
 435 }
 436
 437 static pa_bool_t on_lfe(pa_channel_position_t p) {
 438     return p == PA_CHANNEL_POSITION_LFE;
 439 }
 440
 441 static pa_bool_t on_front(pa_channel_position_t p) {
 442     return !!(PA_CHANNEL_POSITION_MASK(p) & PA_CHANNEL_POSITION_MASK_FRONT);
 443 }
 444
 445 static pa_bool_t on_rear(pa_channel_position_t p) {
 446     return !!(PA_CHANNEL_POSITION_MASK(p) & PA_CHANNEL_POSITION_MASK_REAR);
 447 }
 448
 449 pa_cvolume *pa_cvolume_remap(pa_cvolume *v, const pa_channel_map *from, const pa_channel_map *to) {
 450     int a, b;
 451     pa_cvolume result;
 452
 453     pa_assert(v);
 454     pa_assert(from);
 455     pa_assert(to);
 456
 457     pa_return_val_if_fail(pa_cvolume_valid(v), NULL);
 458     pa_return_val_if_fail(pa_channel_map_valid(from), NULL);
 459     pa_return_val_if_fail(pa_channel_map_valid(to), NULL);
 460     pa_return_val_if_fail(pa_cvolume_compatible_with_channel_map(v, from), NULL);
 461
 462     if (pa_channel_map_equal(from, to))
 463         return v;
 464
 465     result.channels = to->channels;
 466
 467     for (b = 0; b < to->channels; b++) {
 468         pa_volume_t k = 0;
 469         int n = 0;
 470
 471         for (a = 0; a < from->channels; a++)
 472             if (from->map[a] == to->map[b]) {
 473                 k += v->values[a];
 474                 n ++;
 475             }
 476
 477         if (n <= 0) {
 478             for (a = 0; a < from->channels; a++)
 479                 if ((on_left(from->map[a]) && on_left(to->map[b])) ||
 480                     (on_right(from->map[a]) && on_right(to->map[b])) ||
 481                     (on_center(from->map[a]) && on_center(to->map[b])) ||
 482                     (on_lfe(from->map[a]) && on_lfe(to->map[b]))) {
 483
 484                     k += v->values[a];
 485                     n ++;
 486                 }
 487         }
 488
 489         if (n <= 0)
 490             k = pa_cvolume_avg(v);
 491         else
 492             k /= n;
 493
 494         result.values[b] = k;
 495     }
 496
 497     *v = result;
 498     return v;
 499 }
 500
 501 int pa_cvolume_compatible(const pa_cvolume *v, const pa_sample_spec *ss) {
 502
 503     pa_assert(v);
 504     pa_assert(ss);
 505
 506     pa_return_val_if_fail(pa_cvolume_valid(v), 0);
 507     pa_return_val_if_fail(pa_sample_spec_valid(ss), 0);
 508
 509     return v->channels == ss->channels;
 510 }
 511
 512 int pa_cvolume_compatible_with_channel_map(const pa_cvolume *v, const pa_channel_map *cm) {
 513     pa_assert(v);
 514     pa_assert(cm);
 515
 516     pa_return_val_if_fail(pa_cvolume_valid(v), 0);
 517     pa_return_val_if_fail(pa_channel_map_valid(cm), 0);
 518
 519     return v->channels == cm->channels;
 520 }
 521
 522 static void get_avg_lr(const pa_channel_map *map, const pa_cvolume *v, pa_volume_t *l, pa_volume_t *r) {
 523     int c;
 524     pa_volume_t left = 0, right = 0;
 525     unsigned n_left = 0, n_right = 0;
 526
 527     pa_assert(v);
 528     pa_assert(map);
 529     pa_assert(map->channels == v->channels);
 530     pa_assert(l);
 531     pa_assert(r);
 532
 533     for (c = 0; c < map->channels; c++) {
 534         if (on_left(map->map[c])) {
 535             left += v->values[c];
 536             n_left++;
 537         } else if (on_right(map->map[c])) {
 538             right += v->values[c];
 539             n_right++;
 540         }
 541     }
 542
 543     if (n_left <= 0)
 544         *l = PA_VOLUME_NORM;
 545     else
 546         *l = left / n_left;
 547
 548     if (n_right <= 0)
 549         *r = PA_VOLUME_NORM;
 550     else
 551         *r = right / n_right;
 552 }
 553
 554 float pa_cvolume_get_balance(const pa_cvolume *v, const pa_channel_map *map) {
 555     pa_volume_t left, right;
 556
 557     pa_assert(v);
 558     pa_assert(map);
 559
 560     pa_return_val_if_fail(pa_cvolume_valid(v), 0.0f);
 561     pa_return_val_if_fail(pa_channel_map_valid(map), 0.0f);
 562     pa_return_val_if_fail(pa_cvolume_compatible_with_channel_map(v, map), 0.0f);
 563
 564     if (!pa_channel_map_can_balance(map))
 565         return 0.0f;
 566
 567     get_avg_lr(map, v, &left, &right);
 568
 569     if (left == right)
 570         return 0.0f;
 571
 572     /*   1.0,  0.0  =>  -1.0
 573          0.0,  1.0  =>   1.0
 574          0.0,  0.0  =>   0.0
 575          0.5,  0.5  =>   0.0
 576          1.0,  0.5  =>  -0.5
 577          1.0,  0.25 => -0.75
 578          0.75, 0.25 => -0.66
 579          0.5,  0.25 => -0.5   */
 580
 581     if (left > right)
 582         return -1.0f + ((float) right / (float) left);
 583     else
 584         return 1.0f - ((float) left / (float) right);
 585 }
 586
 587 pa_cvolume* pa_cvolume_set_balance(pa_cvolume *v, const pa_channel_map *map, float new_balance) {
 588     pa_volume_t left, nleft, right, nright, m;
 589     unsigned c;
 590
 591     pa_assert(map);
 592     pa_assert(v);
 593     pa_assert(new_balance >= -1.0f);
 594     pa_assert(new_balance <= 1.0f);
 595
 596     pa_return_val_if_fail(pa_cvolume_valid(v), NULL);
 597     pa_return_val_if_fail(pa_channel_map_valid(map), NULL);
 598     pa_return_val_if_fail(pa_cvolume_compatible_with_channel_map(v, map), NULL);
 599
 600     if (!pa_channel_map_can_balance(map))
 601         return v;
 602
 603     get_avg_lr(map, v, &left, &right);
 604
 605     m = PA_MAX(left, right);
 606
 607     if (new_balance <= 0) {
 608         nright  = (new_balance + 1.0f) * m;
 609         nleft = m;
 610     } else  {
 611         nleft = (1.0f - new_balance) * m;
 612         nright = m;
 613     }
 614
 615     for (c = 0; c < map->channels; c++) {
 616         if (on_left(map->map[c])) {
 617             if (left == 0)
 618                 v->values[c] = nleft;
 619             else
 620                 v->values[c] = (pa_volume_t) (((uint64_t) v->values[c] * (uint64_t) nleft) / (uint64_t) left);
 621         } else if (on_right(map->map[c])) {
 622             if (right == 0)
 623                 v->values[c] = nright;
 624             else
 625                 v->values[c] = (pa_volume_t) (((uint64_t) v->values[c] * (uint64_t) nright) / (uint64_t) right);
 626         }
 627     }
 628
 629     return v;
 630 }
 631
 632 pa_cvolume* pa_cvolume_scale(pa_cvolume *v, pa_volume_t max) {
 633     unsigned c;
 634     pa_volume_t t = 0;
 635
 636     pa_assert(v);
 637
 638     pa_return_val_if_fail(pa_cvolume_valid(v), NULL);
 639     pa_return_val_if_fail(max != (pa_volume_t) -1, NULL);
 640
 641     t = pa_cvolume_max(v);
 642
 643     if (t <= PA_VOLUME_MUTED)
 644         return pa_cvolume_set(v, v->channels, max);
 645
 646     for (c = 0; c < v->channels; c++)
 647         v->values[c] = (pa_volume_t) (((uint64_t)  v->values[c] * (uint64_t) max) / (uint64_t) t);
 648
 649     return v;
 650 }
 651
 652 pa_cvolume* pa_cvolume_scale_mask(pa_cvolume *v, pa_volume_t max, pa_channel_map *cm, pa_channel_position_mask_t mask) {
 653     unsigned c;
 654     pa_volume_t t = 0;
 655
 656     pa_assert(v);
 657
 658     pa_return_val_if_fail(pa_cvolume_valid(v), NULL);
 659     pa_return_val_if_fail(max != (pa_volume_t) -1, NULL);
 660
 661     t = pa_cvolume_max_mask(v, cm, mask);
 662
 663     if (t <= PA_VOLUME_MUTED)
 664         return pa_cvolume_set(v, v->channels, max);
 665
 666     for (c = 0; c < v->channels; c++)
 667         v->values[c] = (pa_volume_t) (((uint64_t)  v->values[c] * (uint64_t) max) / (uint64_t) t);
 668
 669     return v;
 670 }
 671
 672 static void get_avg_fr(const pa_channel_map *map, const pa_cvolume *v, pa_volume_t *f, pa_volume_t *r) {
 673     int c;
 674     pa_volume_t front = 0, rear = 0;
 675     unsigned n_front = 0, n_rear = 0;
 676
 677     pa_assert(v);
 678     pa_assert(map);
 679     pa_assert(map->channels == v->channels);
 680     pa_assert(f);
 681     pa_assert(r);
 682
 683     for (c = 0; c < map->channels; c++) {
 684         if (on_front(map->map[c])) {
 685             front += v->values[c];
 686             n_front++;
 687         } else if (on_rear(map->map[c])) {
 688             rear += v->values[c];
 689             n_rear++;
 690         }
 691     }
 692
 693     if (n_front <= 0)
 694         *f = PA_VOLUME_NORM;
 695     else
 696         *f = front / n_front;
 697
 698     if (n_rear <= 0)
 699         *r = PA_VOLUME_NORM;
 700     else
 701         *r = rear / n_rear;
 702 }
 703
 704 float pa_cvolume_get_fade(const pa_cvolume *v, const pa_channel_map *map) {
 705     pa_volume_t front, rear;
 706
 707     pa_assert(v);
 708     pa_assert(map);
 709
 710     pa_return_val_if_fail(pa_cvolume_valid(v), 0.0f);
 711     pa_return_val_if_fail(pa_channel_map_valid(map), 0.0f);
 712     pa_return_val_if_fail(pa_cvolume_compatible_with_channel_map(v, map), 0.0f);
 713
 714     if (!pa_channel_map_can_fade(map))
 715         return 0.0f;
 716
 717     get_avg_fr(map, v, &front, &rear);
 718
 719     if (front == rear)
 720         return 0.0f;
 721
 722     if (rear > front)
 723         return -1.0f + ((float) front / (float) rear);
 724     else
 725         return 1.0f - ((float) rear / (float) front);
 726 }
 727
 728 pa_cvolume* pa_cvolume_set_fade(pa_cvolume *v, const pa_channel_map *map, float new_fade) {
 729     pa_volume_t front, nfront, rear, nrear, m;
 730     unsigned c;
 731
 732     pa_assert(map);
 733     pa_assert(v);
 734     pa_assert(new_fade >= -1.0f);
 735     pa_assert(new_fade <= 1.0f);
 736
 737     pa_return_val_if_fail(pa_cvolume_valid(v), NULL);
 738     pa_return_val_if_fail(pa_channel_map_valid(map), NULL);
 739     pa_return_val_if_fail(pa_cvolume_compatible_with_channel_map(v, map), NULL);
 740
 741     if (!pa_channel_map_can_fade(map))
 742         return v;
 743
 744     get_avg_fr(map, v, &front, &rear);
 745
 746     m = PA_MAX(front, rear);
 747
 748     if (new_fade <= 0) {
 749         nfront  = (new_fade + 1.0f) * m;
 750         nrear = m;
 751     } else  {
 752         nrear = (1.0f - new_fade) * m;
 753         nfront = m;
 754     }
 755
 756     for (c = 0; c < map->channels; c++) {
 757         if (on_front(map->map[c])) {
 758             if (front == 0)
 759                 v->values[c] = nfront;
 760             else
 761                 v->values[c] = (pa_volume_t) (((uint64_t) v->values[c] * (uint64_t) nfront) / (uint64_t) front);
 762         } else if (on_rear(map->map[c])) {
 763             if (rear == 0)
 764                 v->values[c] = nrear;
 765             else
 766                 v->values[c] = (pa_volume_t) (((uint64_t) v->values[c] * (uint64_t) nrear) / (uint64_t) rear);
 767         }
 768     }
 769
 770     return v;
 771 }
 772
 773 pa_cvolume* pa_cvolume_set_position(
 774         pa_cvolume *cv,
 775         const pa_channel_map *map,
 776         pa_channel_position_t t,
 777         pa_volume_t v) {
 778
 779     unsigned c;
 780     pa_bool_t good = FALSE;
 781
 782     pa_assert(cv);
 783     pa_assert(map);
 784
 785     pa_return_val_if_fail(pa_cvolume_compatible_with_channel_map(cv, map), NULL);
 786     pa_return_val_if_fail(t < PA_CHANNEL_POSITION_MAX, NULL);
 787
 788     for (c = 0; c < map->channels; c++)
 789         if (map->map[c] == t) {
 790             cv->values[c] = v;
 791             good = TRUE;
 792         }
 793
 794     return good ? cv : NULL;
 795 }
 796
 797 pa_volume_t pa_cvolume_get_position(
 798         pa_cvolume *cv,
 799         const pa_channel_map *map,
 800         pa_channel_position_t t) {
 801
 802     unsigned c;
 803     pa_volume_t v = PA_VOLUME_MUTED;
 804
 805     pa_assert(cv);
 806     pa_assert(map);
 807
 808     pa_return_val_if_fail(pa_cvolume_compatible_with_channel_map(cv, map), PA_VOLUME_MUTED);
 809     pa_return_val_if_fail(t < PA_CHANNEL_POSITION_MAX, PA_VOLUME_MUTED);
 810
 811     for (c = 0; c < map->channels; c++)
 812         if (map->map[c] == t)
 813             if (cv->values[c] > v)
 814                 v = cv->values[c];
 815
 816     return v;
 817 }