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