summaryrefslogtreecommitdiff
path: root/bridges/bridge_softmix.c
blob: 16e1fb897c19b3baa4e532eca49141f72118c805 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2011, Digium, Inc.
 *
 * Joshua Colp <jcolp@digium.com>
 * David Vossel <dvossel@digium.com>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*! \file
 *
 * \brief Multi-party software based channel mixing
 *
 * \author Joshua Colp <jcolp@digium.com>
 * \author David Vossel <dvossel@digium.com>
 *
 * \ingroup bridges
 */

/*** MODULEINFO
	<support_level>core</support_level>
 ***/

#include "asterisk.h"

#include "asterisk/stream.h"
#include "asterisk/test.h"
#include "asterisk/vector.h"
#include "bridge_softmix/include/bridge_softmix_internal.h"

/*! The minimum sample rate of the bridge. */
#define SOFTMIX_MIN_SAMPLE_RATE 8000	/* 8 kHz sample rate */

/*! \brief Interval at which mixing will take place. Valid options are 10, 20, and 40. */
#define DEFAULT_SOFTMIX_INTERVAL 20

/*! \brief Size of the buffer used for sample manipulation */
#define SOFTMIX_DATALEN(rate, interval) ((rate/50) * (interval / 10))

/*! \brief Number of samples we are dealing with */
#define SOFTMIX_SAMPLES(rate, interval) (SOFTMIX_DATALEN(rate, interval) / 2)

/*! \brief Number of mixing iterations to perform between gathering statistics. */
#define SOFTMIX_STAT_INTERVAL 100

/*!
 * \brief Default time in ms of silence necessary to declare talking stopped by the bridge.
 *
 * \details
 * This is the time at which a channel's own audio will stop getting
 * mixed out of its own write audio stream because it is no longer talking.
 */
#define DEFAULT_SOFTMIX_SILENCE_THRESHOLD 2500

/*! Default minimum average magnitude threshold to determine talking by the DSP. */
#define DEFAULT_SOFTMIX_TALKING_THRESHOLD 160

#define SOFTBRIDGE_VIDEO_DEST_PREFIX "softbridge_dest"
#define SOFTBRIDGE_VIDEO_DEST_LEN strlen(SOFTBRIDGE_VIDEO_DEST_PREFIX)
#define SOFTBRIDGE_VIDEO_DEST_SEPARATOR '_'

struct softmix_stats {
	/*! Each index represents a sample rate used above the internal rate. */
	unsigned int sample_rates[16];
	/*! Each index represents the number of channels using the same index in the sample_rates array.  */
	unsigned int num_channels[16];
	/*! The number of channels above the internal sample rate */
	unsigned int num_above_internal_rate;
	/*! The number of channels at the internal sample rate */
	unsigned int num_at_internal_rate;
	/*! The absolute highest sample rate preferred by any channel in the bridge */
	unsigned int highest_supported_rate;
	/*! Is the sample rate locked by the bridge, if so what is that rate.*/
	unsigned int locked_rate;
};

struct softmix_translate_helper_entry {
	int num_times_requested; /*!< Once this entry is no longer requested, free the trans_pvt
								  and re-init if it was usable. */
	struct ast_format *dst_format; /*!< The destination format for this helper */
	struct ast_trans_pvt *trans_pvt; /*!< the translator for this slot. */
	struct ast_frame *out_frame; /*!< The output frame from the last translation */
	AST_LIST_ENTRY(softmix_translate_helper_entry) entry;
};

struct softmix_translate_helper {
	struct ast_format *slin_src; /*!< the source format expected for all the translators */
	AST_LIST_HEAD_NOLOCK(, softmix_translate_helper_entry) entries;
};

static struct softmix_translate_helper_entry *softmix_translate_helper_entry_alloc(struct ast_format *dst)
{
	struct softmix_translate_helper_entry *entry;
	if (!(entry = ast_calloc(1, sizeof(*entry)))) {
		return NULL;
	}
	entry->dst_format = ao2_bump(dst);
	/* initialize this to one so that the first time through the cleanup code after
	   allocation it won't be removed from the entry list */
	entry->num_times_requested = 1;
	return entry;
}

static void *softmix_translate_helper_free_entry(struct softmix_translate_helper_entry *entry)
{
	ao2_cleanup(entry->dst_format);

	if (entry->trans_pvt) {
		ast_translator_free_path(entry->trans_pvt);
	}
	if (entry->out_frame) {
		ast_frfree(entry->out_frame);
	}
	ast_free(entry);
	return NULL;
}

static void softmix_translate_helper_init(struct softmix_translate_helper *trans_helper, unsigned int sample_rate)
{
	memset(trans_helper, 0, sizeof(*trans_helper));
	trans_helper->slin_src = ast_format_cache_get_slin_by_rate(sample_rate);
}

static void softmix_translate_helper_destroy(struct softmix_translate_helper *trans_helper)
{
	struct softmix_translate_helper_entry *entry;

	while ((entry = AST_LIST_REMOVE_HEAD(&trans_helper->entries, entry))) {
		softmix_translate_helper_free_entry(entry);
	}
}

static void softmix_translate_helper_change_rate(struct softmix_translate_helper *trans_helper, unsigned int sample_rate)
{
	struct softmix_translate_helper_entry *entry;

	trans_helper->slin_src = ast_format_cache_get_slin_by_rate(sample_rate);
	AST_LIST_TRAVERSE_SAFE_BEGIN(&trans_helper->entries, entry, entry) {
		if (entry->trans_pvt) {
			ast_translator_free_path(entry->trans_pvt);
			if (!(entry->trans_pvt = ast_translator_build_path(entry->dst_format, trans_helper->slin_src))) {
				AST_LIST_REMOVE_CURRENT(entry);
				entry = softmix_translate_helper_free_entry(entry);
			}
		}
	}
	AST_LIST_TRAVERSE_SAFE_END;
}

/*!
 * \internal
 * \brief Get the next available audio on the softmix channel's read stream
 * and determine if it should be mixed out or not on the write stream.
 *
 * \retval pointer to buffer containing the exact number of samples requested on success.
 * \retval NULL if no samples are present
 */
static int16_t *softmix_process_read_audio(struct softmix_channel *sc, unsigned int num_samples)
{
	if ((ast_slinfactory_available(&sc->factory) >= num_samples) &&
		ast_slinfactory_read(&sc->factory, sc->our_buf, num_samples)) {
		sc->have_audio = 1;
		return sc->our_buf;
	}
	sc->have_audio = 0;
	return NULL;
}

/*!
 * \internal
 * \brief Process a softmix channel's write audio
 *
 * \details This function will remove the channel's talking from its own audio if present and
 * possibly even do the channel's write translation for it depending on how many other
 * channels use the same write format.
 */
static void softmix_process_write_audio(struct softmix_translate_helper *trans_helper,
	struct ast_format *raw_write_fmt,
	struct softmix_channel *sc, unsigned int default_sample_size)
{
	struct softmix_translate_helper_entry *entry = NULL;
	int i;

	/* If we provided audio that was not determined to be silence,
	 * then take it out while in slinear format. */
	if (sc->have_audio && sc->talking && !sc->binaural) {
		for (i = 0; i < sc->write_frame.samples; i++) {
			ast_slinear_saturated_subtract(&sc->final_buf[i], &sc->our_buf[i]);
		}
		/* check to see if any entries exist for the format. if not we'll want
		   to remove it during cleanup */
		AST_LIST_TRAVERSE(&trans_helper->entries, entry, entry) {
			if (ast_format_cmp(entry->dst_format, raw_write_fmt) == AST_FORMAT_CMP_EQUAL) {
				++entry->num_times_requested;
				break;
			}
		}
		/* do not do any special write translate optimization if we had to make
		 * a special mix for them to remove their own audio. */
		return;
	} else if (sc->have_audio && sc->talking && sc->binaural > 0) {
		/*
		 * Binaural audio requires special saturated substract since we have two
		 * audio signals per channel now.
		 */
		softmix_process_write_binaural_audio(sc, default_sample_size);
		return;
	}

	/* Attempt to optimize channels using the same translation path/codec. Build a list of entries
	   of translation paths and track the number of references for each type. Each one of the same
	   type should be able to use the same out_frame. Since the optimization is only necessary for
	   multiple channels (>=2) using the same codec make sure resources are allocated only when
	   needed and released when not (see also softmix_translate_helper_cleanup */
	AST_LIST_TRAVERSE(&trans_helper->entries, entry, entry) {
		if (sc->binaural != 0) {
			continue;
		}
		if (ast_format_cmp(entry->dst_format, raw_write_fmt) == AST_FORMAT_CMP_EQUAL) {
			entry->num_times_requested++;
		} else {
			continue;
		}
		if (!entry->trans_pvt && (entry->num_times_requested > 1)) {
			entry->trans_pvt = ast_translator_build_path(entry->dst_format, trans_helper->slin_src);
		}
		if (entry->trans_pvt && !entry->out_frame) {
			entry->out_frame = ast_translate(entry->trans_pvt, &sc->write_frame, 0);
		}
		if (entry->out_frame && entry->out_frame->frametype == AST_FRAME_VOICE
				&& entry->out_frame->datalen < MAX_DATALEN) {
			ao2_replace(sc->write_frame.subclass.format, entry->out_frame->subclass.format);
			memcpy(sc->final_buf, entry->out_frame->data.ptr, entry->out_frame->datalen);
			sc->write_frame.datalen = entry->out_frame->datalen;
			sc->write_frame.samples = entry->out_frame->samples;
		}
		break;
	}

	/* add new entry into list if this format destination was not matched. */
	if (!entry && (entry = softmix_translate_helper_entry_alloc(raw_write_fmt))) {
		AST_LIST_INSERT_HEAD(&trans_helper->entries, entry, entry);
	}
}

static void softmix_translate_helper_cleanup(struct softmix_translate_helper *trans_helper)
{
	struct softmix_translate_helper_entry *entry;

	AST_LIST_TRAVERSE_SAFE_BEGIN(&trans_helper->entries, entry, entry) {
		/* if it hasn't been requested then remove it */
		if (!entry->num_times_requested) {
			AST_LIST_REMOVE_CURRENT(entry);
			softmix_translate_helper_free_entry(entry);
			continue;
		}

		if (entry->out_frame) {
			ast_frfree(entry->out_frame);
			entry->out_frame = NULL;
		}

		/* nothing is optimized for a single path reference, so there is
		   no reason to continue to hold onto the codec */
		if (entry->num_times_requested == 1 && entry->trans_pvt) {
			ast_translator_free_path(entry->trans_pvt);
			entry->trans_pvt = NULL;
		}

		/* for each iteration (a mixing run) in the bridge softmix thread the number
		   of references to a given entry is recalculated, so reset the number of
		   times requested */
		entry->num_times_requested = 0;
	}
	AST_LIST_TRAVERSE_SAFE_END;
}

static void set_softmix_bridge_data(int rate, int interval, struct ast_bridge_channel *bridge_channel, int reset, int set_binaural, int binaural_pos_id, int is_announcement)
{
	struct softmix_channel *sc = bridge_channel->tech_pvt;
	struct ast_format *slin_format;
	int setup_fail;

#ifdef BINAURAL_RENDERING
	if (interval != BINAURAL_MIXING_INTERVAL) {
		interval = BINAURAL_MIXING_INTERVAL;
	}
#endif

	/* The callers have already ensured that sc is never NULL. */
	ast_assert(sc != NULL);

	slin_format = ast_format_cache_get_slin_by_rate(rate);

	ast_mutex_lock(&sc->lock);
	if (reset) {
		ast_slinfactory_destroy(&sc->factory);
		ast_dsp_free(sc->dsp);
	}

	/* Setup write frame parameters */
	sc->write_frame.frametype = AST_FRAME_VOICE;
	/*
	 * NOTE: The write_frame format holds a reference because translation
	 * could be needed and the format changed to the translated format
	 * for the channel.  The translated format may not be a
	 * static cached format.
	 */
	ao2_replace(sc->write_frame.subclass.format, slin_format);
	sc->write_frame.data.ptr = sc->final_buf;
	sc->write_frame.datalen = SOFTMIX_DATALEN(rate, interval);
	sc->write_frame.samples = SOFTMIX_SAMPLES(rate, interval);

	/* We will store the rate here cause we need to set the data again when a channel is unsuspended */
	sc->rate = rate;

	/* If the channel will contain binaural data we will set a identifier in the channel
	 * if set_binaural == -1 this is just a sample rate update, will ignore it. */
	if (set_binaural == 1) {
		sc->binaural = 1;
	} else if (set_binaural == 0) {
		sc->binaural = 0;
	}

	/* Setting the binaural position. This doesn't require a change of the overlaying channel infos
	 * and doesn't have to be done if we just updating sample rates. */
	if (binaural_pos_id != -1) {
		sc->binaural_pos = binaural_pos_id;
	}
	if (is_announcement != -1) {
		sc->is_announcement = is_announcement;
	}

	/*
	 * NOTE: The read_slin_format does not hold a reference because it
	 * will always be a signed linear format.
	 */
	sc->read_slin_format = slin_format;

	/* Setup smoother */
	setup_fail = ast_slinfactory_init_with_format(&sc->factory, slin_format);

	/* set new read and write formats on channel. */
	ast_channel_lock(bridge_channel->chan);
	setup_fail |= ast_set_read_format_path(bridge_channel->chan,
		ast_channel_rawreadformat(bridge_channel->chan), slin_format);
	ast_channel_unlock(bridge_channel->chan);

	/* If channel contains binaural data we will set it here for the trans_pvt. */
	if (set_binaural == 1 || (set_binaural == -1 && sc->binaural == 1)) {
		setup_fail |= ast_set_write_format_interleaved_stereo(bridge_channel->chan, slin_format);
	} else if (set_binaural == 0) {
		setup_fail |= ast_set_write_format(bridge_channel->chan, slin_format);
	}

	/* set up new DSP.  This is on the read side only right before the read frame enters the smoother.  */
	sc->dsp = ast_dsp_new_with_rate(rate);
	if (setup_fail || !sc->dsp) {
		/* Bad news.  Could not setup the channel for softmix. */
		ast_mutex_unlock(&sc->lock);
		ast_bridge_channel_leave_bridge(bridge_channel, BRIDGE_CHANNEL_STATE_END, 0);
		return;
	}

	/* we want to aggressively detect silence to avoid feedback */
	if (bridge_channel->tech_args.talking_threshold) {
		ast_dsp_set_threshold(sc->dsp, bridge_channel->tech_args.talking_threshold);
	} else {
		ast_dsp_set_threshold(sc->dsp, DEFAULT_SOFTMIX_TALKING_THRESHOLD);
	}

	ast_mutex_unlock(&sc->lock);
}

/*!
 * \internal
 * \brief Poke the mixing thread in case it is waiting for an active channel.
 * \since 12.0.0
 *
 * \param softmix_data Bridge mixing data.
 *
 * \return Nothing
 */
static void softmix_poke_thread(struct softmix_bridge_data *softmix_data)
{
	ast_mutex_lock(&softmix_data->lock);
	ast_cond_signal(&softmix_data->cond);
	ast_mutex_unlock(&softmix_data->lock);
}

/*! \brief Function called when a channel is unsuspended from the bridge */
static void softmix_bridge_unsuspend(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel)
{
#ifdef BINAURAL_RENDERING
	struct softmix_channel *sc = bridge_channel->tech_pvt;
	if (sc->binaural) {
		/* Restore some usefull data if it was a binaural channel */
		struct ast_format *slin_format;

		slin_format = ast_format_cache_get_slin_by_rate(sc->rate);
		ast_set_write_format_interleaved_stereo(bridge_channel->chan, slin_format);
	}
#endif
	if (bridge->tech_pvt) {
		softmix_poke_thread(bridge->tech_pvt);
	}
}

/*!
 * \brief Determine if a stream is a video source stream.
 *
 * \param stream The stream to test
 * \retval 1 The stream is a video source
 * \retval 0 The stream is not a video source
 */
static int is_video_source(const struct ast_stream *stream)
{
	if (ast_stream_get_state(stream) != AST_STREAM_STATE_REMOVED
		&& ast_stream_get_type(stream) == AST_MEDIA_TYPE_VIDEO
		&& strncmp(ast_stream_get_name(stream), SOFTBRIDGE_VIDEO_DEST_PREFIX,
			SOFTBRIDGE_VIDEO_DEST_LEN)) {
		return 1;
	}

	return 0;
}

/*!
 * \brief Determine if a stream is a video destination stream.
 *
 * A source channel name can be provided to narrow this to a destination stream
 * for a particular source channel. Further, a source stream name can be provided
 * to narrow this to a particular source stream's destination. However, empty strings
 * can be provided to match any destination video stream, regardless of source channel
 * or source stream.
 *
 * \param stream The stream to test
 * \param source_channel_name The name of a source video channel to match
 * \param source_stream_name The name of the source video stream to match
 * \retval 1 The stream is a video destination stream
 * \retval 0 The stream is not a video destination stream
 */
static int is_video_dest(const struct ast_stream *stream, const char *source_channel_name,
	const char *source_stream_name)
{
	char *dest_video_name;
	size_t dest_video_name_len;

	if (ast_stream_get_state(stream) == AST_STREAM_STATE_REMOVED
		|| ast_stream_get_type(stream) != AST_MEDIA_TYPE_VIDEO) {
		return 0;
	}

	dest_video_name_len = SOFTBRIDGE_VIDEO_DEST_LEN + 1;
	if (!ast_strlen_zero(source_channel_name)) {
		dest_video_name_len += strlen(source_channel_name) + 1;
		if (!ast_strlen_zero(source_stream_name)) {
			dest_video_name_len += strlen(source_stream_name) + 1;
		}

		dest_video_name = ast_alloca(dest_video_name_len);
		if (!ast_strlen_zero(source_stream_name)) {
			/* We are looking for an exact stream name */
			snprintf(dest_video_name, dest_video_name_len, "%s%c%s%c%s",
				SOFTBRIDGE_VIDEO_DEST_PREFIX, SOFTBRIDGE_VIDEO_DEST_SEPARATOR,
				source_channel_name, SOFTBRIDGE_VIDEO_DEST_SEPARATOR,
				source_stream_name);
			return !strcmp(ast_stream_get_name(stream), dest_video_name);
		}
		snprintf(dest_video_name, dest_video_name_len, "%s%c%s",
			SOFTBRIDGE_VIDEO_DEST_PREFIX, SOFTBRIDGE_VIDEO_DEST_SEPARATOR,
			source_channel_name);
	} else {
		dest_video_name = SOFTBRIDGE_VIDEO_DEST_PREFIX;
	}

	return !strncmp(ast_stream_get_name(stream), dest_video_name, dest_video_name_len - 1);
}

static int append_source_streams(struct ast_stream_topology *dest,
	const char *channel_name,
	const struct ast_stream_topology *source)
{
	int i;

	for (i = 0; i < ast_stream_topology_get_count(source); ++i) {
		struct ast_stream *stream;
		struct ast_stream *stream_clone;
		char *stream_clone_name = NULL;

		stream = ast_stream_topology_get_stream(source, i);
		if (!is_video_source(stream)) {
			continue;
		}

		if (ast_asprintf(&stream_clone_name, "%s_%s_%s", SOFTBRIDGE_VIDEO_DEST_PREFIX,
			channel_name, ast_stream_get_name(stream)) < 0) {
			return -1;
		}

		stream_clone = ast_stream_clone(stream, stream_clone_name);
		ast_free(stream_clone_name);
		if (!stream_clone) {
			return -1;
		}
		if (ast_stream_topology_append_stream(dest, stream_clone) < 0) {
			ast_stream_free(stream_clone);
			return -1;
		}
	}

	return 0;
}

static int append_all_streams(struct ast_stream_topology *dest,
	const struct ast_stream_topology *source)
{
	int i;
	int dest_index = 0;

	for (i = 0; i < ast_stream_topology_get_count(source); ++i) {
		struct ast_stream *clone;
		int added = 0;

		clone = ast_stream_clone(ast_stream_topology_get_stream(source, i), NULL);
		if (!clone) {
			return -1;
		}

		/* If we can reuse an existing removed stream then do so */
		while (dest_index < ast_stream_topology_get_count(dest)) {
			struct ast_stream *stream = ast_stream_topology_get_stream(dest, dest_index);

			dest_index++;

			if (ast_stream_get_state(stream) == AST_STREAM_STATE_REMOVED) {
				/* This cannot fail because dest_index - 1 is less than the
				 * current count in dest. */
				ast_stream_topology_set_stream(dest, dest_index - 1, clone);
				added = 1;
				break;
			}
		}

		/* If no removed stream exists that we took the place of append the stream */
		if (!added && ast_stream_topology_append_stream(dest, clone) < 0) {
			ast_stream_free(clone);
			return -1;
		}
	}

	return 0;
}

/*!
 * \brief Issue channel stream topology change requests.
 *
 * When in SFU mode, each participant needs to be able to
 * send video directly to other participants in the bridge.
 * This means that all participants need to have their topologies
 * updated. The joiner needs to have destination streams for
 * all current participants, and the current participants need
 * to have destinations streams added for the joiner's sources.
 *
 * \param joiner The channel that is joining the softmix bridge
 * \param participants The current participants in the softmix bridge
 */
static void sfu_topologies_on_join(struct ast_bridge_channel *joiner, struct ast_bridge_channels_list *participants)
{
	struct ast_stream_topology *joiner_video = NULL;
	struct ast_bridge_channel *participant;
	int res;
	struct softmix_channel *sc;

	joiner_video = ast_stream_topology_alloc();
	if (!joiner_video) {
		return;
	}

	sc = joiner->tech_pvt;

	ast_channel_lock(joiner->chan);
	res = append_source_streams(joiner_video, ast_channel_name(joiner->chan), ast_channel_get_stream_topology(joiner->chan));
	sc->topology = ast_stream_topology_clone(ast_channel_get_stream_topology(joiner->chan));
	ast_channel_unlock(joiner->chan);

	if (res || !sc->topology) {
		goto cleanup;
	}

	AST_LIST_TRAVERSE(participants, participant, entry) {
		if (participant == joiner) {
			continue;
		}
		ast_channel_lock(participant->chan);
		res = append_source_streams(sc->topology, ast_channel_name(participant->chan),
				ast_channel_get_stream_topology(participant->chan));
		ast_channel_unlock(participant->chan);
		if (res) {
			goto cleanup;
		}
	}

	ast_channel_request_stream_topology_change(joiner->chan, sc->topology, NULL);

	AST_LIST_TRAVERSE(participants, participant, entry) {
		if (participant == joiner) {
			continue;
		}

		sc = participant->tech_pvt;
		if (append_all_streams(sc->topology, joiner_video)) {
			goto cleanup;
		}
		ast_channel_request_stream_topology_change(participant->chan, sc->topology, NULL);
	}

cleanup:
	ast_stream_topology_free(joiner_video);
}

/*! \brief Function called when a channel is joined into the bridge */
static int softmix_bridge_join(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel)
{
	struct softmix_channel *sc;
	struct softmix_bridge_data *softmix_data;
	int set_binaural = 0;
	/*
	 * If false, the channel will be convolved, but since it is a non stereo channel, output
	 * will be mono.
	 */
	int skip_binaural_output = 1;
	int pos_id;
	int is_announcement = 0;
	int samplerate_change;

	softmix_data = bridge->tech_pvt;
	if (!softmix_data) {
		return -1;
	}

	/* Create a new softmix_channel structure and allocate various things on it */
	if (!(sc = ast_calloc(1, sizeof(*sc)))) {
		return -1;
	}

	samplerate_change = softmix_data->internal_rate;
	pos_id = -1;
	if (bridge->softmix.binaural_active) {
		if (strncmp(ast_channel_name(bridge_channel->chan), "CBAnn", 5) != 0) {
			set_binaural = ast_format_get_channel_count(bridge_channel->write_format) > 1 ? 1 : 0;
			if (set_binaural) {
				softmix_data->internal_rate = samplerate_change;
			}
			skip_binaural_output = 0;
		} else {
			is_announcement = 1;
		}
		if (set_binaural) {
			softmix_data->convolve.binaural_active = 1;
		}
		if (!skip_binaural_output)	{
			pos_id = set_binaural_data_join(&softmix_data->convolve, softmix_data->default_sample_size);
			if (pos_id == -1) {
				ast_log(LOG_ERROR, "Bridge %s: Failed to join channel %s. "
						"Could not allocate enough memory.\n", bridge->uniqueid,
						ast_channel_name(bridge_channel->chan));
				ast_free(sc);
				return -1;
			}
		}
	}

	/* Can't forget the lock */
	ast_mutex_init(&sc->lock);

	/* Can't forget to record our pvt structure within the bridged channel structure */
	bridge_channel->tech_pvt = sc;

	set_softmix_bridge_data(softmix_data->internal_rate,
		softmix_data->internal_mixing_interval
			? softmix_data->internal_mixing_interval
			: DEFAULT_SOFTMIX_INTERVAL,
		bridge_channel, 0, set_binaural, pos_id, is_announcement);

	if (bridge->softmix.video_mode.mode == AST_BRIDGE_VIDEO_MODE_SFU) {
		sfu_topologies_on_join(bridge_channel, &bridge->channels);
	}

	softmix_poke_thread(softmix_data);
	return 0;
}

static int remove_destination_streams(struct ast_stream_topology *topology,
	const char *channel_name)
{
	int i;
	int stream_removed = 0;

	for (i = 0; i < ast_stream_topology_get_count(topology); ++i) {
		struct ast_stream *stream;

		stream = ast_stream_topology_get_stream(topology, i);

		if (is_video_dest(stream, channel_name, NULL)) {
			ast_stream_set_state(stream, AST_STREAM_STATE_REMOVED);
			stream_removed = 1;
		}
	}
	return stream_removed;
}

static int sfu_topologies_on_leave(struct ast_bridge_channel *leaver, struct ast_bridge_channels_list *participants)
{
	struct ast_bridge_channel *participant;
	struct softmix_channel *sc;

	AST_LIST_TRAVERSE(participants, participant, entry) {
		sc = participant->tech_pvt;
		if (!remove_destination_streams(sc->topology, ast_channel_name(leaver->chan))) {
			continue;
		}
		ast_channel_request_stream_topology_change(participant->chan, sc->topology, NULL);
	}

	sc = leaver->tech_pvt;
	if (remove_destination_streams(sc->topology, "")) {
		ast_channel_request_stream_topology_change(leaver->chan, sc->topology, NULL);
	}

	return 0;
}

/*! \brief Function called when a channel leaves the bridge */
static void softmix_bridge_leave(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel)
{
	struct softmix_channel *sc;
	struct softmix_bridge_data *softmix_data;

	softmix_data = bridge->tech_pvt;
	sc = bridge_channel->tech_pvt;
	if (!sc) {
		return;
	}

	if (bridge->softmix.video_mode.mode == AST_BRIDGE_VIDEO_MODE_SFU) {
		sfu_topologies_on_leave(bridge_channel, &bridge->channels);
	}

	if (bridge->softmix.binaural_active) {
		if (sc->binaural) {
			set_binaural_data_leave(&softmix_data->convolve, sc->binaural_pos,
					softmix_data->default_sample_size);
		}
	}

	bridge_channel->tech_pvt = NULL;

	ast_stream_topology_free(sc->topology);

	/* Drop mutex lock */
	ast_mutex_destroy(&sc->lock);

	/* Drop the factory */
	ast_slinfactory_destroy(&sc->factory);

	/* Drop any formats on the frames */
	ao2_cleanup(sc->write_frame.subclass.format);

	/* Drop the DSP */
	ast_dsp_free(sc->dsp);

	/* Eep! drop ourselves */
	ast_free(sc);
}

static void softmix_pass_video_top_priority(struct ast_bridge *bridge, struct ast_frame *frame)
{
	struct ast_bridge_channel *cur;

	AST_LIST_TRAVERSE(&bridge->channels, cur, entry) {
		if (cur->suspended) {
			continue;
		}
		if (ast_bridge_is_video_src(bridge, cur->chan) == 1) {
			ast_bridge_channel_queue_frame(cur, frame);
			break;
		}
	}
}

/*!
 * \internal
 * \brief Determine what to do with a video frame.
 * \since 12.0.0
 *
 * \param bridge Which bridge is getting the frame
 * \param bridge_channel Which channel is writing the frame.
 * \param frame What is being written.
 *
 * \return Nothing
 */
static void softmix_bridge_write_video(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel, struct ast_frame *frame)
{
	struct softmix_channel *sc;
	int video_src_priority;

	/* Determine if the video frame should be distributed or not */
	switch (bridge->softmix.video_mode.mode) {
	case AST_BRIDGE_VIDEO_MODE_NONE:
		break;
	case AST_BRIDGE_VIDEO_MODE_SINGLE_SRC:
		video_src_priority = ast_bridge_is_video_src(bridge, bridge_channel->chan);
		if (video_src_priority == 1) {
			/* Pass to me and everyone else. */
			ast_bridge_queue_everyone_else(bridge, NULL, frame);
		}
		break;
	case AST_BRIDGE_VIDEO_MODE_TALKER_SRC:
		sc = bridge_channel->tech_pvt;
		ast_mutex_lock(&sc->lock);
		ast_bridge_update_talker_src_video_mode(bridge, bridge_channel->chan,
			sc->video_talker.energy_average,
			frame->subclass.frame_ending);
		ast_mutex_unlock(&sc->lock);
		video_src_priority = ast_bridge_is_video_src(bridge, bridge_channel->chan);
		if (video_src_priority == 1) {
			int num_src = ast_bridge_number_video_src(bridge);
			int echo = num_src > 1 ? 0 : 1;

			ast_bridge_queue_everyone_else(bridge, echo ? NULL : bridge_channel, frame);
		} else if (video_src_priority == 2) {
			softmix_pass_video_top_priority(bridge, frame);
		}
		break;
	case AST_BRIDGE_VIDEO_MODE_SFU:
		/* Nothing special to do here, the bridge channel stream map will ensure the
		 * video goes everywhere it needs to
		 */
		ast_bridge_queue_everyone_else(bridge, bridge_channel, frame);
		break;
	}
}

/*!
 * \internal
 * \brief Determine what to do with a voice frame.
 * \since 12.0.0
 *
 * \param bridge Which bridge is getting the frame
 * \param bridge_channel Which channel is writing the frame.
 * \param frame What is being written.
 *
 * \return Nothing
 */
static void softmix_bridge_write_voice(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel, struct ast_frame *frame)
{
	struct softmix_channel *sc = bridge_channel->tech_pvt;
	struct softmix_bridge_data *softmix_data = bridge->tech_pvt;
	int silent = 0;
	int totalsilence = 0;
	int cur_energy = 0;
	int silence_threshold = bridge_channel->tech_args.silence_threshold ?
		bridge_channel->tech_args.silence_threshold :
		DEFAULT_SOFTMIX_SILENCE_THRESHOLD;
	/*
	 * If update_talking is set to 0 or 1, tell the bridge that the channel
	 * has started or stopped talking.
	 */
	char update_talking = -1;

	/* Write the frame into the conference */
	ast_mutex_lock(&sc->lock);

	if (ast_format_cmp(frame->subclass.format, sc->read_slin_format) != AST_FORMAT_CMP_EQUAL) {
		/*
		 * The incoming frame is not the expected format.  Update
		 * the channel's translation path to get us slinear from
		 * the new format for the next frame.
		 *
		 * There is the possibility that this frame is an old slinear
		 * rate frame that was in flight when the softmix bridge
		 * changed rates.  If so it will self correct on subsequent
		 * frames.
		 */
		ast_channel_lock(bridge_channel->chan);
		ast_debug(1, "Channel %s wrote unexpected format into bridge.  Got %s, expected %s.\n",
			ast_channel_name(bridge_channel->chan),
			ast_format_get_name(frame->subclass.format),
			ast_format_get_name(sc->read_slin_format));
		ast_set_read_format_path(bridge_channel->chan, frame->subclass.format,
			sc->read_slin_format);
		ast_channel_unlock(bridge_channel->chan);
	}

	/* The channel will be leaving soon if there is no dsp. */
	if (sc->dsp) {
		silent = ast_dsp_silence_with_energy(sc->dsp, frame, &totalsilence, &cur_energy);
	}

	if (bridge->softmix.video_mode.mode == AST_BRIDGE_VIDEO_MODE_TALKER_SRC) {
		int cur_slot = sc->video_talker.energy_history_cur_slot;

		sc->video_talker.energy_accum -= sc->video_talker.energy_history[cur_slot];
		sc->video_talker.energy_accum += cur_energy;
		sc->video_talker.energy_history[cur_slot] = cur_energy;
		sc->video_talker.energy_average = sc->video_talker.energy_accum / DEFAULT_ENERGY_HISTORY_LEN;
		sc->video_talker.energy_history_cur_slot++;
		if (sc->video_talker.energy_history_cur_slot == DEFAULT_ENERGY_HISTORY_LEN) {
			sc->video_talker.energy_history_cur_slot = 0; /* wrap around */
		}
	}

	if (totalsilence < silence_threshold) {
		if (!sc->talking && !silent) {
			/* Tell the write process we have audio to be mixed out */
			sc->talking = 1;
			update_talking = 1;
		}
	} else {
		if (sc->talking) {
			sc->talking = 0;
			update_talking = 0;
		}
	}

	/* Before adding audio in, make sure we haven't fallen behind. If audio has fallen
	 * behind 4 times the amount of samples mixed on every iteration of the mixer, Re-sync
	 * the audio by flushing the buffer before adding new audio in. */
	if (ast_slinfactory_available(&sc->factory) > (4 * SOFTMIX_SAMPLES(softmix_data->internal_rate, softmix_data->internal_mixing_interval))) {
		ast_slinfactory_flush(&sc->factory);
	}

	if (sc->talking || !bridge_channel->tech_args.drop_silence) {
		/* Add frame to the smoother for mixing with other channels. */
		ast_slinfactory_feed(&sc->factory, frame);
	}

	/* Alllll done */
	ast_mutex_unlock(&sc->lock);

	if (update_talking != -1) {
		ast_bridge_channel_notify_talking(bridge_channel, update_talking);
	}
}

/*!
 * \internal
 * \brief Clear talking flag, stop contributing to mixing and notify handlers.
 * \since 13.21.0, 15.4.0
 *
 * \param bridge_channel Which channel's talking to clear
 *
 * \return Nothing
 */
static void clear_talking(struct ast_bridge_channel *bridge_channel)
{
	struct softmix_channel *sc = bridge_channel->tech_pvt;

	if (sc->talking) {
		ast_mutex_lock(&sc->lock);
		ast_slinfactory_flush(&sc->factory);
		sc->talking = 0;
		ast_mutex_unlock(&sc->lock);

		/* Notify that we are no longer talking. */
		ast_bridge_channel_notify_talking(bridge_channel, 0);
	}
}

/*!
 * \internal
 * \brief Check for voice status updates.
 * \since 13.20.0
 *
 * \param bridge Which bridge we are in
 * \param bridge_channel Which channel we are checking
 *
 * \return Nothing
 */
static void softmix_bridge_check_voice(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel)
{
	if (bridge_channel->features->mute) {
		/*
		 * We were muted while we were talking.
		 *
		 * Immediately stop contributing to mixing
		 * and report no longer talking.
		 */
		clear_talking(bridge_channel);
	}
}

static int remove_all_original_streams(struct ast_stream_topology *dest,
	const struct ast_stream_topology *source,
	const struct ast_stream_topology *original)
{
	int i;

	for (i = 0; i < ast_stream_topology_get_count(source); ++i) {
		struct ast_stream *stream;
		int original_index;

		stream = ast_stream_topology_get_stream(source, i);

		/* Mark the existing stream as removed so we get a new one, this will get
		 * reused on a subsequent renegotiation.
		 */
		for (original_index = 0; original_index < ast_stream_topology_get_count(original); ++original_index) {
			struct ast_stream *original_stream = ast_stream_topology_get_stream(original, original_index);

			if (!strcmp(ast_stream_get_name(stream), ast_stream_get_name(original_stream))) {
				struct ast_stream *removed;

				/* Since the participant is still going to be in the bridge we
				 * change the name so that routing does not attempt to route video
				 * to this stream.
				 */
				removed = ast_stream_clone(stream, "removed");
				if (!removed) {
					return -1;
				}

				ast_stream_set_state(removed, AST_STREAM_STATE_REMOVED);

				/* The destination topology can only ever contain the same, or more,
				 * streams than the original so this is safe.
				 */
				if (ast_stream_topology_set_stream(dest, original_index, removed)) {
					ast_stream_free(removed);
					return -1;
				}

				break;
			}
		}
	}

	return 0;
}

static void sfu_topologies_on_source_change(struct ast_bridge_channel *source, struct ast_bridge_channels_list *participants)
{
	struct ast_stream_topology *source_video = NULL;
	struct ast_bridge_channel *participant;
	int res;

	source_video = ast_stream_topology_alloc();
	if (!source_video) {
		return;
	}

	ast_channel_lock(source->chan);
	res = append_source_streams(source_video, ast_channel_name(source->chan), ast_channel_get_stream_topology(source->chan));
	ast_channel_unlock(source->chan);
	if (res) {
		goto cleanup;
	}

	AST_LIST_TRAVERSE(participants, participant, entry) {
		struct ast_stream_topology *original_topology;
		struct softmix_channel *sc;

		if (participant == source) {
			continue;
		}

		sc = participant->tech_pvt;

		original_topology = ast_stream_topology_clone(sc->topology);
		if (!original_topology) {
			goto cleanup;
		}

		/* We add all the source streams back in, if any removed streams are already present they will
		 * get used first followed by appending new ones.
		 */
		if (append_all_streams(sc->topology, source_video)) {
			ast_stream_topology_free(original_topology);
			goto cleanup;
		}

		/* And the original existing streams get marked as removed. This causes the remote side to see
		 * a new stream for the source streams.
		 */
		if (remove_all_original_streams(sc->topology, source_video, original_topology)) {
			ast_stream_topology_free(original_topology);
			goto cleanup;
		}

		ast_channel_request_stream_topology_change(participant->chan, sc->topology, NULL);
		ast_stream_topology_free(original_topology);
	}

cleanup:
	ast_stream_topology_free(source_video);
}

/*!
 * \internal
 * \brief Determine what to do with a control frame.
 * \since 12.0.0
 *
 * \param bridge Which bridge is getting the frame
 * \param bridge_channel Which channel is writing the frame.
 * \param frame What is being written.
 *
 * \retval 0 Frame accepted into the bridge.
 * \retval -1 Frame needs to be deferred.
 */
static int softmix_bridge_write_control(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel, struct ast_frame *frame)
{
	struct softmix_bridge_data *softmix_data = bridge->tech_pvt;

	/*
	 * XXX Softmix needs to use channel roles to determine what to
	 * do with control frames.
	 */

	switch (frame->subclass.integer) {
	case AST_CONTROL_HOLD:
		/*
		 * Doing anything for holds in a conference bridge could be considered a bit
		 * odd. That being said, in most cases one would probably want the talking
		 * flag cleared when 'hold' is pressed by the remote endpoint, so go ahead
		 * and do that here. However, that is all we'll do. Meaning if for some reason
		 * the endpoint continues to send audio frames despite pressing 'hold' talking
		 * will once again be detected for that channel.
		 */
		clear_talking(bridge_channel);
		break;
	case AST_CONTROL_VIDUPDATE:
		if (!bridge->softmix.video_mode.video_update_discard ||
			ast_tvdiff_ms(ast_tvnow(), softmix_data->last_video_update) > bridge->softmix.video_mode.video_update_discard) {
			ast_bridge_queue_everyone_else(bridge, NULL, frame);
			softmix_data->last_video_update = ast_tvnow();
		}
		break;
	case AST_CONTROL_STREAM_TOPOLOGY_SOURCE_CHANGED:
		if (bridge->softmix.video_mode.mode == AST_BRIDGE_VIDEO_MODE_SFU) {
			sfu_topologies_on_source_change(bridge_channel, &bridge->channels);
		}
		break;
	default:
		break;
	}

	return 0;
}

/*!
 * \internal
 * \brief Determine what to do with a frame written into the bridge.
 * \since 12.0.0
 *
 * \param bridge Which bridge is getting the frame
 * \param bridge_channel Which channel is writing the frame.
 * \param frame What is being written.
 *
 * \retval 0 Frame accepted into the bridge.
 * \retval -1 Frame needs to be deferred.
 *
 * \note On entry, bridge is already locked.
 */
static int softmix_bridge_write(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel, struct ast_frame *frame)
{
	int res = 0;

	if (!bridge->tech_pvt || !bridge_channel || !bridge_channel->tech_pvt) {
		/* "Accept" the frame and discard it. */
		return 0;
	}

	/*
	 * XXX Softmix needs to use channel roles to determine who gets
	 * what frame.  Possible roles: announcer, recorder, agent,
	 * supervisor.
	 */
	switch (frame->frametype) {
	case AST_FRAME_NULL:
		/* "Accept" the frame and discard it. */
		softmix_bridge_check_voice(bridge, bridge_channel);
		break;
	case AST_FRAME_DTMF_BEGIN:
	case AST_FRAME_DTMF_END:
		res = ast_bridge_queue_everyone_else(bridge, bridge_channel, frame);
		break;
	case AST_FRAME_VOICE:
		softmix_bridge_write_voice(bridge, bridge_channel, frame);
		break;
	case AST_FRAME_VIDEO:
		softmix_bridge_write_video(bridge, bridge_channel, frame);
		break;
	case AST_FRAME_CONTROL:
		res = softmix_bridge_write_control(bridge, bridge_channel, frame);
		break;
	case AST_FRAME_BRIDGE_ACTION:
		res = ast_bridge_queue_everyone_else(bridge, bridge_channel, frame);
		break;
	case AST_FRAME_BRIDGE_ACTION_SYNC:
		ast_log(LOG_ERROR, "Synchronous bridge action written to a softmix bridge.\n");
		ast_assert(0);
	default:
		ast_debug(3, "Frame type %u unsupported\n", frame->frametype);
		/* "Accept" the frame and discard it. */
		break;
	}

	return res;
}

static void gather_softmix_stats(struct softmix_stats *stats,
	const struct softmix_bridge_data *softmix_data,
	struct ast_bridge_channel *bridge_channel)
{
	int channel_native_rate;

	/* Gather stats about channel sample rates. */
	ast_channel_lock(bridge_channel->chan);
	channel_native_rate = MAX(SOFTMIX_MIN_SAMPLE_RATE,
		ast_format_get_sample_rate(ast_channel_rawreadformat(bridge_channel->chan)));
	ast_channel_unlock(bridge_channel->chan);

	if (stats->highest_supported_rate < channel_native_rate) {
		stats->highest_supported_rate = channel_native_rate;
	}
	if (softmix_data->internal_rate < channel_native_rate) {
		int i;

		for (i = 0; i < ARRAY_LEN(stats->sample_rates); i++) {
			if (stats->sample_rates[i] == channel_native_rate) {
				stats->num_channels[i]++;
				break;
			} else if (!stats->sample_rates[i]) {
				stats->sample_rates[i] = channel_native_rate;
				stats->num_channels[i]++;
				break;
			}
		}
		stats->num_above_internal_rate++;
	} else if (softmix_data->internal_rate == channel_native_rate) {
		stats->num_at_internal_rate++;
	}
}

/*!
 * \internal
 * \brief Analyse mixing statistics and change bridges internal rate
 * if necessary.
 *
 * \retval 0, no changes to internal rate
 * \retval 1, internal rate was changed, update all the channels on the next mixing iteration.
 */
static unsigned int analyse_softmix_stats(struct softmix_stats *stats,
		struct softmix_bridge_data *softmix_data, int binaural_active)
{
	int i;

	if (binaural_active) {
		stats->locked_rate = SOFTMIX_BINAURAL_SAMPLE_RATE;
	}

	/*
	 * Re-adjust the internal bridge sample rate if
	 * 1. The bridge's internal sample rate is locked in at a sample
	 *    rate other than the current sample rate being used.
	 * 2. two or more channels support a higher sample rate
	 * 3. no channels support the current sample rate or a higher rate
	 */
	if (stats->locked_rate) {
		/* if the rate is locked by the bridge, only update it if it differs
		 * from the current rate we are using. */
		if (softmix_data->internal_rate != stats->locked_rate) {
			ast_debug(1, "Locking at new rate.  Bridge changed from %u to %u.\n",
				softmix_data->internal_rate, stats->locked_rate);
			softmix_data->internal_rate = stats->locked_rate;
			return 1;
		}
	} else if (stats->num_above_internal_rate >= 2) {
		/* the highest rate is just used as a starting point */
		unsigned int best_rate = stats->highest_supported_rate;
		int best_index = -1;

		for (i = 0; i < ARRAY_LEN(stats->num_channels); i++) {
			if (stats->num_channels[i]) {
				break;
			}
			if (2 <= stats->num_channels[i]) {
				/* Two or more channels support this rate. */
				if (best_index == -1
					|| stats->sample_rates[best_index] < stats->sample_rates[i]) {
					/*
					 * best_rate starts out being the first sample rate
					 * greater than the internal sample rate that two or
					 * more channels support.
					 *
					 * or
					 *
					 * There are multiple rates above the internal rate
					 * and this rate is higher than the previous rate two
					 * or more channels support.
					 */
					best_rate = stats->sample_rates[i];
					best_index = i;
				}
			} else if (best_index == -1) {
				/*
				 * It is possible that multiple channels exist with native sample
				 * rates above the internal sample rate, but none of those channels
				 * have the same rate in common.  In this case, the lowest sample
				 * rate among those channels is picked. Over time as additional
				 * statistic runs are made the internal sample rate number will
				 * adjust to the most optimal sample rate, but it may take multiple
				 * iterations.
				 */
				best_rate = MIN(best_rate, stats->sample_rates[i]);
			}
		}

		ast_debug(1, "Multiple above internal rate.  Bridge changed from %u to %u.\n",
			softmix_data->internal_rate, best_rate);
		softmix_data->internal_rate = best_rate;
		return 1;
	} else if (!stats->num_at_internal_rate && !stats->num_above_internal_rate) {
		/* In this case, the highest supported rate is actually lower than the internal rate */
		ast_debug(1, "All below internal rate.  Bridge changed from %u to %u.\n",
			softmix_data->internal_rate, stats->highest_supported_rate);
		softmix_data->internal_rate = stats->highest_supported_rate;
		return 1;
	}
	return 0;
}

static int softmix_mixing_array_init(struct softmix_mixing_array *mixing_array,
		unsigned int starting_num_entries, unsigned int binaural_active)
{
	memset(mixing_array, 0, sizeof(*mixing_array));
	mixing_array->max_num_entries = starting_num_entries;
	if (!(mixing_array->buffers = ast_calloc(mixing_array->max_num_entries, sizeof(int16_t *)))) {
		ast_log(LOG_NOTICE, "Failed to allocate softmix mixing structure.\n");
		return -1;
	}
	if (binaural_active) {
		if (!(mixing_array->chan_pairs = ast_calloc(mixing_array->max_num_entries,
				sizeof(struct convolve_channel_pair *)))) {
			ast_log(LOG_NOTICE, "Failed to allocate softmix mixing structure.\n");
			return -1;
		}
	}
	return 0;
}

static void softmix_mixing_array_destroy(struct softmix_mixing_array *mixing_array,
		unsigned int binaural_active)
{
	ast_free(mixing_array->buffers);
	if (binaural_active) {
		ast_free(mixing_array->chan_pairs);
	}
}

static int softmix_mixing_array_grow(struct softmix_mixing_array *mixing_array,
		unsigned int num_entries, unsigned int binaural_active)
{
	int16_t **tmp;

	/* give it some room to grow since memory is cheap but allocations can be expensive */
	mixing_array->max_num_entries = num_entries;
	if (!(tmp = ast_realloc(mixing_array->buffers, (mixing_array->max_num_entries * sizeof(int16_t *))))) {
		ast_log(LOG_NOTICE, "Failed to re-allocate softmix mixing structure.\n");
		return -1;
	}
	mixing_array->buffers = tmp;

	if (binaural_active) {
		struct convolve_channel_pair **tmp2;
		if (!(tmp2 = ast_realloc(mixing_array->chan_pairs,
				(mixing_array->max_num_entries * sizeof(struct convolve_channel_pair *))))) {
			ast_log(LOG_NOTICE, "Failed to re-allocate softmix mixing structure.\n");
			return -1;
		}
		mixing_array->chan_pairs = tmp2;
	}
	return 0;
}

/*!
 * \brief Mixing loop.
 *
 * \retval 0 on success
 * \retval -1 on failure
 */
static int softmix_mixing_loop(struct ast_bridge *bridge)
{
	struct softmix_stats stats = { { 0 }, };
	struct softmix_mixing_array mixing_array;
	struct softmix_bridge_data *softmix_data = bridge->tech_pvt;
	struct ast_timer *timer;
	struct softmix_translate_helper trans_helper;
	int16_t buf[MAX_DATALEN];
#ifdef BINAURAL_RENDERING
	int16_t bin_buf[MAX_DATALEN];
	int16_t ann_buf[MAX_DATALEN];
#endif
	unsigned int stat_iteration_counter = 0; /* counts down, gather stats at zero and reset. */
	int timingfd;
	int update_all_rates = 0; /* set this when the internal sample rate has changed */
	unsigned int idx;
	unsigned int x;
	int res = -1;

	timer = softmix_data->timer;
	timingfd = ast_timer_fd(timer);
	softmix_translate_helper_init(&trans_helper, softmix_data->internal_rate);
	ast_timer_set_rate(timer, (1000 / softmix_data->internal_mixing_interval));

	/* Give the mixing array room to grow, memory is cheap but allocations are expensive. */
	if (softmix_mixing_array_init(&mixing_array, bridge->num_channels + 10,
			bridge->softmix.binaural_active)) {
		goto softmix_cleanup;
	}

	/*
	 * XXX Softmix needs to use channel roles to determine who gets
	 * what audio mixed.
	 */
	while (!softmix_data->stop && bridge->num_active) {
		struct ast_bridge_channel *bridge_channel;
		int timeout = -1;
		struct ast_format *cur_slin = ast_format_cache_get_slin_by_rate(softmix_data->internal_rate);
		unsigned int softmix_samples = SOFTMIX_SAMPLES(softmix_data->internal_rate, softmix_data->internal_mixing_interval);
		unsigned int softmix_datalen = SOFTMIX_DATALEN(softmix_data->internal_rate, softmix_data->internal_mixing_interval);

		if (softmix_datalen > MAX_DATALEN) {
			/* This should NEVER happen, but if it does we need to know about it. Almost
			 * all the memcpys used during this process depend on this assumption.  Rather
			 * than checking this over and over again through out the code, this single
			 * verification is done on each iteration. */
			ast_log(LOG_WARNING,
				"Bridge %s: Conference mixing error, requested mixing length greater than mixing buffer.\n",
				bridge->uniqueid);
			goto softmix_cleanup;
		}

		/* Grow the mixing array buffer as participants are added. */
		if (mixing_array.max_num_entries < bridge->num_channels
			&& softmix_mixing_array_grow(&mixing_array, bridge->num_channels + 5,
					bridge->softmix.binaural_active)) {
			goto softmix_cleanup;
		}

		/* init the number of buffers stored in the mixing array to 0.
		 * As buffers are added for mixing, this number is incremented. */
		mixing_array.used_entries = 0;

		/* These variables help determine if a rate change is required */
		if (!stat_iteration_counter) {
			memset(&stats, 0, sizeof(stats));
			stats.locked_rate = bridge->softmix.internal_sample_rate;
		}

		/* If the sample rate has changed, update the translator helper */
		if (update_all_rates) {
			softmix_translate_helper_change_rate(&trans_helper, softmix_data->internal_rate);
		}

#ifdef BINAURAL_RENDERING
		check_binaural_position_change(bridge, softmix_data);
#endif

		/* Go through pulling audio from each factory that has it available */
		AST_LIST_TRAVERSE(&bridge->channels, bridge_channel, entry) {
			struct softmix_channel *sc = bridge_channel->tech_pvt;

			if (!sc) {
				/* This channel failed to join successfully. */
				continue;
			}

			/* Update the sample rate to match the bridge's native sample rate if necessary. */
			if (update_all_rates) {
				set_softmix_bridge_data(softmix_data->internal_rate,
						softmix_data->internal_mixing_interval, bridge_channel, 1, -1, -1, -1);
			}

			/* If stat_iteration_counter is 0, then collect statistics during this mixing interation */
			if (!stat_iteration_counter) {
				gather_softmix_stats(&stats, softmix_data, bridge_channel);
			}

			/* if the channel is suspended, don't check for audio, but still gather stats */
			if (bridge_channel->suspended) {
				continue;
			}

			/* Try to get audio from the factory if available */
			ast_mutex_lock(&sc->lock);
			if ((mixing_array.buffers[mixing_array.used_entries] = softmix_process_read_audio(sc, softmix_samples))) {
#ifdef BINAURAL_RENDERING
				add_binaural_mixing(bridge, softmix_data, softmix_samples, &mixing_array, sc,
						ast_channel_name(bridge_channel->chan));
#endif
				mixing_array.used_entries++;
			}
			ast_mutex_unlock(&sc->lock);
		}

		/* mix it like crazy (non binaural channels)*/
		memset(buf, 0, softmix_datalen);
		for (idx = 0; idx < mixing_array.used_entries; ++idx) {
			for (x = 0; x < softmix_samples; ++x) {
				ast_slinear_saturated_add(buf + x, mixing_array.buffers[idx] + x);
			}
		}

#ifdef BINAURAL_RENDERING
		binaural_mixing(bridge, softmix_data, &mixing_array, bin_buf, ann_buf);
#endif

		/* Next step go through removing the channel's own audio and creating a good frame... */
		AST_LIST_TRAVERSE(&bridge->channels, bridge_channel, entry) {
			struct softmix_channel *sc = bridge_channel->tech_pvt;

			if (!sc || bridge_channel->suspended) {
				/* This channel failed to join successfully or is suspended. */
				continue;
			}

			ast_mutex_lock(&sc->lock);

			/* Make SLINEAR write frame from local buffer */
			ao2_t_replace(sc->write_frame.subclass.format, cur_slin,
				"Replace softmix channel slin format");
#ifdef BINAURAL_RENDERING
			if (bridge->softmix.binaural_active && softmix_data->convolve.binaural_active
					&& sc->binaural) {
				create_binaural_frame(bridge_channel, sc, bin_buf, ann_buf, softmix_datalen,
						softmix_samples, buf);
			} else
#endif
			{
				sc->write_frame.datalen = softmix_datalen;
				sc->write_frame.samples = softmix_samples;
				memcpy(sc->final_buf, buf, softmix_datalen);
			}
			/* process the softmix channel's new write audio */
			softmix_process_write_audio(&trans_helper,
					ast_channel_rawwriteformat(bridge_channel->chan), sc,
					softmix_data->default_sample_size);

			ast_mutex_unlock(&sc->lock);

			/* A frame is now ready for the channel. */
			ast_bridge_channel_queue_frame(bridge_channel, &sc->write_frame);
		}

		update_all_rates = 0;
		if (!stat_iteration_counter) {
			update_all_rates = analyse_softmix_stats(&stats, softmix_data,
					bridge->softmix.binaural_active);
			stat_iteration_counter = SOFTMIX_STAT_INTERVAL;
		}
		stat_iteration_counter--;

		ast_bridge_unlock(bridge);
		/* cleanup any translation frame data from the previous mixing iteration. */
		softmix_translate_helper_cleanup(&trans_helper);
		/* Wait for the timing source to tell us to wake up and get things done */
		ast_waitfor_n_fd(&timingfd, 1, &timeout, NULL);
		if (ast_timer_ack(timer, 1) < 0) {
			ast_log(LOG_ERROR, "Bridge %s: Failed to acknowledge timer in softmix.\n",
				bridge->uniqueid);
			ast_bridge_lock(bridge);
			goto softmix_cleanup;
		}
		ast_bridge_lock(bridge);

		/* make sure to detect mixing interval changes if they occur. */
		if (bridge->softmix.internal_mixing_interval
			&& (bridge->softmix.internal_mixing_interval != softmix_data->internal_mixing_interval)) {
			softmix_data->internal_mixing_interval = bridge->softmix.internal_mixing_interval;
			ast_timer_set_rate(timer, (1000 / softmix_data->internal_mixing_interval));
			update_all_rates = 1; /* if the interval changes, the rates must be adjusted as well just to be notified new interval.*/
		}
	}

	res = 0;

softmix_cleanup:
	softmix_translate_helper_destroy(&trans_helper);
	softmix_mixing_array_destroy(&mixing_array, bridge->softmix.binaural_active);
	return res;
}

/*!
 * \internal
 * \brief Mixing thread.
 * \since 12.0.0
 *
 * \note The thread does not have its own reference to the
 * bridge.  The lifetime of the thread is tied to the lifetime
 * of the mixing technology association with the bridge.
 */
static void *softmix_mixing_thread(void *data)
{
	struct softmix_bridge_data *softmix_data = data;
	struct ast_bridge *bridge = softmix_data->bridge;

	ast_bridge_lock(bridge);
	if (bridge->callid) {
		ast_callid_threadassoc_add(bridge->callid);
	}

	ast_debug(1, "Bridge %s: starting mixing thread\n", bridge->uniqueid);

	while (!softmix_data->stop) {
		if (!bridge->num_active) {
			/* Wait for something to happen to the bridge. */
			ast_bridge_unlock(bridge);
			ast_mutex_lock(&softmix_data->lock);
			if (!softmix_data->stop) {
				ast_cond_wait(&softmix_data->cond, &softmix_data->lock);
			}
			ast_mutex_unlock(&softmix_data->lock);
			ast_bridge_lock(bridge);
			continue;
		}

		if (bridge->softmix.binaural_active && !softmix_data->binaural_init) {
#ifndef BINAURAL_RENDERING
			ast_bridge_lock(bridge);
			bridge->softmix.binaural_active = 0;
			ast_bridge_unlock(bridge);
			ast_log(LOG_WARNING, "Bridge: %s: Binaural rendering active by config but not "
					"compiled.\n", bridge->uniqueid);
#else
			/* Set and init binaural data if binaural is activated in the configuration. */
			softmix_data->internal_rate = SOFTMIX_BINAURAL_SAMPLE_RATE;
			softmix_data->default_sample_size = SOFTMIX_SAMPLES(softmix_data->internal_rate,
					softmix_data->internal_mixing_interval);
			/* If init for binaural processing fails we will fall back to mono audio processing. */
			if (init_convolve_data(&softmix_data->convolve, softmix_data->default_sample_size)
					== -1) {
				ast_bridge_lock(bridge);
				bridge->softmix.binaural_active = 0;
				ast_bridge_unlock(bridge);
				ast_log(LOG_ERROR, "Bridge: %s: Unable to allocate memory for "
						"binaural processing,  Will only process mono audio.\n",
						bridge->uniqueid);
			}
			softmix_data->binaural_init = 1;
#endif
		}

		if (softmix_mixing_loop(bridge)) {
			/*
			 * A mixing error occurred.  Sleep and try again later so we
			 * won't flood the logs.
			 */
			ast_bridge_unlock(bridge);
			sleep(1);
			ast_bridge_lock(bridge);
		}
	}

	ast_bridge_unlock(bridge);

	ast_debug(1, "Bridge %s: stopping mixing thread\n", bridge->uniqueid);

	return NULL;
}

static void softmix_bridge_data_destroy(struct softmix_bridge_data *softmix_data)
{
	if (softmix_data->timer) {
		ast_timer_close(softmix_data->timer);
		softmix_data->timer = NULL;
	}
	ast_mutex_destroy(&softmix_data->lock);
	ast_cond_destroy(&softmix_data->cond);
	ast_free(softmix_data);
}

/*! \brief Function called when a bridge is created */
static int softmix_bridge_create(struct ast_bridge *bridge)
{
	struct softmix_bridge_data *softmix_data;

	softmix_data = ast_calloc(1, sizeof(*softmix_data));
	if (!softmix_data) {
		return -1;
	}
	softmix_data->bridge = bridge;
	ast_mutex_init(&softmix_data->lock);
	ast_cond_init(&softmix_data->cond, NULL);
	softmix_data->timer = ast_timer_open();
	if (!softmix_data->timer) {
		ast_log(AST_LOG_WARNING, "Failed to open timer for softmix bridge\n");
		softmix_bridge_data_destroy(softmix_data);
		return -1;
	}
	/* start at minimum rate, let it grow from there */
	softmix_data->internal_rate = SOFTMIX_MIN_SAMPLE_RATE;
	softmix_data->internal_mixing_interval = DEFAULT_SOFTMIX_INTERVAL;

#ifdef BINAURAL_RENDERING
	softmix_data->default_sample_size = SOFTMIX_SAMPLES(softmix_data->internal_rate,
			softmix_data->internal_mixing_interval);
#endif

	bridge->tech_pvt = softmix_data;

	/* Start the mixing thread. */
	if (ast_pthread_create(&softmix_data->thread, NULL, softmix_mixing_thread,
		softmix_data)) {
		softmix_data->thread = AST_PTHREADT_NULL;
		softmix_bridge_data_destroy(softmix_data);
		bridge->tech_pvt = NULL;
		return -1;
	}

	return 0;
}

/*!
 * \internal
 * \brief Request the softmix mixing thread stop.
 * \since 12.0.0
 *
 * \param bridge Which bridge is being stopped.
 *
 * \return Nothing
 */
static void softmix_bridge_stop(struct ast_bridge *bridge)
{
	struct softmix_bridge_data *softmix_data;

	softmix_data = bridge->tech_pvt;
	if (!softmix_data) {
		return;
	}

	ast_mutex_lock(&softmix_data->lock);
	softmix_data->stop = 1;
	ast_mutex_unlock(&softmix_data->lock);
}

/*! \brief Function called when a bridge is destroyed */
static void softmix_bridge_destroy(struct ast_bridge *bridge)
{
	struct softmix_bridge_data *softmix_data;
	pthread_t thread;

	softmix_data = bridge->tech_pvt;
	if (!softmix_data) {
		return;
	}

	/* Stop the mixing thread. */
	ast_mutex_lock(&softmix_data->lock);
	softmix_data->stop = 1;
	ast_cond_signal(&softmix_data->cond);
	thread = softmix_data->thread;
	softmix_data->thread = AST_PTHREADT_NULL;
	ast_mutex_unlock(&softmix_data->lock);
	if (thread != AST_PTHREADT_NULL) {
		ast_debug(1, "Bridge %s: Waiting for mixing thread to die.\n", bridge->uniqueid);
		pthread_join(thread, NULL);
	}
#ifdef BINAURAL_RENDERING
	free_convolve_data(&softmix_data->convolve);
#endif
	softmix_bridge_data_destroy(softmix_data);
	bridge->tech_pvt = NULL;
}

/*!
 * \brief Map a source stream to all of its destination streams.
 *
 * \param source_stream_name Name of the source stream
 * \param source_channel_name Name of channel where the source stream originates
 * \param bridge_stream_position The slot in the bridge where source video will come from
 * \param participants The bridge_channels in the bridge
 */
static void map_source_to_destinations(const char *source_stream_name, const char *source_channel_name,
	size_t bridge_stream_position, struct ast_bridge_channels_list *participants)
{
	struct ast_bridge_channel *participant;

	AST_LIST_TRAVERSE(participants, participant, entry) {
		int i;
		struct ast_stream_topology *topology;

		if (!strcmp(source_channel_name, ast_channel_name(participant->chan))) {
			continue;
		}

		ast_bridge_channel_lock(participant);
		ast_channel_lock(participant->chan);
		topology = ast_channel_get_stream_topology(participant->chan);

		for (i = 0; i < ast_stream_topology_get_count(topology); ++i) {
			struct ast_stream *stream;

			stream = ast_stream_topology_get_stream(topology, i);
			if (is_video_dest(stream, source_channel_name, source_stream_name)) {
				AST_VECTOR_REPLACE(&participant->stream_map.to_channel, bridge_stream_position, i);
				break;
			}
		}
		ast_channel_unlock(participant->chan);
		ast_bridge_channel_unlock(participant);
	}
}

/*!
 * \brief stream_topology_changed callback
 *
 * For most video modes, nothing beyond the ordinary is required.
 * For the SFU case, though, we need to completely remap the streams
 * in order to ensure video gets directed where it is expected to go.
 *
 * \param bridge The bridge
 * \param bridge_channel Channel whose topology has changed
 */
static void softmix_bridge_stream_topology_changed(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel)
{
	struct ast_bridge_channel *participant;
	struct ast_vector_int media_types;
	int nths[AST_MEDIA_TYPE_END] = {0};

	switch (bridge->softmix.video_mode.mode) {
	case AST_BRIDGE_VIDEO_MODE_NONE:
	case AST_BRIDGE_VIDEO_MODE_SINGLE_SRC:
	case AST_BRIDGE_VIDEO_MODE_TALKER_SRC:
	default:
		ast_bridge_channel_stream_map(bridge_channel);
		return;
	case AST_BRIDGE_VIDEO_MODE_SFU:
		break;
	}

	AST_VECTOR_INIT(&media_types, AST_MEDIA_TYPE_END);

	/* First traversal: re-initialize all of the participants' stream maps */
	AST_LIST_TRAVERSE(&bridge->channels, participant, entry) {
		ast_bridge_channel_lock(participant);
		AST_VECTOR_RESET(&participant->stream_map.to_channel, AST_VECTOR_ELEM_CLEANUP_NOOP);
		AST_VECTOR_RESET(&participant->stream_map.to_bridge, AST_VECTOR_ELEM_CLEANUP_NOOP);
		ast_bridge_channel_unlock(participant);
	}

	/* Second traversal: Map specific video channels from their source to their destinations.
	 *
	 * This is similar to what is done in ast_stream_topology_map(),
	 * except that video channels are handled differently.  Each video
	 * source has it's own unique index on the bridge.  This way, a
	 * particular channel's source video can be distributed to the
	 * appropriate destination streams on the other channels.
	 */
	AST_LIST_TRAVERSE(&bridge->channels, participant, entry) {
		int i;
		struct ast_stream_topology *topology;

		ast_bridge_channel_lock(participant);
		ast_channel_lock(participant->chan);

		topology = ast_channel_get_stream_topology(participant->chan);
		if (topology) {
			/*
			 * Sigh.  We have to clone to avoid deadlock in
			 * map_source_to_destinations() because topology
			 * is not an ao2 object.
			 */
			topology = ast_stream_topology_clone(topology);
		}
		if (!topology) {
			/* Oh, my, we are in trouble. */
			ast_channel_unlock(participant->chan);
			ast_bridge_channel_unlock(participant);
			continue;
		}

		for (i = 0; i < ast_stream_topology_get_count(topology); ++i) {
			struct ast_stream *stream = ast_stream_topology_get_stream(topology, i);

			if (is_video_source(stream)) {
				AST_VECTOR_APPEND(&media_types, AST_MEDIA_TYPE_VIDEO);
				AST_VECTOR_REPLACE(&participant->stream_map.to_bridge, i, AST_VECTOR_SIZE(&media_types) - 1);
				AST_VECTOR_REPLACE(&participant->stream_map.to_channel, AST_VECTOR_SIZE(&media_types) - 1, -1);
				/*
				 * Unlock the channel and participant to prevent
				 * potential deadlock in map_source_to_destinations().
				 */
				ast_channel_unlock(participant->chan);
				ast_bridge_channel_unlock(participant);
				map_source_to_destinations(ast_stream_get_name(stream), ast_channel_name(participant->chan),
					AST_VECTOR_SIZE(&media_types) - 1, &bridge->channels);
				ast_bridge_channel_lock(participant);
				ast_channel_lock(participant->chan);
			} else if (is_video_dest(stream, NULL, NULL)) {
				/* We expect to never read media from video destination channels, but just
				 * in case, we should set their to_bridge value to -1.
				 */
				AST_VECTOR_REPLACE(&participant->stream_map.to_bridge, i, -1);
			} else {
				/* XXX This is copied from ast_stream_topology_map(). This likely could
				 * be factored out in some way
				 */
				enum ast_media_type type = ast_stream_get_type(stream);
				int index = AST_VECTOR_GET_INDEX_NTH(&media_types, ++nths[type],
					type, AST_VECTOR_ELEM_DEFAULT_CMP);

				if (index == -1) {
					AST_VECTOR_APPEND(&media_types, type);
					index = AST_VECTOR_SIZE(&media_types) - 1;
				}

				AST_VECTOR_REPLACE(&participant->stream_map.to_bridge, i, index);
				AST_VECTOR_REPLACE(&participant->stream_map.to_channel, index, i);
			}
		}

		ast_stream_topology_free(topology);

		ast_channel_unlock(participant->chan);
		ast_bridge_channel_unlock(participant);
	}
}

static struct ast_bridge_technology softmix_bridge = {
	.name = "softmix",
	.capabilities = AST_BRIDGE_CAPABILITY_MULTIMIX,
	.preference = AST_BRIDGE_PREFERENCE_BASE_MULTIMIX,
	.create = softmix_bridge_create,
	.stop = softmix_bridge_stop,
	.destroy = softmix_bridge_destroy,
	.join = softmix_bridge_join,
	.leave = softmix_bridge_leave,
	.unsuspend = softmix_bridge_unsuspend,
	.write = softmix_bridge_write,
	.stream_topology_changed = softmix_bridge_stream_topology_changed,
};

#ifdef TEST_FRAMEWORK
struct stream_parameters {
	const char *name;
	const char *formats;
	enum ast_media_type type;
};

static struct ast_stream_topology *build_topology(const struct stream_parameters *params, size_t num_streams)
{
	struct ast_stream_topology *topology;
	size_t i;

	topology = ast_stream_topology_alloc();
	if (!topology) {
		return NULL;
	}

	for (i = 0; i < num_streams; ++i) {
		RAII_VAR(struct ast_format_cap *, caps, NULL, ao2_cleanup);
		struct ast_stream *stream;

		caps = ast_format_cap_alloc(AST_FORMAT_CAP_FLAG_DEFAULT);
		if (!caps) {
			goto fail;
		}
		if (ast_format_cap_update_by_allow_disallow(caps, params[i].formats, 1) < 0) {
			goto fail;
		}
		stream = ast_stream_alloc(params[i].name, params[i].type);
		if (!stream) {
			goto fail;
		}
		ast_stream_set_formats(stream, caps);
		if (ast_stream_topology_append_stream(topology, stream) < 0) {
			ast_stream_free(stream);
			goto fail;
		}
	}

	return topology;

fail:
	ast_stream_topology_free(topology);
	return NULL;
}

static int validate_stream(struct ast_test *test, struct ast_stream *stream,
	const struct stream_parameters *params)
{
	struct ast_format_cap *stream_caps;
	struct ast_format_cap *params_caps;

	if (ast_stream_get_type(stream) != params->type) {
		ast_test_status_update(test, "Expected stream type '%s' but got type '%s'\n",
			ast_codec_media_type2str(params->type),
			ast_codec_media_type2str(ast_stream_get_type(stream)));
		return -1;
	}
	if (strcmp(ast_stream_get_name(stream), params->name)) {
		ast_test_status_update(test, "Expected stream name '%s' but got type '%s'\n",
			params->name, ast_stream_get_name(stream));
		return -1;
	}

	stream_caps = ast_stream_get_formats(stream);
	params_caps = ast_format_cap_alloc(AST_FORMAT_CAP_FLAG_DEFAULT);
	if (!params_caps) {
		ast_test_status_update(test, "Allocation error on capabilities\n");
		return -1;
	}
	ast_format_cap_update_by_allow_disallow(params_caps, params->formats, 1);

	if (!ast_format_cap_identical(stream_caps, params_caps)) {
		ast_test_status_update(test, "Formats are not as expected on stream '%s'\n",
			ast_stream_get_name(stream));
		ao2_cleanup(params_caps);
		return -1;
	}

	ao2_cleanup(params_caps);
	return 0;
}

static int validate_original_streams(struct ast_test *test, struct ast_stream_topology *topology,
	const struct stream_parameters *params, size_t num_streams)
{
	int i;

	if (ast_stream_topology_get_count(topology) < num_streams) {
		ast_test_status_update(test, "Topology only has %d streams. Needs to have at least %zu\n",
			ast_stream_topology_get_count(topology), num_streams);
		return -1;
	}

	for (i = 0; i < num_streams; ++i) {
		if (validate_stream(test, ast_stream_topology_get_stream(topology, i), &params[i])) {
			return -1;
		}
	}

	return 0;
}

AST_TEST_DEFINE(sfu_append_source_streams)
{
	enum ast_test_result_state res = AST_TEST_FAIL;
	static const struct stream_parameters bob_streams[] = {
		{ "bob_audio", "ulaw,alaw,g722,opus", AST_MEDIA_TYPE_AUDIO, },
		{ "bob_video", "h264,vp8", AST_MEDIA_TYPE_VIDEO, },
	};
	static const struct stream_parameters alice_streams[] = {
		{ "alice_audio", "ulaw,opus", AST_MEDIA_TYPE_AUDIO, },
		{ "alice_video", "vp8", AST_MEDIA_TYPE_VIDEO, },
	};
	static const struct stream_parameters alice_dest_stream = {
		"softbridge_dest_PJSIP/Bob-00000001_bob_video", "h264,vp8", AST_MEDIA_TYPE_VIDEO,
	};
	static const struct stream_parameters bob_dest_stream = {
		"softbridge_dest_PJSIP/Alice-00000000_alice_video", "vp8", AST_MEDIA_TYPE_VIDEO,
	};
	struct ast_stream_topology *topology_alice = NULL;
	struct ast_stream_topology *topology_bob = NULL;

	switch (cmd) {
	case TEST_INIT:
		info->name = "sfu_append_source_streams";
		info->category = "/bridges/bridge_softmix/";
		info->summary = "Test appending of video streams";
		info->description =
			"This tests does stuff.";
		return AST_TEST_NOT_RUN;
	case TEST_EXECUTE:
		break;
	}

	topology_alice = build_topology(alice_streams, ARRAY_LEN(alice_streams));
	if (!topology_alice) {
		goto end;
	}

	topology_bob = build_topology(bob_streams, ARRAY_LEN(bob_streams));
	if (!topology_bob) {
		goto end;
	}

	if (append_source_streams(topology_alice, "PJSIP/Bob-00000001", topology_bob)) {
		ast_test_status_update(test, "Failed to append Bob's streams to Alice\n");
		goto end;
	}

	if (ast_stream_topology_get_count(topology_alice) != 3) {
		ast_test_status_update(test, "Alice's topology isn't large enough! It's %d but needs to be %d\n",
			ast_stream_topology_get_count(topology_alice), 3);
		goto end;
	}

	if (validate_original_streams(test, topology_alice, alice_streams, ARRAY_LEN(alice_streams))) {
		goto end;
	}

	if (validate_stream(test, ast_stream_topology_get_stream(topology_alice, 2), &alice_dest_stream)) {
		goto end;
	}

	if (append_source_streams(topology_bob, "PJSIP/Alice-00000000", topology_alice)) {
		ast_test_status_update(test, "Failed to append Alice's streams to Bob\n");
		goto end;
	}

	if (ast_stream_topology_get_count(topology_bob) != 3) {
		ast_test_status_update(test, "Bob's topology isn't large enough! It's %d but needs to be %d\n",
			ast_stream_topology_get_count(topology_bob), 3);
		goto end;
	}

	if (validate_original_streams(test, topology_bob, bob_streams, ARRAY_LEN(bob_streams))) {
		goto end;
	}

	if (validate_stream(test, ast_stream_topology_get_stream(topology_bob, 2), &bob_dest_stream)) {
		goto end;
	}

	res = AST_TEST_PASS;

end:
	ast_stream_topology_free(topology_alice);
	ast_stream_topology_free(topology_bob);
	return res;
}

AST_TEST_DEFINE(sfu_remove_destination_streams)
{
	enum ast_test_result_state res = AST_TEST_FAIL;
	static const struct stream_parameters params[] = {
		{ "alice_audio", "ulaw,alaw,g722,opus", AST_MEDIA_TYPE_AUDIO, },
		{ "alice_video", "h264,vp8", AST_MEDIA_TYPE_VIDEO, },
		{ "softbridge_dest_PJSIP/Bob-00000001_video", "vp8", AST_MEDIA_TYPE_VIDEO, },
		{ "softbridge_dest_PJSIP/Carol-00000002_video", "h264", AST_MEDIA_TYPE_VIDEO, },
	};
	static const struct {
		const char *channel_name;
		int num_streams;
		int params_index[4];
	} removal_results[] = {
		{ "PJSIP/Bob-00000001", 4, { 0, 1, 2, 3 }, },
		{ "PJSIP/Edward-00000004", 4, { 0, 1, 2, 3 }, },
		{ "", 4, { 0, 1, 2, 3 }, },
	};
	struct ast_stream_topology *orig = NULL;
	int i;

	switch (cmd) {
	case TEST_INIT:
		info->name = "sfu_remove_destination_streams";
		info->category = "/bridges/bridge_softmix/";
		info->summary = "Test removal of destination video streams";
		info->description =
			"This tests does stuff.";
		return AST_TEST_NOT_RUN;
	case TEST_EXECUTE:
		break;
	}

	orig = build_topology(params, ARRAY_LEN(params));
	if (!orig) {
		ast_test_status_update(test, "Unable to build initial stream topology\n");
		goto end;
	}

	for (i = 0; i < ARRAY_LEN(removal_results); ++i) {
		int j;

		remove_destination_streams(orig, removal_results[i].channel_name);

		if (ast_stream_topology_get_count(orig) != removal_results[i].num_streams) {
			ast_test_status_update(test, "Resulting topology has %d streams, when %d are expected\n",
				ast_stream_topology_get_count(orig), removal_results[i].num_streams);
			goto end;
		}

		for (j = 0; j < removal_results[i].num_streams; ++j) {
			struct ast_stream *actual;
			struct ast_stream *expected;
			int orig_index;

			actual = ast_stream_topology_get_stream(orig, j);

			orig_index = removal_results[i].params_index[j];
			expected = ast_stream_topology_get_stream(orig, orig_index);

			if (!ast_format_cap_identical(ast_stream_get_formats(actual),
				ast_stream_get_formats(expected))) {
				struct ast_str *expected_str;
				struct ast_str *actual_str;

				expected_str = ast_str_alloca(64);
				actual_str = ast_str_alloca(64);

				ast_test_status_update(test, "Mismatch between expected (%s) and actual (%s) stream formats\n",
					ast_format_cap_get_names(ast_stream_get_formats(expected), &expected_str),
					ast_format_cap_get_names(ast_stream_get_formats(actual), &actual_str));
				goto end;
			}

			if (is_video_dest(actual, removal_results[i].channel_name, NULL) &&
				ast_stream_get_state(actual) != AST_STREAM_STATE_REMOVED) {
				ast_test_status_update(test, "Removed stream %s does not have a state of removed\n", ast_stream_get_name(actual));
				goto end;
			}
		}
	}

	res = AST_TEST_PASS;

end:
	ast_stream_topology_free(orig);
	return res;
}

#endif

static int unload_module(void)
{
	ast_bridge_technology_unregister(&softmix_bridge);
	AST_TEST_UNREGISTER(sfu_append_source_streams);
	AST_TEST_UNREGISTER(sfu_remove_destination_streams);
	return 0;
}

static int load_module(void)
{
	if (ast_bridge_technology_register(&softmix_bridge)) {
		unload_module();
		return AST_MODULE_LOAD_DECLINE;
	}
	AST_TEST_REGISTER(sfu_append_source_streams);
	AST_TEST_REGISTER(sfu_remove_destination_streams);
	return AST_MODULE_LOAD_SUCCESS;
}

AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Multi-party software based channel mixing");