bridges/bridge_softmix.c

   1 /*
   2  * Asterisk -- An open source telephony toolkit.
   3  *
   4  * Copyright (C) 2011, Digium, Inc.
   5  *
   6  * Joshua Colp <jcolp@digium.com>
   7  * David Vossel <dvossel@digium.com>
   8  *
   9  * See http://www.asterisk.org for more information about
  10  * the Asterisk project. Please do not directly contact
  11  * any of the maintainers of this project for assistance;
  12  * the project provides a web site, mailing lists and IRC
  13  * channels for your use.
  14  *
  15  * This program is free software, distributed under the terms of
  16  * the GNU General Public License Version 2. See the LICENSE file
  17  * at the top of the source tree.
  18  */
  19
  20 /*! \file
  21  *
  22  * \brief Multi-party software based channel mixing
  23  *
  24  * \author Joshua Colp <jcolp@digium.com>
  25  * \author David Vossel <dvossel@digium.com>
  26  *
  27  * \ingroup bridges
  28  */
  29
  30 #include "asterisk.h"
  31
  32 ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
  33
  34 #include <stdio.h>
  35 #include <stdlib.h>
  36 #include <string.h>
  37 #include <sys/time.h>
  38 #include <signal.h>
  39 #include <errno.h>
  40 #include <unistd.h>
  41
  42 #include "asterisk/module.h"
  43 #include "asterisk/channel.h"
  44 #include "asterisk/bridging.h"
  45 #include "asterisk/bridging_technology.h"
  46 #include "asterisk/frame.h"
  47 #include "asterisk/options.h"
  48 #include "asterisk/logger.h"
  49 #include "asterisk/slinfactory.h"
  50 #include "asterisk/astobj2.h"
  51 #include "asterisk/timing.h"
  52 #include "asterisk/translate.h"
  53
  54 #define MAX_DATALEN 8096
  55
  56 /*! \brief Interval at which mixing will take place. Valid options are 10, 20, and 40. */
  57 #define DEFAULT_SOFTMIX_INTERVAL 20
  58
  59 /*! \brief Size of the buffer used for sample manipulation */
  60 #define SOFTMIX_DATALEN(rate, interval) ((rate/50) * (interval / 10))
  61
  62 /*! \brief Number of samples we are dealing with */
  63 #define SOFTMIX_SAMPLES(rate, interval) (SOFTMIX_DATALEN(rate, interval) / 2)
  64
  65 /*! \brief Number of mixing iterations to perform between gathering statistics. */
  66 #define SOFTMIX_STAT_INTERVAL 100
  67
  68 /* This is the threshold in ms at which a channel's own audio will stop getting
  69  * mixed out its own write audio stream because it is not talking. */
  70 #define DEFAULT_SOFTMIX_SILENCE_THRESHOLD 2500
  71 #define DEFAULT_SOFTMIX_TALKING_THRESHOLD 160
  72
  73 #define DEFAULT_ENERGY_HISTORY_LEN 150
  74
  75 struct video_follow_talker_data {
  76         /*! audio energy history */
  77         int energy_history[DEFAULT_ENERGY_HISTORY_LEN];
  78         /*! The current slot being used in the history buffer, this
  79          *  increments and wraps around */
  80         int energy_history_cur_slot;
  81         /*! The current energy sum used for averages. */
  82         int energy_accum;
  83         /*! The current energy average */
  84         int energy_average;
  85 };
  86
  87 /*! \brief Structure which contains per-channel mixing information */
  88 struct softmix_channel {
  89         /*! Lock to protect this structure */
  90         ast_mutex_t lock;
  91         /*! Factory which contains audio read in from the channel */
  92         struct ast_slinfactory factory;
  93         /*! Frame that contains mixed audio to be written out to the channel */
  94         struct ast_frame write_frame;
  95         /*! Frame that contains mixed audio read from the channel */
  96         struct ast_frame read_frame;
  97         /*! DSP for detecting silence */
  98         struct ast_dsp *dsp;
  99         /*! Bit used to indicate if a channel is talking or not. This affects how
 100          * the channel's audio is mixed back to it. */
 101         int talking:1;
 102         /*! Bit used to indicate that the channel provided audio for this mixing interval */
 103         int have_audio:1;
 104         /*! Bit used to indicate that a frame is available to be written out to the channel */
 105         int have_frame:1;
 106         /*! Buffer containing final mixed audio from all sources */
 107         short final_buf[MAX_DATALEN];
 108         /*! Buffer containing only the audio from the channel */
 109         short our_buf[MAX_DATALEN];
 110         /*! Data pertaining to talker mode for video conferencing */
 111         struct video_follow_talker_data video_talker;
 112 };
 113
 114 struct softmix_bridge_data {
 115         struct ast_timer *timer;
 116         unsigned int internal_rate;
 117         unsigned int internal_mixing_interval;
 118 };
 119
 120 struct softmix_stats {
 121                 /*! Each index represents a sample rate used above the internal rate. */
 122                 unsigned int sample_rates[16];
 123                 /*! Each index represents the number of channels using the same index in the sample_rates array.  */
 124                 unsigned int num_channels[16];
 125                 /*! the number of channels above the internal sample rate */
 126                 unsigned int num_above_internal_rate;
 127                 /*! the number of channels at the internal sample rate */
 128                 unsigned int num_at_internal_rate;
 129                 /*! the absolute highest sample rate supported by any channel in the bridge */
 130                 unsigned int highest_supported_rate;
 131                 /*! Is the sample rate locked by the bridge, if so what is that rate.*/
 132                 unsigned int locked_rate;
 133 };
 134
 135 struct softmix_mixing_array {
 136         int max_num_entries;
 137         int used_entries;
 138         int16_t **buffers;
 139 };
 140
 141 struct softmix_translate_helper_entry {
 142         int num_times_requested; /*!< Once this entry is no longer requested, free the trans_pvt
 143                                       and re-init if it was usable. */
 144         struct ast_format dst_format; /*!< The destination format for this helper */
 145         struct ast_trans_pvt *trans_pvt; /*!< the translator for this slot. */
 146         struct ast_frame *out_frame; /*!< The output frame from the last translation */
 147         AST_LIST_ENTRY(softmix_translate_helper_entry) entry;
 148 };
 149
 150 struct softmix_translate_helper {
 151         struct ast_format slin_src; /*!< the source format expected for all the translators */
 152         AST_LIST_HEAD_NOLOCK(, softmix_translate_helper_entry) entries;
 153 };
 154
 155 static struct softmix_translate_helper_entry *softmix_translate_helper_entry_alloc(struct ast_format *dst)
 156 {
 157         struct softmix_translate_helper_entry *entry;
 158         if (!(entry = ast_calloc(1, sizeof(*entry)))) {
 159                 return NULL;
 160         }
 161         ast_format_copy(&entry->dst_format, dst);
 162         return entry;
 163 }
 164
 165 static void *softmix_translate_helper_free_entry(struct softmix_translate_helper_entry *entry)
 166 {
 167         if (entry->trans_pvt) {
 168                 ast_translator_free_path(entry->trans_pvt);
 169         }
 170         if (entry->out_frame) {
 171                 ast_frfree(entry->out_frame);
 172         }
 173         ast_free(entry);
 174         return NULL;
 175 }
 176
 177 static void softmix_translate_helper_init(struct softmix_translate_helper *trans_helper, unsigned int sample_rate)
 178 {
 179         memset(trans_helper, 0, sizeof(*trans_helper));
 180         ast_format_set(&trans_helper->slin_src, ast_format_slin_by_rate(sample_rate), 0);
 181 }
 182
 183 static void softmix_translate_helper_destroy(struct softmix_translate_helper *trans_helper)
 184 {
 185         struct softmix_translate_helper_entry *entry;
 186
 187         while ((entry = AST_LIST_REMOVE_HEAD(&trans_helper->entries, entry))) {
 188                 softmix_translate_helper_free_entry(entry);
 189         }
 190 }
 191
 192 static void softmix_translate_helper_change_rate(struct softmix_translate_helper *trans_helper, unsigned int sample_rate)
 193 {
 194         struct softmix_translate_helper_entry *entry;
 195
 196         ast_format_set(&trans_helper->slin_src, ast_format_slin_by_rate(sample_rate), 0);
 197         AST_LIST_TRAVERSE_SAFE_BEGIN(&trans_helper->entries, entry, entry) {
 198                 if (entry->trans_pvt) {
 199                         ast_translator_free_path(entry->trans_pvt);
 200                         if (!(entry->trans_pvt = ast_translator_build_path(&entry->dst_format, &trans_helper->slin_src))) {
 201                                 AST_LIST_REMOVE_CURRENT(entry);
 202                                 entry = softmix_translate_helper_free_entry(entry);
 203                         }
 204                 }
 205         }
 206         AST_LIST_TRAVERSE_SAFE_END;
 207 }
 208
 209 /*!
 210  * \internal
 211  * \brief Get the next available audio on the softmix channel's read stream
 212  * and determine if it should be mixed out or not on the write stream.
 213  *
 214  * \retval pointer to buffer containing the exact number of samples requested on success.
 215  * \retval NULL if no samples are present
 216  */
 217 static int16_t *softmix_process_read_audio(struct softmix_channel *sc, unsigned int num_samples)
 218 {
 219         if ((ast_slinfactory_available(&sc->factory) >= num_samples) &&
 220                 ast_slinfactory_read(&sc->factory, sc->our_buf, num_samples)) {
 221                 sc->have_audio = 1;
 222                 return sc->our_buf;
 223         }
 224         sc->have_audio = 0;
 225         return NULL;
 226 }
 227
 228 /*!
 229  * \internal
 230  * \brief Process a softmix channel's write audio
 231  *
 232  * \details This function will remove the channel's talking from its own audio if present and
 233  * possibly even do the channel's write translation for it depending on how many other
 234  * channels use the same write format.
 235  */
 236 static void softmix_process_write_audio(struct softmix_translate_helper *trans_helper,
 237         struct ast_format *raw_write_fmt,
 238         struct softmix_channel *sc)
 239 {
 240         struct softmix_translate_helper_entry *entry = NULL;
 241         int i;
 242
 243         /* If we provided audio that was not determined to be silence,
 244          * then take it out while in slinear format. */
 245         if (sc->have_audio && sc->talking) {
 246                 for (i = 0; i < sc->write_frame.samples; i++) {
 247                         ast_slinear_saturated_subtract(&sc->final_buf[i], &sc->our_buf[i]);
 248                 }
 249                 /* do not do any special write translate optimization if we had to make
 250                  * a special mix for them to remove their own audio. */
 251                 return;
 252         }
 253
 254         AST_LIST_TRAVERSE(&trans_helper->entries, entry, entry) {
 255                 if (ast_format_cmp(&entry->dst_format, raw_write_fmt) == AST_FORMAT_CMP_EQUAL) {
 256                         entry->num_times_requested++;
 257                 } else {
 258                         continue;
 259                 }
 260                 if (!entry->trans_pvt && (entry->num_times_requested > 1)) {
 261                         entry->trans_pvt = ast_translator_build_path(&entry->dst_format, &trans_helper->slin_src);
 262                 }
 263                 if (entry->trans_pvt && !entry->out_frame) {
 264                         entry->out_frame = ast_translate(entry->trans_pvt, &sc->write_frame, 0);
 265                 }
 266                 if (entry->out_frame && (entry->out_frame->datalen < MAX_DATALEN)) {
 267                         ast_format_copy(&sc->write_frame.subclass.format, &entry->out_frame->subclass.format);
 268                         memcpy(sc->final_buf, entry->out_frame->data.ptr, entry->out_frame->datalen);
 269                         sc->write_frame.datalen = entry->out_frame->datalen;
 270                         sc->write_frame.samples = entry->out_frame->samples;
 271                 }
 272                 break;
 273         }
 274
 275         /* add new entry into list if this format destination was not matched. */
 276         if (!entry && (entry = softmix_translate_helper_entry_alloc(raw_write_fmt))) {
 277                 AST_LIST_INSERT_HEAD(&trans_helper->entries, entry, entry);
 278         }
 279 }
 280
 281 static void softmix_translate_helper_cleanup(struct softmix_translate_helper *trans_helper)
 282 {
 283         struct softmix_translate_helper_entry *entry = NULL;
 284         AST_LIST_TRAVERSE(&trans_helper->entries, entry, entry) {
 285                 if (entry->out_frame) {
 286                         ast_frfree(entry->out_frame);
 287                         entry->out_frame = NULL;
 288                 }
 289                 entry->num_times_requested = 0;
 290         }
 291 }
 292
 293 static void softmix_bridge_data_destroy(void *obj)
 294 {
 295         struct softmix_bridge_data *softmix_data = obj;
 296         ast_timer_close(softmix_data->timer);
 297 }
 298
 299 /*! \brief Function called when a bridge is created */
 300 static int softmix_bridge_create(struct ast_bridge *bridge)
 301 {
 302         struct softmix_bridge_data *softmix_data;
 303
 304         if (!(softmix_data = ao2_alloc(sizeof(*softmix_data), softmix_bridge_data_destroy))) {
 305                 return -1;
 306         }
 307         if (!(softmix_data->timer = ast_timer_open())) {
 308                 ao2_ref(softmix_data, -1);
 309                 return -1;
 310         }
 311
 312         /* start at 8khz, let it grow from there */
 313         softmix_data->internal_rate = 8000;
 314         softmix_data->internal_mixing_interval = DEFAULT_SOFTMIX_INTERVAL;
 315
 316         bridge->bridge_pvt = softmix_data;
 317         return 0;
 318 }
 319
 320 /*! \brief Function called when a bridge is destroyed */
 321 static int softmix_bridge_destroy(struct ast_bridge *bridge)
 322 {
 323         struct softmix_bridge_data *softmix_data = bridge->bridge_pvt;
 324         if (!bridge->bridge_pvt) {
 325                 return -1;
 326         }
 327         ao2_ref(softmix_data, -1);
 328         bridge->bridge_pvt = NULL;
 329         return 0;
 330 }
 331
 332 static void set_softmix_bridge_data(int rate, int interval, struct ast_bridge_channel *bridge_channel, int reset)
 333 {
 334         struct softmix_channel *sc = bridge_channel->bridge_pvt;
 335         unsigned int channel_read_rate = ast_format_rate(&bridge_channel->chan->rawreadformat);
 336
 337         ast_mutex_lock(&sc->lock);
 338         if (reset) {
 339                 ast_slinfactory_destroy(&sc->factory);
 340                 ast_dsp_free(sc->dsp);
 341         }
 342         /* Setup read/write frame parameters */
 343         sc->write_frame.frametype = AST_FRAME_VOICE;
 344         ast_format_set(&sc->write_frame.subclass.format, ast_format_slin_by_rate(rate), 0);
 345         sc->write_frame.data.ptr = sc->final_buf;
 346         sc->write_frame.datalen = SOFTMIX_DATALEN(rate, interval);
 347         sc->write_frame.samples = SOFTMIX_SAMPLES(rate, interval);
 348
 349         sc->read_frame.frametype = AST_FRAME_VOICE;
 350         ast_format_set(&sc->read_frame.subclass.format, ast_format_slin_by_rate(channel_read_rate), 0);
 351         sc->read_frame.data.ptr = sc->our_buf;
 352         sc->read_frame.datalen = SOFTMIX_DATALEN(channel_read_rate, interval);
 353         sc->read_frame.samples = SOFTMIX_SAMPLES(channel_read_rate, interval);
 354
 355         /* Setup smoother */
 356         ast_slinfactory_init_with_format(&sc->factory, &sc->write_frame.subclass.format);
 357
 358         /* set new read and write formats on channel. */
 359         ast_set_read_format(bridge_channel->chan, &sc->read_frame.subclass.format);
 360         ast_set_write_format(bridge_channel->chan, &sc->write_frame.subclass.format);
 361
 362         /* set up new DSP.  This is on the read side only right before the read frame enters the smoother.  */
 363         sc->dsp = ast_dsp_new_with_rate(channel_read_rate);
 364         /* we want to aggressively detect silence to avoid feedback */
 365         if (bridge_channel->tech_args.talking_threshold) {
 366                 ast_dsp_set_threshold(sc->dsp, bridge_channel->tech_args.talking_threshold);
 367         } else {
 368                 ast_dsp_set_threshold(sc->dsp, DEFAULT_SOFTMIX_TALKING_THRESHOLD);
 369         }
 370
 371         ast_mutex_unlock(&sc->lock);
 372 }
 373
 374 /*! \brief Function called when a channel is joined into the bridge */
 375 static int softmix_bridge_join(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel)
 376 {
 377         struct softmix_channel *sc = NULL;
 378         struct softmix_bridge_data *softmix_data = bridge->bridge_pvt;
 379
 380         /* Create a new softmix_channel structure and allocate various things on it */
 381         if (!(sc = ast_calloc(1, sizeof(*sc)))) {
 382                 return -1;
 383         }
 384
 385         /* Can't forget the lock */
 386         ast_mutex_init(&sc->lock);
 387
 388         /* Can't forget to record our pvt structure within the bridged channel structure */
 389         bridge_channel->bridge_pvt = sc;
 390
 391         set_softmix_bridge_data(softmix_data->internal_rate,
 392                 softmix_data->internal_mixing_interval ? softmix_data->internal_mixing_interval : DEFAULT_SOFTMIX_INTERVAL,
 393                 bridge_channel, 0);
 394
 395         return 0;
 396 }
 397
 398 /*! \brief Function called when a channel leaves the bridge */
 399 static int softmix_bridge_leave(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel)
 400 {
 401         struct softmix_channel *sc = bridge_channel->bridge_pvt;
 402
 403         if (!(bridge_channel->bridge_pvt)) {
 404                 return 0;
 405         }
 406         bridge_channel->bridge_pvt = NULL;
 407
 408         /* Drop mutex lock */
 409         ast_mutex_destroy(&sc->lock);
 410
 411         /* Drop the factory */
 412         ast_slinfactory_destroy(&sc->factory);
 413
 414         /* Drop the DSP */
 415         ast_dsp_free(sc->dsp);
 416
 417         /* Eep! drop ourselves */
 418         ast_free(sc);
 419
 420         return 0;
 421 }
 422
 423 /*!
 424  * \internal
 425  * \brief If the bridging core passes DTMF to us, then they want it to be distributed out to all memebers. Do that here.
 426  */
 427 static void softmix_pass_dtmf(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel, struct ast_frame *frame)
 428 {
 429         struct ast_bridge_channel *tmp;
 430         AST_LIST_TRAVERSE(&bridge->channels, tmp, entry) {
 431                 if (tmp == bridge_channel) {
 432                         continue;
 433                 }
 434                 ast_write(tmp->chan, frame);
 435         }
 436 }
 437
 438 static void softmix_pass_video(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel, struct ast_frame *frame)
 439 {
 440         struct ast_bridge_channel *tmp;
 441         AST_LIST_TRAVERSE(&bridge->channels, tmp, entry) {
 442                 if (tmp->suspended) {
 443                         continue;
 444                 }
 445                 ast_write(tmp->chan, frame);
 446         }
 447 }
 448
 449 /*! \brief Function called when a channel writes a frame into the bridge */
 450 static enum ast_bridge_write_result softmix_bridge_write(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel, struct ast_frame *frame)
 451 {
 452         struct softmix_channel *sc = bridge_channel->bridge_pvt;
 453         struct softmix_bridge_data *softmix_data = bridge->bridge_pvt;
 454         int totalsilence = 0;
 455         int cur_energy = 0;
 456         int silence_threshold = bridge_channel->tech_args.silence_threshold ?
 457                 bridge_channel->tech_args.silence_threshold :
 458                 DEFAULT_SOFTMIX_SILENCE_THRESHOLD;
 459         char update_talking = -1;  /* if this is set to 0 or 1, tell the bridge that the channel has started or stopped talking. */
 460         int res = AST_BRIDGE_WRITE_SUCCESS;
 461
 462         /* Only accept audio frames, all others are unsupported */
 463         if (frame->frametype == AST_FRAME_DTMF_END || frame->frametype == AST_FRAME_DTMF_BEGIN) {
 464                 softmix_pass_dtmf(bridge, bridge_channel, frame);
 465                 goto bridge_write_cleanup;
 466         } else if (frame->frametype != AST_FRAME_VOICE && frame->frametype != AST_FRAME_VIDEO) {
 467                 res = AST_BRIDGE_WRITE_UNSUPPORTED;
 468                 goto bridge_write_cleanup;
 469         } else if (frame->datalen == 0) {
 470                 goto bridge_write_cleanup;
 471         }
 472
 473         /* Determine if this video frame should be distributed or not */
 474         if (frame->frametype == AST_FRAME_VIDEO) {
 475                 switch (bridge->video_mode.mode) {
 476                 case AST_BRIDGE_VIDEO_MODE_NONE:
 477                         break;
 478                 case AST_BRIDGE_VIDEO_MODE_SINGLE_SRC:
 479                         if (ast_bridge_is_video_src(bridge, bridge_channel->chan)) {
 480                                 softmix_pass_video(bridge, bridge_channel, frame);
 481                         }
 482                         break;
 483                 case AST_BRIDGE_VIDEO_MODE_TALKER_SRC:
 484                         ast_mutex_lock(&sc->lock);
 485                         ast_bridge_update_talker_src_video_mode(bridge, bridge_channel->chan, sc->video_talker.energy_average, ast_format_get_video_mark(&frame->subclass.format));
 486                         ast_mutex_unlock(&sc->lock);
 487                         if (ast_bridge_is_video_src(bridge, bridge_channel->chan)) {
 488                                 softmix_pass_video(bridge, bridge_channel, frame);
 489                         }
 490                         break;
 491                 }
 492                 goto bridge_write_cleanup;
 493         }
 494
 495         /* If we made it here, we are going to write the frame into the conference */
 496         ast_mutex_lock(&sc->lock);
 497         ast_dsp_silence_with_energy(sc->dsp, frame, &totalsilence, &cur_energy);
 498
 499         if (bridge->video_mode.mode == AST_BRIDGE_VIDEO_MODE_TALKER_SRC) {
 500                 int cur_slot = sc->video_talker.energy_history_cur_slot;
 501                 sc->video_talker.energy_accum -= sc->video_talker.energy_history[cur_slot];
 502                 sc->video_talker.energy_accum += cur_energy;
 503                 sc->video_talker.energy_history[cur_slot] = cur_energy;
 504                 sc->video_talker.energy_average = sc->video_talker.energy_accum / DEFAULT_ENERGY_HISTORY_LEN;
 505                 sc->video_talker.energy_history_cur_slot++;
 506                 if (sc->video_talker.energy_history_cur_slot == DEFAULT_ENERGY_HISTORY_LEN) {
 507                         sc->video_talker.energy_history_cur_slot = 0; /* wrap around */
 508                 }
 509         }
 510
 511         if (totalsilence < silence_threshold) {
 512                 if (!sc->talking) {
 513                         update_talking = 1;
 514                 }
 515                 sc->talking = 1; /* tell the write process we have audio to be mixed out */
 516         } else {
 517                 if (sc->talking) {
 518                         update_talking = 0;
 519                 }
 520                 sc->talking = 0;
 521         }
 522
 523         /* Before adding audio in, make sure we haven't fallen behind. If audio has fallen
 524          * behind 4 times the amount of samples mixed on every iteration of the mixer, Re-sync
 525          * the audio by flushing the buffer before adding new audio in. */
 526         if (ast_slinfactory_available(&sc->factory) > (4 * SOFTMIX_SAMPLES(softmix_data->internal_rate, softmix_data->internal_mixing_interval))) {
 527                 ast_slinfactory_flush(&sc->factory);
 528         }
 529
 530         /* If a frame was provided add it to the smoother, unless drop silence is enabled and this frame
 531          * is not determined to be talking. */
 532         if (!(bridge_channel->tech_args.drop_silence && !sc->talking) &&
 533                 (frame->frametype == AST_FRAME_VOICE && ast_format_is_slinear(&frame->subclass.format))) {
 534                 ast_slinfactory_feed(&sc->factory, frame);
 535         }
 536
 537         /* If a frame is ready to be written out, do so */
 538         if (sc->have_frame) {
 539                 ast_write(bridge_channel->chan, &sc->write_frame);
 540                 sc->have_frame = 0;
 541         }
 542
 543         /* Alllll done */
 544         ast_mutex_unlock(&sc->lock);
 545
 546         if (update_talking != -1) {
 547                 ast_bridge_notify_talking(bridge, bridge_channel, update_talking);
 548         }
 549
 550         return res;
 551
 552 bridge_write_cleanup:
 553         /* Even though the frame is not being written into the conference because it is not audio,
 554          * we should use this opportunity to check to see if a frame is ready to be written out from
 555          * the conference to the channel. */
 556         ast_mutex_lock(&sc->lock);
 557         if (sc->have_frame) {
 558                 ast_write(bridge_channel->chan, &sc->write_frame);
 559                 sc->have_frame = 0;
 560         }
 561         ast_mutex_unlock(&sc->lock);
 562
 563         return res;
 564 }
 565
 566 /*! \brief Function called when the channel's thread is poked */
 567 static int softmix_bridge_poke(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel)
 568 {
 569         struct softmix_channel *sc = bridge_channel->bridge_pvt;
 570
 571         ast_mutex_lock(&sc->lock);
 572
 573         if (sc->have_frame) {
 574                 ast_write(bridge_channel->chan, &sc->write_frame);
 575                 sc->have_frame = 0;
 576         }
 577
 578         ast_mutex_unlock(&sc->lock);
 579
 580         return 0;
 581 }
 582
 583 static void gather_softmix_stats(struct softmix_stats *stats,
 584         const struct softmix_bridge_data *softmix_data,
 585         struct ast_bridge_channel *bridge_channel)
 586 {
 587         int channel_native_rate;
 588         int i;
 589         /* Gather stats about channel sample rates. */
 590         channel_native_rate = MAX(ast_format_rate(&bridge_channel->chan->rawwriteformat),
 591                 ast_format_rate(&bridge_channel->chan->rawreadformat));
 592
 593         if (channel_native_rate > stats->highest_supported_rate) {
 594                 stats->highest_supported_rate = channel_native_rate;
 595         }
 596         if (channel_native_rate > softmix_data->internal_rate) {
 597                 for (i = 0; i < ARRAY_LEN(stats->sample_rates); i++) {
 598                         if (stats->sample_rates[i] == channel_native_rate) {
 599                                 stats->num_channels[i]++;
 600                                 break;
 601                         } else if (!stats->sample_rates[i]) {
 602                                 stats->sample_rates[i] = channel_native_rate;
 603                                 stats->num_channels[i]++;
 604                                 break;
 605                         }
 606                 }
 607                 stats->num_above_internal_rate++;
 608         } else if (channel_native_rate == softmix_data->internal_rate) {
 609                 stats->num_at_internal_rate++;
 610         }
 611 }
 612 /*!
 613  * \internal
 614  * \brief Analyse mixing statistics and change bridges internal rate
 615  * if necessary.
 616  *
 617  * \retval 0, no changes to internal rate
 618  * \ratval 1, internal rate was changed, update all the channels on the next mixing iteration.
 619  */
 620 static unsigned int analyse_softmix_stats(struct softmix_stats *stats, struct softmix_bridge_data *softmix_data)
 621 {
 622         int i;
 623         /* Re-adjust the internal bridge sample rate if
 624          * 1. The bridge's internal sample rate is locked in at a sample
 625          *    rate other than the current sample rate being used.
 626          * 2. two or more channels support a higher sample rate
 627          * 3. no channels support the current sample rate or a higher rate
 628          */
 629         if (stats->locked_rate) {
 630                 /* if the rate is locked by the bridge, only update it if it differs
 631                  * from the current rate we are using. */
 632                 if (softmix_data->internal_rate != stats->locked_rate) {
 633                         softmix_data->internal_rate = stats->locked_rate;
 634                         ast_debug(1, " Bridge is locked in at sample rate %d\n", softmix_data->internal_rate);
 635                         return 1;
 636                 }
 637         } else if (stats->num_above_internal_rate >= 2) {
 638                 /* the highest rate is just used as a starting point */
 639                 unsigned int best_rate = stats->highest_supported_rate;
 640                 int best_index = -1;
 641
 642                 for (i = 0; i < ARRAY_LEN(stats->num_channels); i++) {
 643                         if (stats->num_channels[i]) {
 644                                 break;
 645                         }
 646                         /* best_rate starts out being the first sample rate
 647                          * greater than the internal sample rate that 2 or
 648                          * more channels support. */
 649                         if (stats->num_channels[i] >= 2 && (best_index == -1)) {
 650                                 best_rate = stats->sample_rates[i];
 651                                 best_index = i;
 652                         /* If it has been detected that multiple rates above
 653                          * the internal rate are present, compare those rates
 654                          * to each other and pick the highest one two or more
 655                          * channels support. */
 656                         } else if (((best_index != -1) &&
 657                                 (stats->num_channels[i] >= 2) &&
 658                                 (stats->sample_rates[best_index] < stats->sample_rates[i]))) {
 659                                 best_rate = stats->sample_rates[i];
 660                                 best_index = i;
 661                         /* It is possible that multiple channels exist with native sample
 662                          * rates above the internal sample rate, but none of those channels
 663                          * have the same rate in common.  In this case, the lowest sample
 664                          * rate among those channels is picked. Over time as additional
 665                          * statistic runs are made the internal sample rate number will
 666                          * adjust to the most optimal sample rate, but it may take multiple
 667                          * iterations. */
 668                         } else if (best_index == -1) {
 669                                 best_rate = MIN(best_rate, stats->sample_rates[i]);
 670                         }
 671                 }
 672
 673                 ast_debug(1, " Bridge changed from %d To %d\n", softmix_data->internal_rate, best_rate);
 674                 softmix_data->internal_rate = best_rate;
 675                 return 1;
 676         } else if (!stats->num_at_internal_rate && !stats->num_above_internal_rate) {
 677                 /* In this case, the highest supported rate is actually lower than the internal rate */
 678                 softmix_data->internal_rate = stats->highest_supported_rate;
 679                 ast_debug(1, " Bridge changed from %d to %d\n", softmix_data->internal_rate, stats->highest_supported_rate);
 680                 return 1;
 681         }
 682         return 0;
 683 }
 684
 685 static int softmix_mixing_array_init(struct softmix_mixing_array *mixing_array, unsigned int starting_num_entries)
 686 {
 687         memset(mixing_array, 0, sizeof(*mixing_array));
 688         mixing_array->max_num_entries = starting_num_entries;
 689         if (!(mixing_array->buffers = ast_calloc(mixing_array->max_num_entries, sizeof(int16_t *)))) {
 690                 ast_log(LOG_NOTICE, "Failed to allocate softmix mixing structure. \n");
 691                 return -1;
 692         }
 693         return 0;
 694 }
 695
 696 static void softmix_mixing_array_destroy(struct softmix_mixing_array *mixing_array)
 697 {
 698         ast_free(mixing_array->buffers);
 699 }
 700
 701 static int softmix_mixing_array_grow(struct softmix_mixing_array *mixing_array, unsigned int num_entries)
 702 {
 703         int16_t **tmp;
 704         /* give it some room to grow since memory is cheap but allocations can be expensive */
 705         mixing_array->max_num_entries = num_entries;
 706         if (!(tmp = ast_realloc(mixing_array->buffers, (mixing_array->max_num_entries * sizeof(int16_t *))))) {
 707                 ast_log(LOG_NOTICE, "Failed to re-allocate softmix mixing structure. \n");
 708                 return -1;
 709         }
 710         mixing_array->buffers = tmp;
 711         return 0;
 712 }
 713
 714 /*! \brief Function which acts as the mixing thread */
 715 static int softmix_bridge_thread(struct ast_bridge *bridge)
 716 {
 717         struct softmix_stats stats = { { 0 }, };
 718         struct softmix_mixing_array mixing_array;
 719         struct softmix_bridge_data *softmix_data = bridge->bridge_pvt;
 720         struct ast_timer *timer;
 721         struct softmix_translate_helper trans_helper;
 722         int16_t buf[MAX_DATALEN] = { 0, };
 723         unsigned int stat_iteration_counter = 0; /* counts down, gather stats at zero and reset. */
 724         int timingfd;
 725         int update_all_rates = 0; /* set this when the internal sample rate has changed */
 726         int i, x;
 727         int res = -1;
 728
 729         if (!(softmix_data = bridge->bridge_pvt)) {
 730                 goto softmix_cleanup;
 731         }
 732
 733         ao2_ref(softmix_data, 1);
 734         timer = softmix_data->timer;
 735         timingfd = ast_timer_fd(timer);
 736         softmix_translate_helper_init(&trans_helper, softmix_data->internal_rate);
 737         ast_timer_set_rate(timer, (1000 / softmix_data->internal_mixing_interval));
 738
 739         /* Give the mixing array room to grow, memory is cheap but allocations are expensive. */
 740         if (softmix_mixing_array_init(&mixing_array, bridge->num + 10)) {
 741                 ast_log(LOG_NOTICE, "Failed to allocate softmix mixing structure. \n");
 742                 goto softmix_cleanup;
 743         }
 744
 745         while (!bridge->stop && !bridge->refresh && bridge->array_num) {
 746                 struct ast_bridge_channel *bridge_channel = NULL;
 747                 int timeout = -1;
 748                 enum ast_format_id cur_slin_id = ast_format_slin_by_rate(softmix_data->internal_rate);
 749                 unsigned int softmix_samples = SOFTMIX_SAMPLES(softmix_data->internal_rate, softmix_data->internal_mixing_interval);
 750                 unsigned int softmix_datalen = SOFTMIX_DATALEN(softmix_data->internal_rate, softmix_data->internal_mixing_interval);
 751
 752                 if (softmix_datalen > MAX_DATALEN) {
 753                         /* This should NEVER happen, but if it does we need to know about it. Almost
 754                          * all the memcpys used during this process depend on this assumption.  Rather
 755                          * than checking this over and over again through out the code, this single
 756                          * verification is done on each iteration. */
 757                         ast_log(LOG_WARNING, "Conference mixing error, requested mixing length greater than mixing buffer.\n");
 758                         goto softmix_cleanup;
 759                 }
 760
 761                 /* Grow the mixing array buffer as participants are added. */
 762                 if (mixing_array.max_num_entries < bridge->num && softmix_mixing_array_grow(&mixing_array, bridge->num + 5)) {
 763                         goto softmix_cleanup;
 764                 }
 765
 766                 /* init the number of buffers stored in the mixing array to 0.
 767                  * As buffers are added for mixing, this number is incremented. */
 768                 mixing_array.used_entries = 0;
 769
 770                 /* These variables help determine if a rate change is required */
 771                 if (!stat_iteration_counter) {
 772                         memset(&stats, 0, sizeof(stats));
 773                         stats.locked_rate = bridge->internal_sample_rate;
 774                 }
 775
 776                 /* If the sample rate has changed, update the translator helper */
 777                 if (update_all_rates) {
 778                         softmix_translate_helper_change_rate(&trans_helper, softmix_data->internal_rate);
 779                 }
 780
 781                 /* Go through pulling audio from each factory that has it available */
 782                 AST_LIST_TRAVERSE(&bridge->channels, bridge_channel, entry) {
 783                         struct softmix_channel *sc = bridge_channel->bridge_pvt;
 784
 785                         /* Update the sample rate to match the bridge's native sample rate if necessary. */
 786                         if (update_all_rates) {
 787                                 set_softmix_bridge_data(softmix_data->internal_rate, softmix_data->internal_mixing_interval, bridge_channel, 1);
 788                         }
 789
 790                         /* If stat_iteration_counter is 0, then collect statistics during this mixing interation */
 791                         if (!stat_iteration_counter) {
 792                                 gather_softmix_stats(&stats, softmix_data, bridge_channel);
 793                         }
 794
 795                         /* if the channel is suspended, don't check for audio, but still gather stats */
 796                         if (bridge_channel->suspended) {
 797                                 continue;
 798                         }
 799
 800                         /* Try to get audio from the factory if available */
 801                         ast_mutex_lock(&sc->lock);
 802                         if ((mixing_array.buffers[mixing_array.used_entries] = softmix_process_read_audio(sc, softmix_samples))) {
 803                                 mixing_array.used_entries++;
 804                         }
 805                         ast_mutex_unlock(&sc->lock);
 806                 }
 807
 808                 /* mix it like crazy */
 809                 memset(buf, 0, softmix_datalen);
 810                 for (i = 0; i < mixing_array.used_entries; i++) {
 811                         for (x = 0; x < softmix_samples; x++) {
 812                                 ast_slinear_saturated_add(buf + x, mixing_array.buffers[i] + x);
 813                         }
 814                 }
 815
 816                 /* Next step go through removing the channel's own audio and creating a good frame... */
 817                 AST_LIST_TRAVERSE(&bridge->channels, bridge_channel, entry) {
 818                         struct softmix_channel *sc = bridge_channel->bridge_pvt;
 819
 820                         if (bridge_channel->suspended) {
 821                                 continue;
 822                         }
 823
 824                         ast_mutex_lock(&sc->lock);
 825
 826                         /* Make SLINEAR write frame from local buffer */
 827                         if (sc->write_frame.subclass.format.id != cur_slin_id) {
 828                                 ast_format_set(&sc->write_frame.subclass.format, cur_slin_id, 0);
 829                         }
 830                         sc->write_frame.datalen = softmix_datalen;
 831                         sc->write_frame.samples = softmix_samples;
 832                         memcpy(sc->final_buf, buf, softmix_datalen);
 833
 834                         /* process the softmix channel's new write audio */
 835                         softmix_process_write_audio(&trans_helper, &bridge_channel->chan->rawwriteformat, sc);
 836
 837                         /* The frame is now ready for use... */
 838                         sc->have_frame = 1;
 839
 840                         ast_mutex_unlock(&sc->lock);
 841
 842                         /* Poke bridged channel thread just in case */
 843                         pthread_kill(bridge_channel->thread, SIGURG);
 844                 }
 845
 846                 update_all_rates = 0;
 847                 if (!stat_iteration_counter) {
 848                         update_all_rates = analyse_softmix_stats(&stats, softmix_data);
 849                         stat_iteration_counter = SOFTMIX_STAT_INTERVAL;
 850                 }
 851                 stat_iteration_counter--;
 852
 853                 ao2_unlock(bridge);
 854                 /* cleanup any translation frame data from the previous mixing iteration. */
 855                 softmix_translate_helper_cleanup(&trans_helper);
 856                 /* Wait for the timing source to tell us to wake up and get things done */
 857                 ast_waitfor_n_fd(&timingfd, 1, &timeout, NULL);
 858                 ast_timer_ack(timer, 1);
 859                 ao2_lock(bridge);
 860
 861                 /* make sure to detect mixing interval changes if they occur. */
 862                 if (bridge->internal_mixing_interval && (bridge->internal_mixing_interval != softmix_data->internal_mixing_interval)) {
 863                         softmix_data->internal_mixing_interval = bridge->internal_mixing_interval;
 864                         ast_timer_set_rate(timer, (1000 / softmix_data->internal_mixing_interval));
 865                         update_all_rates = 1; /* if the interval changes, the rates must be adjusted as well just to be notified new interval.*/
 866                 }
 867         }
 868
 869         res = 0;
 870
 871 softmix_cleanup:
 872         softmix_translate_helper_destroy(&trans_helper);
 873         softmix_mixing_array_destroy(&mixing_array);
 874         if (softmix_data) {
 875                 ao2_ref(softmix_data, -1);
 876         }
 877         return res;
 878 }
 879
 880 static struct ast_bridge_technology softmix_bridge = {
 881         .name = "softmix",
 882         .capabilities = AST_BRIDGE_CAPABILITY_MULTIMIX | AST_BRIDGE_CAPABILITY_THREAD | AST_BRIDGE_CAPABILITY_MULTITHREADED | AST_BRIDGE_CAPABILITY_OPTIMIZE | AST_BRIDGE_CAPABILITY_VIDEO,
 883         .preference = AST_BRIDGE_PREFERENCE_LOW,
 884         .create = softmix_bridge_create,
 885         .destroy = softmix_bridge_destroy,
 886         .join = softmix_bridge_join,
 887         .leave = softmix_bridge_leave,
 888         .write = softmix_bridge_write,
 889         .thread = softmix_bridge_thread,
 890         .poke = softmix_bridge_poke,
 891 };
 892
 893 static int unload_module(void)
 894 {
 895         ast_format_cap_destroy(softmix_bridge.format_capabilities);
 896         return ast_bridge_technology_unregister(&softmix_bridge);
 897 }
 898
 899 static int load_module(void)
 900 {
 901         struct ast_format tmp;
 902         if (!(softmix_bridge.format_capabilities = ast_format_cap_alloc())) {
 903                 return AST_MODULE_LOAD_DECLINE;
 904         }
 905         ast_format_cap_add(softmix_bridge.format_capabilities, ast_format_set(&tmp, AST_FORMAT_SLINEAR, 0));
 906         return ast_bridge_technology_register(&softmix_bridge);
 907 }
 908
 909 AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Multi-party software based channel mixing");