bridge_softmix.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2011, Digium, Inc.
 *
 * Joshua Colp <[email protected]>
 * David Vossel <[email protected]>
 *
 * 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 <[email protected]>
 * \author David Vossel <[email protected]>
 *
 * \ingroup bridges
 */

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

#include "asterisk.h"

#include <math.h>

#include "asterisk/stream.h"
#include "asterisk/test.h"
#include "asterisk/vector.h"
#include "asterisk/message.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_remb_collector {
   /*! The frame which will be given to each source stream */
   struct ast_frame frame;
   /*! The REMB to send to the source which is collecting REMB reports */
   struct ast_rtp_rtcp_feedback feedback;
   /*! The maximum bitrate (A single precision floating point is big enough) */
   float bitrate;
};

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 above the maximum sample rate */
   unsigned int num_above_maximum_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;
   /*! The maximum sample rate the bridge may use */
   unsigned int maximum_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 any audio then take it out while in slinear format. */
   if (sc->have_audio && !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->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_channel_stream_position The position of the video on the source channel
 * \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,
   int source_channel_stream_position)
{
   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 (source_channel_stream_position != -1) {
         dest_video_name_len += 11;
      }

      dest_video_name = ast_alloca(dest_video_name_len);
      if (source_channel_stream_position != -1) {
         /* We are looking for an exact stream position */
         snprintf(dest_video_name, dest_video_name_len, "%s%c%s%c%d",
            SOFTBRIDGE_VIDEO_DEST_PREFIX, SOFTBRIDGE_VIDEO_DEST_SEPARATOR,
            source_channel_name, SOFTBRIDGE_VIDEO_DEST_SEPARATOR,
            source_channel_stream_position);
         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_stream(struct ast_stream_topology *dest,
   const char *channel_name, const char *sdp_label,
   struct ast_stream *stream, int index)
{
   char *stream_clone_name = NULL;
   struct ast_stream *stream_clone;

   /* We use the stream topology index for the stream to uniquely identify and recognize it.
    * This is guaranteed to remain the same across renegotiation of the source channel and
    * ensures that the stream name is unique.
    */
   if (ast_asprintf(&stream_clone_name, "%s%c%s%c%d", SOFTBRIDGE_VIDEO_DEST_PREFIX,
      SOFTBRIDGE_VIDEO_DEST_SEPARATOR, channel_name, SOFTBRIDGE_VIDEO_DEST_SEPARATOR,
      index) < 0) {
      return -1;
   }

   stream_clone = ast_stream_clone(stream, stream_clone_name);
   ast_free(stream_clone_name);
   if (!stream_clone) {
      return -1;
   }

   /* Sends an "a:label" attribute in the SDP for participant event correlation */
   if (!ast_strlen_zero(sdp_label)) {
      ast_stream_set_metadata(stream_clone, "SDP:LABEL", sdp_label);
   }

   /* We will be sending them a stream and not expecting anything in return */
   ast_stream_set_state(stream_clone, AST_STREAM_STATE_SENDONLY);

   if (ast_stream_topology_append_stream(dest, stream_clone) < 0) {
      ast_stream_free(stream_clone);
      return -1;
   }

   return 0;
}


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

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

      stream = ast_stream_topology_get_stream(source, i);

      if (!is_video_source(stream)) {
         continue;
      }

      if (append_source_stream(dest, channel_name, sdp_label, stream, i)) {
         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 *bridge,
   struct ast_bridge_channel *joiner)
{
   RAII_VAR(struct ast_stream_topology *, joiner_video, NULL, ast_stream_topology_free);
   struct ast_bridge_channels_list *participants = &bridge->channels;
   struct ast_bridge_channel *participant;
   int res;
   struct softmix_channel *sc;
   SCOPE_ENTER(3, "%s: \n", ast_channel_name(joiner->chan));

   joiner_video = ast_stream_topology_alloc();
   if (!joiner_video) {
      SCOPE_EXIT_LOG_RTN(LOG_ERROR, "%s: Couldn't alloc topology\n", ast_channel_name(joiner->chan));
   }

   sc = joiner->tech_pvt;

   ast_channel_lock(joiner->chan);
   res = append_source_streams(joiner_video, ast_channel_name(joiner->chan),
      bridge->softmix.send_sdp_label ? ast_channel_uniqueid(joiner->chan) : NULL,
      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) {
      SCOPE_EXIT_LOG_RTN(LOG_ERROR, "%s: Couldn't append source streams\n", ast_channel_name(joiner->chan));
   }

   AST_LIST_TRAVERSE(participants, participant, entry) {
      if (participant == joiner) {
         continue;
      }
      ast_trace(-1, "%s: Appending existing participant %s\n", ast_channel_name(joiner->chan),
         ast_channel_name(participant->chan));
      ast_channel_lock(participant->chan);
      res = append_source_streams(sc->topology, ast_channel_name(participant->chan),
         bridge->softmix.send_sdp_label ? ast_channel_uniqueid(participant->chan) : NULL,
         ast_channel_get_stream_topology(participant->chan));
      ast_channel_unlock(participant->chan);
      if (res) {
         SCOPE_EXIT_LOG_RTN(LOG_ERROR, "%s/%s: Couldn't append source streams\n",
            ast_channel_name(participant->chan), ast_channel_name(joiner->chan));
      }
   }

   ast_trace(-1, "%s: Requesting topology change.\n", ast_channel_name(joiner->chan));
   res = ast_channel_request_stream_topology_change(joiner->chan, sc->topology, NULL);
   if (res) {
      SCOPE_EXIT_LOG_RTN(LOG_ERROR, "%s: Couldn't request topology change\n", ast_channel_name(joiner->chan));
   }

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

      sc = participant->tech_pvt;
      ast_trace(-1, "%s: Appending joiner %s\n", ast_channel_name(participant->chan),
         ast_channel_name(joiner->chan));

      if (append_all_streams(sc->topology, joiner_video)) {
         SCOPE_EXIT_LOG_RTN(LOG_ERROR, "%s/%s: Couldn't append streams\n",
            ast_channel_name(participant->chan), ast_channel_name(joiner->chan));
      }
      ast_trace(-1, "%s: Requesting topology change\n", ast_channel_name(participant->chan));
      res = ast_channel_request_stream_topology_change(participant->chan, sc->topology, NULL);
      if (res) {
         ast_trace(-1, "%s/%s: Couldn't request topology change\n",
            ast_channel_name(participant->chan), ast_channel_name(joiner->chan));
      }
   }

   SCOPE_EXIT();
}

/*! \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;
   SCOPE_ENTER(3, "%s:\n", ast_channel_name(bridge_channel->chan));

   softmix_data = bridge->tech_pvt;
   if (!softmix_data) {
      SCOPE_EXIT_RTN_VALUE(-1, "No tech_pvt\n");
   }

   /* Create a new softmix_channel structure and allocate various things on it */
   if (!(sc = ast_calloc(1, sizeof(*sc)))) {
      SCOPE_EXIT_RTN_VALUE(-1, "Couldn't alloc tech_pvt\n");
   }

   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);
            SCOPE_EXIT_RTN_VALUE(-1, "Couldn't do binaural join\n");
         }
      }
   }

   /* 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, bridge_channel);
   }

   /* Complete any active hold before entering, or transitioning to softmix. */
   if (ast_channel_hold_state(bridge_channel->chan) == AST_CONTROL_HOLD) {
      ast_debug(1, "Channel %s simulating UNHOLD for bridge softmix join.\n",
         ast_channel_name(bridge_channel->chan));
      ast_indicate(bridge_channel->chan, AST_CONTROL_UNHOLD);
   }

   softmix_poke_thread(softmix_data);
   SCOPE_EXIT_RTN_VALUE(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, -1)) {
         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);

   ao2_cleanup(sc->remb_collector);

   AST_VECTOR_FREE(&sc->video_sources);

   /* 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;

            removed = ast_stream_clone(stream, NULL);
            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 *bridge,
   struct ast_bridge_channel *source)
{
   struct ast_stream_topology *source_video = NULL;
   struct ast_bridge_channels_list *participants = &bridge->channels;
   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),
      bridge->softmix.send_sdp_label ? ast_channel_uniqueid(source->chan) : NULL,
      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 text frame.
 * \since 13.22.0
 * \since 15.5.0
 *
 * \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_text(struct ast_bridge *bridge,
   struct ast_bridge_channel *bridge_channel, struct ast_frame *frame)
{
   if (DEBUG_ATLEAST(1)) {
      struct ast_msg_data *msg = frame->data.ptr;
      char frame_type[64];

      ast_frame_type2str(frame->frametype, frame_type, sizeof(frame_type));

      if (frame->frametype == AST_FRAME_TEXT_DATA) {
         ast_log(LOG_DEBUG, "Received %s frame from '%s:%s': %s\n", frame_type,
            ast_msg_data_get_attribute(msg, AST_MSG_DATA_ATTR_FROM),
            ast_channel_name(bridge_channel->chan),
            ast_msg_data_get_attribute(msg, AST_MSG_DATA_ATTR_BODY));
      } else {
         ast_log(LOG_DEBUG, "Received %s frame from '%s': %.*s\n", frame_type,
            ast_channel_name(bridge_channel->chan), frame->datalen,
            (char *)frame->data.ptr);
      }
   }

   ast_bridge_queue_everyone_else(bridge, bridge_channel, frame);
}

/*!
 * \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, bridge_channel);
      }
      break;
   default:
      break;
   }

   return 0;
}

/*!
 * \internal
 * \brief Determine what to do with an RTCP frame.
 * \since 15.4.0
 *
 * \param bridge Which bridge is getting the frame
 * \param bridge_channel Which channel is writing the frame.
 * \param frame What is being written.
 */
static void softmix_bridge_write_rtcp(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel, struct ast_frame *frame)
{
   struct ast_rtp_rtcp_feedback *feedback = frame->data.ptr;
   struct softmix_channel *sc = bridge_channel->tech_pvt;

   /* We only care about REMB reports right now. In the future we may be able to use sender or
    * receiver reports to further tweak things, but not yet.
    */
   if (frame->subclass.integer != AST_RTP_RTCP_PSFB || feedback->fmt != AST_RTP_RTCP_FMT_REMB ||
      bridge->softmix.video_mode.mode != AST_BRIDGE_VIDEO_MODE_SFU ||
      !bridge->softmix.video_mode.mode_data.sfu_data.remb_send_interval) {
      return;
   }

   /* REMB is the total estimated maximum bitrate across all streams within the session, so we store
    * only the latest report and use it everywhere.
    */
   ast_mutex_lock(&sc->lock);
   sc->remb = feedback->remb;
   ast_mutex_unlock(&sc->lock);

   return;
}

/*!
 * \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_TEXT:
   case AST_FRAME_TEXT_DATA:
      softmix_bridge_write_text(bridge, bridge_channel, frame);
      break;
   case AST_FRAME_CONTROL:
      res = softmix_bridge_write_control(bridge, bridge_channel, frame);
      break;
   case AST_FRAME_RTCP:
      softmix_bridge_write_rtcp(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 remb_collect_report_all(struct ast_bridge *bridge, struct softmix_bridge_data *softmix_data,
   float bitrate)
{
   if (!softmix_data->bitrate) {
      softmix_data->bitrate = bitrate;
      return;
   }

   switch (bridge->softmix.video_mode.mode_data.sfu_data.remb_behavior) {
   case AST_BRIDGE_VIDEO_SFU_REMB_AVERAGE_ALL:
      softmix_data->bitrate = (softmix_data->bitrate + bitrate) / 2;
      break;
   case AST_BRIDGE_VIDEO_SFU_REMB_LOWEST_ALL:
      if (bitrate < softmix_data->bitrate) {
         softmix_data->bitrate = bitrate;
      }
      break;
   case AST_BRIDGE_VIDEO_SFU_REMB_HIGHEST_ALL:
      if (bitrate > softmix_data->bitrate) {
         softmix_data->bitrate = bitrate;
      }
      break;
   case AST_BRIDGE_VIDEO_SFU_REMB_AVERAGE:
   case AST_BRIDGE_VIDEO_SFU_REMB_LOWEST:
   case AST_BRIDGE_VIDEO_SFU_REMB_HIGHEST:
   case AST_BRIDGE_VIDEO_SFU_REMB_FORCE:
      /* These will never actually get hit due to being handled by remb_collect_report below */
      break;
   }
}

static void remb_collect_report(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel,
   struct softmix_bridge_data *softmix_data, struct softmix_channel *sc)
{
   int i;
   float bitrate;

   /* If there are no video sources that we are a receiver of then we have noone to
    * report REMB to.
    */
   if (!AST_VECTOR_SIZE(&sc->video_sources)) {
      return;
   }

   /* We evenly divide the available maximum bitrate across the video sources
    * to this receiver so each source gets an equal slice.
    */

   if (bridge->softmix.video_mode.mode_data.sfu_data.remb_behavior == AST_BRIDGE_VIDEO_SFU_REMB_FORCE) {
      softmix_data->bitrate = bridge->softmix.video_mode.mode_data.sfu_data.estimated_bitrate;
      return;
   }

   bitrate = (sc->remb.br_mantissa << sc->remb.br_exp) / AST_VECTOR_SIZE(&sc->video_sources);

   /* If this receiver has no bitrate yet ignore it */
   if (!bitrate) {
      return;
   }

   /* If we are using the "all" variants then we should use the bridge bitrate to store information */
   if (bridge->softmix.video_mode.mode_data.sfu_data.remb_behavior == AST_BRIDGE_VIDEO_SFU_REMB_AVERAGE_ALL ||
      bridge->softmix.video_mode.mode_data.sfu_data.remb_behavior == AST_BRIDGE_VIDEO_SFU_REMB_LOWEST_ALL ||
      bridge->softmix.video_mode.mode_data.sfu_data.remb_behavior == AST_BRIDGE_VIDEO_SFU_REMB_HIGHEST_ALL) {
      remb_collect_report_all(bridge, softmix_data, bitrate);
      return;
   }

   for (i = 0; i < AST_VECTOR_SIZE(&sc->video_sources); ++i) {
      struct softmix_remb_collector *collector;

      /* The collector will always exist if a video source is in our list */
      collector = AST_VECTOR_GET(&softmix_data->remb_collectors, AST_VECTOR_GET(&sc->video_sources, i));

      if (!collector->bitrate) {
         collector->bitrate = bitrate;
         continue;
      }

      switch (bridge->softmix.video_mode.mode_data.sfu_data.remb_behavior) {
      case AST_BRIDGE_VIDEO_SFU_REMB_AVERAGE:
         collector->bitrate = (collector->bitrate + bitrate) / 2;
         break;
      case AST_BRIDGE_VIDEO_SFU_REMB_LOWEST:
         if (bitrate < collector->bitrate) {
            collector->bitrate = bitrate;
         }
         break;
      case AST_BRIDGE_VIDEO_SFU_REMB_HIGHEST:
         if (bitrate > collector->bitrate) {
            collector->bitrate = bitrate;
         }
         break;
      case AST_BRIDGE_VIDEO_SFU_REMB_AVERAGE_ALL:
      case AST_BRIDGE_VIDEO_SFU_REMB_LOWEST_ALL:
      case AST_BRIDGE_VIDEO_SFU_REMB_HIGHEST_ALL:
         /* These will never actually get hit due to being handled by remb_collect_report_all above */
         break;
      case AST_BRIDGE_VIDEO_SFU_REMB_FORCE:
         /* Don't do anything, we've already forced it */
         break;
      }
   }

   /* After the report is integrated we reset this to 0 in case they stop producing
    * REMB reports.
    */
   sc->remb.br_mantissa = 0;
   sc->remb.br_exp = 0;
}

static void remb_send_report(struct ast_bridge_channel *bridge_channel, struct softmix_bridge_data *softmix_data,
   struct softmix_channel *sc)
{
   float bitrate = softmix_data->bitrate;
   int i;
   int exp;

   if (!sc->remb_collector) {
      return;
   }

   /* If there is no bridge level bitrate fall back to collector level */
   if (!bitrate) {
      bitrate = sc->remb_collector->bitrate;
      sc->remb_collector->bitrate = 0;
   }

   /* We always do this calculation as even when the bitrate is zero the browser
    * still prefers it to be accurate instead of lying.
    *
    * The mantissa only has 18 bits available, so make sure it fits. Adjust the
    * value and exponent for those values that don't.
    *
    * For example given the following:
    *
    * bitrate = 123456789.0
    * frexp(bitrate, &exp);
    *
    * 'exp' should now equal 27 (number of bits needed to represent the value). Since
    * the mantissa must fit into an 18-bit unsigned integer, and the given bitrate is
    * too large to fit, we must subtract 18 from the exponent in order to get the
    * number of times the bitrate will fit into that size integer.
    *
    * exp -= 18;
    *
    * 'exp' is now equal to 9. Now we can get the mantissa that fits into an 18-bit
    * unsigned integer by dividing the bitrate by 2^exp:
    *
    * mantissa = 123456789.0 / 2^9
    *
    * This makes the final mantissa equal to 241126 (implicitly cast), which is less
    * than 262143 (the max value that can be put into an unsigned 18-bit integer).
    * So now we have the following:
    *
    * exp = 9;
    * mantissa = 241126;
    *
    * If we multiply that back we should come up with something close to the original
    * bit rate:
    *
    * 241126 * 2^9 = 123456512
    *
    * Precision is lost due to the nature of floating point values. Easier to why from
    * the binary:
    *
    * 241126 * 2^9 = 241126 << 9 = 111010110111100110 << 9 = 111010110111100110000000000
    *
    * Precision on the "lower" end is lost due to zeros being shifted in. This loss is
    * both expected and acceptable.
    */
   frexp(bitrate, &exp);
   exp = exp > 18 ? exp - 18 : 0;

   sc->remb_collector->feedback.remb.br_mantissa = bitrate / (1 << exp);
   sc->remb_collector->feedback.remb.br_exp = exp;

   for (i = 0; i < AST_VECTOR_SIZE(&bridge_channel->stream_map.to_bridge); ++i) {
      int bridge_num = AST_VECTOR_GET(&bridge_channel->stream_map.to_bridge, i);

      /* If this stream is not being provided to the bridge there can be no receivers of it
       * so therefore no REMB reports.
       */
      if (bridge_num == -1) {
         continue;
      }

      /* We need to update the frame with this stream, or else it won't be
       * properly routed. We don't use the actual channel stream identifier as
       * the bridging core will do the translation from bridge stream identifier to
       * channel stream identifier.
       */
      sc->remb_collector->frame.stream_num = bridge_num;
      ast_bridge_channel_queue_frame(bridge_channel, &sc->remb_collector->frame);
   }
}

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 (stats->maximum_rate && stats->maximum_rate < channel_native_rate) {
      stats->num_above_maximum_rate++;
   } else 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_maximum_rate) {
      /* if the bridge has a maximum rate set and channels are above it only
       * update if it differs from the current rate we are using. */
      if (softmix_data->internal_rate != stats->maximum_rate) {
         ast_debug(1, "Locking at new maximum rate.  Bridge changed from %u to %u.\n",
            softmix_data->internal_rate, stats->maximum_rate);
         softmix_data->internal_rate = stats->maximum_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);
      int remb_update = 0;

      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;
         stats.maximum_rate = bridge->softmix.maximum_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

      /* If we need to do a REMB update to all video sources then do so */
      if (bridge->softmix.video_mode.mode == AST_BRIDGE_VIDEO_MODE_SFU &&
         bridge->softmix.video_mode.mode_data.sfu_data.remb_send_interval &&
         ast_tvdiff_ms(ast_tvnow(), softmix_data->last_remb_update) > bridge->softmix.video_mode.mode_data.sfu_data.remb_send_interval) {
         remb_update = 1;
         softmix_data->last_remb_update = ast_tvnow();
      }

      /* 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++;
         }
         if (remb_update) {
            remb_collect_report(bridge, bridge_channel, softmix_data, sc);
         }
         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);

         if (remb_update) {
            remb_send_report(bridge_channel, softmix_data, sc);
         }
      }

      if (remb_update) {
         /* In case we are doing bridge level REMB reset the bitrate so we start fresh */
         softmix_data->bitrate = 0;
      }

      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_VECTOR_RESET(&softmix_data->remb_collectors, ao2_cleanup);
   AST_VECTOR_FREE(&softmix_data->remb_collectors);
   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

   AST_VECTOR_INIT(&softmix_data->remb_collectors, 0);

   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_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
 * \param source_channel_stream_position The position of the stream on the source channel
 */
static void map_source_to_destinations(const char *source_channel_name,
   size_t bridge_stream_position, struct ast_bridge_channels_list *participants, int source_channel_stream_position)
{
   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_channel_stream_position)) {
            struct softmix_channel *sc = participant->tech_pvt;

            AST_VECTOR_REPLACE(&participant->stream_map.to_channel, bridge_stream_position, i);
            AST_VECTOR_APPEND(&sc->video_sources, bridge_stream_position);
            break;
         }
      }
      ast_channel_unlock(participant->chan);
      ast_bridge_channel_unlock(participant);
   }
}

/*!
 * \brief Allocate a REMB collector
 *
 * \retval non-NULL success
 * \retval NULL failure
 */
static struct softmix_remb_collector *remb_collector_alloc(void)
{
   struct softmix_remb_collector *collector;

   collector = ao2_alloc_options(sizeof(*collector), NULL, AO2_ALLOC_OPT_LOCK_NOLOCK);
   if (!collector) {
      return NULL;
   }

   collector->frame.frametype = AST_FRAME_RTCP;
   collector->frame.subclass.integer = AST_RTP_RTCP_PSFB;
   collector->feedback.fmt = AST_RTP_RTCP_FMT_REMB;
   collector->frame.data.ptr = &collector->feedback;
   collector->frame.datalen = sizeof(collector->feedback);

   return collector;
}

/*!
 * \brief Setup REMB collection for a particular bridge stream and channel.
 *
 * \param bridge The bridge
 * \param bridge_channel Channel that is collecting REMB information
 * \param bridge_stream_position The slot in the bridge where source video comes from
 */
static void remb_enable_collection(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel,
   size_t bridge_stream_position)
{
   struct softmix_channel *sc = bridge_channel->tech_pvt;
   struct softmix_bridge_data *softmix_data = bridge->tech_pvt;

   if (!sc->remb_collector) {
      sc->remb_collector = remb_collector_alloc();
      if (!sc->remb_collector) {
         /* This is not fatal. Things will still continue to work but we won't
          * produce a REMB report to the sender.
          */
         return;
      }
   }

   ao2_ref(sc->remb_collector, +1);
   if (AST_VECTOR_REPLACE(&softmix_data->remb_collectors, bridge_stream_position,
      sc->remb_collector)) {
      ao2_ref(sc->remb_collector, -1);
   }
}

static void softmix_bridge_stream_sources_update(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel,
   struct softmix_channel *sc)
{
   int index;
   struct ast_stream_topology *old_topology = sc->topology;
   struct ast_stream_topology *new_topology = ast_channel_get_stream_topology(bridge_channel->chan);
   int removed_streams[MAX(ast_stream_topology_get_count(sc->topology), ast_stream_topology_get_count(new_topology))];
   size_t removed_streams_count = 0;
   struct ast_stream_topology *added_streams;
   struct ast_bridge_channels_list *participants = &bridge->channels;
   struct ast_bridge_channel *participant;
   SCOPE_ENTER(3, "%s: OT: %s NT: %s\n", ast_channel_name(bridge_channel->chan),
      ast_str_tmp(256, ast_stream_topology_to_str(old_topology, &STR_TMP)),
      ast_str_tmp(256, ast_stream_topology_to_str(new_topology, &STR_TMP)));

   added_streams = ast_stream_topology_alloc();
   if (!added_streams) {
      SCOPE_EXIT_LOG(LOG_ERROR, "%s: Couldn't alloc topology\n", ast_channel_name(bridge_channel->chan));
   }

   /* We go through the old topology comparing it to the new topology to determine what streams
    * changed state. A state transition can result in the stream being considered a new source
    * (for example it was removed and is now present) or being removed (a stream became inactive).
    * Added streams are copied into a topology and added to each other participant while for
    * removed streams we merely store their position and mark them as removed later.
    */
   ast_trace(-1, "%s: Checking for state changes\n", ast_channel_name(bridge_channel->chan));
   for (index = 0; index < ast_stream_topology_get_count(sc->topology) && index < ast_stream_topology_get_count(new_topology); ++index) {
      struct ast_stream *old_stream = ast_stream_topology_get_stream(sc->topology, index);
      struct ast_stream *new_stream = ast_stream_topology_get_stream(new_topology, index);
      SCOPE_ENTER(4, "%s:   Slot: %d  Old stream: %s  New stream: %s\n",  ast_channel_name(bridge_channel->chan),
         index, ast_str_tmp(256, ast_stream_to_str(old_stream, &STR_TMP)),
         ast_str_tmp(256, ast_stream_to_str(new_stream, &STR_TMP)));

      /* Ignore all streams that don't carry video and streams that are strictly outgoing destination streams */
      if ((ast_stream_get_type(old_stream) != AST_MEDIA_TYPE_VIDEO && ast_stream_get_type(new_stream) != AST_MEDIA_TYPE_VIDEO) ||
         !strncmp(ast_stream_get_name(new_stream), SOFTBRIDGE_VIDEO_DEST_PREFIX,
            SOFTBRIDGE_VIDEO_DEST_LEN)) {
         SCOPE_EXIT_EXPR(continue, "%s: Stream %d ignored\n",  ast_channel_name(bridge_channel->chan), index);
      }

      if (ast_stream_get_type(old_stream) == AST_MEDIA_TYPE_VIDEO && ast_stream_get_type(new_stream) != AST_MEDIA_TYPE_VIDEO) {
         /* If a stream renegotiates from video to non-video then we need to remove it as a source */
         ast_trace(-1, "%s: Stream %d added to remove list\n",  ast_channel_name(bridge_channel->chan), index);
         removed_streams[removed_streams_count++] = index;
      } else if (ast_stream_get_type(old_stream) != AST_MEDIA_TYPE_VIDEO && ast_stream_get_type(new_stream) == AST_MEDIA_TYPE_VIDEO) {
         if (ast_stream_get_state(new_stream) != AST_STREAM_STATE_REMOVED) {
            /* If a stream renegotiates from non-video to video in a non-removed state we need to add it as a source */
            if (append_source_stream(added_streams, ast_channel_name(bridge_channel->chan),
                     bridge->softmix.send_sdp_label ? ast_channel_uniqueid(bridge_channel->chan) : NULL,
                     new_stream, index)) {
               SCOPE_EXIT_EXPR(goto cleanup, "%s: Couldn't append source stream %d:%s\n",  ast_channel_name(bridge_channel->chan),
                  index, ast_stream_get_name(new_stream));
            }
            ast_trace(-1, "%s: Stream %d changed from non-video to video\n",  ast_channel_name(bridge_channel->chan), index);
         }
      } else if (ast_stream_get_state(old_stream) != AST_STREAM_STATE_REMOVED &&
            ast_stream_get_state(new_stream) != AST_STREAM_STATE_SENDRECV && ast_stream_get_state(new_stream) != AST_STREAM_STATE_RECVONLY) {
         ast_trace(-1, "%s: Stream %d added to remove list\n",  ast_channel_name(bridge_channel->chan), index);
         /* If a stream renegotiates and is removed then we remove it */
         removed_streams[removed_streams_count++] = index;
      } else if ((ast_stream_get_state(old_stream) == AST_STREAM_STATE_REMOVED || ast_stream_get_state(old_stream) == AST_STREAM_STATE_INACTIVE ||
            ast_stream_get_state(old_stream) == AST_STREAM_STATE_SENDONLY) &&
            ast_stream_get_state(new_stream) != AST_STREAM_STATE_INACTIVE && ast_stream_get_state(new_stream) != AST_STREAM_STATE_SENDONLY &&
            ast_stream_get_state(new_stream) != AST_STREAM_STATE_REMOVED) {
         /* If a stream renegotiates and is added then we add it */
         if (append_source_stream(added_streams, ast_channel_name(bridge_channel->chan),
                  bridge->softmix.send_sdp_label ? ast_channel_uniqueid(bridge_channel->chan) : NULL,
                  new_stream, index)) {
            SCOPE_EXIT_EXPR(goto cleanup, "%s: Couldn't append source stream %d:%s\n",  ast_channel_name(bridge_channel->chan),
               index, ast_stream_get_name(new_stream));
         }
         ast_trace(-1, "%s: Stream %d:%s changed state from %s to %s\n",  ast_channel_name(bridge_channel->chan),
            index, ast_stream_get_name(old_stream), ast_stream_state2str(ast_stream_get_state(old_stream)),
            ast_stream_state2str(ast_stream_get_state(new_stream)));
      } else {
         ast_trace(-1, "%s: Stream %d:%s didn't do anything\n",  ast_channel_name(bridge_channel->chan),
            index, ast_stream_get_name(old_stream));
      }
      SCOPE_EXIT();
   }

   /* Any newly added streams that did not take the position of a removed stream
    * will be present at the end of the new topology. Since streams are never
    * removed from the topology but merely marked as removed we can pick up where we
    * left off when comparing the old and new topologies.
    */
   ast_trace(-1, "%s: Checking for newly added streams\n", ast_channel_name(bridge_channel->chan));

   for (; index < ast_stream_topology_get_count(new_topology); ++index) {
      struct ast_stream *stream = ast_stream_topology_get_stream(new_topology, index);
      SCOPE_ENTER(4, "%s: Checking stream %d:%s\n",  ast_channel_name(bridge_channel->chan), index,
         ast_stream_get_name(stream));

      if (!is_video_source(stream)) {
         SCOPE_EXIT_EXPR(continue, "%s: Stream %d:%s is not video source\n",  ast_channel_name(bridge_channel->chan),
            index, ast_stream_get_name(stream));
      }

      if (append_source_stream(added_streams, ast_channel_name(bridge_channel->chan),
               bridge->softmix.send_sdp_label ? ast_channel_uniqueid(bridge_channel->chan) : NULL,
               stream, index)) {
         SCOPE_EXIT_EXPR(goto cleanup, "%s: Couldn't append stream %d:%s\n",  ast_channel_name(bridge_channel->chan),
            index, ast_stream_get_name(stream));
      }
      SCOPE_EXIT("%s:   Added new stream %s\n", ast_channel_name(bridge_channel->chan),
         ast_str_tmp(256, ast_stream_to_str(stream, &STR_TMP)));
   }

   /*  We always update the stored topology if we can to reflect what is currently negotiated */
   sc->topology = ast_stream_topology_clone(new_topology);
   if (!sc->topology) {
      sc->topology = old_topology;
   } else {
      ast_stream_topology_free(old_topology);
   }

   /* If there are no removed sources and no added sources we don't need to renegotiate the
    * other participants.
    */
   if (!removed_streams_count && !ast_stream_topology_get_count(added_streams)) {
      ast_trace(-1, "%s: Nothing added or removed\n", ast_channel_name(bridge_channel->chan));
      goto cleanup;
   }

   ast_trace(-1, "%s: Processing adds and removes\n", ast_channel_name(bridge_channel->chan));
   /* Go through each participant adding in the new streams and removing the old ones */
   AST_LIST_TRAVERSE(participants, participant, entry)
   {
      struct softmix_channel *participant_sc = participant->tech_pvt;
      SCOPE_ENTER(4, "%s/%s: Old participant topology %s\n",
         ast_channel_name(bridge_channel->chan),
         ast_channel_name(participant->chan),
         ast_str_tmp(256, ast_stream_topology_to_str(participant_sc->topology, &STR_TMP)));

      if (participant == bridge_channel) {
         SCOPE_EXIT_EXPR(continue, "%s/%s: Same channel.  Skipping\n",
            ast_channel_name(bridge_channel->chan),
            ast_channel_name(participant->chan));
      }

      /* We add in all the new streams first so that they do not take the place
       * of any of our removed streams, allowing the remote side to reset the state
       * for each removed stream. */
      if (append_all_streams(participant_sc->topology, added_streams)) {
         SCOPE_EXIT_EXPR(goto cleanup, "%s/%s: Couldn't append streams\n",  ast_channel_name(bridge_channel->chan),
            ast_channel_name(participant->chan));
      }
      ast_trace(-1, "%s/%s:   Adding streams %s\n", ast_channel_name(bridge_channel->chan),
         ast_channel_name(participant->chan),
         ast_str_tmp(256, ast_stream_topology_to_str(added_streams, &STR_TMP)));

      /* Then we go through and remove any ones that were removed */
      for (index = 0;
         removed_streams_count && index < ast_stream_topology_get_count(sc->topology); ++index) {
         struct ast_stream *stream = ast_stream_topology_get_stream(sc->topology, index);
         int removed_stream;

         for (removed_stream = 0; removed_stream < removed_streams_count; ++removed_stream) {
            if (is_video_dest(stream, ast_channel_name(bridge_channel->chan),
               removed_streams[removed_stream])) {
               ast_trace(-1, "%s/%s:    Removing stream %s\n",
                  ast_channel_name(bridge_channel->chan),
                  ast_channel_name(participant->chan),
                  ast_str_tmp(256, ast_stream_to_str(stream, &STR_TMP)));
               ast_stream_set_state(stream, AST_STREAM_STATE_REMOVED);
            }
         }
      }
      ast_channel_request_stream_topology_change(participant->chan, participant_sc->topology, NULL);
      SCOPE_EXIT("%s/%s:   New participant topology %s\n",
         ast_channel_name(bridge_channel->chan),
         ast_channel_name(participant->chan),
         ast_str_tmp(256, ast_stream_topology_to_str(participant_sc->topology, &STR_TMP)));
   }

   ast_trace(-1, "%s: New topology %s\n", ast_channel_name(bridge_channel->chan),
      ast_str_tmp(256, ast_stream_topology_to_str(sc->topology, &STR_TMP)));

cleanup:
   ast_stream_topology_free(added_streams);
   SCOPE_EXIT();
}

/*!
 * \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 softmix_bridge_data *softmix_data = bridge->tech_pvt;
   struct softmix_channel *sc = bridge_channel->tech_pvt;
   struct ast_bridge_channel *participant;
   struct ast_vector_int media_types;
   int nths[AST_MEDIA_TYPE_END] = {0};
   int idx;
   SCOPE_ENTER(3, "%s: \n", ast_channel_name(bridge_channel->chan));

   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);
      SCOPE_EXIT_RTN("%s: Not in SFU mode\n", ast_channel_name(bridge_channel->chan));
   case AST_BRIDGE_VIDEO_MODE_SFU:
      break;
   }

   ast_channel_lock(bridge_channel->chan);
   softmix_bridge_stream_sources_update(bridge, bridge_channel, sc);
   ast_channel_unlock(bridge_channel->chan);

   AST_VECTOR_INIT(&media_types, AST_MEDIA_TYPE_END);

   /* The bridge stream identifiers may change, so reset the mapping for them.
    * When channels end up getting added back in they'll reuse their existing
    * collector and won't need to allocate a new one (unless they were just added).
    */
   for (idx = 0; idx < AST_VECTOR_SIZE(&softmix_data->remb_collectors); ++idx) {
      ao2_cleanup(AST_VECTOR_GET(&softmix_data->remb_collectors, idx));
      AST_VECTOR_REPLACE(&softmix_data->remb_collectors, idx, NULL);
   }

   /* 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);

      sc = participant->tech_pvt;
      AST_VECTOR_RESET(&sc->video_sources, 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 = ao2_bump(ast_channel_get_stream_topology(participant->chan));
      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);
            /*
             * There are cases where we need to bidirectionally send frames, such as for REMB reports
             * so we also map back to the channel.
             */
            AST_VECTOR_REPLACE(&participant->stream_map.to_channel, AST_VECTOR_SIZE(&media_types) - 1, i);
            remb_enable_collection(bridge, participant, AST_VECTOR_SIZE(&media_types) - 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_channel_name(participant->chan),
               AST_VECTOR_SIZE(&media_types) - 1, &bridge->channels, i);
            ast_bridge_channel_lock(participant);
            ast_channel_lock(participant->chan);
         } else if (ast_stream_get_type(stream) == AST_MEDIA_TYPE_VIDEO) {
            /* Video stream mapping occurs directly when a video source stream
             * is found on a channel. Video streams should otherwise remain
             * unmapped.
             */
            AST_VECTOR_REPLACE(&participant->stream_map.to_bridge, i, -1);
         } else if (ast_stream_get_state(stream) != AST_STREAM_STATE_REMOVED) {
            /* 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);
   }

   AST_VECTOR_FREE(&media_types);
   SCOPE_EXIT_RTN("%s\n", ast_channel_name(bridge_channel->chan));
}

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)
{
   const 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_1", "h264,vp8", AST_MEDIA_TYPE_VIDEO,
   };
   static const struct stream_parameters bob_dest_stream = {
      "softbridge_dest_PJSIP/Alice-00000000_1", "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", NULL, 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", NULL, 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, -1) &&
            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");