bridges/bridge_softmix.c

   1 /*
   2  * Asterisk -- An open source telephony toolkit.
   3  *
   4  * Copyright (C) 2007, Digium, Inc.
   5  *
   6  * Joshua Colp <jcolp@digium.com>
   7  *
   8  * See http://www.asterisk.org for more information about
   9  * the Asterisk project. Please do not directly contact
  10  * any of the maintainers of this project for assistance;
  11  * the project provides a web site, mailing lists and IRC
  12  * channels for your use.
  13  *
  14  * This program is free software, distributed under the terms of
  15  * the GNU General Public License Version 2. See the LICENSE file
  16  * at the top of the source tree.
  17  */
  18
  19 /*! \file
  20  *
  21  * \brief Multi-party software based channel mixing
  22  *
  23  * \author Joshua Colp <jcolp@digium.com>
  24  *
  25  * \ingroup bridges
  26  *
  27  * \todo This bridge operates in 8 kHz mode unless a define is uncommented.
  28  * This needs to be improved so the bridge moves between the dominant codec as needed depending
  29  * on channels present in the bridge and transcoding capabilities.
  30  */
  31
  32 #include "asterisk.h"
  33
  34 ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
  35
  36 #include <stdio.h>
  37 #include <stdlib.h>
  38 #include <string.h>
  39 #include <sys/time.h>
  40 #include <signal.h>
  41 #include <errno.h>
  42 #include <unistd.h>
  43
  44 #include "asterisk/module.h"
  45 #include "asterisk/channel.h"
  46 #include "asterisk/bridging.h"
  47 #include "asterisk/bridging_technology.h"
  48 #include "asterisk/frame.h"
  49 #include "asterisk/options.h"
  50 #include "asterisk/logger.h"
  51 #include "asterisk/slinfactory.h"
  52 #include "asterisk/astobj2.h"
  53 #include "asterisk/timing.h"
  54
  55 /*! \brief Interval at which mixing will take place. Valid options are 10, 20, and 40. */
  56 #define SOFTMIX_INTERVAL 20
  57
  58 /*! \brief Size of the buffer used for sample manipulation */
  59 #define SOFTMIX_DATALEN (160 * (SOFTMIX_INTERVAL / 10))
  60
  61 /*! \brief Number of samples we are dealing with */
  62 #define SOFTMIX_SAMPLES (SOFTMIX_DATALEN / 2)
  63
  64 /*! \brief Define used to turn on 16 kHz audio support */
  65 /* #define SOFTMIX_16_SUPPORT */
  66
  67 /*! \brief Structure which contains per-channel mixing information */
  68 struct softmix_channel {
  69         /*! Lock to protect this structure */
  70         ast_mutex_t lock;
  71         /*! Factory which contains audio read in from the channel */
  72         struct ast_slinfactory factory;
  73         /*! Frame that contains mixed audio to be written out to the channel */
  74         struct ast_frame frame;
  75         /*! Bit used to indicate that the channel provided audio for this mixing interval */
  76         int have_audio:1;
  77         /*! Bit used to indicate that a frame is available to be written out to the channel */
  78         int have_frame:1;
  79         /*! Buffer containing final mixed audio from all sources */
  80         short final_buf[SOFTMIX_DATALEN];
  81         /*! Buffer containing only the audio from the channel */
  82         short our_buf[SOFTMIX_DATALEN];
  83 };
  84
  85 /*! \brief Function called when a bridge is created */
  86 static int softmix_bridge_create(struct ast_bridge *bridge)
  87 {
  88         struct ast_timer *timer;
  89
  90         if (!(timer = ast_timer_open())) {
  91                 return -1;
  92         }
  93
  94         bridge->bridge_pvt = timer;
  95
  96         return 0;
  97 }
  98
  99 /*! \brief Function called when a bridge is destroyed */
 100 static int softmix_bridge_destroy(struct ast_bridge *bridge)
 101 {
 102         ast_timer_close((struct ast_timer *) bridge->bridge_pvt);
 103
 104         return 0;
 105 }
 106
 107 /*! \brief Function called when a channel is joined into the bridge */
 108 static int softmix_bridge_join(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel)
 109 {
 110         struct softmix_channel *sc = NULL;
 111
 112         /* Create a new softmix_channel structure and allocate various things on it */
 113         if (!(sc = ast_calloc(1, sizeof(*sc)))) {
 114                 return -1;
 115         }
 116
 117         /* Can't forget the lock */
 118         ast_mutex_init(&sc->lock);
 119
 120         /* Setup smoother */
 121         ast_slinfactory_init(&sc->factory);
 122
 123         /* Setup frame parameters */
 124         sc->frame.frametype = AST_FRAME_VOICE;
 125 #ifdef SOFTMIX_16_SUPPORT
 126         sc->frame.subclass.codec = AST_FORMAT_SLINEAR16;
 127 #else
 128         sc->frame.subclass.codec = AST_FORMAT_SLINEAR;
 129 #endif
 130         sc->frame.data.ptr = sc->final_buf;
 131         sc->frame.datalen = SOFTMIX_DATALEN;
 132         sc->frame.samples = SOFTMIX_SAMPLES;
 133
 134         /* Can't forget to record our pvt structure within the bridged channel structure */
 135         bridge_channel->bridge_pvt = sc;
 136
 137         return 0;
 138 }
 139
 140 /*! \brief Function called when a channel leaves the bridge */
 141 static int softmix_bridge_leave(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel)
 142 {
 143         struct softmix_channel *sc = bridge_channel->bridge_pvt;
 144
 145         /* Drop mutex lock */
 146         ast_mutex_destroy(&sc->lock);
 147
 148         /* Drop the factory */
 149         ast_slinfactory_destroy(&sc->factory);
 150
 151         /* Eep! drop ourselves */
 152         ast_free(sc);
 153
 154         return 0;
 155 }
 156
 157 /*! \brief Function called when a channel writes a frame into the bridge */
 158 static enum ast_bridge_write_result softmix_bridge_write(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel, struct ast_frame *frame)
 159 {
 160         struct softmix_channel *sc = bridge_channel->bridge_pvt;
 161
 162         /* Only accept audio frames, all others are unsupported */
 163         if (frame->frametype != AST_FRAME_VOICE) {
 164                 return AST_BRIDGE_WRITE_UNSUPPORTED;
 165         }
 166
 167         ast_mutex_lock(&sc->lock);
 168
 169         /* If a frame was provided add it to the smoother */
 170 #ifdef SOFTMIX_16_SUPPORT
 171         if (frame->frametype == AST_FRAME_VOICE && frame->subclass.codec == AST_FORMAT_SLINEAR16) {
 172 #else
 173         if (frame->frametype == AST_FRAME_VOICE && frame->subclass.codec == AST_FORMAT_SLINEAR) {
 174 #endif
 175                 ast_slinfactory_feed(&sc->factory, frame);
 176         }
 177
 178         /* If a frame is ready to be written out, do so */
 179         if (sc->have_frame) {
 180                 ast_write(bridge_channel->chan, &sc->frame);
 181                 sc->have_frame = 0;
 182         }
 183
 184         /* Alllll done */
 185         ast_mutex_unlock(&sc->lock);
 186
 187         return AST_BRIDGE_WRITE_SUCCESS;
 188 }
 189
 190 /*! \brief Function called when the channel's thread is poked */
 191 static int softmix_bridge_poke(struct ast_bridge *bridge, struct ast_bridge_channel *bridge_channel)
 192 {
 193         struct softmix_channel *sc = bridge_channel->bridge_pvt;
 194
 195         ast_mutex_lock(&sc->lock);
 196
 197         if (sc->have_frame) {
 198                 ast_write(bridge_channel->chan, &sc->frame);
 199                 sc->have_frame = 0;
 200         }
 201
 202         ast_mutex_unlock(&sc->lock);
 203
 204         return 0;
 205 }
 206
 207 /*! \brief Function which acts as the mixing thread */
 208 static int softmix_bridge_thread(struct ast_bridge *bridge)
 209 {
 210         struct ast_timer *timer = (struct ast_timer *) bridge->bridge_pvt;
 211         int timingfd = ast_timer_fd(timer);
 212
 213         ast_timer_set_rate(timer, (1000 / SOFTMIX_INTERVAL));
 214
 215         while (!bridge->stop && !bridge->refresh && bridge->array_num) {
 216                 struct ast_bridge_channel *bridge_channel = NULL;
 217                 short buf[SOFTMIX_DATALEN] = {0, };
 218                 int timeout = -1;
 219
 220                 /* Go through pulling audio from each factory that has it available */
 221                 AST_LIST_TRAVERSE(&bridge->channels, bridge_channel, entry) {
 222                         struct softmix_channel *sc = bridge_channel->bridge_pvt;
 223
 224                         ast_mutex_lock(&sc->lock);
 225
 226                         /* Try to get audio from the factory if available */
 227                         if (ast_slinfactory_available(&sc->factory) >= SOFTMIX_SAMPLES && ast_slinfactory_read(&sc->factory, sc->our_buf, SOFTMIX_SAMPLES)) {
 228                                 short *data1, *data2;
 229                                 int i;
 230
 231                                 /* Put into the local final buffer */
 232                                 for (i = 0, data1 = buf, data2 = sc->our_buf; i < SOFTMIX_DATALEN; i++, data1++, data2++)
 233                                         ast_slinear_saturated_add(data1, data2);
 234                                 /* Yay we have our own audio */
 235                                 sc->have_audio = 1;
 236                         } else {
 237                                 /* Awww we don't have audio ;( */
 238                                 sc->have_audio = 0;
 239                         }
 240                         ast_mutex_unlock(&sc->lock);
 241                 }
 242
 243                 /* Next step go through removing the channel's own audio and creating a good frame... */
 244                 AST_LIST_TRAVERSE(&bridge->channels, bridge_channel, entry) {
 245                         struct softmix_channel *sc = bridge_channel->bridge_pvt;
 246                         int i = 0;
 247
 248                         /* Copy from local final buffer to our final buffer */
 249                         memcpy(sc->final_buf, buf, sizeof(sc->final_buf));
 250
 251                         /* If we provided audio then take it out */
 252                         if (sc->have_audio) {
 253                                 for (i = 0; i < SOFTMIX_DATALEN; i++) {
 254                                         ast_slinear_saturated_subtract(&sc->final_buf[i], &sc->our_buf[i]);
 255                                 }
 256                         }
 257
 258                         /* The frame is now ready for use... */
 259                         sc->have_frame = 1;
 260
 261                         /* Poke bridged channel thread just in case */
 262                         pthread_kill(bridge_channel->thread, SIGURG);
 263                 }
 264
 265                 ao2_unlock(bridge);
 266
 267                 /* Wait for the timing source to tell us to wake up and get things done */
 268                 ast_waitfor_n_fd(&timingfd, 1, &timeout, NULL);
 269
 270                 ast_timer_ack(timer, 1);
 271
 272                 ao2_lock(bridge);
 273         }
 274
 275         return 0;
 276 }
 277
 278 static struct ast_bridge_technology softmix_bridge = {
 279         .name = "softmix",
 280         .capabilities = AST_BRIDGE_CAPABILITY_MULTIMIX | AST_BRIDGE_CAPABILITY_THREAD | AST_BRIDGE_CAPABILITY_MULTITHREADED,
 281         .preference = AST_BRIDGE_PREFERENCE_LOW,
 282 #ifdef SOFTMIX_16_SUPPORT
 283         .formats = AST_FORMAT_SLINEAR16,
 284 #else
 285         .formats = AST_FORMAT_SLINEAR,
 286 #endif
 287         .create = softmix_bridge_create,
 288         .destroy = softmix_bridge_destroy,
 289         .join = softmix_bridge_join,
 290         .leave = softmix_bridge_leave,
 291         .write = softmix_bridge_write,
 292         .thread = softmix_bridge_thread,
 293         .poke = softmix_bridge_poke,
 294 };
 295
 296 static int unload_module(void)
 297 {
 298         return ast_bridge_technology_unregister(&softmix_bridge);
 299 }
 300
 301 static int load_module(void)
 302 {
 303         return ast_bridge_technology_register(&softmix_bridge);
 304 }
 305
 306 AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Multi-party software based channel mixing");