Multi-party software based channel mixing. More...

#include "asterisk.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/time.h>
#include <signal.h>
#include <errno.h>
#include <unistd.h>
#include "asterisk/module.h"
#include "asterisk/channel.h"
#include "asterisk/bridging.h"
#include "asterisk/bridging_technology.h"
#include "asterisk/frame.h"
#include "asterisk/options.h"
#include "asterisk/logger.h"
#include "asterisk/slinfactory.h"
#include "asterisk/astobj2.h"
#include "asterisk/timing.h"

Include dependency graph for bridge_softmix.c:

Go to the source code of this file.

Data Structures
struct	softmix_channel
	Define used to turn on 16 kHz audio support. More...
Defines
#define	SOFTMIX_DATALEN (160 * (SOFTMIX_INTERVAL / 10))
	Size of the buffer used for sample manipulation.
#define	SOFTMIX_INTERVAL 20
	Interval at which mixing will take place. Valid options are 10, 20, and 40.
#define	SOFTMIX_SAMPLES (SOFTMIX_DATALEN / 2)
	Number of samples we are dealing with.
Functions
static void	__reg_module (void)
static void	__unreg_module (void)
static int	load_module (void)
static int	softmix_bridge_create (struct ast_bridge *bridge)
	Function called when a bridge is created.
static int	softmix_bridge_destroy (struct ast_bridge *bridge)
	Function called when a bridge is destroyed.
static int	softmix_bridge_join (struct ast_bridge bridge, struct ast_bridge_channel bridge_channel)
	Function called when a channel is joined into the bridge.
static int	softmix_bridge_leave (struct ast_bridge bridge, struct ast_bridge_channel bridge_channel)
	Function called when a channel leaves the bridge.
static int	softmix_bridge_poke (struct ast_bridge bridge, struct ast_bridge_channel bridge_channel)
	Function called when the channel's thread is poked.
static int	softmix_bridge_thread (struct ast_bridge *bridge)
	Function which acts as the mixing thread.
static enum ast_bridge_write_result	softmix_bridge_write (struct ast_bridge bridge, struct ast_bridge_channel bridge_channel, struct ast_frame *frame)
	Function called when a channel writes a frame into the bridge.
static int	unload_module (void)
Variables
static struct ast_module_info __MODULE_INFO_SECTION	__mod_info = { __MODULE_INFO_GLOBALS .name = AST_MODULE, .flags = AST_MODFLAG_DEFAULT , .description = "Multi-party software based channel mixing" , .key = ASTERISK_GPL_KEY , .buildopt_sum = AST_BUILDOPT_SUM, .load = load_module, .unload = unload_module, }
static struct ast_module_info *	ast_module_info = &__mod_info
static struct ast_bridge_technology	softmix_bridge

Detailed Description

Multi-party software based channel mixing.

Author:: Joshua Colp <jcolp@digium.com>

Todo:: This bridge operates in 8 kHz mode unless a define is uncommented. This needs to be improved so the bridge moves between the dominant codec as needed depending on channels present in the bridge and transcoding capabilities.

Definition in file bridge_softmix.c.

Define Documentation

#define SOFTMIX_DATALEN (160 * (SOFTMIX_INTERVAL / 10))

Size of the buffer used for sample manipulation.

Definition at line 59 of file bridge_softmix.c.

Referenced by softmix_bridge_join(), and softmix_bridge_thread().

#define SOFTMIX_INTERVAL 20

Interval at which mixing will take place. Valid options are 10, 20, and 40.

Definition at line 56 of file bridge_softmix.c.

Referenced by softmix_bridge_thread().

#define SOFTMIX_SAMPLES (SOFTMIX_DATALEN / 2)

Number of samples we are dealing with.

Definition at line 62 of file bridge_softmix.c.

Referenced by softmix_bridge_join(), and softmix_bridge_thread().

Function Documentation

static void __reg_module ( void ) [static]

Definition at line 309 of file bridge_softmix.c.

static void __unreg_module ( void ) [static]

Definition at line 309 of file bridge_softmix.c.

static int load_module ( void ) [static]

Definition at line 304 of file bridge_softmix.c.

References ast_bridge_technology_register.

{
   return ast_bridge_technology_register(&softmix_bridge);
}

static int softmix_bridge_create ( struct ast_bridge * bridge ) [static]

Function called when a bridge is created.

Definition at line 86 of file bridge_softmix.c.

References ast_timer_open(), ast_bridge::bridge_pvt, and timer.

{
   struct ast_timer *timer;

   if (!(timer = ast_timer_open())) {
      return -1;
   }

   bridge->bridge_pvt = timer;

   return 0;
}

static int softmix_bridge_destroy ( struct ast_bridge * bridge ) [static]

Function called when a bridge is destroyed.

Definition at line 100 of file bridge_softmix.c.

References ast_timer_close(), and ast_bridge::bridge_pvt.

{
   if (!bridge->bridge_pvt) {
      return -1;
   }
   ast_timer_close((struct ast_timer *) bridge->bridge_pvt);

   return 0;
}

static int softmix_bridge_join	(	struct ast_bridge *	bridge,
		struct ast_bridge_channel *	bridge_channel
	)		`[static]`

Function called when a channel is joined into the bridge.

Definition at line 111 of file bridge_softmix.c.

References ast_calloc, AST_FORMAT_SLINEAR, AST_FORMAT_SLINEAR16, AST_FRAME_VOICE, ast_mutex_init(), ast_slinfactory_init(), ast_bridge_channel::bridge_pvt, ast_frame::data, ast_frame::datalen, softmix_channel::factory, softmix_channel::final_buf, softmix_channel::frame, ast_frame::frametype, softmix_channel::lock, ast_frame::ptr, ast_frame::samples, SOFTMIX_DATALEN, SOFTMIX_SAMPLES, and ast_frame::subclass.

{
   struct softmix_channel *sc = NULL;

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

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

   /* Setup smoother */
   ast_slinfactory_init(&sc->factory);

   /* Setup frame parameters */
   sc->frame.frametype = AST_FRAME_VOICE;
#ifdef SOFTMIX_16_SUPPORT
   sc->frame.subclass = AST_FORMAT_SLINEAR16;
#else
   sc->frame.subclass = AST_FORMAT_SLINEAR;
#endif
   sc->frame.data.ptr = sc->final_buf;
   sc->frame.datalen = SOFTMIX_DATALEN;
   sc->frame.samples = SOFTMIX_SAMPLES;

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

   return 0;
}

static int softmix_bridge_leave	(	struct ast_bridge *	bridge,
		struct ast_bridge_channel *	bridge_channel
	)		`[static]`

Function called when a channel leaves the bridge.

Definition at line 144 of file bridge_softmix.c.

References ast_free, ast_mutex_destroy(), ast_slinfactory_destroy(), ast_bridge_channel::bridge_pvt, softmix_channel::factory, and softmix_channel::lock.

{
   struct softmix_channel *sc = bridge_channel->bridge_pvt;

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

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

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

   return 0;
}

static int softmix_bridge_poke	(	struct ast_bridge *	bridge,
		struct ast_bridge_channel *	bridge_channel
	)		`[static]`

Function called when the channel's thread is poked.

Definition at line 194 of file bridge_softmix.c.

References ast_mutex_lock(), ast_mutex_unlock(), ast_write(), ast_bridge_channel::bridge_pvt, ast_bridge_channel::chan, softmix_channel::frame, softmix_channel::have_frame, and softmix_channel::lock.

{
   struct softmix_channel *sc = bridge_channel->bridge_pvt;

   ast_mutex_lock(&sc->lock);

   if (sc->have_frame) {
      ast_write(bridge_channel->chan, &sc->frame);
      sc->have_frame = 0;
   }

   ast_mutex_unlock(&sc->lock);

   return 0;
}

static int softmix_bridge_thread ( struct ast_bridge * bridge ) [static]

Function which acts as the mixing thread.

Definition at line 211 of file bridge_softmix.c.

References ao2_lock(), ao2_unlock(), ast_bridge::array_num, AST_LIST_TRAVERSE, ast_mutex_lock(), ast_mutex_unlock(), ast_slinear_saturated_add(), ast_slinear_saturated_subtract(), ast_slinfactory_available(), ast_slinfactory_read(), ast_timer_ack(), ast_timer_fd(), ast_timer_set_rate(), ast_waitfor_n_fd(), ast_bridge_channel::bridge_pvt, ast_bridge::bridge_pvt, buf, ast_bridge::channels, ast_bridge_channel::entry, softmix_channel::factory, softmix_channel::final_buf, softmix_channel::have_audio, softmix_channel::have_frame, softmix_channel::lock, softmix_channel::our_buf, ast_bridge::refresh, SOFTMIX_DATALEN, SOFTMIX_INTERVAL, SOFTMIX_SAMPLES, ast_bridge::stop, ast_bridge_channel::thread, and timer.

{
   struct ast_timer *timer = (struct ast_timer *) bridge->bridge_pvt;
   int timingfd = ast_timer_fd(timer);

   ast_timer_set_rate(timer, (1000 / SOFTMIX_INTERVAL));

   while (!bridge->stop && !bridge->refresh && bridge->array_num) {
      struct ast_bridge_channel *bridge_channel = NULL;
      short buf[SOFTMIX_DATALEN] = {0, };
      int timeout = -1;

      /* 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->bridge_pvt;

         ast_mutex_lock(&sc->lock);

         /* Try to get audio from the factory if available */
         if (ast_slinfactory_available(&sc->factory) >= SOFTMIX_SAMPLES && ast_slinfactory_read(&sc->factory, sc->our_buf, SOFTMIX_SAMPLES)) {
            short *data1, *data2;
            int i;

            /* Put into the local final buffer */
            for (i = 0, data1 = buf, data2 = sc->our_buf; i < SOFTMIX_DATALEN; i++, data1++, data2++)
               ast_slinear_saturated_add(data1, data2);
            /* Yay we have our own audio */
            sc->have_audio = 1;
         } else {
            /* Awww we don't have audio ;( */
            sc->have_audio = 0;
         }
         ast_mutex_unlock(&sc->lock);
      }

      /* 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->bridge_pvt;
         int i = 0;

         /* Copy from local final buffer to our final buffer */
         memcpy(sc->final_buf, buf, sizeof(sc->final_buf));

         /* If we provided audio then take it out */
         if (sc->have_audio) {
            for (i = 0; i < SOFTMIX_DATALEN; i++) {
               ast_slinear_saturated_subtract(&sc->final_buf[i], &sc->our_buf[i]);
            }
         }

         /* The frame is now ready for use... */
         sc->have_frame = 1;

         /* Poke bridged channel thread just in case */
         pthread_kill(bridge_channel->thread, SIGURG);
      }

      ao2_unlock(bridge);

      /* Wait for the timing source to tell us to wake up and get things done */
      ast_waitfor_n_fd(&timingfd, 1, &timeout, NULL);

      ast_timer_ack(timer, 1);

      ao2_lock(bridge);
   }

   return 0;
}

static enum ast_bridge_write_result softmix_bridge_write	(	struct ast_bridge *	bridge,
		struct ast_bridge_channel *	bridge_channel,
		struct ast_frame *	frame
	)		`[static]`

Function called when a channel writes a frame into the bridge.

Definition at line 161 of file bridge_softmix.c.

References AST_BRIDGE_WRITE_SUCCESS, AST_BRIDGE_WRITE_UNSUPPORTED, AST_FORMAT_SLINEAR, AST_FORMAT_SLINEAR16, AST_FRAME_VOICE, ast_mutex_lock(), ast_mutex_unlock(), ast_slinfactory_feed(), ast_write(), ast_bridge_channel::bridge_pvt, ast_bridge_channel::chan, softmix_channel::factory, softmix_channel::frame, ast_frame::frametype, softmix_channel::have_frame, softmix_channel::lock, and ast_frame::subclass.

{
   struct softmix_channel *sc = bridge_channel->bridge_pvt;

   /* Only accept audio frames, all others are unsupported */
   if (frame->frametype != AST_FRAME_VOICE) {
      return AST_BRIDGE_WRITE_UNSUPPORTED;
   }

   ast_mutex_lock(&sc->lock);

   /* If a frame was provided add it to the smoother */
#ifdef SOFTMIX_16_SUPPORT
   if (frame->frametype == AST_FRAME_VOICE && frame->subclass == AST_FORMAT_SLINEAR16) {
#else
   if (frame->frametype == AST_FRAME_VOICE && frame->subclass == AST_FORMAT_SLINEAR) {
#endif
      ast_slinfactory_feed(&sc->factory, frame);
   }

   /* If a frame is ready to be written out, do so */
   if (sc->have_frame) {
      ast_write(bridge_channel->chan, &sc->frame);
      sc->have_frame = 0;
   }

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

   return AST_BRIDGE_WRITE_SUCCESS;
}

static int unload_module ( void ) [static]

Definition at line 299 of file bridge_softmix.c.

References ast_bridge_technology_unregister().

{
   return ast_bridge_technology_unregister(&softmix_bridge);
}

Variable Documentation

struct ast_module_info __MODULE_INFO_SECTION __mod_info = { __MODULE_INFO_GLOBALS .name = AST_MODULE, .flags = AST_MODFLAG_DEFAULT , .description = "Multi-party software based channel mixing" , .key = ASTERISK_GPL_KEY , .buildopt_sum = AST_BUILDOPT_SUM, .load = load_module, .unload = unload_module, } [static]

Definition at line 309 of file bridge_softmix.c.

struct ast_module_info* ast_module_info = &__mod_info [static]

Definition at line 309 of file bridge_softmix.c.

struct ast_bridge_technology softmix_bridge [static]

Definition at line 281 of file bridge_softmix.c.

Asterisk developer's documentation

bridge_softmix.c File Reference

Data Structures

Defines

Functions

Variables

Detailed Description

Define Documentation

Function Documentation

Variable Documentation