Tue Aug 20 16:34:48 2013

Asterisk developer's documentation


bridge_softmix.c File Reference

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"

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

 AST_MODULE_INFO_STANDARD (ASTERISK_GPL_KEY,"Multi-party software based channel mixing")
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_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 63 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 60 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 66 of file bridge_softmix.c.

Referenced by softmix_bridge_join(), and softmix_bridge_thread().


Function Documentation

AST_MODULE_INFO_STANDARD ( ASTERISK_GPL_KEY  ,
"Multi-party software based channel mixing"   
)
static int load_module ( void   )  [static]

Definition at line 317 of file bridge_softmix.c.

References ast_bridge_technology_register.

00318 {
00319    return ast_bridge_technology_register(&softmix_bridge);
00320 }

static int softmix_bridge_create ( struct ast_bridge bridge  )  [static]

Function called when a bridge is created.

Definition at line 90 of file bridge_softmix.c.

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

00091 {
00092    struct ast_timer *timer;
00093 
00094    if (!(timer = ast_timer_open())) {
00095       return -1;
00096    }
00097 
00098    bridge->bridge_pvt = timer;
00099 
00100    return 0;
00101 }

static int softmix_bridge_destroy ( struct ast_bridge bridge  )  [static]

Function called when a bridge is destroyed.

Definition at line 104 of file bridge_softmix.c.

References ast_timer_close(), and ast_bridge::bridge_pvt.

00105 {
00106    if (!bridge->bridge_pvt) {
00107       return -1;
00108    }
00109    ast_timer_close((struct ast_timer *) bridge->bridge_pvt);
00110    bridge->bridge_pvt = NULL;
00111    return 0;
00112 }

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 115 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_subclass::codec, 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.

00116 {
00117    struct softmix_channel *sc = NULL;
00118 
00119    /* Create a new softmix_channel structure and allocate various things on it */
00120    if (!(sc = ast_calloc(1, sizeof(*sc)))) {
00121       return -1;
00122    }
00123 
00124    /* Can't forget the lock */
00125    ast_mutex_init(&sc->lock);
00126 
00127    /* Setup smoother */
00128    ast_slinfactory_init(&sc->factory);
00129 
00130    /* Setup frame parameters */
00131    sc->frame.frametype = AST_FRAME_VOICE;
00132 #ifdef SOFTMIX_16_SUPPORT
00133    sc->frame.subclass.codec = AST_FORMAT_SLINEAR16;
00134 #else
00135    sc->frame.subclass.codec = AST_FORMAT_SLINEAR;
00136 #endif
00137    sc->frame.data.ptr = sc->final_buf;
00138    sc->frame.datalen = SOFTMIX_DATALEN;
00139    sc->frame.samples = SOFTMIX_SAMPLES;
00140 
00141    /* Can't forget to record our pvt structure within the bridged channel structure */
00142    bridge_channel->bridge_pvt = sc;
00143 
00144    return 0;
00145 }

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 148 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.

00149 {
00150    struct softmix_channel *sc = bridge_channel->bridge_pvt;
00151 
00152    if (!(bridge_channel->bridge_pvt)) {
00153       return 0;
00154    }
00155    bridge_channel->bridge_pvt = NULL;
00156 
00157    /* Drop mutex lock */
00158    ast_mutex_destroy(&sc->lock);
00159 
00160    /* Drop the factory */
00161    ast_slinfactory_destroy(&sc->factory);
00162 
00163    /* Eep! drop ourselves */
00164    ast_free(sc);
00165 
00166    return 0;
00167 }

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 203 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.

00204 {
00205    struct softmix_channel *sc = bridge_channel->bridge_pvt;
00206 
00207    ast_mutex_lock(&sc->lock);
00208 
00209    if (sc->have_frame) {
00210       ast_write(bridge_channel->chan, &sc->frame);
00211       sc->have_frame = 0;
00212    }
00213 
00214    ast_mutex_unlock(&sc->lock);
00215 
00216    return 0;
00217 }

static int softmix_bridge_thread ( struct ast_bridge bridge  )  [static]

Function which acts as the mixing thread.

Definition at line 220 of file bridge_softmix.c.

References ao2_lock, ao2_unlock, ast_bridge::array_num, AST_LIST_TRAVERSE, ast_log(), 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, softmix_channel::factory, softmix_channel::final_buf, softmix_channel::have_audio, softmix_channel::have_frame, softmix_channel::lock, LOG_ERROR, softmix_channel::our_buf, ast_bridge::refresh, SOFTMIX_DATALEN, SOFTMIX_INTERVAL, SOFTMIX_SAMPLES, ast_bridge::stop, ast_bridge_channel::thread, and timer.

00221 {
00222    struct ast_timer *timer = (struct ast_timer *) bridge->bridge_pvt;
00223    int timingfd = ast_timer_fd(timer);
00224 
00225    ast_timer_set_rate(timer, (1000 / SOFTMIX_INTERVAL));
00226 
00227    while (!bridge->stop && !bridge->refresh && bridge->array_num) {
00228       struct ast_bridge_channel *bridge_channel = NULL;
00229       short buf[SOFTMIX_DATALEN] = {0, };
00230       int timeout = -1;
00231 
00232       /* Go through pulling audio from each factory that has it available */
00233       AST_LIST_TRAVERSE(&bridge->channels, bridge_channel, entry) {
00234          struct softmix_channel *sc = bridge_channel->bridge_pvt;
00235 
00236          ast_mutex_lock(&sc->lock);
00237 
00238          /* Try to get audio from the factory if available */
00239          if (ast_slinfactory_available(&sc->factory) >= SOFTMIX_SAMPLES && ast_slinfactory_read(&sc->factory, sc->our_buf, SOFTMIX_SAMPLES)) {
00240             short *data1, *data2;
00241             int i;
00242 
00243             /* Put into the local final buffer */
00244             for (i = 0, data1 = buf, data2 = sc->our_buf; i < SOFTMIX_DATALEN; i++, data1++, data2++)
00245                ast_slinear_saturated_add(data1, data2);
00246             /* Yay we have our own audio */
00247             sc->have_audio = 1;
00248          } else {
00249             /* Awww we don't have audio ;( */
00250             sc->have_audio = 0;
00251          }
00252          ast_mutex_unlock(&sc->lock);
00253       }
00254 
00255       /* Next step go through removing the channel's own audio and creating a good frame... */
00256       AST_LIST_TRAVERSE(&bridge->channels, bridge_channel, entry) {
00257          struct softmix_channel *sc = bridge_channel->bridge_pvt;
00258          int i = 0;
00259 
00260          /* Copy from local final buffer to our final buffer */
00261          memcpy(sc->final_buf, buf, sizeof(sc->final_buf));
00262 
00263          /* If we provided audio then take it out */
00264          if (sc->have_audio) {
00265             for (i = 0; i < SOFTMIX_DATALEN; i++) {
00266                ast_slinear_saturated_subtract(&sc->final_buf[i], &sc->our_buf[i]);
00267             }
00268          }
00269 
00270          /* The frame is now ready for use... */
00271          sc->have_frame = 1;
00272 
00273          /* Poke bridged channel thread just in case */
00274          pthread_kill(bridge_channel->thread, SIGURG);
00275       }
00276 
00277       ao2_unlock(bridge);
00278 
00279       /* Wait for the timing source to tell us to wake up and get things done */
00280       ast_waitfor_n_fd(&timingfd, 1, &timeout, NULL);
00281 
00282       if (ast_timer_ack(timer, 1) < 0) {
00283          ast_log(LOG_ERROR, "Failed to acknowledge timer in softmix bridge\n");
00284          ao2_lock(bridge);
00285          break;
00286       }
00287 
00288       ao2_lock(bridge);
00289    }
00290 
00291    return 0;
00292 }

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 170 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, ast_frame_subclass::codec, softmix_channel::factory, softmix_channel::frame, ast_frame::frametype, softmix_channel::have_frame, softmix_channel::lock, and ast_frame::subclass.

00171 {
00172    struct softmix_channel *sc = bridge_channel->bridge_pvt;
00173 
00174    /* Only accept audio frames, all others are unsupported */
00175    if (frame->frametype != AST_FRAME_VOICE) {
00176       return AST_BRIDGE_WRITE_UNSUPPORTED;
00177    }
00178 
00179    ast_mutex_lock(&sc->lock);
00180 
00181    /* If a frame was provided add it to the smoother */
00182 #ifdef SOFTMIX_16_SUPPORT
00183    if (frame->frametype == AST_FRAME_VOICE && frame->subclass.codec == AST_FORMAT_SLINEAR16) {
00184 #else
00185    if (frame->frametype == AST_FRAME_VOICE && frame->subclass.codec == AST_FORMAT_SLINEAR) {
00186 #endif
00187       ast_slinfactory_feed(&sc->factory, frame);
00188    }
00189 
00190    /* If a frame is ready to be written out, do so */
00191    if (sc->have_frame) {
00192       ast_write(bridge_channel->chan, &sc->frame);
00193       sc->have_frame = 0;
00194    }
00195 
00196    /* Alllll done */
00197    ast_mutex_unlock(&sc->lock);
00198 
00199    return AST_BRIDGE_WRITE_SUCCESS;
00200 }

static int unload_module ( void   )  [static]

Definition at line 312 of file bridge_softmix.c.

References ast_bridge_technology_unregister().

00313 {
00314    return ast_bridge_technology_unregister(&softmix_bridge);
00315 }


Variable Documentation

Definition at line 294 of file bridge_softmix.c.


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