abstract_jb.c

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/*
 * abstract_jb: common implementation-independent jitterbuffer stuff
 *
 * Copyright (C) 2005, Attractel OOD
 *
 * Contributors:
 * Slav Klenov <slav@securax.org>
 *
 * 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.
 *
 * A license has been granted to Digium (via disclaimer) for the use of
 * this code.
 */

/*! \file
 *
 * \brief Common implementation-independent jitterbuffer stuff.
 *
 * \author Slav Klenov <slav@securax.org>
 *
 *
 */

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

#include "asterisk.h"

ASTERISK_FILE_VERSION(__FILE__, "$Revision: 399403 $")

#include "asterisk/frame.h"
#include "asterisk/channel.h"
#include "asterisk/term.h"
#include "asterisk/utils.h"

#include "asterisk/abstract_jb.h"
#include "fixedjitterbuf.h"
#include "jitterbuf.h"

/*! Internal jb flags */
enum {
   JB_USE =                  (1 << 0),
   JB_TIMEBASE_INITIALIZED = (1 << 1),
   JB_CREATED =              (1 << 2)
};


/* Implementation functions */
/* fixed */
static void *jb_create_fixed(struct ast_jb_conf *general_config);
static void jb_destroy_fixed(void *jb);
static int jb_put_first_fixed(void *jb, struct ast_frame *fin, long now);
static int jb_put_fixed(void *jb, struct ast_frame *fin, long now);
static int jb_get_fixed(void *jb, struct ast_frame **fout, long now, long interpl);
static long jb_next_fixed(void *jb);
static int jb_remove_fixed(void *jb, struct ast_frame **fout);
static void jb_force_resynch_fixed(void *jb);
static void jb_empty_and_reset_fixed(void *jb);
/* adaptive */
static void * jb_create_adaptive(struct ast_jb_conf *general_config);
static void jb_destroy_adaptive(void *jb);
static int jb_put_first_adaptive(void *jb, struct ast_frame *fin, long now);
static int jb_put_adaptive(void *jb, struct ast_frame *fin, long now);
static int jb_get_adaptive(void *jb, struct ast_frame **fout, long now, long interpl);
static long jb_next_adaptive(void *jb);
static int jb_remove_adaptive(void *jb, struct ast_frame **fout);
static void jb_force_resynch_adaptive(void *jb);
static void jb_empty_and_reset_adaptive(void *jb);

/* Available jb implementations */
static const struct ast_jb_impl avail_impl[] = {
   {
      .name = "fixed",
      .type = AST_JB_FIXED,
      .create = jb_create_fixed,
      .destroy = jb_destroy_fixed,
      .put_first = jb_put_first_fixed,
      .put = jb_put_fixed,
      .get = jb_get_fixed,
      .next = jb_next_fixed,
      .remove = jb_remove_fixed,
      .force_resync = jb_force_resynch_fixed,
      .empty_and_reset = jb_empty_and_reset_fixed,
   },
   {
      .name = "adaptive",
      .type = AST_JB_ADAPTIVE,
      .create = jb_create_adaptive,
      .destroy = jb_destroy_adaptive,
      .put_first = jb_put_first_adaptive,
      .put = jb_put_adaptive,
      .get = jb_get_adaptive,
      .next = jb_next_adaptive,
      .remove = jb_remove_adaptive,
      .force_resync = jb_force_resynch_adaptive,
      .empty_and_reset = jb_empty_and_reset_adaptive,
   }
};

static int default_impl = 0;

/* Translations between impl and abstract return codes */
static const int fixed_to_abstract_code[] =
   {AST_JB_IMPL_OK, AST_JB_IMPL_DROP, AST_JB_IMPL_INTERP, AST_JB_IMPL_NOFRAME};
static const int adaptive_to_abstract_code[] =
   {AST_JB_IMPL_OK, AST_JB_IMPL_NOFRAME, AST_JB_IMPL_NOFRAME, AST_JB_IMPL_INTERP, AST_JB_IMPL_DROP, AST_JB_IMPL_OK};

/* JB_GET actions (used only for the frames log) */
static const char * const jb_get_actions[] = {"Delivered", "Dropped", "Interpolated", "No"};

/*! \brief Macros for the frame log files */
#define jb_framelog(...) do { \
   if (jb->logfile) { \
      fprintf(jb->logfile, __VA_ARGS__); \
      fflush(jb->logfile); \
   } \
} while (0)


/* Internal utility functions */
static void jb_choose_impl(struct ast_channel *chan);
static void jb_get_and_deliver(struct ast_channel *chan);
static int create_jb(struct ast_channel *chan, struct ast_frame *first_frame);
static long get_now(struct ast_jb *jb, struct timeval *tv);


/* Interface ast jb functions impl */


static void jb_choose_impl(struct ast_channel *chan)
{
   struct ast_jb *jb = ast_channel_jb(chan);
   struct ast_jb_conf *jbconf = &jb->conf;
   const struct ast_jb_impl *test_impl;
   int i, avail_impl_count = ARRAY_LEN(avail_impl);

   jb->impl = &avail_impl[default_impl];

   if (ast_strlen_zero(jbconf->impl)) {
      return;
   }

   for (i = 0; i < avail_impl_count; i++) {
      test_impl = &avail_impl[i];
      if (!strcasecmp(jbconf->impl, test_impl->name)) {
         jb->impl = test_impl;
         return;
      }
   }
}

int ast_jb_do_usecheck(struct ast_channel *c0, struct ast_channel *c1)
{
   struct ast_jb *jb0 = ast_channel_jb(c0);
   struct ast_jb *jb1 = ast_channel_jb(c1);
   struct ast_jb_conf *conf0 = &jb0->conf;
   struct ast_jb_conf *conf1 = &jb1->conf;
   int c0_wants_jitter = ast_channel_tech(c0)->properties & AST_CHAN_TP_WANTSJITTER;
   int c0_creates_jitter = ast_channel_tech(c0)->properties & AST_CHAN_TP_CREATESJITTER;
   int c0_jb_enabled = ast_test_flag(conf0, AST_JB_ENABLED);
   int c0_force_jb = ast_test_flag(conf0, AST_JB_FORCED);
   int c0_jb_timebase_initialized = ast_test_flag(jb0, JB_TIMEBASE_INITIALIZED);
   int c0_jb_created = ast_test_flag(jb0, JB_CREATED);
   int c1_wants_jitter = ast_channel_tech(c1)->properties & AST_CHAN_TP_WANTSJITTER;
   int c1_creates_jitter = ast_channel_tech(c1)->properties & AST_CHAN_TP_CREATESJITTER;
   int c1_jb_enabled = ast_test_flag(conf1, AST_JB_ENABLED);
   int c1_force_jb = ast_test_flag(conf1, AST_JB_FORCED);
   int c1_jb_timebase_initialized = ast_test_flag(jb1, JB_TIMEBASE_INITIALIZED);
   int c1_jb_created = ast_test_flag(jb1, JB_CREATED);
   int inuse = 0;

   /* Determine whether audio going to c0 needs a jitter buffer */
   if (((!c0_wants_jitter && c1_creates_jitter) || (c0_force_jb && c1_creates_jitter)) && c0_jb_enabled) {
      ast_set_flag(jb0, JB_USE);
      if (!c0_jb_timebase_initialized) {
         if (c1_jb_timebase_initialized) {
            memcpy(&jb0->timebase, &jb1->timebase, sizeof(struct timeval));
         } else {
            gettimeofday(&jb0->timebase, NULL);
         }
         ast_set_flag(jb0, JB_TIMEBASE_INITIALIZED);
      }

      if (!c0_jb_created) {
         jb_choose_impl(c0);
      }

      inuse = 1;
   }

   /* Determine whether audio going to c1 needs a jitter buffer */
   if (((!c1_wants_jitter && c0_creates_jitter) || (c1_force_jb && c0_creates_jitter)) && c1_jb_enabled) {
      ast_set_flag(jb1, JB_USE);
      if (!c1_jb_timebase_initialized) {
         if (c0_jb_timebase_initialized) {
            memcpy(&jb1->timebase, &jb0->timebase, sizeof(struct timeval));
         } else {
            gettimeofday(&jb1->timebase, NULL);
         }
         ast_set_flag(jb1, JB_TIMEBASE_INITIALIZED);
      }

      if (!c1_jb_created) {
         jb_choose_impl(c1);
      }

      inuse = 1;
   }

   return inuse;
}

int ast_jb_get_when_to_wakeup(struct ast_channel *c0, struct ast_channel *c1, int time_left)
{
   struct ast_jb *jb0 = ast_channel_jb(c0);
   struct ast_jb *jb1 = ast_channel_jb(c1);
   int c0_use_jb = ast_test_flag(jb0, JB_USE);
   int c0_jb_is_created = ast_test_flag(jb0, JB_CREATED);
   int c1_use_jb = ast_test_flag(jb1, JB_USE);
   int c1_jb_is_created = ast_test_flag(jb1, JB_CREATED);
   int wait, wait0, wait1;
   struct timeval tv_now;

   if (time_left == 0) {
      /* No time left - the bridge will be retried */
      /* TODO: Test disable this */
      /*return 0;*/
   }

   if (time_left < 0) {
      time_left = INT_MAX;
   }

   gettimeofday(&tv_now, NULL);

   wait0 = (c0_use_jb && c0_jb_is_created) ? jb0->next - get_now(jb0, &tv_now) : time_left;
   wait1 = (c1_use_jb && c1_jb_is_created) ? jb1->next - get_now(jb1, &tv_now) : time_left;

   wait = wait0 < wait1 ? wait0 : wait1;
   wait = wait < time_left ? wait : time_left;

   if (wait == INT_MAX) {
      wait = -1;
   } else if (wait < 1) {
      /* don't let wait=0, because this can cause the pbx thread to loop without any sleeping at all */
      wait = 1;
   }

   return wait;
}


int ast_jb_put(struct ast_channel *chan, struct ast_frame *f)
{
   struct ast_jb *jb = ast_channel_jb(chan);
   const struct ast_jb_impl *jbimpl = jb->impl;
   void *jbobj = jb->jbobj;
   struct ast_frame *frr;
   long now = 0;

   if (!ast_test_flag(jb, JB_USE))
      return -1;

   if (f->frametype != AST_FRAME_VOICE) {
      if (f->frametype == AST_FRAME_DTMF && ast_test_flag(jb, JB_CREATED)) {
         jb_framelog("JB_PUT {now=%ld}: Received DTMF frame. Force resynching jb...\n", now);
         jbimpl->force_resync(jbobj);
      }

      return -1;
   }

   /* We consider an enabled jitterbuffer should receive frames with valid timing info. */
   if (!ast_test_flag(f, AST_FRFLAG_HAS_TIMING_INFO) || f->len < 2 || f->ts < 0) {
      ast_log(LOG_WARNING, "%s received frame with invalid timing info: "
         "has_timing_info=%d, len=%ld, ts=%ld, src=%s\n",
         ast_channel_name(chan), ast_test_flag(f, AST_FRFLAG_HAS_TIMING_INFO), f->len, f->ts, f->src);
      return -1;
   }

   frr = ast_frdup(f);

   if (!frr) {
      ast_log(LOG_ERROR, "Failed to isolate frame for the jitterbuffer on channel '%s'\n", ast_channel_name(chan));
      return -1;
   }

   if (!ast_test_flag(jb, JB_CREATED)) {
      if (create_jb(chan, frr)) {
         ast_frfree(frr);
         /* Disable the jitterbuffer */
         ast_clear_flag(jb, JB_USE);
         return -1;
      }

      ast_set_flag(jb, JB_CREATED);
      return 0;
   } else {
      now = get_now(jb, NULL);
      if (jbimpl->put(jbobj, frr, now) != AST_JB_IMPL_OK) {
         jb_framelog("JB_PUT {now=%ld}: Dropped frame with ts=%ld and len=%ld\n", now, frr->ts, frr->len);
         ast_frfree(frr);
         /*return -1;*/
         /* TODO: Check this fix - should return 0 here, because the dropped frame shouldn't
            be delivered at all */
         return 0;
      }

      jb->next = jbimpl->next(jbobj);

      jb_framelog("JB_PUT {now=%ld}: Queued frame with ts=%ld and len=%ld\n", now, frr->ts, frr->len);

      return 0;
   }
}


void ast_jb_get_and_deliver(struct ast_channel *c0, struct ast_channel *c1)
{
   struct ast_jb *jb0 = ast_channel_jb(c0);
   struct ast_jb *jb1 = ast_channel_jb(c1);
   int c0_use_jb = ast_test_flag(jb0, JB_USE);
   int c0_jb_is_created = ast_test_flag(jb0, JB_CREATED);
   int c1_use_jb = ast_test_flag(jb1, JB_USE);
   int c1_jb_is_created = ast_test_flag(jb1, JB_CREATED);

   if (c0_use_jb && c0_jb_is_created)
      jb_get_and_deliver(c0);

   if (c1_use_jb && c1_jb_is_created)
      jb_get_and_deliver(c1);
}


static void jb_get_and_deliver(struct ast_channel *chan)
{
   struct ast_jb *jb = ast_channel_jb(chan);
   const struct ast_jb_impl *jbimpl = jb->impl;
   void *jbobj = jb->jbobj;
   struct ast_frame *f, finterp = { .frametype = AST_FRAME_VOICE, };
   long now;
   int interpolation_len, res;

   now = get_now(jb, NULL);
   jb->next = jbimpl->next(jbobj);
   if (now < jb->next) {
      jb_framelog("\tJB_GET {now=%ld}: now < next=%ld\n", now, jb->next);
      return;
   }

   while (now >= jb->next) {
      interpolation_len = ast_codec_interp_len(&jb->last_format);

      res = jbimpl->get(jbobj, &f, now, interpolation_len);

      switch (res) {
      case AST_JB_IMPL_OK:
         /* deliver the frame */
         ast_write(chan, f);
      case AST_JB_IMPL_DROP:
         jb_framelog("\tJB_GET {now=%ld}: %s frame with ts=%ld and len=%ld\n",
            now, jb_get_actions[res], f->ts, f->len);
         ast_format_copy(&jb->last_format, &f->subclass.format);
         ast_frfree(f);
         break;
      case AST_JB_IMPL_INTERP:
         /* interpolate a frame */
         f = &finterp;
         ast_format_copy(&f->subclass.format, &jb->last_format);
         f->samples  = interpolation_len * 8;
         f->src  = "JB interpolation";
         f->delivery = ast_tvadd(jb->timebase, ast_samp2tv(jb->next, 1000));
         f->offset = AST_FRIENDLY_OFFSET;
         /* deliver the interpolated frame */
         ast_write(chan, f);
         jb_framelog("\tJB_GET {now=%ld}: Interpolated frame with len=%d\n", now, interpolation_len);
         break;
      case AST_JB_IMPL_NOFRAME:
         ast_log(LOG_WARNING,
            "AST_JB_IMPL_NOFRAME is returned from the %s jb when now=%ld >= next=%ld, jbnext=%ld!\n",
            jbimpl->name, now, jb->next, jbimpl->next(jbobj));
         jb_framelog("\tJB_GET {now=%ld}: No frame for now!?\n", now);
         return;
      default:
         ast_log(LOG_ERROR, "This should never happen!\n");
         ast_assert("JB type unknown" == NULL);
         break;
      }

      jb->next = jbimpl->next(jbobj);
   }
}


static int create_jb(struct ast_channel *chan, struct ast_frame *frr)
{
   struct ast_jb *jb = ast_channel_jb(chan);
   struct ast_jb_conf *jbconf = &jb->conf;
   const struct ast_jb_impl *jbimpl = jb->impl;
   void *jbobj;
   struct ast_channel *bridged;
   long now;
   char logfile_pathname[20 + AST_JB_IMPL_NAME_SIZE + 2*AST_CHANNEL_NAME + 1];
   char name1[AST_CHANNEL_NAME], name2[AST_CHANNEL_NAME], *tmp;
   int res;

   jbobj = jb->jbobj = jbimpl->create(jbconf);
   if (!jbobj) {
      ast_log(LOG_WARNING, "Failed to create jitterbuffer on channel '%s'\n", ast_channel_name(chan));
      return -1;
   }

   now = get_now(jb, NULL);
   res = jbimpl->put_first(jbobj, frr, now);

   /* The result of putting the first frame should not differ from OK. However, its possible
      some implementations (i.e. adaptive's when resynch_threshold is specified) to drop it. */
   if (res != AST_JB_IMPL_OK) {
      ast_log(LOG_WARNING, "Failed to put first frame in the jitterbuffer on channel '%s'\n", ast_channel_name(chan));
      /*
      jbimpl->destroy(jbobj);
      return -1;
      */
   }

   /* Init next */
   jb->next = jbimpl->next(jbobj);

   /* Init last format for a first time. */
   ast_format_copy(&jb->last_format, &frr->subclass.format);

   /* Create a frame log file */
   if (ast_test_flag(jbconf, AST_JB_LOG)) {
      char safe_logfile[30] = "/tmp/logfile-XXXXXX";
      int safe_fd;
      snprintf(name2, sizeof(name2), "%s", ast_channel_name(chan));
      while ((tmp = strchr(name2, '/'))) {
         *tmp = '#';
      }

      bridged = ast_bridged_channel(chan);
      /* We should always have bridged chan if a jitterbuffer is in use */
      ast_assert(bridged != NULL);

      snprintf(name1, sizeof(name1), "%s", ast_channel_name(bridged));
      while ((tmp = strchr(name1, '/'))) {
         *tmp = '#';
      }

      snprintf(logfile_pathname, sizeof(logfile_pathname),
         "/tmp/ast_%s_jb_%s--%s.log", jbimpl->name, name1, name2);
      unlink(logfile_pathname);
      safe_fd = mkstemp(safe_logfile);
      if (safe_fd < 0 || link(safe_logfile, logfile_pathname) || unlink(safe_logfile) || !(jb->logfile = fdopen(safe_fd, "w+b"))) {
         ast_log(LOG_ERROR, "Failed to create frame log file with pathname '%s': %s\n", logfile_pathname, strerror(errno));
         jb->logfile = NULL;
         if (safe_fd > -1) {
            close(safe_fd);
         }
      }

      if (res == AST_JB_IMPL_OK) {
         jb_framelog("JB_PUT_FIRST {now=%ld}: Queued frame with ts=%ld and len=%ld\n",
            now, frr->ts, frr->len);
      } else {
         jb_framelog("JB_PUT_FIRST {now=%ld}: Dropped frame with ts=%ld and len=%ld\n",
            now, frr->ts, frr->len);
      }
   }

   ast_verb(3, "%s jitterbuffer created on channel %s\n", jbimpl->name, ast_channel_name(chan));

   /* Free the frame if it has not been queued in the jb */
   if (res != AST_JB_IMPL_OK) {
      ast_frfree(frr);
   }

   return 0;
}


void ast_jb_destroy(struct ast_channel *chan)
{
   struct ast_jb *jb = ast_channel_jb(chan);
   const struct ast_jb_impl *jbimpl = jb->impl;
   void *jbobj = jb->jbobj;
   struct ast_frame *f;

   if (jb->logfile) {
      fclose(jb->logfile);
      jb->logfile = NULL;
   }

   if (ast_test_flag(jb, JB_CREATED)) {
      /* Remove and free all frames still queued in jb */
      while (jbimpl->remove(jbobj, &f) == AST_JB_IMPL_OK) {
         ast_frfree(f);
      }

      jbimpl->destroy(jbobj);
      jb->jbobj = NULL;

      ast_clear_flag(jb, JB_CREATED);

      ast_verb(3, "%s jitterbuffer destroyed on channel %s\n", jbimpl->name, ast_channel_name(chan));
   }
}


static long get_now(struct ast_jb *jb, struct timeval *when)
{
   struct timeval now;

   if (!when) {
      when = &now;
      gettimeofday(when, NULL);
   }

   return ast_tvdiff_ms(*when, jb->timebase);
}


int ast_jb_read_conf(struct ast_jb_conf *conf, const char *varname, const char *value)
{
   int prefixlen = sizeof(AST_JB_CONF_PREFIX) - 1;
   const char *name;
   int tmp;

   if (strncasecmp(AST_JB_CONF_PREFIX, varname, prefixlen)) {
      return -1;
   }

   name = varname + prefixlen;

   if (!strcasecmp(name, AST_JB_CONF_ENABLE)) {
      ast_set2_flag(conf, ast_true(value), AST_JB_ENABLED);
   } else if (!strcasecmp(name, AST_JB_CONF_FORCE)) {
      ast_set2_flag(conf, ast_true(value), AST_JB_FORCED);
   } else if (!strcasecmp(name, AST_JB_CONF_MAX_SIZE)) {
      if ((tmp = atoi(value)) > 0)
         conf->max_size = tmp;
   } else if (!strcasecmp(name, AST_JB_CONF_RESYNCH_THRESHOLD)) {
      if ((tmp = atoi(value)) > 0)
         conf->resync_threshold = tmp;
   } else if (!strcasecmp(name, AST_JB_CONF_IMPL)) {
      if (!ast_strlen_zero(value))
         snprintf(conf->impl, sizeof(conf->impl), "%s", value);
   } else if (!strcasecmp(name, AST_JB_CONF_TARGET_EXTRA)) {
      if (sscanf(value, "%30d", &tmp) == 1) {
         conf->target_extra = tmp;
      }
   } else if (!strcasecmp(name, AST_JB_CONF_LOG)) {
      ast_set2_flag(conf, ast_true(value), AST_JB_LOG);
   } else {
      return -1;
   }

   return 0;
}


void ast_jb_configure(struct ast_channel *chan, const struct ast_jb_conf *conf)
{
   memcpy(&ast_channel_jb(chan)->conf, conf, sizeof(*conf));
}


void ast_jb_get_config(const struct ast_channel *chan, struct ast_jb_conf *conf)
{
   memcpy(conf, &ast_channel_jb((struct ast_channel *) chan)->conf, sizeof(*conf));
}

void ast_jb_empty_and_reset(struct ast_channel *c0, struct ast_channel *c1)
{
   struct ast_jb *jb0 = ast_channel_jb(c0);
   struct ast_jb *jb1 = ast_channel_jb(c1);
   int c0_use_jb = ast_test_flag(jb0, JB_USE);
   int c0_jb_is_created = ast_test_flag(jb0, JB_CREATED);
   int c1_use_jb = ast_test_flag(jb1, JB_USE);
   int c1_jb_is_created = ast_test_flag(jb1, JB_CREATED);

   if (c0_use_jb && c0_jb_is_created && jb0->impl->empty_and_reset) {
      jb0->impl->empty_and_reset(jb0->jbobj);
   }

   if (c1_use_jb && c1_jb_is_created && jb1->impl->empty_and_reset) {
      jb1->impl->empty_and_reset(jb1->jbobj);
   }
}

/* Implementation functions */

/* fixed */
static void * jb_create_fixed(struct ast_jb_conf *general_config)
{
   struct fixed_jb_conf conf;

   conf.jbsize = general_config->max_size;
   conf.resync_threshold = general_config->resync_threshold;

   return fixed_jb_new(&conf);
}

static void jb_destroy_fixed(void *jb)
{
   struct fixed_jb *fixedjb = (struct fixed_jb *) jb;

   /* Ensure the fixed jb is empty - otherwise it will raise an ASSERT */
   jb_empty_and_reset_fixed(jb);

   /* destroy the jb */
   fixed_jb_destroy(fixedjb);
}


static int jb_put_first_fixed(void *jb, struct ast_frame *fin, long now)
{
   struct fixed_jb *fixedjb = (struct fixed_jb *) jb;
   int res;

   res = fixed_jb_put_first(fixedjb, fin, fin->len, fin->ts, now);

   return fixed_to_abstract_code[res];
}


static int jb_put_fixed(void *jb, struct ast_frame *fin, long now)
{
   struct fixed_jb *fixedjb = (struct fixed_jb *) jb;
   int res;

   res = fixed_jb_put(fixedjb, fin, fin->len, fin->ts, now);

   return fixed_to_abstract_code[res];
}


static int jb_get_fixed(void *jb, struct ast_frame **fout, long now, long interpl)
{
   struct fixed_jb *fixedjb = (struct fixed_jb *) jb;
   struct fixed_jb_frame frame;
   int res;

   res = fixed_jb_get(fixedjb, &frame, now, interpl);
   *fout = frame.data;

   return fixed_to_abstract_code[res];
}


static long jb_next_fixed(void *jb)
{
   struct fixed_jb *fixedjb = (struct fixed_jb *) jb;

   return fixed_jb_next(fixedjb);
}


static int jb_remove_fixed(void *jb, struct ast_frame **fout)
{
   struct fixed_jb *fixedjb = (struct fixed_jb *) jb;
   struct fixed_jb_frame frame;
   int res;

   res = fixed_jb_remove(fixedjb, &frame);
   *fout = frame.data;

   return fixed_to_abstract_code[res];
}


static void jb_force_resynch_fixed(void *jb)
{
   struct fixed_jb *fixedjb = (struct fixed_jb *) jb;

   fixed_jb_set_force_resynch(fixedjb);
}

static void jb_empty_and_reset_fixed(void *jb)
{
   struct fixed_jb *fixedjb = jb;
   struct fixed_jb_frame f;

   while (fixed_jb_remove(fixedjb, &f) == FIXED_JB_OK) {
      ast_frfree(f.data);
   }
}

/* adaptive */

static void *jb_create_adaptive(struct ast_jb_conf *general_config)
{
   jb_conf jbconf;
   jitterbuf *adaptivejb;

   adaptivejb = jb_new();
   if (adaptivejb) {
      jbconf.max_jitterbuf = general_config->max_size;
      jbconf.resync_threshold = general_config->resync_threshold;
      jbconf.max_contig_interp = 10;
      jbconf.target_extra = general_config->target_extra;
      jb_setconf(adaptivejb, &jbconf);
   }

   return adaptivejb;
}


static void jb_destroy_adaptive(void *jb)
{
   jitterbuf *adaptivejb = (jitterbuf *) jb;

   jb_destroy(adaptivejb);
}


static int jb_put_first_adaptive(void *jb, struct ast_frame *fin, long now)
{
   return jb_put_adaptive(jb, fin, now);
}


static int jb_put_adaptive(void *jb, struct ast_frame *fin, long now)
{
   jitterbuf *adaptivejb = (jitterbuf *) jb;
   int res;

   res = jb_put(adaptivejb, fin, JB_TYPE_VOICE, fin->len, fin->ts, now);

   return adaptive_to_abstract_code[res];
}


static int jb_get_adaptive(void *jb, struct ast_frame **fout, long now, long interpl)
{
   jitterbuf *adaptivejb = (jitterbuf *) jb;
   jb_frame frame;
   int res;

   res = jb_get(adaptivejb, &frame, now, interpl);
   *fout = frame.data;

   return adaptive_to_abstract_code[res];
}


static long jb_next_adaptive(void *jb)
{
   jitterbuf *adaptivejb = (jitterbuf *) jb;

   return jb_next(adaptivejb);
}


static int jb_remove_adaptive(void *jb, struct ast_frame **fout)
{
   jitterbuf *adaptivejb = (jitterbuf *) jb;
   jb_frame frame;
   int res;

   res = jb_getall(adaptivejb, &frame);
   *fout = frame.data;

   return adaptive_to_abstract_code[res];
}


static void jb_force_resynch_adaptive(void *jb)
{
}

static void jb_empty_and_reset_adaptive(void *jb)
{
   jitterbuf *adaptivejb = jb;
   jb_frame f;

   while (jb_getall(adaptivejb, &f) == JB_OK) {
      ast_frfree(f.data);
   }

   jb_reset(adaptivejb);
}

const struct ast_jb_impl *ast_jb_get_impl(enum ast_jb_type type)
{
   int i;
   for (i = 0; i < ARRAY_LEN(avail_impl); i++) {
      if (avail_impl[i].type == type) {
         return &avail_impl[i];
      }
   }
   return NULL;
}