codec.c

Go to the documentation of this file.

/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2014, Digium, Inc.
 *
 * Joshua Colp <[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 Codecs API
 *
 * \author Joshua Colp <[email protected]>
 */

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

#include "asterisk.h"

#include "asterisk/logger.h"
#include "asterisk/codec.h"
#include "asterisk/format.h"
#include "asterisk/frame.h"
#include "asterisk/astobj2.h"
#include "asterisk/strings.h"
#include "asterisk/module.h"
#include "asterisk/cli.h"

/*! \brief Number of buckets to use for codecs (should be prime for performance reasons) */
#define CODEC_BUCKETS 53

/*! \brief Current identifier value for newly registered codec */
static int codec_id = 1;

/*! \brief Registered codecs */
static struct ao2_container *codecs;

/*!
 * \internal
 * \brief Internal codec structure
 *
 * External codecs won't know about the format_name field so the public
 * ast_codec structure has to leave it out.  This structure will be used
 * for the internal codecs.
 *
 */
struct internal_ast_codec {
   /*! \brief Public codec structure.  Must remain first. */
   struct ast_codec external;
   /*! \brief A format name for a default sane format using this codec */
   const char *format_name;
};

/*!
 * \internal
 * \brief Internal function for registration with format name
 *
 * This function is only used by codec.c and codec_builtin.c and
 * will be removed in Asterisk 14
 */
int __ast_codec_register_with_format(struct ast_codec *codec, const char *format_name,
   struct ast_module *mod);

AO2_STRING_FIELD_HASH_FN(ast_codec, name)

static int codec_cmp(void *obj, void *arg, int flags)
{
   const struct ast_codec *left = obj;
   const struct ast_codec *right = arg;
   const char *right_key = arg;
   int cmp;

   switch (flags & OBJ_SEARCH_MASK) {
   case OBJ_SEARCH_OBJECT:
      right_key = right->name;
      cmp = strcmp(left->name, right_key);

      if (right->type != AST_MEDIA_TYPE_UNKNOWN) {
         cmp |= (right->type != left->type);
      }

      /* BUGBUG: this will allow a match on a codec by name only.
       * This is particularly useful when executed by the CLI; if
       * that is not needed in translate.c, this can be removed.
       */
      if (right->sample_rate) {
         cmp |= (right->sample_rate != left->sample_rate);
      }
      break;
   case OBJ_SEARCH_KEY:
      cmp = strcmp(left->name, right_key);
      break;
   case OBJ_SEARCH_PARTIAL_KEY:
      cmp = strncmp(left->name, right_key, strlen(right_key));
      break;
   default:
      ast_assert(0);
      cmp = 0;
      break;
   }
   if (cmp) {
      return 0;
   }

   return CMP_MATCH;
}

static char *show_codecs(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
{
   struct ao2_iterator i;
   struct internal_ast_codec *codec;

   switch (cmd) {
   case CLI_INIT:
      e->command = "core show codecs [audio|video|image|text]";
      e->usage =
         "Usage: core show codecs [audio|video|image|text]\n"
         "       Displays codec mapping\n";
      return NULL;
   case CLI_GENERATE:
      return NULL;
   }

   if ((a->argc < 3) || (a->argc > 4)) {
      return CLI_SHOWUSAGE;
   }

   if (!ast_opt_dont_warn) {
      ast_cli(a->fd, "Disclaimer: this command is for informational purposes only.\n"
            "\tIt does not indicate anything about your configuration.\n");
   }

   ast_cli(a->fd, "%8s %-5s %-12s %-16s %s\n","ID","TYPE","NAME","FORMAT","DESCRIPTION");
   ast_cli(a->fd, "------------------------------------------------------------------------------------------------\n");

   ao2_rdlock(codecs);
   i = ao2_iterator_init(codecs, AO2_ITERATOR_DONTLOCK);

   for (; (codec = ao2_iterator_next(&i)); ao2_ref(codec, -1)) {
      if (a->argc == 4) {
         if (!strcasecmp(a->argv[3], "audio")) {
            if (codec->external.type != AST_MEDIA_TYPE_AUDIO) {
               continue;
            }
         } else if (!strcasecmp(a->argv[3], "video")) {
            if (codec->external.type != AST_MEDIA_TYPE_VIDEO) {
               continue;
            }
         } else if (!strcasecmp(a->argv[3], "image")) {
            if (codec->external.type != AST_MEDIA_TYPE_IMAGE) {
               continue;
            }
         } else if (!strcasecmp(a->argv[3], "text")) {
            if (codec->external.type != AST_MEDIA_TYPE_TEXT) {
               continue;
            }
         } else {
            continue;
         }
      }

      ast_cli(a->fd, "%8u %-5s %-12s %-16s (%s)\n",
         codec->external.id,
         ast_codec_media_type2str(codec->external.type),
         codec->external.name,
         S_OR(codec->format_name, "no cached format"),
         codec->external.description);
   }

   ao2_iterator_destroy(&i);
   ao2_unlock(codecs);

   return CLI_SUCCESS;
}

/*! \brief Callback function for getting a codec based on unique identifier */
static int codec_id_cmp(void *obj, void *arg, int flags)
{
   struct ast_codec *codec = obj;
   int *id = arg;

   return (codec->id == *id) ? CMP_MATCH | CMP_STOP : 0;
}

static char *show_codec(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
{
   int type_punned_codec;
   struct internal_ast_codec *codec;

   switch (cmd) {
   case CLI_INIT:
      e->command = "core show codec";
      e->usage =
         "Usage: core show codec <number>\n"
         "       Displays codec mapping\n";
      return NULL;
   case CLI_GENERATE:
      return NULL;
   }

   if (a->argc != 4) {
      return CLI_SHOWUSAGE;
   }

   if (sscanf(a->argv[3], "%30d", &type_punned_codec) != 1) {
      return CLI_SHOWUSAGE;
   }

   codec = ao2_callback(codecs, 0, codec_id_cmp, &type_punned_codec);
   if (!codec) {
      ast_cli(a->fd, "Codec %d not found\n", type_punned_codec);
      return CLI_SUCCESS;
   }

   ast_cli(a->fd, "%11u %s (%s)\n", (unsigned int) codec->external.id, codec->external.description,
      S_OR(codec->format_name, "no format"));

   ao2_ref(codec, -1);

   return CLI_SUCCESS;
}

/* Builtin Asterisk CLI-commands for debugging */
static struct ast_cli_entry codec_cli[] = {
   AST_CLI_DEFINE(show_codecs, "Displays a list of registered codecs"),
   AST_CLI_DEFINE(show_codec, "Shows a specific codec"),
};

/*! \brief Function called when the process is shutting down */
static void codec_shutdown(void)
{
   ast_cli_unregister_multiple(codec_cli, ARRAY_LEN(codec_cli));
   ao2_cleanup(codecs);
   codecs = NULL;
}

int ast_codec_init(void)
{
   codecs = ao2_container_alloc_hash(AO2_ALLOC_OPT_LOCK_RWLOCK, 0, CODEC_BUCKETS,
      ast_codec_hash_fn, NULL, codec_cmp);
   if (!codecs) {
      return -1;
   }

   ast_cli_register_multiple(codec_cli, ARRAY_LEN(codec_cli));
   ast_register_cleanup(codec_shutdown);

   return 0;
}

static void codec_dtor(void *obj)
{
   struct ast_codec *codec;

   codec = obj;

   ast_module_unref(codec->mod);
}

int __ast_codec_register(struct ast_codec *codec, struct ast_module *mod)
{
   return __ast_codec_register_with_format(codec, NULL, mod);
}

int __ast_codec_register_with_format(struct ast_codec *codec, const char *format_name, struct ast_module *mod)
{
   SCOPED_AO2WRLOCK(lock, codecs);
   struct internal_ast_codec *codec_new;

   /* Some types have specific requirements */
   if (codec->type == AST_MEDIA_TYPE_UNKNOWN) {
      ast_log(LOG_ERROR, "A media type must be specified for codec '%s'\n", codec->name);
      return -1;
   } else if (codec->type == AST_MEDIA_TYPE_AUDIO) {
      if (!codec->sample_rate) {
         ast_log(LOG_ERROR, "A sample rate must be specified for codec '%s' of type '%s'\n",
            codec->name, ast_codec_media_type2str(codec->type));
         return -1;
      }
   }

   codec_new = ao2_find(codecs, codec, OBJ_SEARCH_OBJECT | OBJ_NOLOCK);
   if (codec_new) {
      ast_log(LOG_ERROR, "A codec with name '%s' of type '%s' and sample rate '%u' is already registered\n",
         codec->name, ast_codec_media_type2str(codec->type), codec->sample_rate);
      ao2_ref(codec_new, -1);
      return -1;
   }

   codec_new = ao2_t_alloc_options(sizeof(*codec_new), codec_dtor,
      AO2_ALLOC_OPT_LOCK_NOLOCK, S_OR(codec->description, ""));
   if (!codec_new) {
      ast_log(LOG_ERROR, "Could not allocate a codec with name '%s' of type '%s' and sample rate '%u'\n",
         codec->name, ast_codec_media_type2str(codec->type), codec->sample_rate);
      return -1;
   }
   codec_new->external = *codec;
   codec_new->format_name = format_name;
   codec_new->external.id = codec_id++;

   ao2_link_flags(codecs, codec_new, OBJ_NOLOCK);

   /* Once registered a codec can not be unregistered, and the module must persist until shutdown */
   ast_module_shutdown_ref(mod);

   ast_verb(2, "Registered '%s' codec '%s' at sample rate '%u' with id '%u'\n",
      ast_codec_media_type2str(codec->type), codec->name, codec->sample_rate, codec_new->external.id);

   ao2_ref(codec_new, -1);

   return 0;
}

struct ast_codec *ast_codec_get(const char *name, enum ast_media_type type, unsigned int sample_rate)
{
   struct ast_codec codec = {
      .name = name,
      .type = type,
      .sample_rate = sample_rate,
   };

   return ao2_find(codecs, &codec, OBJ_SEARCH_OBJECT);
}

struct ast_codec *ast_codec_get_by_id(int id)
{
   return ao2_callback(codecs, 0, codec_id_cmp, &id);
}

int ast_codec_get_max(void)
{
   return codec_id;
}

const char *ast_codec_media_type2str(enum ast_media_type type)
{
   switch (type) {
   case AST_MEDIA_TYPE_AUDIO:
      return "audio";
   case AST_MEDIA_TYPE_VIDEO:
      return "video";
   case AST_MEDIA_TYPE_IMAGE:
      return "image";
   case AST_MEDIA_TYPE_TEXT:
      return "text";
   default:
      return "<unknown>";
   }
}

enum ast_media_type ast_media_type_from_str(const char *media_type_str)
{
   if (!strcasecmp(media_type_str, "audio")) {
      return AST_MEDIA_TYPE_AUDIO;
   } else if (!strcasecmp(media_type_str, "video")) {
      return AST_MEDIA_TYPE_VIDEO;
   } else if (!strcasecmp(media_type_str, "image")) {
      return AST_MEDIA_TYPE_IMAGE;
   } else if (!strcasecmp(media_type_str, "text")) {
      return AST_MEDIA_TYPE_TEXT;
   } else {
      return AST_MEDIA_TYPE_UNKNOWN;
   }
}

unsigned int ast_codec_samples_count(struct ast_frame *frame)
{
   struct ast_codec *codec;
   unsigned int samples = 0;

   if ((frame->frametype != AST_FRAME_VOICE) &&
      (frame->frametype != AST_FRAME_VIDEO) &&
      (frame->frametype != AST_FRAME_IMAGE)) {
      return 0;
   }

   codec = ast_format_get_codec(frame->subclass.format);

   if (codec->samples_count) {
      samples = codec->samples_count(frame);
      if ((int) samples < 0) {
         ast_log(LOG_WARNING, "Codec %s returned invalid number of samples.\n",
            ast_format_get_name(frame->subclass.format));
         samples = 0;
      }
   } else {
      ast_log(LOG_WARNING, "Unable to calculate samples for codec %s\n",
         ast_format_get_name(frame->subclass.format));
   }

   ao2_ref(codec, -1);
   return samples;
}

unsigned int ast_codec_determine_length(const struct ast_codec *codec, unsigned int samples)
{
   if (!codec->get_length) {
      return 0;
   }

   return codec->get_length(samples);
}