codec.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2014, Digium, Inc.
 *
 * Joshua Colp <jcolp@digium.com>
 *
 * 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 <jcolp@digium.com>
 */
 
/*** 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 %7s %s\n","ID","TYPE","NAME","FORMAT","QUALITY", "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 %7d (%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.quality,
            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(5, "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);
}