res_format_attr_opus.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2013, Digium, Inc.
 *
 * Lorenzo Miniero <lorenzo@meetecho.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 Opus format attribute interface
 *
 * \author Lorenzo Miniero <lorenzo@meetecho.com>
 */
 
/*** MODULEINFO
    <support_level>core</support_level>
 ***/
 
#include "asterisk.h"
 
#include <ctype.h>
 
#include "asterisk/module.h"
#include "asterisk/format.h"
#include "asterisk/astobj2.h"
#include "asterisk/logger.h"
#include "asterisk/strings.h"
#include "asterisk/utils.h"
#include "asterisk/opus.h"
 
/*!
 * \brief Opus attribute structure.
 *
 * \note http://tools.ietf.org/html/rfc7587#section-6
 */
struct opus_attr {
    int maxbitrate;
    int maxplayrate;
    int ptime;
    int stereo;
    int cbr;
    int fec;
    int dtx;
    int spropmaxcapturerate;
    int spropstereo;
    int maxptime;
    /* Note data is expected to be an ao2_object type */
    void *data;
};
 
static struct opus_attr default_opus_attr = {
    .maxbitrate = CODEC_OPUS_DEFAULT_BITRATE,
    .maxplayrate = CODEC_OPUS_DEFAULT_SAMPLE_RATE,
    .ptime = CODEC_OPUS_DEFAULT_PTIME,
    .stereo = CODEC_OPUS_DEFAULT_STEREO,
    .cbr = CODEC_OPUS_DEFAULT_CBR,
    .fec = CODEC_OPUS_DEFAULT_FEC,
    .dtx = CODEC_OPUS_DEFAULT_DTX,
    .spropmaxcapturerate = CODEC_OPUS_DEFAULT_SAMPLE_RATE,
    .spropstereo = CODEC_OPUS_DEFAULT_STEREO,
    .maxptime = CODEC_OPUS_DEFAULT_MAX_PTIME
};
 
static void opus_destroy(struct ast_format *format)
{
    struct opus_attr *attr = ast_format_get_attribute_data(format);
 
    if (!attr) {
        return;
    }
 
    ao2_cleanup(attr->data);
    ast_free(attr);
}
 
static int opus_clone(const struct ast_format *src, struct ast_format *dst)
{
    struct opus_attr *original = ast_format_get_attribute_data(src);
    struct opus_attr *attr = ast_malloc(sizeof(*attr));
 
    if (!attr) {
        return -1;
    }
 
    *attr = original ? *original : default_opus_attr;
    ao2_bump(attr->data);
 
    ast_format_set_attribute_data(dst, attr);
    ast_format_set_channel_count(dst, ast_format_get_channel_count(src));
 
    return 0;
}
 
static void sdp_fmtp_get(const char *attributes, const char *name, int *attr)
{
    const char *kvp = attributes;
    int val;
 
    if (ast_strlen_zero(attributes)) {
        return;
    }
 
    /* This logic goes through each attribute in the fmtp line looking for the
     * requested named attribute.
     */
    while (*kvp) {
        /* Skip any preceeding blanks as some implementations separate attributes using spaces too */
        kvp = ast_skip_blanks(kvp);
 
        /* If we are at the requested attribute get its value and return */
        if (!strncmp(kvp, name, strlen(name)) && kvp[strlen(name)] == '=') {
            if (sscanf(kvp, "%*[^=]=%30d", &val) == 1) {
                *attr = val;
                break;
            }
        }
 
        /* Move on to the next attribute if possible */
        kvp = strchr(kvp, ';');
        if (!kvp) {
            break;
        }
 
        kvp++;
    }
}
 
static struct ast_format *opus_parse_sdp_fmtp(const struct ast_format *format, const char *attributes)
{
    char *attribs = ast_strdupa(attributes), *attrib;
    struct ast_format *cloned;
    struct opus_attr *attr;
 
    cloned = ast_format_clone(format);
    if (!cloned) {
        return NULL;
    }
 
    attr = ast_format_get_attribute_data(cloned);
 
    /* lower-case everything, so we are case-insensitive */
    for (attrib = attribs; *attrib; ++attrib) {
        *attrib = tolower(*attrib);
    } /* based on channels/chan_sip.c:process_a_sdp_image() */
 
    sdp_fmtp_get(attribs, CODEC_OPUS_ATTR_MAX_PLAYBACK_RATE, &attr->maxplayrate);
    sdp_fmtp_get(attribs, CODEC_OPUS_ATTR_MAX_CODED_AUDIO_BANDWIDTH,
        &attr->maxplayrate);
    sdp_fmtp_get(attribs, CODEC_OPUS_ATTR_SPROP_MAX_CAPTURE_RATE,
        &attr->spropmaxcapturerate);
    sdp_fmtp_get(attribs, CODEC_OPUS_ATTR_MAX_PTIME, &attr->maxptime);
    sdp_fmtp_get(attribs, CODEC_OPUS_ATTR_PTIME, &attr->ptime);
    sdp_fmtp_get(attribs, CODEC_OPUS_ATTR_MAX_AVERAGE_BITRATE, &attr->maxbitrate);
    sdp_fmtp_get(attribs, CODEC_OPUS_ATTR_STEREO, &attr->stereo);
    if (attr->stereo) {
        ast_format_set_channel_count(cloned, 2);
    }
    sdp_fmtp_get(attribs, CODEC_OPUS_ATTR_SPROP_STEREO, &attr->spropstereo);
    sdp_fmtp_get(attribs, CODEC_OPUS_ATTR_CBR, &attr->cbr);
    sdp_fmtp_get(attribs, CODEC_OPUS_ATTR_FEC, &attr->fec);
    sdp_fmtp_get(attribs, CODEC_OPUS_ATTR_DTX, &attr->dtx);
 
    return cloned;
}
 
static void opus_generate_sdp_fmtp(const struct ast_format *format, unsigned int payload, struct ast_str **str)
{
    struct opus_attr *attr = ast_format_get_attribute_data(format);
    int base_fmtp_size;
    int original_size;
 
    if (!attr) {
        /*
         * (Only) cached formats do not have attribute data assigned because
         * they were created before this attribute module was registered.
         * Therefore, we assume the default attribute values here.
         */
        attr = &default_opus_attr;
    }
 
    original_size = ast_str_strlen(*str);
    base_fmtp_size = ast_str_append(str, 0, "a=fmtp:%u ", payload);
 
    if (CODEC_OPUS_DEFAULT_SAMPLE_RATE != attr->maxplayrate) {
        ast_str_append(str, 0, "%s=%d;",
            CODEC_OPUS_ATTR_MAX_PLAYBACK_RATE, attr->maxplayrate);
    }
 
    if (CODEC_OPUS_DEFAULT_SAMPLE_RATE != attr->spropmaxcapturerate) {
        ast_str_append(str, 0, "%s=%d;",
            CODEC_OPUS_ATTR_SPROP_MAX_CAPTURE_RATE, attr->spropmaxcapturerate);
    }
 
    if (CODEC_OPUS_DEFAULT_BITRATE != attr->maxbitrate || attr->maxbitrate > 0) {
        ast_str_append(str, 0, "%s=%d;",
            CODEC_OPUS_ATTR_MAX_AVERAGE_BITRATE, attr->maxbitrate);
    }
 
    if (CODEC_OPUS_DEFAULT_STEREO != attr->stereo) {
        ast_str_append(str, 0, "%s=%d;",
            CODEC_OPUS_ATTR_STEREO, attr->stereo);
    }
 
    if (CODEC_OPUS_DEFAULT_STEREO != attr->spropstereo) {
        ast_str_append(str, 0, "%s=%d;",
            CODEC_OPUS_ATTR_SPROP_STEREO, attr->spropstereo);
    }
 
    if (CODEC_OPUS_DEFAULT_CBR != attr->cbr) {
        ast_str_append(str, 0, "%s=%d;",
            CODEC_OPUS_ATTR_CBR, attr->cbr);
    }
 
    if (CODEC_OPUS_DEFAULT_FEC!= attr->fec) {
        ast_str_append(str, 0, "%s=%d;",
               CODEC_OPUS_ATTR_FEC, attr->fec);
    }
 
    if (CODEC_OPUS_DEFAULT_DTX != attr->dtx) {
        ast_str_append(str, 0, "%s=%d;",
            CODEC_OPUS_ATTR_DTX, attr->dtx);
    }
 
    if (base_fmtp_size == ast_str_strlen(*str) - original_size) {
        ast_str_truncate(*str, original_size);
    } else {
        ast_str_truncate(*str, -1);
        ast_str_append(str, 0, "\r\n");
    }
}
 
static struct ast_format *opus_getjoint(const struct ast_format *format1, const struct ast_format *format2)
{
    struct opus_attr *attr1 = ast_format_get_attribute_data(format1);
    struct opus_attr *attr2 = ast_format_get_attribute_data(format2);
    struct ast_format *jointformat;
    struct opus_attr *attr_res;
 
    if (!attr1) {
        attr1 = &default_opus_attr;
    }
 
    if (!attr2) {
        attr2 = &default_opus_attr;
    }
 
    jointformat = ast_format_clone(format1);
    if (!jointformat) {
        return NULL;
    }
 
    if (ast_format_get_channel_count(format1) == 2 || ast_format_get_channel_count(format2) == 2) {
        ast_format_set_channel_count(jointformat, 2);
    }
    attr_res = ast_format_get_attribute_data(jointformat);
 
    attr_res->dtx = attr1->dtx || attr2->dtx ? 1 : 0;
 
    /* Only do FEC if both sides want it.  If a peer specifically requests not
     * to receive with FEC, it may be a waste of bandwidth. */
    attr_res->fec = attr1->fec && attr2->fec ? 1 : 0;
 
    attr_res->cbr = attr1->cbr || attr2->cbr ? 1 : 0;
    attr_res->spropstereo = attr1->spropstereo || attr2->spropstereo ? 1 : 0;
 
    /* Only do stereo if both sides want it.  If a peer specifically requests not
     * to receive stereo signals, it may be a waste of bandwidth. */
    attr_res->stereo = attr1->stereo && attr2->stereo ? 1 : 0;
 
    if (attr1->maxbitrate < 0) {
        attr_res->maxbitrate = attr2->maxbitrate;
    } else if (attr2->maxbitrate < 0) {
        attr_res->maxbitrate = attr1->maxbitrate;
    } else {
        attr_res->maxbitrate = MIN(attr1->maxbitrate, attr2->maxbitrate);
    }
 
    attr_res->spropmaxcapturerate = MIN(attr1->spropmaxcapturerate, attr2->spropmaxcapturerate);
    attr_res->maxplayrate = MIN(attr1->maxplayrate, attr2->maxplayrate);
 
    return jointformat;
}
 
static struct ast_format *opus_set(const struct ast_format *format,
    const char *name, const char *value)
{
    struct ast_format *cloned;
    struct opus_attr *attr;
    int val;
 
    if (!(cloned = ast_format_clone(format))) {
        return NULL;
    }
 
    attr = ast_format_get_attribute_data(cloned);
 
    if (!strcmp(name, CODEC_OPUS_ATTR_DATA)) {
        ao2_cleanup(attr->data);
        attr->data = ao2_bump((void*)value);
        return cloned;
    }
 
    if (sscanf(value, "%30d", &val) != 1) {
        ast_log(LOG_WARNING, "Unknown value '%s' for attribute type '%s'\n",
            value, name);
        ao2_ref(cloned, -1);
        return NULL;
    }
 
    if (!strcasecmp(name, CODEC_OPUS_ATTR_MAX_PLAYBACK_RATE)) {
        attr->maxplayrate = val;
    } else if (!strcasecmp(name, CODEC_OPUS_ATTR_MAX_CODED_AUDIO_BANDWIDTH)) {
        attr->maxplayrate = val;
    } else if (!strcasecmp(name, CODEC_OPUS_ATTR_SPROP_MAX_CAPTURE_RATE)) {
        attr->spropmaxcapturerate = val;
    } else if (!strcasecmp(name, CODEC_OPUS_ATTR_MAX_PTIME)) {
        attr->maxptime = val;
    } else if (!strcasecmp(name, CODEC_OPUS_ATTR_PTIME)) {
        attr->ptime = val;
    } else if (!strcasecmp(name, CODEC_OPUS_ATTR_MAX_AVERAGE_BITRATE)) {
        attr->maxbitrate = val;
    } else if (!strcasecmp(name, CODEC_OPUS_ATTR_STEREO)) {
        attr->stereo = val;
    } else if (!strcasecmp(name, CODEC_OPUS_ATTR_SPROP_STEREO)) {
        attr->spropstereo = val;
    } else if (!strcasecmp(name, CODEC_OPUS_ATTR_CBR)) {
        attr->cbr = val;
    } else if (!strcasecmp(name, CODEC_OPUS_ATTR_FEC)) {
        attr->fec = val;
    } else if (!strcasecmp(name, CODEC_OPUS_ATTR_DTX)) {
        attr->dtx = val;
    } else {
        ast_log(LOG_WARNING, "unknown attribute type %s\n", name);
    }
 
    return cloned;
}
 
static const void *opus_get(const struct ast_format *format, const char *name)
{
    struct opus_attr *attr = ast_format_get_attribute_data(format);
    int *val = NULL;
 
    if (!attr) {
        return NULL;
    }
 
    if (!strcasecmp(name, CODEC_OPUS_ATTR_DATA)) {
        return ao2_bump(attr->data);
    } else if (!strcasecmp(name, CODEC_OPUS_ATTR_MAX_PLAYBACK_RATE)) {
        val = &attr->maxplayrate;
    } else if (!strcasecmp(name, CODEC_OPUS_ATTR_SPROP_MAX_CAPTURE_RATE)) {
        val = &attr->spropmaxcapturerate;
    } else if (!strcasecmp(name, CODEC_OPUS_ATTR_MAX_PTIME)) {
        val = &attr->maxptime;
    } else if (!strcasecmp(name, CODEC_OPUS_ATTR_PTIME)) {
        val = &attr->ptime;
    } else if (!strcasecmp(name, CODEC_OPUS_ATTR_MAX_AVERAGE_BITRATE)) {
        val = &attr->maxbitrate;
    } else if (!strcasecmp(name, CODEC_OPUS_ATTR_STEREO)) {
        val = &attr->stereo;
    } else if (!strcasecmp(name, CODEC_OPUS_ATTR_SPROP_STEREO)) {
        val = &attr->spropstereo;
    } else if (!strcasecmp(name, CODEC_OPUS_ATTR_CBR)) {
        val = &attr->cbr;
    } else if (!strcasecmp(name, CODEC_OPUS_ATTR_FEC)) {
        val = &attr->fec;
    } else if (!strcasecmp(name, CODEC_OPUS_ATTR_DTX)) {
        val = &attr->dtx;
    } else {
        ast_log(LOG_WARNING, "unknown attribute type %s\n", name);
    }
 
    return val;
}
 
static struct ast_format_interface opus_interface = {
    .format_destroy = opus_destroy,
    .format_clone = opus_clone,
    .format_get_joint = opus_getjoint,
    .format_attribute_set = opus_set,
    .format_parse_sdp_fmtp = opus_parse_sdp_fmtp,
    .format_generate_sdp_fmtp = opus_generate_sdp_fmtp,
    .format_attribute_get = opus_get
};
 
static int load_module(void)
{
    if (__ast_format_interface_register("opus", &opus_interface, ast_module_info->self)) {
        return AST_MODULE_LOAD_DECLINE;
    }
 
    return AST_MODULE_LOAD_SUCCESS;
}
 
static int unload_module(void)
{
    return 0;
}
 
AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_GLOBAL_SYMBOLS | AST_MODFLAG_LOAD_ORDER, "Opus Format Attribute Module",
    .support_level = AST_MODULE_SUPPORT_CORE,
    .load = load_module,
    .unload = unload_module,
    .load_pri = AST_MODPRI_REALTIME_DRIVER /* Needs to load before codec_opus */
);