res_format_attr_opus.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2013, Digium, Inc.
 *
 * Lorenzo Miniero <[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 Opus format attribute interface
 *
 * \author Lorenzo Miniero <[email protected]>
 */

/*** 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 */
);