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 */
);