This patch adds the .get callback to the format attribute module, such that the Asterisk core or other third party modules can query for the negotiated format attributes. Change-Id: Ia24f55cf9b661d651ce89b4f4b023d921380f19c
257 lines
6.7 KiB
C
257 lines
6.7 KiB
C
/*
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* Asterisk -- An open source telephony toolkit.
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*
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* Copyright (C) 2011, Digium, Inc.
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*
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* David Vossel <dvossel@digium.com>
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*
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* See http://www.asterisk.org for more information about
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* the Asterisk project. Please do not directly contact
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* any of the maintainers of this project for assistance;
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* the project provides a web site, mailing lists and IRC
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* channels for your use.
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*
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* This program is free software, distributed under the terms of
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* the GNU General Public License Version 2. See the LICENSE file
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* at the top of the source tree.
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*/
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/*!
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* \file
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* \brief SILK format attribute interface
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*
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* \author David Vossel <dvossel@digium.com>
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*/
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/*** MODULEINFO
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<support_level>core</support_level>
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***/
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#include "asterisk.h"
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ASTERISK_REGISTER_FILE()
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#include "asterisk/module.h"
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#include "asterisk/format.h"
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/*!
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* \brief SILK attribute structure.
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*
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* \note The only attribute that affects compatibility here is the sample rate.
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*/
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struct silk_attr {
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unsigned int samplerate;
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unsigned int maxbitrate;
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unsigned int dtx;
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unsigned int fec;
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unsigned int packetloss_percentage;
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};
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static void silk_destroy(struct ast_format *format)
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{
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struct silk_attr *attr = ast_format_get_attribute_data(format);
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ast_free(attr);
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}
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static int silk_clone(const struct ast_format *src, struct ast_format *dst)
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{
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struct silk_attr *original = ast_format_get_attribute_data(src);
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struct silk_attr *attr = ast_calloc(1, sizeof(*attr));
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if (!attr) {
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return -1;
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}
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if (original) {
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*attr = *original;
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}
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ast_format_set_attribute_data(dst, attr);
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return 0;
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}
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static struct ast_format *silk_parse_sdp_fmtp(const struct ast_format *format, const char *attributes)
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{
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struct ast_format *cloned;
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struct silk_attr *attr;
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unsigned int val;
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cloned = ast_format_clone(format);
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if (!cloned) {
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return NULL;
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}
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attr = ast_format_get_attribute_data(cloned);
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if (sscanf(attributes, "maxaveragebitrate=%30u", &val) == 1) {
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attr->maxbitrate = val;
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}
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if (sscanf(attributes, "usedtx=%30u", &val) == 1) {
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attr->dtx = val;
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}
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if (sscanf(attributes, "useinbandfec=%30u", &val) == 1) {
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attr->fec = val;
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}
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return cloned;
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}
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static void silk_generate_sdp_fmtp(const struct ast_format *format, unsigned int payload, struct ast_str **str)
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{
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struct silk_attr *attr = ast_format_get_attribute_data(format);
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if (!attr) {
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return;
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}
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if ((attr->maxbitrate > 5000) && (attr->maxbitrate < 40000)) {
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ast_str_append(str, 0, "a=fmtp:%u maxaveragebitrate=%u\r\n", payload, attr->maxbitrate);
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}
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ast_str_append(str, 0, "a=fmtp:%u usedtx=%u\r\n", payload, attr->dtx);
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ast_str_append(str, 0, "a=fmtp:%u useinbandfec=%u\r\n", payload, attr->fec);
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}
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static enum ast_format_cmp_res silk_cmp(const struct ast_format *format1, const struct ast_format *format2)
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{
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struct silk_attr *attr1 = ast_format_get_attribute_data(format1);
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struct silk_attr *attr2 = ast_format_get_attribute_data(format2);
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if (((!attr1 || !attr1->samplerate) && (!attr2 || !attr2->samplerate)) ||
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(attr1->samplerate == attr2->samplerate)) {
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return AST_FORMAT_CMP_EQUAL;
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}
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return AST_FORMAT_CMP_NOT_EQUAL;
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}
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static struct ast_format *silk_getjoint(const struct ast_format *format1, const struct ast_format *format2)
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{
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struct silk_attr *attr1 = ast_format_get_attribute_data(format1);
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struct silk_attr *attr2 = ast_format_get_attribute_data(format2);
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unsigned int samplerate;
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struct ast_format *jointformat;
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struct silk_attr *attr_res;
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samplerate = attr1->samplerate & attr2->samplerate;
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/* sample rate is the only attribute that has any bearing on if joint capabilities exist or not */
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if (samplerate) {
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return NULL;
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}
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jointformat = ast_format_clone(format1);
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if (!jointformat) {
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return NULL;
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}
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attr_res = ast_format_get_attribute_data(jointformat);
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attr_res->samplerate = samplerate;
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/* Take the lowest max bitrate */
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attr_res->maxbitrate = MIN(attr1->maxbitrate, attr2->maxbitrate);
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/* Only do dtx if both sides want it. DTX is a trade off between
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* computational complexity and bandwidth. */
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attr_res->dtx = attr1->dtx && attr2->dtx ? 1 : 0;
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/* Only do FEC if both sides want it. If a peer specifically requests not
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* to receive with FEC, it may be a waste of bandwidth. */
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attr_res->fec = attr1->fec && attr2->fec ? 1 : 0;
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/* Use the maximum packetloss percentage between the two attributes. This affects how
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* much redundancy is used in the FEC. */
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attr_res->packetloss_percentage = MAX(attr1->packetloss_percentage, attr2->packetloss_percentage);
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return jointformat;
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}
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static struct ast_format *silk_set(const struct ast_format *format, const char *name, const char *value)
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{
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struct ast_format *cloned;
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struct silk_attr *attr;
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unsigned int val;
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if (sscanf(value, "%30u", &val) != 1) {
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ast_log(LOG_WARNING, "Unknown value '%s' for attribute type '%s'\n",
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value, name);
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return NULL;
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}
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cloned = ast_format_clone(format);
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if (!cloned) {
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return NULL;
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}
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attr = ast_format_get_attribute_data(cloned);
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if (!strcasecmp(name, "sample_rate")) {
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attr->samplerate = val;
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} else if (!strcasecmp(name, "max_bitrate")) {
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attr->maxbitrate = val;
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} else if (!strcasecmp(name, "dtx")) {
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attr->dtx = val;
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} else if (!strcasecmp(name, "fec")) {
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attr->fec = val;
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} else if (!strcasecmp(name, "packetloss_percentage")) {
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attr->packetloss_percentage = val;
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} else {
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ast_log(LOG_WARNING, "unknown attribute type %s\n", name);
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}
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return cloned;
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}
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static const void *silk_get(const struct ast_format *format, const char *name)
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{
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struct silk_attr *attr = ast_format_get_attribute_data(format);
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unsigned int *val;
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if (!strcasecmp(name, "sample_rate")) {
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val = &attr->samplerate;
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} else if (!strcasecmp(name, "max_bitrate")) {
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val = &attr->maxbitrate;
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} else if (!strcasecmp(name, "dtx")) {
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val = &attr->dtx;
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} else if (!strcasecmp(name, "fec")) {
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val = &attr->fec;
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} else if (!strcasecmp(name, "packetloss_percentage")) {
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val = &attr->packetloss_percentage;
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} else {
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ast_log(LOG_WARNING, "unknown attribute type %s\n", name);
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return NULL;
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}
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return val;
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}
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static struct ast_format_interface silk_interface = {
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.format_destroy = silk_destroy,
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.format_clone = silk_clone,
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.format_cmp = silk_cmp,
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.format_get_joint = silk_getjoint,
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.format_attribute_set = silk_set,
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.format_attribute_get = silk_get,
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.format_parse_sdp_fmtp = silk_parse_sdp_fmtp,
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.format_generate_sdp_fmtp = silk_generate_sdp_fmtp,
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};
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static int load_module(void)
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{
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if (ast_format_interface_register("silk", &silk_interface)) {
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return AST_MODULE_LOAD_DECLINE;
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}
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return AST_MODULE_LOAD_SUCCESS;
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}
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static int unload_module(void)
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{
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return 0;
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}
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AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_ORDER, "SILK Format Attribute Module",
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.support_level = AST_MODULE_SUPPORT_CORE,
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.load = load_module,
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.unload = unload_module,
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.load_pri = AST_MODPRI_CHANNEL_DEPEND,
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);
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