res_format_attr_vp8: In SDP, forward max-fr and max-fs for video-codec VP8.

ASTERISK-25584 #close

Change-Id: Iae00071b4ff1ae76f24995aeac4d00284fd14f91

CHANGES

@@ -20,6 +20,11 @@ bridge_t38
    several esoteric issues that can occur when channels are removed from a
    bridge after completing a T.38 fax.
 
+Codecs
+------------------
+ * Added format attribute negotiation for the VP8 video codec. Format attribute
+   negotiation is provided by the res_format_attr_vp8 module.
+
 ConfBridge
 ------------------
  * A new "timeout" user profile option has been added. This configures the number

res/res_format_attr_vp8.c

@@ -0,0 +1,228 @@
+/*
+ * Asterisk -- An open source telephony toolkit.
+ *
+ * Copyright (C) 2015, Alexander Traud
+ *
+ * Alexander Traud <pabstraud@compuserve.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 VP8 format attribute interface
+ *
+ * \author Alexander Traud <pabstraud@compuserve.com>
+ *
+ * \note http://tools.ietf.org/html/draft-ietf-payload-vp8
+ */
+
+/*** MODULEINFO
+	<support_level>core</support_level>
+ ***/
+
+#include "asterisk.h"
+
+ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
+
+#include "asterisk/module.h"
+#include "asterisk/format.h"
+#include "asterisk/logger.h"            /* for ast_log, LOG_WARNING */
+#include "asterisk/strings.h"           /* for ast_str_append */
+#include "asterisk/utils.h"             /* for MIN, ast_malloc, ast_free */
+
+struct vp8_attr {
+	unsigned int maximum_frame_rate;
+	unsigned int maximum_frame_size;
+};
+
+static struct vp8_attr default_vp8_attr = {
+	.maximum_frame_rate = UINT_MAX,
+	.maximum_frame_size = UINT_MAX,
+};
+
+static void vp8_destroy(struct ast_format *format)
+{
+	struct vp8_attr *attr = ast_format_get_attribute_data(format);
+
+	ast_free(attr);
+}
+
+static int vp8_clone(const struct ast_format *src, struct ast_format *dst)
+{
+	struct vp8_attr *original = ast_format_get_attribute_data(src);
+	struct vp8_attr *attr = ast_malloc(sizeof(*attr));
+
+	if (!attr) {
+		return -1;
+	}
+
+	if (original) {
+		*attr = *original;
+	} else {
+		*attr = default_vp8_attr;
+	}
+
+	ast_format_set_attribute_data(dst, attr);
+
+	return 0;
+}
+
+static struct ast_format *vp8_parse_sdp_fmtp(const struct ast_format *format, const char *attributes)
+{
+	struct ast_format *cloned;
+	struct vp8_attr *attr;
+	const char *kvp;
+	unsigned int val;
+
+	cloned = ast_format_clone(format);
+	if (!cloned) {
+		return NULL;
+	}
+	attr = ast_format_get_attribute_data(cloned);
+
+	if ((kvp = strstr(attributes, "max-fr")) && sscanf(kvp, "max-fr=%30u", &val) == 1) {
+		attr->maximum_frame_rate = val;
+	} else {
+		attr->maximum_frame_rate = UINT_MAX;
+	}
+
+	if ((kvp = strstr(attributes, "max-fs")) && sscanf(kvp, "max-fs=%30u", &val) == 1) {
+		attr->maximum_frame_size = val;
+	} else {
+		attr->maximum_frame_size = UINT_MAX;
+	}
+
+	return cloned;
+}
+
+static void vp8_generate_sdp_fmtp(const struct ast_format *format, unsigned int payload, struct ast_str **str)
+{
+	struct vp8_attr *attr = ast_format_get_attribute_data(format);
+	int added = 0;
+
+	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_vp8_attr;
+	}
+
+	if (UINT_MAX != attr->maximum_frame_rate) {
+		if (added) {
+			ast_str_append(str, 0, ";");
+		} else if (0 < ast_str_append(str, 0, "a=fmtp:%u ", payload)) {
+			added = 1;
+		}
+		ast_str_append(str, 0, "max-fr=%u", attr->maximum_frame_rate);
+	}
+
+	if (UINT_MAX != attr->maximum_frame_size) {
+		if (added) {
+			ast_str_append(str, 0, ";");
+		} else if (0 < ast_str_append(str, 0, "a=fmtp:%u ", payload)) {
+			added = 1;
+		}
+		ast_str_append(str, 0, "max-fs=%u", attr->maximum_frame_size);
+	}
+
+	if (added) {
+		ast_str_append(str, 0, "\r\n");
+	}
+}
+
+static struct ast_format *vp8_getjoint(const struct ast_format *format1, const struct ast_format *format2)
+{
+	struct vp8_attr *attr1 = ast_format_get_attribute_data(format1);
+	struct vp8_attr *attr2 = ast_format_get_attribute_data(format2);
+	struct ast_format *jointformat;
+	struct vp8_attr *attr_res;
+
+	if (!attr1) {
+		attr1 = &default_vp8_attr;
+	}
+
+	if (!attr2) {
+		attr2 = &default_vp8_attr;
+	}
+
+	jointformat = ast_format_clone(format1);
+	if (!jointformat) {
+		return NULL;
+	}
+	attr_res = ast_format_get_attribute_data(jointformat);
+
+	attr_res->maximum_frame_rate = MIN(attr1->maximum_frame_rate, attr2->maximum_frame_rate);
+	attr_res->maximum_frame_size = MIN(attr1->maximum_frame_size, attr2->maximum_frame_size);
+
+	return jointformat;
+}
+
+static struct ast_format *vp8_set(const struct ast_format *format, const char *name, const char *value)
+{
+	struct ast_format *cloned;
+	struct vp8_attr *attr;
+	unsigned int val;
+
+	if (sscanf(value, "%30u", &val) != 1) {
+		ast_log(LOG_WARNING, "Unknown value '%s' for attribute type '%s'\n",
+			value, name);
+		return NULL;
+	}
+
+	cloned = ast_format_clone(format);
+	if (!cloned) {
+		return NULL;
+	}
+	attr = ast_format_get_attribute_data(cloned);
+
+	if (!strcasecmp(name, "maximum_frame_rate")) {
+		attr->maximum_frame_rate = val;
+	} else if (!strcasecmp(name, "maximum_frame_size")) {
+		attr->maximum_frame_size = val;
+	} else {
+		ast_log(LOG_WARNING, "unknown attribute type %s\n", name);
+	}
+
+	return cloned;
+}
+
+static struct ast_format_interface vp8_interface = {
+	.format_destroy = vp8_destroy,
+	.format_clone = vp8_clone,
+	.format_get_joint = vp8_getjoint,
+	.format_attribute_set = vp8_set,
+	.format_parse_sdp_fmtp = vp8_parse_sdp_fmtp,
+	.format_generate_sdp_fmtp = vp8_generate_sdp_fmtp,
+};
+
+static int load_module(void)
+{
+	if (ast_format_interface_register("vp8", &vp8_interface)) {
+		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_LOAD_ORDER, "VP8 Format Attribute Module",
+	.support_level = AST_MODULE_SUPPORT_CORE,
+	.load = load_module,
+	.unload = unload_module,
+	.load_pri = AST_MODPRI_CHANNEL_DEPEND,
+);