+
+static char *
+vsdp_AddAttribute (char **sdp, const char *name, const char *fmt, va_list ap)
+{
+ size_t oldlen = strlen (*sdp);
+ size_t addlen =
+ sizeof ("a=:\r\n") + strlen (name) + vsnprintf (NULL, 0, fmt, ap);
+ char *ret = realloc (*sdp, oldlen + addlen);
+
+ if (ret == NULL)
+ return NULL;
+
+ oldlen += sprintf (ret + oldlen, "a=%s:", name);
+ sprintf (ret + oldlen, fmt, ap);
+ return *sdp = ret;
+}
+
+
+char *sdp_AddAttribute (char **sdp, const char *name, const char *fmt, ...)
+{
+ char *ret;
+
+ if (fmt != NULL)
+ {
+ va_list ap;
+
+ va_start (ap, fmt);
+ ret = vsdp_AddAttribute (sdp, name, fmt, ap);
+ va_end (ap);
+ }
+ else
+ {
+ size_t oldlen = strlen (*sdp);
+ ret = realloc (*sdp, oldlen + strlen (name) + sizeof ("a=\r\n"));
+ if (ret == NULL)
+ return NULL;
+
+ sprintf (ret + oldlen, "a=%s\r\n", name);
+ }
+ return ret;
+}
+
+
+char *sdp_AddMedia (char **sdp,
+ const char *type, const char *protocol, int dport,
+ unsigned pt, vlc_bool_t bw_indep, unsigned bw,
+ const char *rtpmap, const char *fmtp)
+{
+ char *newsdp, *ptr;
+ size_t inlen = strlen (*sdp), outlen = inlen;
+
+ /* Some default values */
+ if (type == NULL)
+ type = "video";
+ if (protocol == NULL)
+ protocol = "RTP/AVP";
+ assert (pt < 128u);
+
+ outlen += snprintf (NULL, 0,
+ "m=%s %u %s %d\r\n"
+ "b=RR:0\r\n",
+ type, dport, protocol, pt);
+
+ newsdp = realloc (*sdp, outlen + 1);
+ if (newsdp == NULL)
+ return NULL;
+
+ *sdp = newsdp;
+ ptr = newsdp + inlen;
+
+ ptr += sprintf (ptr, "m=%s %u %s %d\r\n"
+ "b=RR:0\r\n",
+ type, dport, protocol, pt);
+
+ /* RTP payload type map */
+ if (rtpmap != NULL)
+ sdp_AddAttribute ("rtpmap", "%u %s", pt, rtpmap);
+ /* Format parameters */
+ if (fmtp != NULL)
+ sdp_AddAttribute ("fmtp", "%u %s", pt, fmtp);
+
+ return newsdp;
+}