ffserver: Send a Content-Base header in the reply to RTSP DESCRIBE requests

This is needed for QuickTime Player to be able to connect properly.

Originally committed as revision 23325 to svn://svn.ffmpeg.org/ffmpeg/trunk

ffserver.c

@@ -3010,6 +3010,7 @@ static void rtsp_cmd_describe(HTTPContext *c, const char *url)
         return;
     }
     rtsp_reply_header(c, RTSP_STATUS_OK);
+    url_fprintf(c->pb, "Content-Base: %s/\r\n", url);
     url_fprintf(c->pb, "Content-Type: application/sdp\r\n");
     url_fprintf(c->pb, "Content-Length: %d\r\n", content_length);
     url_fprintf(c->pb, "\r\n");