add ms_get_mtu() that can be used by streams and filters to adapt their buffers.

include/mediastreamer2/mscommon.h

@@ -258,6 +258,12 @@ MS2_PUBLIC int ms_discover_mtu(const char *destination_host);
 **/
 MS2_PUBLIC void ms_set_mtu(int mtu);
 
+
+/**
+ * Get mediastreamer default mtu, used to compute the default RTP max payload size.
+**/
+MS2_PUBLIC int ms_get_mtu(void);
+
 /**
  * Declare how many cpu (cores) are available on the platform
  */

src/base/mtu.c

@@ -274,11 +274,24 @@ int ms_discover_mtu(const char*host){
 
 #endif
 
+#define MS_MTU_DEFAULT 1500
+
+static int ms_mtu=MS_MTU_DEFAULT;
 
 void ms_set_mtu(int mtu){
 	/*60= IPv6+UDP+RTP overhead */
 	if (mtu>60){
-		if (mtu>1500) mtu=1500;/*limit to 1500, the mediastreamer2 buffer are not large enough anyway*/
+		ms_mtu=mtu;
 		ms_set_payload_max_size(mtu-60);
-	}else ms_set_payload_max_size(0);
+	}else {
+		if (mtu>0){
+			ms_warning("MTU is too short: %i bytes, using default value instead.",mtu);
+		}
+		ms_set_mtu(MS_MTU_DEFAULT);
+	}
 }
+
+int ms_get_mtu(void){
+	return ms_mtu;
+}
+

src/voip/mediastream.c

@@ -120,7 +120,7 @@ RtpSession * create_duplex_rtpsession(int loc_rtp_port, int loc_rtcp_port, bool_
 	RtpSession *rtpr;
 
 	rtpr = rtp_session_new(RTP_SESSION_SENDRECV);
-	rtp_session_set_recv_buf_size(rtpr, MAX_RTP_SIZE);
+	rtp_session_set_recv_buf_size(rtpr, ms_get_mtu());
 	rtp_session_set_scheduling_mode(rtpr, 0);
 	rtp_session_set_blocking_mode(rtpr, 0);
 	rtp_session_enable_adaptive_jitter_compensation(rtpr, TRUE);

tools/mediastream.c

@@ -85,6 +85,7 @@ typedef struct _MediastreamDatas {
 	char *fmtp;
 	int jitter;
 	int bitrate;
+	int mtu;
 	MSVideoSize vs;
 	bool_t ec;
 	bool_t agc;
@@ -198,6 +199,7 @@ const char *usage="mediastream --local <port> --remote <ip:port> \n"
 								"[ --zoom zoomfactor]\n"
 								"[ --ice-local-candidate <ip:port:[host|srflx|prflx|relay]> ]\n"
 								"[ --ice-remote-candidate <ip:port:[host|srflx|prflx|relay]> ]\n"
+								"[ --mtu <mtu> (specify MTU)]\n"
 		;
 
 #if TARGET_OS_IPHONE
@@ -492,7 +494,13 @@ bool_t parse_args(int argc, char** argv, MediastreamDatas* out) {
 				ms_error("Invalid zoom triplet");
 				return FALSE;
 			}
-		} else if (strcmp(argv[i],"--help")==0){
+		}else if (strcmp(argv[i],"--mtu")==0){
+			i++;
+			if (sscanf(argv[i], "%i", &out->mtu) != 1) {
+				ms_error("Invalid mtu value");
+				return FALSE;
+			}
+		}else if (strcmp(argv[i],"--help")==0){
 			printf("%s",usage);
 			return FALSE;
 		}
@@ -549,6 +557,7 @@ void setup_media_streams(MediastreamDatas* args) {
 	args->q=ortp_ev_queue_new();
 
 	ms_init();
+	if (args->mtu) ms_set_mtu(args->mtu);
 	ms_filter_enable_statistics(TRUE);
 	ms_filter_reset_statistics();
 	args->ice_session=ice_session_new();