diff --git a/coreapi/callbacks.c b/coreapi/callbacks.c
index af1cfb919..1694c7e4f 100644
--- a/coreapi/callbacks.c
+++ b/coreapi/callbacks.c
@@ -405,7 +405,7 @@ static void start_remote_ring(LinphoneCore *lc, LinphoneCall *call) {
 		if (call->audiostream)
 			audio_stream_unprepare_sound(call->audiostream);
 		if( lc->sound_conf.remote_ring ){
-			lc->ringstream=ring_start(lc->sound_conf.remote_ring,2000,ringcard);
+			lc->ringstream=ring_start(lc->sound_conf.remote_ring,2000,ringcard,lc->factory);
 		}
 	}
 }
diff --git a/coreapi/linphonecore.c b/coreapi/linphonecore.c
index 02ea2c21b..0e48a2c4c 100644
--- a/coreapi/linphonecore.c
+++ b/coreapi/linphonecore.c
@@ -4788,6 +4788,9 @@ int linphone_core_preview_ring(LinphoneCore *lc, const char *ring,LinphoneCoreCb
 	return err;
 }
 
+MSFactory *linphone_core_get_factory(void *lc){
+	return ((LinphoneCore*)lc)->factory;
+}
 /**
  * Sets the path to a wav file used for ringing back.
  *
@@ -5231,6 +5234,7 @@ static void toggle_video_preview(LinphoneCore *lc, bool_t val){
 				video_preview_set_native_window_id(lc->previewstream,lc->preview_window_id);
 			video_preview_set_fps(lc->previewstream,linphone_core_get_preferred_framerate(lc));
 			video_preview_start(lc->previewstream,lc->video_conf.device);
+			lc->previewstream->ms.factory = lc->factory;
 		}
 	}else{
 		if (lc->previewstream!=NULL){
@@ -5917,7 +5921,7 @@ static MSFilter *get_audio_resource(LinphoneCore *lc, LinphoneAudioResourceType
 		if (ringcard == NULL)
 			return NULL;
 
-		ringstream=lc->ringstream=ring_start(NULL,0,ringcard);
+		ringstream=lc->ringstream=ring_start(NULL,0,ringcard, lc->factory);
 		ms_filter_call_method(lc->ringstream->gendtmf,MS_DTMF_GEN_SET_DEFAULT_AMPLITUDE,&amp);
 		lc->dmfs_playing_start_time = ms_get_cur_time_ms()/1000;
 	}else{
@@ -6081,9 +6085,9 @@ void linphone_core_set_mtu(LinphoneCore *lc, int mtu){
 			ms_error("MTU too small !");
 			mtu=500;
 		}
-		ms_set_mtu(mtu);
-		ms_message("MTU is supposed to be %i, rtp payload max size will be %i",mtu, ms_get_payload_max_size());
-	}else ms_set_mtu(0);//use mediastreamer2 default value
+		ms_factory_set_mtu(lc->factory, mtu);
+		ms_message("MTU is supposed to be %i, rtp payload max size will be %i",mtu, ms_factory_get_payload_max_size(lc->factory));
+	}else ms_factory_set_mtu(lc->factory, 0);//use mediastreamer2 default value
 }
 
 void linphone_core_set_waiting_callback(LinphoneCore *lc, LinphoneCoreWaitingCallback cb, void *user_context){
diff --git a/coreapi/linphonecore.h b/coreapi/linphonecore.h
index 0fb78538e..36da70623 100644
--- a/coreapi/linphonecore.h
+++ b/coreapi/linphonecore.h
@@ -3241,6 +3241,7 @@ LINPHONE_PUBLIC void linphone_core_set_ring_during_incoming_early_media(Linphone
 LINPHONE_PUBLIC bool_t linphone_core_get_ring_during_incoming_early_media(const LinphoneCore *lc);
 
 LINPHONE_PUBLIC int linphone_core_preview_ring(LinphoneCore *lc, const char *ring,LinphoneCoreCbFunc func,void * userdata);
+LINPHONE_PUBLIC MSFactory* linphone_core_get_factory(void* lc);
 LINPHONE_PUBLIC int linphone_core_play_local(LinphoneCore *lc, const char *audiofile);
 LINPHONE_PUBLIC	void linphone_core_enable_echo_cancellation(LinphoneCore *lc, bool_t val);
 LINPHONE_PUBLIC	bool_t linphone_core_echo_cancellation_enabled(LinphoneCore *lc);
diff --git a/coreapi/ringtoneplayer.c b/coreapi/ringtoneplayer.c
index 1955da18d..fe63c451e 100644
--- a/coreapi/ringtoneplayer.c
+++ b/coreapi/ringtoneplayer.c
@@ -85,7 +85,7 @@ int linphone_ringtoneplayer_start_with_cb(LinphoneRingtonePlayer* rp, MSSndCard*
 		ms_message("Starting local ringtone...");
 		rp->end_of_ringtone = end_of_ringtone;
 		rp->end_of_ringtone_ud = user_data;
-		rp->ringstream=ring_start_with_cb(ringtone,loop_pause_ms,card,notify_end_of_ringtone,rp);
+		rp->ringstream=ring_start_with_cb(ringtone,loop_pause_ms,card,notify_end_of_ringtone,rp,linphone_core_get_factory(user_data));
 		return rp->ringstream != NULL ? 0 : 1;
 	}
 	return 3;
diff --git a/mediastreamer2 b/mediastreamer2
index 8fc4323f8..68ec6e611 160000
--- a/mediastreamer2
+++ b/mediastreamer2
@@ -1 +1 @@
-Subproject commit 8fc4323f8166b7432bdbf409fdeb426e08cdff32
+Subproject commit 68ec6e6113d0bdada57fdfac462e0dd8ebc6a53e