do not check fps if late tick occurred recently

include/mediastreamer2/msticker.h

@@ -62,6 +62,13 @@ enum _MSTickerPrio{
 
 typedef enum _MSTickerPrio MSTickerPrio;
 
+struct _MSTickerLateEvent{
+	int lateMs; /**<number of milliseconds late*/
+	uint64_t time; /**<time of late event, in milliseconds*/
+};
+
+typedef struct _MSTickerLateEvent MSTickerLateEvent;
+
 struct _MSTicker
 {
 	ms_mutex_t lock;
@@ -81,6 +88,7 @@ struct _MSTicker
 	MSTickerPrio prio;
 	MSTickerTickFunc wait_next_tick;
 	void *wait_next_tick_data;
+	MSTickerLateEvent late_event;
 	bool_t run;       /* flag to indicate whether the ticker must be run or not */
 };
 
@@ -226,6 +234,13 @@ MS2_PUBLIC void ms_ticker_print_graphs(MSTicker *ticker);
 **/
 MS2_PUBLIC float ms_ticker_get_average_load(MSTicker *ticker);
 
+
+/**
+ * Get last late tick event description.
+ * @param ticker the MSTicker
+ * @param ev a MSTickerLaterEvent structure that will be filled in return by the ticker.
+**/
+MS2_PUBLIC void ms_ticker_get_last_late_tick(MSTicker *ticker, MSTickerLateEvent *ev);
 /**
  * Create a ticker synchronizer.
  *

src/base/msticker.c

@@ -435,6 +435,8 @@ void * ms_ticker_run(void *arg)
 	ms_mutex_lock(&s->lock);
 
 	while(s->run){
+		uint64_t late_tick_time=0;
+		
 		s->ticks++;
 		/*Step 1: run the graphs*/
 		{
@@ -458,9 +460,14 @@ void * ms_ticker_run(void *arg)
 		late=s->wait_next_tick(s->wait_next_tick_data,s->time);
 		if (late>s->interval*5 && late>lastlate){
 			ms_warning("%s: We are late of %d miliseconds.",s->name,late);
+			late_tick_time=ms_get_cur_time_ms();
 		}
 		lastlate=late;
 		ms_mutex_lock(&s->lock);
+		if (late_tick_time){
+			s->late_event.lateMs=late;
+			s->late_event.time=late_tick_time;
+		}
 	}
 	ms_mutex_unlock(&s->lock);
 	unset_high_prio(precision);
@@ -548,6 +555,11 @@ float ms_ticker_get_average_load(MSTicker *ticker){
 	return ticker->av_load;
 }
 
+void ms_ticker_get_last_late_tick(MSTicker *ticker, MSTickerLateEvent *ev){
+	ms_mutex_lock(&ticker->lock);
+	memcpy(ev,&ticker->late_event,sizeof(MSTickerLateEvent));
+	ms_mutex_unlock(&ticker->lock);
+}
 
 static uint64_t get_ms(const MSTimeSpec *ts){
 	return (ts->tv_sec*1000LL) + ((ts->tv_nsec+500000LL)/1000000LL);

src/voip/videostream.c

@@ -173,21 +173,26 @@ static void video_stream_track_fps_changes(VideoStream *stream){
 		stream->last_fps_check=curtime;
 		return;
 	}
-	if (curtime-stream->last_fps_check>=2000 && stream->configured_fps>0){
-		if (stream->source && stream->ms.encoder &&
-			ms_filter_has_method(stream->source,MS_FILTER_GET_FPS) &&
-			ms_filter_has_method(stream->ms.encoder,MS_FILTER_SET_FPS)){
-			float fps=0;
-			if (ms_filter_call_method(stream->source,MS_FILTER_GET_FPS,&fps)==0 && fps!=0){
-				if (fabsf(fps-stream->configured_fps)/stream->configured_fps>0.2){
-					ms_warning("Measured and target fps significantly different (%f<->%f), updating encoder.",
-						fps,stream->configured_fps);
-					stream->configured_fps=fps;
-					ms_filter_call_method(stream->ms.encoder,MS_FILTER_SET_FPS,&stream->configured_fps);
+	if (curtime-stream->last_fps_check>=2000 && stream->configured_fps>0 && stream->ms.sessions.ticker){
+		MSTickerLateEvent late_ev={0};
+		/*we must check that no late tick occured during the last 2 seconds, otherwise the fps measurement is severely biased.*/
+		ms_ticker_get_last_late_tick(stream->ms.sessions.ticker,&late_ev);
+		if (curtime > late_ev.time + 2000){
+			if (stream->source && stream->ms.encoder &&
+				ms_filter_has_method(stream->source,MS_FILTER_GET_FPS) &&
+				ms_filter_has_method(stream->ms.encoder,MS_FILTER_SET_FPS)){
+				float fps=0;
+				if (ms_filter_call_method(stream->source,MS_FILTER_GET_FPS,&fps)==0 && fps!=0){
+					if (fabsf(fps-stream->configured_fps)/stream->configured_fps>0.2){
+						ms_warning("Measured and target fps significantly different (%f<->%f), updating encoder.",
+							fps,stream->configured_fps);
+						stream->configured_fps=fps;
+						ms_filter_call_method(stream->ms.encoder,MS_FILTER_SET_FPS,&stream->configured_fps);
+					}
 				}
 			}
+			stream->last_fps_check=curtime;
 		}
-		stream->last_fps_check=curtime;
 	}
 }