UI: Warn if high resource usage when encoding

Shows a warning stating that encoding is stalling, and shows the number
and percentage of frames that were skipped due to encoding.

obs/data/locale/en-US.ini

@@ -43,6 +43,7 @@ Untitled="Untitled"
 New="New"
 Duplicate="Duplicate"
 Enable="Enable"
+HighResourceUsage="Encoding overloaded!  Consider turning down video settings or using a faster encoding preset."
 
 # title bar strings
 TitleBar.Profile="Profile"

obs/window-basic-status-bar.cpp

@@ -40,9 +40,16 @@ void OBSBasicStatusBar::Activate()
 		refreshTimer = new QTimer(this);
 		connect(refreshTimer, SIGNAL(timeout()),
 				this, SLOT(UpdateStatusBar()));
-		totalSeconds = 0;
-		refreshTimer->start(1000);
 
+		int skipped = video_output_get_skipped_frames(obs_get_video());
+		int total   = video_output_get_total_frames(obs_get_video());
+
+		totalSeconds = 0;
+		lastSkippedFrameCount = 0;
+		startSkippedFrameCount = skipped;
+		startTotalFrameCount = total;
+
+		refreshTimer->start(1000);
 		active = true;
 	}
 }
@@ -244,6 +251,20 @@ void OBSBasicStatusBar::UpdateStatusBar()
 	UpdateBandwidth();
 	UpdateSessionTime();
 	UpdateDroppedFrames();
+
+	int skipped = video_output_get_skipped_frames(obs_get_video());
+	int total   = video_output_get_total_frames(obs_get_video());
+
+	skipped -= startSkippedFrameCount;
+	total   -= startTotalFrameCount;
+
+	int diff = skipped - lastSkippedFrameCount;
+	double percentage = double(skipped) / double(total) * 100.0;
+
+	if (diff && percentage >= 0.1f)
+		showMessage(QTStr("HighResourceUsage"), 4000);
+
+	lastSkippedFrameCount = skipped;
 }
 
 void OBSBasicStatusBar::StreamDelayStarting(int sec)

obs/window-basic-status-bar.hpp

@@ -31,6 +31,10 @@ private:
 	int delaySecStarting = 0;
 	int delaySecStopping = 0;
 
+	int startSkippedFrameCount = 0;
+	int startTotalFrameCount = 0;
+	int lastSkippedFrameCount = 0;
+
 	int      bitrateUpdateSeconds = 0;
 	uint64_t lastBytesSent = 0;
 	uint64_t lastBytesSentTime = 0;