Merge pull request #448 from wisc17/blackborder_alternative

Blackborder Improved

Former-commit-id: 762bb519ebefd6755362178fdc5b9d5ed3508c3b

include/blackborder/BlackBorderDetector.h

@@ -61,49 +61,45 @@ namespace hyperion
 		template <typename Pixel_T>
 		BlackBorder process(const Image<Pixel_T> & image)
 		{
-			// only test the topleft third of the image
-			int width = image.width() /3;
+
+			// test center and 1/3, 2/3 of width/heigth
+			int width = image.width() / 3;
 			int height = image.height() / 3;
-			int maxSize = std::max(width, height);
+			int width2 = width * 2;
+			int height2 = height * 2;
+			int xCenter = image.width() / 2;
+			int yCenter = image.height() / 2;
+
 
 			int firstNonBlackXPixelIndex = -1;
 			int firstNonBlackYPixelIndex = -1;
 
-			// find some pixel of the image
-			for (int i = 0; i < maxSize; ++i)
+			// find first X pixel of the image
+			for (int x = 0; x < width; ++x)
 			{
-				int x = std::min(i, width);
-				int y = std::min(i, height);
-
-				const Pixel_T & color = image(x, y);
-				if (!isBlack(color))
+				const Pixel_T & color1 = image(x, yCenter);
+				const Pixel_T & color2 = image(x, height);
+				const Pixel_T & color3 = image(x, height2);
+				if (!isBlack(color1) || !isBlack(color2) || !isBlack(color3))
 				{
 					firstNonBlackXPixelIndex = x;
+					break;
+				}
+			}
+
+			// find first Y pixel of the image
+			for (int y = 0; y < height; ++y)
+			{
+				const Pixel_T & color1 = image(xCenter, y);
+				const Pixel_T & color2 = image(width, y);
+				const Pixel_T & color3 = image(width2, y);
+				if (!isBlack(color1) || !isBlack(color2) || !isBlack(color3))
+				{
 					firstNonBlackYPixelIndex = y;
 					break;
 				}
 			}
 
-			// expand image to the left
-			for(; firstNonBlackXPixelIndex > 0; --firstNonBlackXPixelIndex)
-			{
-				const Pixel_T & color = image(firstNonBlackXPixelIndex-1, firstNonBlackYPixelIndex);
-				if (isBlack(color))
-				{
-					break;
-				}
-			}
-
-			// expand image to the top
-			for(; firstNonBlackYPixelIndex > 0; --firstNonBlackYPixelIndex)
-			{
-				const Pixel_T & color = image(firstNonBlackXPixelIndex, firstNonBlackYPixelIndex-1);
-				if (isBlack(color))
-				{
-					break;
-				}
-			}
-
 			// Construct result
 			BlackBorder detectedBorder;
 			detectedBorder.unknown = firstNonBlackXPixelIndex == -1 || firstNonBlackYPixelIndex == -1;

include/blackborder/BlackBorderProcessor.h

@@ -94,5 +94,7 @@ namespace hyperion
 
 		/// The number of frame the previous detected border matched the incomming border
 		unsigned _consistentCnt;
+		/// The number of frame the previous detected border NOT matched the incomming border
+		unsigned _inconsistentCnt;
 	};
 } // end namespace hyperion

libsrc/blackborder/BlackBorderProcessor.cpp

@@ -14,7 +14,8 @@ BlackBorderProcessor::BlackBorderProcessor(const unsigned unknownFrameCnt,
 	_detector(blackborderThreshold),
 	_currentBorder({true, -1, -1}),
 	_previousDetectedBorder({true, -1, -1}),
-	_consistentCnt(0)
+	_consistentCnt(0),
+	_inconsistentCnt(0)
 {
 	// empty
 }
@@ -30,11 +31,13 @@ bool BlackBorderProcessor::updateBorder(const BlackBorder & newDetectedBorder)
 	if (newDetectedBorder == _previousDetectedBorder)
 	{
 		++_consistentCnt;
+		_inconsistentCnt         = 0;
 	}
 	else
 	{
 		_previousDetectedBorder = newDetectedBorder;
 		_consistentCnt          = 0;
+		++_inconsistentCnt;
 	}
 
 	// check if there is a change
@@ -64,14 +67,18 @@ bool BlackBorderProcessor::updateBorder(const BlackBorder & newDetectedBorder)
 		}
 		else
 		{
-			// apply smaller borders immediately
-			if (newDetectedBorder.verticalSize < _currentBorder.verticalSize)
+			bool stable = (_consistentCnt >= 10) || (_inconsistentCnt >=30 );
+			//more then 10 consistent seems like a new size not only a short flicker 
+			//more then 30 inconsistent seems like the image is changing a lot and we need to set smaller border
+
+			// apply smaller borders (almost) immediately -> avoid switching for "abnormal" frames
+			if ( (newDetectedBorder.verticalSize < _currentBorder.verticalSize) && (stable) )
 			{
 				_currentBorder.verticalSize = newDetectedBorder.verticalSize;
 				borderChanged = true;
 			}
 
-			if (newDetectedBorder.horizontalSize < _currentBorder.horizontalSize)
+			if ( (newDetectedBorder.horizontalSize < _currentBorder.horizontalSize) && (stable) )
 			{
 				_currentBorder.horizontalSize = newDetectedBorder.horizontalSize;
 				borderChanged = true;
@@ -80,4 +87,4 @@ bool BlackBorderProcessor::updateBorder(const BlackBorder & newDetectedBorder)
 	}
 
 	return borderChanged;
-}
+}