[Sumover-dev] [svn commit] r4516 - in vic/branches/mpeg4: video

[sumover-dev at cs.ucl.ac.uk]

Author: piers
Date: Thu Oct 15 17:37:41 2009
New Revision: 4516

Modified:
   vic/branches/mpeg4/   (props changed)
   vic/branches/mpeg4/module.h
   vic/branches/mpeg4/video/grabber-file.cpp

Log:
Updated props to exclude a few files so svn status is cleaner
Added comments explaining the default YUV format (ie four-cc I420)


Modified: vic/branches/mpeg4/module.h
==============================================================================
--- vic/branches/mpeg4/module.h	(original)
+++ vic/branches/mpeg4/module.h	Thu Oct 15 17:37:41 2009
@@ -54,6 +54,12 @@
 	int layer_;
 };
 
+/* YUV Frame uses I420(fourcc code) representation - Each frame is
+ * stored as firstly the Y(Intensity) at full resolution - ie WxH
+ * Followed by U(Chrominance Cb) subsampled 2x2 i.e. W/2*H/2
+ * Followed by V(Chrominance Cr) also subsampled 2x2 
+ * Hence 12 bits/pixel and frame size = WxH+2*(W/2*H/2)
+ */
 class YuvFrame : public VideoFrame {
     public:
 	    inline YuvFrame(u_int32_t ts, u_int8_t* bp, u_int8_t* crvec,

Modified: vic/branches/mpeg4/video/grabber-file.cpp
==============================================================================
--- vic/branches/mpeg4/video/grabber-file.cpp	(original)
+++ vic/branches/mpeg4/video/grabber-file.cpp	Thu Oct 15 17:37:41 2009
@@ -238,10 +238,13 @@
 
     int frc = 0; 
 
-	// "framesize_" is just the number of pixels, 
-	// so the number of bytes becomes "3 * framesize_ / 2"
+	// "framesize_" is just the number of pixels for a frame, 
+	// YUV frame is Y at full res followed by Y then U subsampled
+	// by 2x2 so the number of bytes becomes = W*H + 2*(W/2*H/2)
+	// which = framesize_ + framesize_/2
 	memcpy (frame_, file_device.frame_ + num_frame_, 
 			framesize_ + (framesize_ >> 1));
+	//memset(frame_+framesize_+framesize_/4,128,framesize_/4);
 
 	if ((num_frame_ += framesize_ + (framesize_ >> 1)) 
 			< file_device.len_) {