Differences

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--- square-division_versus_two-sample_interleave [2016/11/21 21:49] – walkeradmin
+++ square-division_versus_two-sample_interleave [2023/03/21 20:39] (current) – walkeradmin
@@ Line 1: / Line 1: @@
-====== Square-division versus two-sample interleave ======
+====== Square-division versus two-sample interleave (2SI) ======
+<color purple>Or in AVP terminology, Quad vs Interleaving</color>
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-Or in AVP terminology, Quad vs Interleaving (2SI).
-\\
+==== Quad (Square Division) ====
-\\
-==== Quad ====
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 Quad (Square Division) is the way we started our AVP H.264 contribution. The 4K signal is presented as 4xHD-SDI (up to p30) or 4x3G-SDI (up to p60). Each input is a quarter of the image (quadrant).
@@ Line 21: / Line 20: @@
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 <file>
-Top Left                    \Top Left
+Method 1                    Method 2
-Top Right                   \Bottom Left
-Bottom Left                 \Top Right
+Top Left                    Top Left
-Bottom Right                \Bottom Right
+Top Right                   Bottom Left
+Bottom Left                 Top Right
+Bottom Right                Bottom Right
 </file>
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-or:
-\\
-<file>
-Top Left
-Bottom Left
-Top Right
-Bottom Right
-</file>
-\\
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@@ Line 48: / Line 39: @@
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-In the above example it can be seen that the interleave is only across the top two quadrants, and the bottom two quadrants (so no top to bottom interleaving).
+The interleaving is done two samples at a time, so from the top left quadrant (1) and the top right quadrant (2) we order the pixels 2x2. Hence the 112211221122 pattern. The same is also performed on quadrants 3 and 4. The two pixel interleave is alternated down the frame on each line.
+\\
+\\
+Quadrant order is still an issue though, in fact more so than the square division format. In square division, if your quadrants are out of order, it's really obvious (except on extremely random patterns) it's like a mis-assembled jigsaw. However on 2SI, if you invert say quadrant 1 and 2, the result is quite subtle, and on still or slow moving material, it's not obvious at all. So great care still has to be take to ensure the quadrant order is correct.
+\\
+\\
+The SDI specification now allows for the signalling of the SDI number in the SDI stream. On the AVP, if this SDI numbering is present, you can plug the SDI inputs in using any order, and the AVP HEVC card will work it out (in 2SI mode).
+\\
+\\
+In Square Division QUAD mode, the picture is split in to four quadrants, each quadrant containg a quarter of the image.
+\\
+\\
+{{:square_division_quad.jpg?900|}}
+\\
+Each quadrant comprises exactly 1/4 of the UHD Image (so a 1920x1080 HD image)
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-The interleaving is done two samples at a time, so from the top left quadrant (1) and the top right quadrant (2) we order the pixels 2x2. Hence the 112211221122 pattern. The same is also performed on quadrants 3 and 4.
+For 2SI mode, each quadrant contains a quarter of the picture information, but as a fully decodable HD image.
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-Quadrant order is still an issue though, in fact more so than the square division quad format. In square division, if your quadrants are out of order, it's really obvious (except on extremely random patterns) it's like a mis-assembled jigsaw. However on 2SI, if you invert say quadrant 1 and 2, the result is quite subtle, and on still or slow moving material, it's not obvious at all. So great care still has to be take to ensure the quadrant order is correct.
+{{:2si.jpg?900|}}
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+SI method allows picture
+monitoring on standard 1080P displays as each link carries the whole image at ¼ of its original resolution