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3rd December 2005, 12:07 | #1 | Link |
Learning...
Join Date: Nov 2005
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Posts: 135
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Chroma sampling (and Cedocida YV12 option)
I'm quite confused (ignorant rather)... Here's what I THINK happens. Correct me if I'm wrong.
NTSC DV YC Y Y Y YC Y Y Y C is the chroma info for pixel 1 only PAL DV YV Y YV Y YU Y YU Y No U info on line 1, no V info on line 2 MPEG 2 Yc1 Y Yc3 Y Yc1 Y Yc3 Y c1/c3 are the average vertical chroma of two consecutive pixels on two lines (2x2 block) ? I'm guessing that the YV12 MPEG sampling option is needed to "copy" the chroma info in pixel 1 to pixel 3 in case of NTSC. Else an application would treat it as 4:2:0 and the pixels in col 3 & 4 would be displayed without colour ? Or is the chroma info calculated depending on the lines above and below it and assigning some weightage ? Also can an application differentiate between MPEG2 YV12 and DV YV12 sampling? If not, then DV would be displayed with U info missing in one line and V info missing on the next ! Last edited by ariga; 3rd December 2005 at 12:55. |
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