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1st January 2002, 20:57 | #1 | Link |
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Join Date: Dec 2001
Posts: 30
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capturing anamorphic tv content (e.g. German Television)
Hello,
As some of you living in central western Europe might know, some tv stations broadcast some of their shows in anamorphic encoding. With my Radeon AiW I get black bars at top and bottom and the picture is skewed. Can anyone supply me with details on anamorphic tv broadcasts? How do I have to change the aspect ratio of my capture to get the original aspect ratio? Many thanks, Triggerle |
1st January 2002, 22:53 | #2 | Link |
newbie extraordinaire
Join Date: Oct 2001
Location: Pacifica
Posts: 248
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I don't think there's such a thing as anamorphic TV, you just mean letterboxed. Then the black bars are normal and you have to crop & resize to "make them go away" which is bad. (sorry if I insult your intelligence)
I don't know what you mean by skewed but if you mean that it has the wrong aspect ratio, then the theory is simple. To get correct aspect ratio for non-anamorphic signals (this includes all analog TV) you resize so that width/height = 4/3; for anamorphic signals width/height = 16/9.
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2nd January 2002, 10:15 | #3 | Link |
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not letterboxed but PALplus
These broadcasts are not just letterboxed...the black bars contain (almost) invisible information of the original 16:9 source. Newer television sets can decode this extra information and display a better 16:9 picture. This broadcasting standard is called PALplus. It is only selected shows on some stations that are broadcasted in this format (ARD's 'Tatort' is such a show for example).
On an old 4:3 display i get a letterboxed image which is also off in the aspect ratio (the people look thinner than they are.) However, the aspect ratio is not off by much (still noticeable, I think) and a letterboxed->16:9 conversion would result in much too fat people Triggerle --edit-- I found something: http://tallyho.bc.nu/~steve/palplus.html --/edit-- Last edited by Triggerle; 2nd January 2002 at 10:23. |
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