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The Zenith HDV420 has options for three image formats: Cropped, Squeezed, and Letterbox. Not all will work on all program material and whether you can use the feature or not seems to be keyed to the broadcast station or program or both. KXAN always allows me to use it while KEYE sometimes and WB rarely. My 36" Sony TV can only handle 480i so it gets fed thru a SVHS connector. The TV can, on its' own, be set to vertically compress the image so as to properly format 16:9 DVDs.


My question is this: what is the difference between using just letterbox thru the HDV420 versus using a combination of Squeezed thru the HDV420 -and- 16:9 vertical compression thru the TV? The end results are -almost- identical in their framing, but not quite. The latter combination results in a very slightly (1/2" physical) taller image. Both approaches will show a wider image if the source material is HDTV, and even a bit wider image on non-HDTV material (I'm guessing the overscan gets brought back into the picture).


The HDV420 manual doesn't really go into any detail as to what is going on when each of these modes are applied. Knowing that the TV itself, when in 16:9 mode, is packing more horizontal resolution lines into a smaller space -suggests- that the HDV420 is passing along a

more detailed image in Squeezed mode than in Letterbox mode.
 

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You are correct in your assumption. Letterbox using the HDV420 will reduce resolution by about 1/4, since scan lines are used to create the black bars above and below the image, whereas when you invoke the 16:9 squeeze, you are using all 480 scan lines to draw the image.


As to why the "letterbox" mode looks different: it appears that the HDV420 crops a small portion of the top and bottom of the image when it letterboxes to simulate overscan, I presume. You won't see any "junk" at the top or bottom of the image with the letterbox mode, but I don't like it, since the aspect ratio is noticibly altered.
 
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