No DVD-R pass-thru device changes the dimensions of the signal. The UT or SMPTE combinations from the analog era affect the final capture according to the way they are interpreted by various tape player and capture devices. Some players present an image with up to 16 pixels of bottom-border head switching noise and one thick border on one side, another player presents the same tape with only 4 pixels of bottom-border noise and two thin borders on each side, while a third player presents the same tape with 8 pixels of bottom border noise, 4 pixels cropped off the bottom of the image, and one thick border on the side opposite from the other players. The pass-thru device doesn't care about that. It passes whatever it gets.
If you capture such images, the final image depends on how the analog player has conformed to various playback specs. A strict player considers the convention to be 4:3 material placed inside the central 704 pixels of a 720-wide frame, while 16:9 material often usually occupies the entire frame minus some head-switching noise at the bottom. The 720-wide image is not cropped. If you want, you can capture 4:3 at 640x480 and get a somewhat smaller 4:3 image in the central 624 pixels of the 640-wide frame if you want (and which will have to be rersized to 720-wide for DVD or BluRay), although different players will display differences in geometry.
The basic rule to remember is that there is very little consistency in the analog world. What is consistent is that the image that gets passed by a pass-thru device is what gets into it, minus the timing defects. Nothing gets resized or cropped in the pass-thru device when it's used as pass-thru.
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