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Poster: spuder Date: Sep 11, 2013 7:48pm
Forum: prelinger Subject: Why 4x3 aspect and 30fps framerate?

I love the content in Prelinger Archives but have a question that I haven't found a discussion of recently. I apologize if this has been covered before and I don't like to complain about free stuff. But ...

I see even the new encodes are being scanned at 4x3 aspect ratio. This leads to the cropping off of titles and credits on many films that are a wider format. Most of the 16mm content here should be at 1.37:1 so I assume the image is being over-zoomed to cause noticeable cropping in a 1.33:1 frame. Some material such as American Look (1958) is in a super-16 format (SuperScope) that ends up badly cropped. Pretty much all modern video display devices are 16x9 (1.78:1) format. This includes televisions, desktop computer displays, tablets and smartphones. Wouldn't 16x9 be a better default aspect ratio? If HD resolution cannot be justified then 852x480 (square pixels) would be great. Over in the "Movies/35MM Stock Footage" section they use 1280x720 (16x9) for everything, leaving black bars on right and left for non-widescreen material.

I would not want to see letterbox used in a 4x3 frame. One only has to compare the earlier letterbox scan of American Look (http://archive.org/details/american_look) with the recent cropped scan (http://archive.org/details/6391_American_Look_M04199_01_15_18_17) to see that you have made the right choice to crop given the 4x3 constraint. But, is 16x9 a possibility? Some black bars on right & left are far less troublesome than large black areas on top & bottom which shrink the main subject. Now, American Look is one of those rare 16MMs that are even wider than 16x9 so there would still be some minimal cropping but the credits would probably remain intact.

Most of the material in the Prelinger Archive should be 24fps footage. Is there a reason why everything is scanned at 30fps? This is an old NTSC requirement. Virtually all modern devices that can be used to play digital files are very happy with 24fps progressive scan video. That includes home theater media players, personal computer software, and tablets and smartphones. Scanning 24fps film at 30fps requires the addition of many duplicate frames which compromises encoding efficiency and leads to undesirable slow-motion artifacts.

Anyway, I'm happy to have all this material available in spite of some shortcomings.

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Poster: spuder Date: Sep 20, 2013 12:30pm
Forum: prelinger Subject: Re: Why 4x3 aspect and 30fps framerate?

I'll answer my own question in case others are wondering the same thing.

In more reading I've discovered we are not scanning films here, but rather digitizing NTSC videotape transfers (telecine) made years ago. That explains the 4x3 & 30fps thing.

The quality of the videotape copy is quite good though, so it should be adequate for most purposes.