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Old Aug 16, 2005, 01:31 AM   #1
rainman::|:|
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basic aspect ratio cropping question

As i'm getting used to the widescreen iMac, I'm having a minor annoyance. A lot of (quicktime) videos I have are widescreen (16:9) with the black bars intact (so the video itself is 4:3), rather than being the true aspect ratio of the video. Since the computer thinks the movies are 4:3 ratio, it puts black bars on the sides, leaving me with a 2" thick black margin around the movie. I think the black bars were left in to preserve the widescreen ratio should a movie player stretch the image, however my iMac will add (smaller) black bars of it's own, allowing the movie itself to span to the edges. Obviously whoever encoded these never anticipated widescreens Anyway, my question is, what's the easiest way to crop the entire video down to just the movie, removing the black bars, without screwing with video quality. Usually when people speak of cropping movies, they mean cropping linear time, which is not what I mean... rather removing extra black around the edges. Any help is appreciated. Thanks!
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Old Aug 16, 2005, 07:00 PM   #2
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It looks like you have a bunch of Letterboxed videos (16:9 image in a 4:3 video).

So, in effect, you want to extract the 16:9 image from a Letterboxed 4:3 video and turn it into a true 16:9 video? This will probably effect video quality 'cause you are going to be blowing up the 16:9 image to fill an entire 4:3 frame (where as before it was just filling the width of a 4:3 frame).

There is a program talked about here that does that. But it looks a bit cumbersome, and the results may not be too good depending on how good your source material.

Unless it's driving you absolutely batty I wouldn't worry about, IMO.


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Old Aug 17, 2005, 01:29 PM   #3
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Unless you are going to view this on a 16x9 TV, there is no point.

Encoding it as a 4:3 video that contains video with black bars on top/bottom will yield the same image as a 16x9 encoding of a cropped version.

on a regular 4:3 TV.

Viewing the 4:3 letterboxed video on a 16x9 tv would look all funky.
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Old Aug 17, 2005, 10:24 PM   #4
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It depends on the tools you have available to you. If you have FCP, you could simply start a new project in Widescreen, pull in the video, and scale the video so it fills the screen properly. You could then export the video from final cut using whatever codec floats your boat, and make sure that width and height are appropriate.

Another option might simply be QT Pro. You could open the file in QT, do "Save As..." and simply lower the "height" to whatever will crop out those pesky black bars. You don't lose quality, you simply eliminate the bars. Likewise, you don't gain quality either, and when you view those films "full screen," they might look a bit pixelated, since QT is now trying to make the most of your screen.

Anyway, those are my suggestions. Let me know how it works out for ya!

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Old Aug 18, 2005, 12:09 PM   #5
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Quote:
Originally Posted by Sdashiki
Unless you are going to view this on a 16x9 TV, there is no point.

Encoding it as a 4:3 video that contains video with black bars on top/bottom will yield the same image as a 16x9 encoding of a cropped version.

on a regular 4:3 TV.

Viewing the 4:3 letterboxed video on a 16x9 tv would look all funky.
My monitor is in-between It would have smaller black bars for a 16x9, but it doesn't get the chance, because the 4:3 black bars are already present.

Lethal and rand, thanks for the tips, I'll try them out tonight... I know the video quality will be less when it's scaled larger, but it's worth it to be able to show clips as close to full-screen as possible. Plus, the black bars added to the clips are a slightly different color than the side-bars that the iMac adds, so it looks like a hack job. I just like things to work properly on my Mac
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Old Sep 7, 2005, 01:10 AM   #6
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How did you get on? I just got my G5 today and I've run into the same problem. Did you find a "best" solution?

Thanks
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Old Sep 7, 2005, 01:47 AM   #7
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I'm surprised there's no video zoom thing like the DVD player has... seems like such an obvious thing to include into a video application.
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Old Sep 7, 2005, 01:47 AM   #8
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I would think the easiest way would be using ffmpegX, in the Filters tab, on the bottom left there is a crop option, and you can click the preview button on the right to see the video with a white box representing where the video will be cropped.
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Old Sep 7, 2005, 12:17 PM   #9
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Quote:
Originally Posted by pdpfilms
I'm surprised there's no video zoom thing like the DVD player has... seems like such an obvious thing to include into a video application.
One could use the built-in zoom feature of the OS.

System Preferences - Universal Access - turn Zoom on - remember the key combinations to zoom in and out. Hit "zoom options" to change the zoom focus so it moves when you reach the edge of the screen; the default setting is annoying because the mouse's pointer sits at the center at all times.
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