When to Crop?

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When to Crop?

Postby -MajinLink- » Tue Aug 15, 2006 3:36 pm

Hi, the footage that ripped has those black bars on the sides and stuff and I want to crop them. But I'm not too sure when the best time to it is? I'm editing my .avs files in Adobe so I could crop them all off before I start my project and work with no bars/borders.

Or can I just export my movie when I'm finished and crop them all all off in AVISynth via Avisource.

Note that some episodes have thicker bars than others.
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Postby Krisqo » Tue Aug 15, 2006 6:03 pm

I would do it before simply because you have several different amounts of cropping. It just eliminates the hassel of doing it when you have the final video and you need to switch from scene to scene trying to pinpoint the exact number of pixles. Just don't forget to resize to compensate for the cut off parts.
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Postby Melanchthon » Tue Aug 15, 2006 7:10 pm

Krisqo wrote:Just don't forget to resize to compensate for the cut off parts.

Won't the remaining stuff be out of ratio then (unless the card squeezes the whole picture)? If the footage itself is the right ratio, then wouldn't you just need to resize to the final resolution? I really don't know much about capturing.

For the script, I usually do cropping as the very last thing (in theory, it cuts down on border pixel weirdness. In practice, it has to go somewhere, so it might as well make itself useful). If you're cropping a lot of pixels off each side then it might be worth removing most of the black beforehand so your filters have less pixels to process. Crop is pretty much a free function in terms of speed, but it's your choice.
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Postby Gepetto » Tue Aug 15, 2006 7:11 pm

Krisqo wrote:I would do it before simply because you have several different amounts of cropping. It just eliminates the hassel of doing it when you have the final video and you need to switch from scene to scene trying to pinpoint the exact number of pixles. Just don't forget to resize to compensate for the cut off parts.


x2

It also prevents you from missing the position or shape of an effect in Premiere because the aspect ratio of the actual image will change when you crop the black bars.
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Postby x_rex30 » Tue Aug 15, 2006 7:12 pm

Well if you're going to make your footage 640x480 and there isn't much borders to crop.. then add the cropping before your aspect ratio change in your script that way you don't have to worry later about getting rid of black borders later. That's what I do anyways.. depending on how big the black borders are though I sometimes use crop after I change the aspect ratio to avoid getting my footage all stretched up. Hope that helps.. though I don't know if my method is all that great. And try to do the cropping in the video editing program than after you render your video. It works just fine in Vegas.. it might cut off some of the image sometimes but depending on what you are going for you could zoom in and get some of the image cut off or turn off the maintain aspect ratio option and have it stretch out a little bit. I don't know how to work with that in Premiere because I have not tried messing with that in there.

I think you would want to keep your aspect ratio at 640x480 so if you for some reason plan to crop after you render your video you might end up with a different aspect ratio unless you put it in avisynth and do the cropping and resizing technique to keep the fixed aspect ratio but I don't think you should crop after you finish your video and if you do end up doing that at least make sure that you render your video to a lossless video/audio format. I hope you are doing that in the first place though because doing compression for online distribution in Premiere is not recommended. There are free programs that do it a lot better that exist out there for example vdub/mod.
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Postby Shazzy » Tue Aug 15, 2006 10:02 pm

Yes, just cropping would make your size funny. You want to crop and scale = cropping while keeping the video at a standard frame size.
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Postby Willen » Wed Aug 16, 2006 2:32 am

I generally don't worry about messing up aspect ratio when cropping off a bit of black from the sides (or top and bottom). The change is pretty minor if it is only a few pixels (8 to 16 horizontal, 6 to 12 vertical). Just make sure you resize to 640x480 for 4:3 material (or 848x480 for 16:9, etc.) after you crop.
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