Couple of tech questions

[Ashton]

Alright, I want to do a couple of things, but some of them are a bit tricky technically, so I would like some input.
Alright, I'm using anamorphic source, and I want to line up an image with te source perfectly, but I'll be editing with the source in 720x480 stretched to preserve quality. My concerns are these, if I just put the image down (one image, as a subset of a larger image) then the overscan will look wierd. Should I just cut it off before editing, and then stretch it out to 720x480? Will I loose quality that way? Also, since it's anamorphic, do I need to have the image stretched so that it will look normal when it's output, or will that happen automatically?

As a seperate question, how does one extract the luma from a video stream? I can use Premiere, After Effects, AVS, or VDub, I don't care, but how do I do it?

Thanks!

[Zarxrax]

For your image, I believe you will need to divide its horizontal resolution by 1.4. Someone PLEASE correct me if this is wrong. I just did some quick match on the windows calculator, and I have no idea if I'm correct.

If I'm not mistaken, you get the luma of a clip by simply applying a grayscale filter to it.

[trythil]

Alright, I want to do a couple of things, but some of them are a bit tricky technically, so I would like some input.
Alright, I'm using anamorphic source, and I want to line up an image with te source perfectly, but I'll be editing with the source in 720x480 stretched to preserve quality. My concerns are these, if I just put the image down (one image, as a subset of a larger image) then the overscan will look wierd. Should I just cut it off before editing, and then stretch it out to 720x480? Will I loose quality that way? Also, since it's anamorphic, do I need to have the image stretched so that it will look normal when it's output, or will that happen automatically?

As a seperate question, how does one extract the luma from a video stream? I can use Premiere, After Effects, AVS, or VDub, I don't care, but how do I do it?

Thanks!

To maintain aspect ratio, you have two choices:

- Edit the anamorphic source as-is, keeping aspect ratio and all. Then when you do graphics you will want to create them at 720xnnn, where nnn is the post-aspect ratio correction vertical resolution.

For 4:3 (1.33:1) source, you'd create graphics at 720x540.
For 16:9 (1.78:1) source, it'd be 720x405.

Whatever the aspect ratio of the source is, you will have to make it 720x480 again at the end. If you are planning to export your final project at 720x480 at the original widescreen ratio, this method is fine.

Keep in mind though that most conventions don't deal with widescreen video, so if you're submitting your video to a con you'll have to maintain the aspect ratio inside a 720x480 @ 4:3 window. The procedure is pretty much the same as the one I described above, with only numerical tweaks; check the Guides for more information.

--

As far extracting luma goes, AVISynth can do this:

AVISource("F:\amv\ddr3-backup\ddr3_track12_era_2997_retouch.avi")
clip = ConvertToYUY2()
clip1 = BlankClip(clip)
MergeLuma(clip1, clip)

That MergeLuma statement takes the luma channel from clip (the AVI file) and merges it into the blank clip.

[AbsoluteDestiny]

For 4:3 (1.33:1) source, you'd create graphics at 720x540.
For 16:9 (1.78:1) source, it'd be 720x405.

Remember, those resolutions are useless if you ever want the video to be output to a tv or similar because they dont allow for the 0.9 pixel aspect ratio. You want 720x480 and 720x360 to keep the same PAR.

[Ashton]

Ok, this is giving me a wee bit o' headache trying to think about. So, should I crop the footage and prepare it for editing at 640x480 and then render my final product at 640x...errr.. whatever the hell the widescreen ratio is in order to compensate for the .9 aspect ratio difference? I'm really concerned with getting this right the first time... and this is tough to think about especially because I know I'd like to crop before editing to take care of overscan because I know I'l be moving the video within the frame.

And thank you all for the help, the luma track was right on, very cool looking, thanks!