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View Full Version : Compositing progressive footage over interlaced backplates?

Backenbotten
09-12-2004, 04:39 PM
Hi!

I am working on a broadcast project which is based on widescreen 16:9 PAL. The backplates are 16:9 anamorphic (interlaced), and the final output of my compositing needs to be the same. I am creating my additional layers at 1024x576. So, my "stack" looks like below:

Additional layers (progressive, 1024x576, pixel aspect 1)
Backplate (lower field, 720x576, pixel aspect 1,4222)

Final output: lower field, 720x576, pixel aspect 1,4222

There is hardly any motion in any of the footage.

My question is, are my layers (which are progressive=no fields) likely to blend nicely with the field-based backplate? If not, what is a better way? I'd rather not deinterlace my backplate.

I have no other tool for de-interlacing than the ones built in in CS3, and using those I lose defininition. The backplate is a landscape and the only motion are some distant cows and a treebranches that sway slowly in the wind. I will not composite any layer over these areas with motion, only over the "still" areas. I have no means to output to a PAL monitor to check it unfortunately...

Any help or advice greatly appreciated!
Backenbotten
09-15-2004, 10:32 AM
Hey...
Fortunately I managed to get my hands on a friends DV-camera (don't have one myself), with Firewire and S-video I/O (and firewire in to s-video out throughput). With that I could have output from CS3 to a PAL monitor. Worked like a charm reallyhttp://cgtalk.com/images/smilies/smile.gif

So, to answer my own question: yes, it did blend nicely (progressive over interlaced), at least in this case with a very "calm" backplate. The backplate was left crisp, and correctly interlaced, while my additional layers blended seemlessly without any strange stuff introduced. The PAL monitor was also very useful to finetune color correction and other final touches.

Having PAL output is soo great since WYSIWYG, I regret I didn't get a DV-cam earlier (or something that can be used to have PAL output, like the Matrox Parhelia cards or those Czech drivers and the compatible graphics cards).
bartrobinson
09-30-2004, 04:21 PM
Just an idea, but potentially requires money....rather elaborate, possibly unnecessary if there isn't much movement. You might try a sequence retimer (ReTimer, Twixtor, etc.) on your progressive footage. Retime it from 25 fps (assuming PAL) to 50 fps, make two sequences (perhaps in something like Digital Fusion) remove even lines from one and odd from the other so you end up with half height frames. Drop even frames from the odd lined sequence, drop odd frames from the even lined sequence. Combine sequence frames. Reinterlace with something like VirtualDub or AviSynth, or possibly even Digital Fusion (can't remember there).
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