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Ragged, pixelated images when there is lots of movement

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Kris De Meyer
Ragged, pixelated images when there is lots of movement
on Apr 10, 2014 at 10:27:14 pm

We shot footage for a documentary on a Canon XF305 in HD format (1920x1080 at 50mbps).

As we shot a lot of footage we converted the rushes to ProRes Proxy for off-line editing in FCP7. Normally we watch the footage on a computer screen on which it looks fine. Today I had the chance to test our cut on a big screen in a cinema, and moving images look pixelated and frayed at surface edges.

The clip I tested was exported from FCP as Quicktime video with the sequence settings unchanged. I used Compressor 3.5 with the recommended settings for Vimeo HD (720p - 5000kbps - multi-pass).

I have the feeling that the pixelation problem does not lie with the compression (as steady images look beautiful on the big screen), but lies earlier in our shooting or processing of the rushes.

Two possible culprits I can think of:

(1) Perhaps we made a mistake in interlacing/de-interlacing images? I think we shot in 50i (but would have to double-check on our rushes drive). Should we de-interlace the footage when we export/compress using Compressor or before when importing the footage into FCP? If we shot in 50i, should our FCP editing sequence be 50i?
(2) Is it a problem of ProRes Proxy and would it disappear if we used the full ProRes 422?

Would really appreciate if somebody could confirm what the most likely cause is.

Thanks in advance,


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Eric Strand
Re: Ragged, pixelated images when there is lots of movement
on Apr 14, 2014 at 8:29:25 pm

If you shot 50i and can deliver interlaced, then yes, edit 50i.

You're exporting from FCP with the prores proxy footage? Or you're reconnecting it back to the original then exporting?
If you're exporting the ProRes Proxy then compressing that, that's likely what's causing the pixelation.


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