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Interlacing issue FCP - Varying frame rates

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Gillian Borg
Interlacing issue FCP - Varying frame rates
on Oct 27, 2011 at 3:16:18 pm

Hi,

I'm quite a novice with FCP still but have been closely reading many threads here that have been very useful.

I've been working for a short film to send to a big film festival and the project has been quite ambitious except that we ended up messing our resolution by quite a length.

It was decided to shoot everything in 1280x720 at 50fps CANON 550D as a lot of the film was going to be in slow motion and after reading some posts it seemed like converting 50 fps to 25 fps would make slow mo look much smoother.

Accidentally, one block of the shoot was, for some reason, filmed at 640x480 at 50 fps. We decided to conform them all to 25 fps using Cinema Tools and I also then rescaled the 640x480 footage in Compressor to 1280x720 while we changed the codec to Apple PRo Res 422.

This rescaling of course, cut out the frames and distorted the film quite a bit but as it was showing medieval times, we turned it black and white and decided to keep it as it is, and imported it and started working in FCP in a 25 fps sequence workflow.

Everything looked very neat in the sequence until I exported the film using QT conversion.

THe Codec for Conversion is still Apple PRo Res, frame rate Current, and size is 1280x720.

There seem to be many jarring lines all over the film which seem to be some kind of interlacing issue.

I have since tried to put the De-Interlace effect in all frames and only Flicker Fix (Max) seems to tone it down a bit but the image is now very distorted and you can still see some lines.

No clue why it's happening - I thought the 50 fps to 25 fps conversion was straightforward enough?

Please help!

Gillian


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Colin McQuillan
Re: Interlacing issue FCP - Varying frame rates
on Oct 27, 2011 at 3:51:30 pm

Can you post a clip or frame? I'm curious to see if it is an interlacing issue. I think it may be something else as your camera only shoots progressive. Perhaps a lighting frequency issue or something else.

Colin McQuillan
Vancouver, B.C.


"Live, love, laugh and be happy."


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Gillian Borg
Re: Interlacing issue FCP - Varying frame rates
on Oct 27, 2011 at 9:54:31 pm

Thanks for getting back to me, Colin.

My internet is playing up but I've taken screenshots of two images together to show the difference.

I just discovered that my sequence settings had Lower Field Dominance set. Just changed that to 'None' and removed the De-interlace filter to check - it's much better but still, the lines can be seen.

On the left side of the frame you'll see the frame without the filter, the right one is with filter. If you look closely at her hand/eyes - you'll see lines whilst the one with the filter is blurry and not as sharp. Can't figure out why!



Also the link to see it bigger:

untitled.jpg


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Michael Gissing
Re: Interlacing issue FCP - Varying frame rates
on Oct 27, 2011 at 10:25:42 pm

It is likely that the converted footage has also has interlace settings. Both your sequence and the clips should be set to none.


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Gillian Borg
Re: Interlacing issue FCP - Varying frame rates
on Oct 27, 2011 at 11:29:11 pm

I've checked both source footage and the sequence - all are set to field dominance - none.

:(


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Michael Gissing
Re: Interlacing issue FCP - Varying frame rates
on Oct 27, 2011 at 11:47:28 pm

You may be seeing aliasing that happened when the image was scaled up. If it is interlacing related then that shouldn't show up when you watch on an external monitor. The FCP viewers are poor and not the best way to judge image quality.

One trick is to change the scaling of the canvas to 100%. It should correctly display interlacing at that scale so see if the image still looks bad with that setting and also try monitoring externally by burning a DVD.


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Gillian Borg
Re: Interlacing issue FCP - Varying frame rates
on Oct 28, 2011 at 1:11:31 am

It might well be that as I can't understand how it could be an interlacing issue?!

I've written a DVD, and also watched it on other monitor but the problem persists - what causes this? I thought it was only limited to animation?

I've done some read around and it suggests that not converting to right codec does it but the conversion was a simple H.264 to Pro Res 422.


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Michael Gissing
Re: Interlacing issue FCP - Varying frame rates
on Oct 28, 2011 at 2:35:59 am

So is this on all the footage or just the scaled up? In Compressor did you set frame controls on and resize to best? And output fields 'same as source'?


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Gillian Borg
Re: Interlacing issue FCP - Varying frame rates
on Oct 28, 2011 at 11:39:21 am

Hmm, that might be the problem.

All I did in compressor was import the files, add the Apple pro res codec, and in settings, set the geometry to 1280x780 and in padding, selected Preserve Aspect Ratio.

Was I supposed to do something with the Frame Controls as well?

You're right, the problem is more obvious with the rescaled ones.

However, the shots that haven't been rescaled and originally shot in 1280x780 also seem to have this issue (or am I looking into it too much?)

Here's an original clip frame:




Or Link here:



night.jpg



Could this be more because it's a night shot and we used an ISO up to 800 hence bad quality or something else?


Thanks!


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Rafael Amador
Re: Interlacing issue FCP - Varying frame rates
on Oct 28, 2011 at 3:32:00 pm

Hi Gillian,
I agree with Michael. I don't think that is an interlacing effect but some pixelation due to the poor upscaling (normally you can check if there is interlacing in a computer screen setting the canvas at 100%)
As Michael said the "FrameControl ON" will helps with the process. Will be done at higher quality (32b Floating Point instead of 8b).
rafael

http://www.nagavideo.com


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Gillian Borg
Re: Interlacing issue FCP - Varying frame rates
on Oct 30, 2011 at 6:12:03 pm

Thanks so much for you response, Rafael.

It looks like that is the issue indeed.

Simply means that I'll have to go back to all the clips used, rescale them again with the right setting and reconnect them!

Just so I understand the workflow a bit better, in compressor, apart from the Geometry, I put Frame Controls as ON,

Resize Filter to BEST,

Output fileds - Same as Source

and what about the rest:

De-interlace - BEST (?)

Check 'Adaptive Details' ?

Rate conversion - Best (?)

Set Duration - 100%

Or something else?

If I am missing something, then please let me know. Thanks so much for your help.

Gillian


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