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Riddled with Reverse Field Dominance - Take 2

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Michael Pfost
Riddled with Reverse Field Dominance - Take 2
on Mar 18, 2011 at 5:43:53 pm

So I've been working on converting a popular 1960's TV series into the PAL format. The film was telecined to NTSC DigiBeta.

I was hoping to reverse telecine it (using Compressor), add bar and tones in FCP and render to a QT file (at 23.98 fps). I'd then take the file, conform it (using Cinema Tools) to 25fps and then finally run it through Compressor to make the frame size correct for PAL. (All of this using ProRes 4:2:2 files).

So this all worked out perfectly (or so I thought). It is beautiful. I then needed to convert the final PAL file to a MXF using Episode Pro (IMX-50 Op1a format) to send off to the network. The MXF file looked great using VLC player.

I do all of this and then got told that my test file was "riddled with reverse field domination" and therefore rejected.

How could this happen? I made sure that "Top Field" was selected throughout my workflow. The one thing is that the original material was captured in Lower Field (using a Matrox Mini), but I don't have a choice with this evidently. Also, it seems that by selecting TFF my final workflow would fix this?

So the question too is can a clip change field domination while playing? Or is the clip one domination or the other?

PAL files are supposed to be TFF? Right?

Any insight or help would be appreciated. I'm not finding many people that work with MXF files...

Is there a program (Mac or PC) that will analyze a file and tell you the true field order and if there are issues? I've used Compressor and pulled up the "inspector" window and it always says TFF.


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Michael Pfost
Re: Riddled with Reverse Field Dominance - Take 2
on Mar 18, 2011 at 6:18:29 pm

Ok - one thing I failed to mention is that in Compressor (when it creates the final PAL file from a 720x486 file) -- I am cropping 2 lines at the top and 2 lines at the bottom (as there is a little bit on garbage that I want to remove).

Will this create any issues?


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Dave LaRonde
Re: Riddled with Reverse Field Dominance - Take 2
on Mar 18, 2011 at 7:19:23 pm

It sure could! It could totally mess up the field order. If you can, send these guys a 1-minute clip of your stuff without cropping, and ask if they find any field order problems.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Michael Pfost
Re: Riddled with Reverse Field Dominance - Take 2
on Mar 19, 2011 at 9:13:16 pm

Thanks for the advice! Just sent a couple of test clips without cropping the top 2 lines and bottom 2 lines.

So if these do work, what would be the best way to eliminate the top 2 lines of the NTSC image before being blown up to PAL using Compressor (without potentially changing the field dominance?)


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Rafael Amador
Re: Riddled with Reverse Field Dominance - Take 2
on Mar 18, 2011 at 8:08:01 pm

[Michael Pfost] "
How could this happen? I made sure that "Top Field" was selected throughout my workflow. The one thing is that the original material was captured in Lower Field (using a Matrox Mini), but I don't have a choice with this evidently. Also, it seems that by selecting TFF my final workflow would fix this"

OK, so where did you make the fields-shift?
In which place of your workflow, did you told to the application "This stuff is gets in as Lower and needs to get out as Upper"?

[Michael Pfost] "Is there a program (Mac or PC) that will analyze a file and tell you the true field order and if there are issues?"
The best way to see that is any application (like AE) where you can step field by field.
rafael

http://www.nagavideo.com


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Michael Pfost
Re: Riddled with Reverse Field Dominance - Take 2
on Mar 20, 2011 at 4:32:27 pm

The first time I shifted the frames to TFF is when I went from the Progressive 23.98 fps ProRes file to a PAL ProRes file. I basically just set the file settings in Compressor to "Top Field."

So -- question -- what does "Two fields forward, one field back" mean?


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Michael Pfost
Re: Riddled with Reverse Field Dominance - Take 2
on Mar 23, 2011 at 4:42:55 am

Ok - well I figured out the problem. It had nothing to do with cropping in Compressor. I had a wrong setting in Episode Pro (used to create the MXF file).

It was approved by the network. Thanks to all!




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