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Field Order Issue for Broadcast

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Thomas Kymn
Field Order Issue for Broadcast
on Dec 1, 2010 at 8:14:41 am

Hi everyone,

I'm an avid reader of these forums but this is my first ever post. So I have a little issue here that maybe some of you can help to expedite this process:

I am currently receiving an output of a client's file in MPEG-2 (Lower-Field) for broadcast. After QC'ing I see that its Field Order is wrong which is causing the video to have a jittery effect.

Here is their current setup:

Sequence is set using AJA Kona LHi: 29.97 8-bit uncompressed.

Frame Size: 720 x 486 pixels
29.97 fps
Lower Field Dominance

They are currently playing back through AJA 525 29.97 8 Bit also on a JVC monitor (not sure of the model).

All their clips are LFF, their clip having been captured as 8-bit uncompressed LFF from a Digibeta (NTSC - I thought NTSC Digibetas were UFF?). Anyways, the clip plays fine when played off FCP timeline (on the monitor as well, no jitter effect). However, once sent off to Compressor and output as MPEG-2 LFF, we have the jitter issue on the broadcast server end.

First off, here's the compressor setting:

NTSC, 29.97, 4:3, Automatic (Also tried BFF). Quality is set to Best in estimation along with one pass VBR and 10 / 15 average and maximum bit rate. GOP Structure is IBBP Closed. It is also set as a transport stream.

So I suggested a shift field filter to fix the issue, however, on their monitor it apparently gets worse - they've tried all settings, +1, -1 ( I have yet to see it for myself).

The current workaround is the flicker filter set to max. Although this works, we lose resolution, but it's still definitely better than the jitter.

So my question is, could it possibly be the monitor reversing the field perhaps? Do you see anything wrong with the workflow that I've laid out here so far? I haven't really had the time to go visit and check thoroughly to rule out some things, but if anyone has an idea and can help, it'd be appreciated. Thanks!


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David Roth Weiss
Re: Field Order Issue for Broadcast
on Dec 1, 2010 at 4:18:21 pm

SD 8-bit unc. NTSC is lower field dominant

David Roth Weiss
Director/Editor/Colorist
David Weiss Productions, Inc.
Los Angeles
http://www.drwfilms.com

POST-PRODUCTION WITHOUT THE USUAL INSANITY ™


A forum host of Creative COW's Business & Marketing and Apple Final Cut Pro forums. Formerly host of the Apple Final Cut Basics, Indie Film & Documentary, and Film History & Appreciations forums.


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Thomas Kymn
Re: Field Order Issue for Broadcast
on Dec 1, 2010 at 5:46:43 pm

Hi David,

The content was brought in as lower field first. Anything else that may stick out from what you see? By the way, I've learned a lot from your posts in the previous years so thanks in advance :)


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David Roth Weiss
Re: Field Order Issue for Broadcast
on Dec 1, 2010 at 6:06:13 pm

[Thomas Kymn] "The content was brought in as lower field first."

Yep, I saw that, and that makes this more mysterious.

[Thomas Kymn] "Anything else that may stick out from what you see?"

No, making it even more mysterious.

I must say, just lately I've been consulting for a number of clients who have had some very mysterious field-related issues, and I have uncovered several strange misinterpretations of fields when moving material from FCP to Compressor. I suggest you very, very carefully go over the log generated by Compressor to see if there's anything that stands out to you as a mistake.

And, I might also suggest that you use try running Digital Rebellion's free Compressor Repair app. I've heard rumor that there are possible issues with bad remnants or fragments of outdated Quicktime installations stored away in Compressor cache or preferences that are possibly confusing to the app's automatic field interpretation.

[Thomas Kymn] "I've learned a lot from your posts in the previous years so thanks in advance :)"

Thank you for your kind words :} :} :} It's always good to feel appreciated.

David Roth Weiss
Director/Editor/Colorist
David Weiss Productions, Inc.
Los Angeles
http://www.drwfilms.com

POST-PRODUCTION WITHOUT THE USUAL INSANITY ™


A forum host of Creative COW's Business & Marketing and Apple Final Cut Pro forums. Formerly host of the Apple Final Cut Basics, Indie Film & Documentary, and Film History & Appreciations forums.


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Thomas Kymn
Re: Field Order Issue for Broadcast
on Dec 7, 2010 at 5:27:02 am

Hi David,

Just to give you an update, when we changed from MPEG 2 to DVCPRO50 it fixed the issue. It's also very odd because these field order issues were happening on only certain files. Any idea as to why perhaps? Thank you.


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