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Field issue converting Digi to ProRes

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Peter Wolsey
Field issue converting Digi to ProRes
on Feb 18, 2013 at 7:32:54 pm

I'm having a problem turning interlaced Digi into ProRes. It becomes progressive! A bit of a problem as we have 8 x 30minute shows to finish.

On our XDcam timeline we have a mixture of XDcam EX footage (HD) and Digibeta (SD). All the Digi footage is scaled correctly to fit the 1080 frame. It plays beautifully on the original XDCAM timeline albeit with the occasional stutter, but I want to convert it all to ProRes because there's a lot of finishing to do (effects, colour correction etc).

When I use Media Manager to convert the clips to ProRes I find that the Digi footage has turned from interlaced to (what looks like) progressive. The interlaced XDcam footage plays fine after conversion, but the Digi footage (now ProRes) is stuttery. Looking at the Clip Properties reveals the field dominance is Upper, as it should be. But scrolling through the timeline, the clip appears to be progressive. I even tried reversing the original field order as an experiment, but it just turns out the same.

Any ideas to fix this? A horrible workround would be to replace all the converted Digi clips with the original clips (tried this and it does work, but that seems such a waste of time)


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Dave LaRonde
Re: Field issue converting Digi to ProRes
on Feb 18, 2013 at 7:44:23 pm

What kind of video monitor do you have? What kind of third-party capture card? Do you have neither?

I makes a big difference.

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


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Nick Meyers
Re: Field issue converting Digi to ProRes
on Feb 18, 2013 at 10:56:17 pm

"When I use Media Manager to convert the clips to ProRes I find that the Digi footage has turned from interlaced to (what looks like) progressive."

using Media Manger to up-res your footage is not a good idea.
yes, it can transcode as part of it;s operations, but you are better off using a dedicated tool such as Compressor.
i have no idea what MM's scaling algorithms are. for all i know they may match your timeline's "Fastest" option, not it's "best"

actually if you can CAPTURE your digi beta, the simplest option, and one that will yield good results, is to capture it again as 1080i.


nick


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Shane Ross
Re: Field issue converting Digi to ProRes
on Feb 18, 2013 at 11:18:34 pm

How was the digibeta captured in the first place? With what capture card? If you have access to the AJA Kona 3, or LHi, you can get very good results:

http://library.creativecow.net/ross_shane/aja_kona3/1

Shane
Little Frog Post
Read my blog, Little Frog in High Def


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Peter Wolsey
Re: Field issue converting Digi to ProRes
on Feb 19, 2013 at 10:00:45 am

Dave- We use a Sony CRT monitor, and will finish on a Flanders Scientific LM1760W monitor, so we're seeing accurate pictures.

Shane - We captured the footage as 8bit uncompressed SD with a Blackmagic card (where I suspect my mistake was.)

Nick - Two of our suites are fitted with the Kona Lhi cards, I suspect that your right and we may have the unwelcome task of recapturing in 1080.

However, the programmes will be delivered in SD on Digi tape. Does this make any difference to the possible solutions?


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Nick Meyers
Re: Field issue converting Digi to ProRes
on Feb 19, 2013 at 10:09:53 am

"However, the programmes will be delivered in SD on Digi tape. Does this make any difference to the possible solutions?"

i don't think so.

if you tried to keep the SD material "pure" then you'd be in for a lot more time and effort.

i suspect it's simpler to re-capture as HD through your Kona card,
and down-res the whole show, again though the card.

also you'll be ready when someone turns around and asks for an HD master.
it's probably why you've been cutting in HD, right?


nick


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Peter Wolsey
Re: Field issue converting Digi to ProRes
on Feb 19, 2013 at 10:50:34 am

The bulk of the footage was shot HD, that's why we chose to edit in HD, though it's only ever going to be broadcast in SD.

Interestingly, the picture quality is great after the Digi up-convert to ProRes. But the clips simply appear to have lost their interlace properties. In hindsight we should have captured the Digi stuff properly through the Kona card.

It's the first time we've ever tried to do this and I assumed that Media Manager would handle the up convert without a problem, so I guess we learn by our mistakes. Oh well, a few late nights ahead then...

Thanks for input though. Always reassuring to know there's a good resource out there.


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Peter Wolsey
Re: Field issue converting Digi to ProRes
on Feb 19, 2013 at 6:13:12 pm

As an addendum, for the benefit of anyone else with this particular problem - we found a solution.

Bearing in mind that the shows have to be delivered in SD (and will never surface as HD) we hit upon this solution. We created a new SD timeline and copied/pasted all the original HD timeline onto it. This made the Digi clips play perfectly, as expected, and the HD clips look fine after rendering (about an hour for a 30min show). No problems with interlace issues, though inevitably there's a lot of resizing to be done.

Lessons learned:
1. It seems that FCP doesn't like upscaling SD to HD - in fact it can't do it successfully unless you go via Compressor.
2. FCP is totally fine at downscaling HD clips to SD with no visible interlace or quality issues.
3. If you have to mix HD and SD footage, then capture the material using a Kona 3 or LHi card (or similar) that will upscale properly in real time.

We live and learn!


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