DBeta interlacing

[SimonLL]

Hi everyone,

I'm onlining a short student film shot on s16 and transferred to a Digibeta master tape with pulldown. My workflow is as follow. We had the lab capture our Dbeta footage to 3 uncompressed 10-bit QT movs. One per reel of film so all the footage was captured. I'm using the edit operator in combustion to conform the editing (very few shots so not that much work). I then apply my reframe (1.66 to 1.85 aspect ratio), CC and other effects (flare highlights, dustbusting, etc)to each shot separately in the edit operator. Then export to blackmagic 10-bit codec (I'm on pc, so I don't have the Uncompressed 10-bit codec) to bring back to the lab for final output on Dbeta.

I'm mainly confused by the fields and field order I have to work with. I don't have a broadcast monitor hooked to my computer (student finances oblige), so I can't really check it without burning a dvd which might induce another field order mistake in the transcoding to mpeg2.

I've been told that DigiBeta is upper field first, but I noticed something strange when watching the fields separately in combustion. I have a burn-in timecode, keycode and pulldown phase on the images, and when I watch the field separately in CMB the following happens with the pulldown sequence:

In upper field first mode: A2-A1 B2-B1 C1-B3 D1-C2 D3-D2
In Lower field first mode: A1-A2 B1-B2 B3-C1 C2-D1 D2-D3

( In the order: 1st field-2nd field 1st field-2nd field...)

Would that mean that the footage is Lower field first because each field are in the correct order?

I'm thinking of deinterlacing everything treat the footage and exporting without fields and just let the output deck handle the interlacing. That would also be a time saver since I have to output both on DVCam which is lower field first and DigiBeta which is Upper first. Would that solution compromise optimum quality or is it the way to go for less hassle?

Thanks for your answers.

[SimonLL]

Anyone can help? I really need to know the field dominance of these images soon, because the deadline is coming fast.

Thanks.

[loops]

Looks like your footage is lower first to get the right pulldown cadence. If you're dustbusting maybe you should remove the pulldown and work deinterlaced, otherwise you'll be painting on some film frames twice or three times and gettting strokes split across two film frames...

Was the offline done with the pulldown left in? If so you might want to check whether the cadence breaks across the edits, which will screw up removing it all in one go, you'd have to split into clips.

What to output as depends on what's next in the chain - are you going out a deck from FCP or what? I would output interlaced with pulldown, you can always switch the field order later but interlacing and 3:2 is more likely to get confusing.

When it comes to output time... test and check with a deck that can pause on fields!

I hope that helps a bit... I'm from a PAL country and really hate all this shit, can you tell ;)

[SimonLL]

Thanks a lot,

Yes the offline was done with the pulldown in, but since I have the complete footage online, I can remove the pull down before the edit operator on the 3 master clips. However, I don't think the offline editor was aware of the pulldown issue, so he might have cut on fake frames which won't exist when I remove the pulldown. Removing the pulldown also worries me because the sound mix is done, and I don't want to lose the sync. If I remove the pull down from the master clips, conform the editing and redo the pulldown on the edited clip, will this keep the sync with the offline that was all done with the pulldown in?

For the output, the DvCam output will be done from an avid to a DVCam deck, and I still have to check with the lab for the DBeta master, but it is more likely to be from FCP.

Since I don't have much time left to try stuff I was thinking of deinterlacing but keep the pulldown so everything stays sync, export as progressive and choose the field ordering at the output.

I'm starting to really hate all this too, my next projects are gonna be shot progressive on DVCPro HD which is a bliss. For my next film work, I'll also try to get a progressive transfer.

Again thanks a lot for the reply.

[loops]

Removing the pulldown also worries me because the sound mix is done, and I don't want to lose the sync. If I remove the pull down from the master clips, conform the editing and redo the pulldown on the edited clip, will this keep the sync with the offline that was all done with the pulldown in?
Not nessecarily if you have to move clips which are cut halfway through a frame. Unless you've got something really sync-y you might not notice, I would think lips would be ok.


Since I don't have much time left to try stuff I was thinking of deinterlacing but keep the pulldown so everything stays sync, export as progressive and choose the field ordering at the output.
Careful! If you deinterlace something with pulldown in, horrible things can happen! You'll probably end up with slightly stuttery motion - if you take the first field for example and throw the second away, looking at you sequence above you'll end up with film frames ABBCDABBCDABBCD - too many B's! You might get away with it but I'm sure your film school profs wouldn't approve! Slow pans and titles are the worst for this.


For my next film work, I'll also try to get a progressive transfer.
If you have to deliver NTSC, shoot at 29.97 fps in the camera if you can, for less messing about!

Good luck!

[camene73]

Hey,

I would remove the pulldown, compose everything on 24 fps and add the pulldown back while render.
The audio will be just fine.

camene73