Annoying Interlacing Issue with mpeg2s – got any ideas?

[Sean Oneil]

Do some Googling and read up on 3:2 pulldown.

This is a very complicated issue. I can’t see your MPEG footage, and I don’t know what you are using to monitor it. What I can say is that any footage containing 3:2 pulldown will show “scan lines” when played back a certain way. This is normal to a degree. But there is a continuous field pattern, called 3:2 cadence, that needs to remain intact in order for basic software like Compressor to properly deinterlace it.

I’m gonna guess that your HVX200 was set to record 23.98 frames per second – but you captured and edited at 59.94. This means that you have duplicate frames in your footage, so when you edit this footage the 3:2 cadence is destroyed. This is not good and it will cause the exact problem you described. Programs like Compressor are not capable of fixing it. You need a Teranex or something similar to do that.

The only good news is that when played back on a DVD player, the problem will not be visible on a regular Standard Def tube television set. Because CRT sets are interlaced, it will mask these artifacts.

The solution to avoid this problem is to edit at the actual framerate you shoot at. So you should have captured the HVX footage at 23.98 or used the Panasonic framerate converter plugin prior to editing anything.

Again, this is a complicated issue that most people don’t understand. But it’s important to know it if you are working with equipment like the HVX200.

Sean

[David Roth weiss]

[_adam_] “no matter what I do I’m getting scan lines in the mpeg2 anytime there’s a great deal of motion in the frame.”

Adam,

How are you monitoring, computer screen or NTSC monitor/TV?

59.94 is interlaced. If you’re looking at the MPEG2 on your computer screen you will see the scan lines. As soon as you author and create a finshed DVD and play it on an NTSC monitor you won’t.

In the future, if you shoot, edit, and encode your MPEG2 at 23.98, keeping the entire project progressive, you won’t see interlacing.

David

David Roth Weiss
Director/Editor/Post-production Supervisor
David Weiss Productions, Inc.
Los Angeles

[Chris Borjis]

quicktime and the mac dvd player seem to have this problem.

I’ve noticed though that pc based software dvd players seem to blend them altogether.

[Todd Beabout]

I’ve run into this same problem (even with SD footage) on FCP 5.1.x when my process involves first exporting the native QuickTime, then importing that into Compressor. I can offer no reason as to why, but I can take the same sequence and export through FCP “using Compressor” and while it ties up Final Cut, the end result looks right.

Give it a try.

-Todd Beabout
Vazda Studios

[_adam_]

Hi Sean,

Yeah, we shot at 24p, and then ingested from a Firestore, which came in at 60fps (which makes sense according to this: https://images.apple.com/pro/pdf/L317074A_FCP_Wkflw.pdf) where it says “720p 24/30 ingests at 60 fps” (or 59.94). Okay, so far so good.

I didn’t think it was a cadence issue because the scan lines don’t seem to follow pattern, they just seem to appear whenever there’s a great deal of motion in the frame.

Okay, the 59.94 thing… in Compressor I’m selecting 29.97 as the frame rate… doesn’t Compressor compensate for the interlacing? For whatever reason (ie. I’m an idiot) I thought that it would recognize that 59.94 is a 29.97 derivative.

Well, as for the good news, well, that’s good! I’m currently previewing this in Quicktime & DVD Studio Pro and freaking out, but when I submit this stuff to festivals hopefully they’ll be looking at them on NTSC TVs.

I think it’s weird that the FCP white paper doesn’t mention you require a third-party solution to properly get your footage down to an mpeg2 stream.

Do some Googling and read up on 3:2 pulldown.

This is a very complicated issue. I can’t see your MPEG footage, and I don’t know what you are using to monitor it. What I can say is that any footage containing 3:2 pulldown will show “scan lines” when played back a certain way. This is normal to a degree. But there is a continuous field pattern, called 3:2 cadence, that needs to remain intact in order for basic software like Compressor to properly deinterlace it.

I’m gonna guess that your HVX200 was set to record 23.98 frames per second – but you captured and edited at 59.94. This means that you have duplicate frames in your footage, so when you edit this footage the 3:2 cadence is destroyed. This is not good and it will cause the exact problem you described. Programs like Compressor are not capable of fixing it. You need a Teranex or something similar to do that.

The only good news is that when played back on a DVD player, the problem will not be visible on a regular Standard Def tube television set. Because CRT sets are interlaced, it will mask these artifacts.

The solution to avoid this problem is to edit at the actual framerate you shoot at. So you should have captured the HVX footage at 23.98 or used the Panasonic framerate converter plugin prior to editing anything.

Again, this is a complicated issue that most people don’t understand. But it’s important to know it if you are working with equipment like the HVX200.

Sean

[_adam_]

Okay! I will! I promise.

Man, have I ever learned my lesson the hard way this time.

Thanks 🙂

Adam

In the future, if you shoot, edit, and encode your MPEG2 at 23.98, keeping the entire project progressive, you won’t see interlacing.

David

[_adam_]

Thanks for the idea! I tried, and… well… it didn’t work, but I was more than happy to give it a shot.

Adam

I’ve run into this same problem (even with SD footage) on FCP 5.1.x when my process involves first exporting the native QuickTime, then importing that into Compressor. I can offer no reason as to why, but I can take the same sequence and export through FCP “using Compressor” and while it ties up Final Cut, the end result looks right.

[Sean Oneil]

[Todd Beabout] “I’ve run into this same problem (even with SD footage) on FCP 5.1.x when my process involves first exporting the native QuickTime, then importing that into Compressor. I can offer no reason as to why, but I can take the same sequence and export through FCP “using Compressor” and while it ties up Final Cut, the end result looks right.”

This is a different issue. I’ll try to explain what’s going on with that….

When you export to Compressor from within FCP, Final Cut tells Compressor extra information about the video. Particularly it tells it what the field dominance is supposed to be.

But, if you export a QT file and then import it into Compressor, Compressor just guesses what the field dominance is based on what the default is for that particular codec. For example, it will think PhotoJPEG is upper field first – even though in Final Cut it should be lower-field first. For whatever reason, PhotoJPEG was orginally designed to be upper-field first, yet Final Cut captures and edits PJPEG as lower field first.

So the end result is that you get horrible field flickering after compressing an MPEG for DVD.

That is most likely why you have that problem. Different problem that what Adam had.

Sean

[Sean Oneil]

Adam,

I just though of something that might help you. I don’t remember if this works or not so just try it out.

Open up your sequence, Select All, Copy. Then change your Easy Setup to DVCProHD 720p 23.98 Varicam, and create a new sequence with those settings (check the sequence settings and make sure editing timebase is 23.98). Now paste your footage in that timeline.

Because of the Varicam features built into FCP, Final Cut may be able to recognize the duplicate frames and remove them appropriately. Render a few seconds of it and jog through. If the motion looks find and there are no duplicate frames, then you’re good. Just export using Compressor to a 23.98 MPEG.

Sean

[_adam_]

Thanks so much for the idea! I really really really hate to say this, but this task actually got turfed (no one’s more annoyed at it than me), but if I’m ever in this situation again, that’s what I’ll try!

Thanks again (everybody!)

Adam