Aliasing issues with drone footage shot 23.97fps

[dhtbrowne]

Hey team,

I'm doing the finishing on a TV show at the moment. I haven't shot any of the footage, or done the edit, but I'm responsible for delivering the final files to the station and meeting their specs. Unfortunately the DOP shot all the drone footage not in log and at 23.97fps and we need to deliver the show in New Zealand at 25fps interlaced upper channel priority in HD. All the rest of the programme has been fine, but this drone footage is causing big aliasing issues and the station is rejecting it. I'm pretty sure the issue is the frame rate, and the fact they need the final delivery interlaced. Ie if I do a render at 25fps progressive the issue is still slightly there but not really that visible, and all the other drone stuff in the show shot at a higher frame rate is fine. I think the sharpening that DJI puts on the image and the lack of LOG are probably adding to the issue, but they're not the main thing.

This is the footage here: https://f.io/IFZeCuam. The original drone file is there, along with the exported section of the show at the format I have to deliver it in. I've tried pushing it through a bunch of different encoders, but have a similar result each time.

Does anyone have any ideas for how to smooth it out? Main most noticeable stuff is in the pebbles of the river at the top of the frame.

[dhtbrowne]

My sequence is at 25fps. And in this export I've tried interpreting the drone footage as 25fps so it's theoretically playing back at the same frame rate so shouldn't be creating a stutter from dropped frames.

[MyerPj]

I downloaded the 06s clip using the Original option (45.3mb) and it's coming to me @25 fps. It sounds like that's not what it should be?

[dhtbrowne]

Nah thats right. The 6 second clip (mxf) is in the final format I need to send to the station which shows you what it looks like when I do the final render. The long clip is the original shot of the drone at 23.97

[Ann Bens]

Your final clip shows interlaced (upper field) Might want to correct that.

[dhtbrowne]

Nah thats part of the broadcast specs. Needs to be interlaced. The problem goes away if I export progressive.

[Averdahl]

Does anyone have any ideas for how to smooth it out? Main most noticeable stuff is in the pebbles of the river at the top of the frame.

By @dhtbrowne

I did some tests today and it turned out to be hard/impossible to get it right. I did also try different encoders but all produced the same issue. Yes, i think the sharpening in camera is set too high as well since i have seen issues like this before.

The best result visually was to apply Gaussian Blur with the Blur Dimensions set to Vertical. I set the Blurriness to 5 but did not test hundred of different values, so it can probably be tuned much better.

Pros: The flicker in the pebbles of the river almost disappeared.

Cons: Well, the whole shot gets blurrier...

So though the pebbles of the river visually looks better the station may reject it again, either due to still having (less) interlcaing issues and/or because the shot looks blurrier than they accept.

Is this the only shot in the TV show that has those issues?

[MyerPj]

I'm surprised they will not accept a progressive scan, that means all these years, they have no equiptment that can convert progressive scans at runtime? 

FWIW: Yeah, the pebbles are the problem.

[dhtbrowne]

Yeah it's a pain. I submitted ep1 as progressive scan and they rejected it because of that 😞

[dhtbrowne]

Mmmmm thats the conclusion I got to but then figured they'd fault it for bluryness. Although thought maybe I could make it look like an intentional effect like tilt shift or something like that.

There are a bunch of shots at this location with this same drone (all shot 23.97) that have been failed in the same episode. But the other eps have been fine, but from memory the DOP shot all the drone stuff at 30fps for all of that.

Thanks for trying! I'll talk to the producers and see if they might be open to the tilt shift thing or changing out the whole shot

[MyerPj]

I gave it a last shot. The vid in all the tests was good with progressive, even the XD-HD

I converted to 25fps and interlaced and it just looked so, so. 

Interlaced 

Progressive