Deinterlace from 50i to 25p

Is there a way of getting resolve to deinterlace 50i as 25p rather than 50p? I've read a lot of the threads about deinterlacing and I know it deinterlaces this way by default.

I do a avid roundtrip so I'd love the clips to be 25p if possible. Is there an option or way of making it force 25p?

I know it deinterlaces this way by default.

This is incorrect.
How the material is deinterlaced depends on the timeline settings.
If you create a 25p timeline and insert 50i material, the result will be 25p.
If you have the Studio version of Resolve, you can use 3 different algorithms for deinterlacing.
Project settings > Image scaling > Deinterlace quality
Sometimes DaVinci Resolve does not interpret the footage correctly.
In this case, you must manually set the field dominance in the clip attributes.

If that is the case, then can you explain why this is happening.

I am using a 25p timeline with 50i footage. The clips are being interpreted by resolve as upper field which is exactly what they are.

I am using an imported aaf from avid set to 25p, and when I render from that timeline 50p clips are created from the interlaced footage. I have tested this with image scaling set to 'high' and 'neural engine' with the same result.

I then thought, maybe the avid aaf timeline is doing something weird. So I put that footage on a new resolve created 25p timeline and rendered from that, which also created 50p clips.

I have read people on other boards saying that resolve deinterlaces at 1 field to 1 frame, as in 50i to 50p which is what is happening for me, so I can only surmise that is actually correct.

Am I missing some other option somewhere?

If that is the case, then can you explain why this is happening.

I have read people on other boards saying that resolve deinterlaces at 1 field to 1 frame, as in 50i to 50p which is what is happening for me, so I can only surmise that is actually correct.

Am I missing some other option somewhere?

No the other user is incorrect, it works as you've described, although it sounds odd, you must set a frame rate of 25 frames per second into master settings then bring in your video, say no to automatic timeline settings, and then you will be able to export at 25fps. It would seem like you're asking for trouble and it's not really deinterlacing but it does or the moving square would show interlace artifacts.

First 5 seconds is Resolve default for NTSC, and you'll notice the flashing decimal point indicating top field, last 5 seconds encoding to 30fps and the decimal point no longer flashes and the square will not move as smoothly as the top and bottom field have been integrated into one frame. You must watch in 720P or higher to see the difference

you must set a frame rate of 25 frames per second into master settings then bring in your video, say no to automatic timeline settings, and then you will be able to export at 25fps.

This is how I brought everything in? So I'm not sure what I've messed up in the process.

When I import 50i material and create a 25p timeline i get perfectly fine 25p !

I am using an imported aaf from avid set to 25p, and when I render from that timeline 50p clips are created from the interlaced footage.

You didn't mention this in your first post.
And I missed the "roundtrip to Avid" part.
AAF are known to be buggy in Resolve.

I put that footage on a new resolve created 25p timeline and rendered from that, which also created 50p clips.

Are you exporting the 25P timeline, or individual clips?

Are you exporting the 25P timeline, or individual clips?

Individual clips from a 25p timeline.

If you are exporting individual clips make sure to check "Render Timeline Effects".

Hi Alyce!!

I think this is fixed in the latest version v19.1.4.

If not, here's a workaround:

In the Resolve Media Pool change the clip attributes of all the interlaced clips from Upper Field to Progressive.

Grade the clips but avoid any resizing, stabilising etc as this will break the interlacing. Just do colour adjustments.

Do the round trip back to Avid avoiding any scaling (so Source Resolution and Disable Sizing might be best). In Avid the Interlaced clips will be marked as Progressive but they are actually still interlaced because they were never de-interlaced. If you'd like to tag them as interlaced you can show column 'Field Order' and change the clips back to Interlaced.

Now the clips can be de-interlaced in Avid. You could use BCC Deinterlace for this, make sure there's no motion adapter on the clip before adding BCC.

Hope that helps.

I think this is fixed in the latest version v19.1.4.

Thanks, Brendan!

I'm on v19.1.4 so unfortunately not fixed.

Ideally I'd rather not deinterlace in avid just cos of render times etc. Avid is adapting and playing the 50p clips fine. And is actually relinking perfectly. Do you see any problem with just going with that? We have had it checked with our QC peeps and they say it looks okay.

Everyone here is baffled as to where the extra information is coming from to make 50 frames out of 50 fields? haha

I thought I had some Interlaced clips recently that came out as 25p so I thought the problem was fixed, obviously that's not the case.

You could use Avid Motion Adapters to do the de-interlace of the graded clips (after marking them as Interlaced and refreshing adapters) and this would be real-time/fast renders but the quality of the de-interlace wouldn't be as good as BCC or Resolve.

But it sounds like you have it all working quite well anyway. If your 50fps clips are linking okay then that's great!

Resolve is turning each field into a frame to make 50fps and then I assume Avid is dropping every second frame when using motion adapters to go from 50fps to 25fps. So the end result sounds similar to the old fashioned de-interlace method of 'dropping a field.'

Technically it should be fine for QC/broadcast. If it's not showing really obvious jagged edges/aliasing then I'd say what you're doing is totally fine.

I thought I had some Interlaced clips recently that came out as 25p so I thought the problem was fixed, obviously that's not the case.

Hmmm, I wonder if there's something else somewhere I need to set, I dunno. I've trouble shooting loads (rendering out on different timelines etc) and have only managed to get 50p out haha.

Resolve is turning each field into a frame to make 50fps and then I assume Avid is dropping every second frame when using motion adapters to go from 50fps to 25fps. So the end result sounds similar to the old fashioned de-interlace method of 'dropping a field.'

We used to resort to using a Version16 project to get the original 'deinterlace' option in clip attributes. But then we had trouble with getting it back into avid (relinking out of sync etc). This deinterlace looks better than that, so I guess I'll just go with it for now.

I just did a quick test and got the same as you - 25i comes out as 50p.

I did make it work by using BCC Deinterlace in Resolve.

Change the Interlaced clips to Progressive in Clip Attributes, then add the BCC Deinterlace effect to those clips in the timeline.

Or you can add it in the Colour page. So if you have a complex timeline you could flag the Interlaced clips, filter the clips in the colour page and batch apply the BCC Deinterlace, or put them in a group etc.

That'll render out 25p, but your render time might go up a bit.

If you are exporting individual clips make sure to check "Render Timeline Effects".

This works!

However that option disappears when using the Avid AAF export preset. Alyce, if you're able to relink to the graded media in Avid without using the graded AAF you might be able to export the individual source clips using Custom Export and enabling Render Timeline Effects.

I haven't tried this myself on a large sequence, so I don't know if enabling Render Timeline Effects breaks anything else when doing the round trip. I'm curious about why the option isn't there for the AAF preset.

Definitely worth testing if you have time.

This works!

However that option disappears when using the Avid AAF export preset. Alyce, if you're able to relink to the graded media in Avid without using the graded AAF you might be able to export the individual source clips using Custom Export and enabling Render Timeline Effects.

Oh, great! I was looking for it when Christoph suggested it and couldn't find it, but that all makes sense if its not on the avid preset.
I will give this a try!

I haven't tried this myself on a large sequence, so I don't know if enabling Render Timeline Effects breaks anything else when doing the round trip. I'm curious about why the option isn't there for the AAF preset.

Definitely worth testing if you have time.

Okay so I tried this.

Yes it did make 25p clips. But it gave them the timeline timecode rather than source timecode. So can’t relink in avid.

Will look more tomorrow as I ran out of time today. But anyone know if there’s a way around this?

But it gave them the timeline timecode rather than source timecode.

Oh no! Well that explains why Render Timeline Effects isn't an option for the AAF export!

But it gave them the timeline timecode rather than source timecode.

Oh no! Well that explains why Render Timeline Effects isn't an option for the AAF export!

Yeah, sorry, I forgot about that silly restriction.
It really should be possible to render the timeline effects AND export with the source timecode.
But as far as I know, that's not possible at the moment.

But it gave them the timeline timecode rather than source timecode.

Oh no! Well that explains why Render Timeline Effects isn't an option for the AAF export!

Yeah, sorry, I forgot about that silly restriction.
It really should be possible to render the timeline effects AND export with the source timecode.
But as far as I know, that's not possible at the moment.

I guess it's because there could be speed effects in the timeline that wouldn't translate to source timecode (although deinterlacing would be OK)