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25 Jan 2021
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Strange Problem after Improving Aliasing on Drone Footage 31 Jul 2021 20:17 #115595

  • Finbo
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Here in the UK, broadcasters are still very much living in an interlaced world.

When using drone progressive footage on an interlaced timeline in FCPX, on my MacBook Pro, I see a lot of aliasing and moire present. It does not look good at all.

I've been looking online for any workarounds to improve the picture quality, but without much success. There is an article on this site whereby someone suggested using Optical Flow but I found it didn't make any real difference.

I then tried setting up an interlaced pre-set in Compressor using the best quality and anti aliasing options. My workflow was to initially export the original clip in Pro Res rather than H264 and then bring that clip into Compressor and apply the preset.
This was exported to my Desktop and when I looked at what Compressor had done to the clip in Quicktime Player it looked much improved and the aliasing and moire was greatly reduced.

Great I thought, I'd found a workaround to solve my problem.

But, when I imported this clip back into FCPX to use on an interlaced timeline edit, the aliasing and moire was present again!

Any thoughts on why this might have happened?

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Strange Problem after Improving Aliasing on Drone Footage 01 Aug 2021 06:11 #115596

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Quicktime is not the best solution to judge interlaced footage as, I believe, it automatically de-interlaces your footage when playing back. Try using VLC player for a more realistic interpretation of how your compressor setting worked. In FCPX, when you drop your footage on the timeline you can change it from progressive to interlaced by setting parameters in the video inspector - select the info tab and choose "settings". Here you can check de-interlace and above that you can choose the field dominance override. See the screenshot.
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Strange Problem after Improving Aliasing on Drone Footage 01 Aug 2021 07:27 #115597

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Ok, thanks for this.
The Compressor setting also looks much better in VLC as well as Quicktime, but not good when re-imported into FCPX.
The reason I looked into a setting in Compressor is when the drone footage is just dropped on to an interlaced timeline alongside footage originally filmed at 50i, it doesn't look great on my MacBook Pro. Footage from a GoPro, for example, does look ok when just dropped onto an interlaced timeline.
The settings from the posted screenshot are only available to change if you're working in a progressive timeline and not an interlaced one, from what I can see.
Obviously wondering then why the footage doesn't look so good after being re-imported into FCPX when it looks ok in VLC?

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Strange Problem after Improving Aliasing on Drone Footage 01 Aug 2021 17:06 #115599

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....when the drone footage is just dropped on to an interlaced timeline alongside footage originally filmed at 50i, it doesn't look great on my MacBook Pro. Footage from a GoPro, for example, does look ok when just dropped onto an interlaced timeline...

If the timeline is interlaced, the FCP viewer may not not show both interlaced fields. To see both: View>Show in Viewer>Both Fields.

However showing both fields might make it look "worse" in the viewer, because it then shows both interlaced fields without deinterlacing the viewer. But trying it both ways can sometimes help verify the clip's attributes.

.The settings from the posted screenshot are only available to change if you're working in a progressive timeline and not an interlaced one, from what I can see...

That is correct. An interlaced timeline by definition is interlaced. There is no such thing as a "deinterlaced interlaced" timeline. FCP will not let you apply deinterlacing to a clip in an interlaced project. The entire exported timeline consists of a single video file with metadata in the header. That metadata flags the whole file as either interlaced or progressive.

The exported interlaced timeline is supposed to be deinterlaced by the playback chain, whether that is a TV or playback app, etc. By contrast you can put interlaced clips into a progressive project and "hard deinterlace" them by applying the FCP deinterlace attribute to those clips. The exported timeline will be flagged progressive in the file metadata.

....Obviously wondering then why the footage doesn't look so good after being re-imported into FCPX when it looks ok in VLC?

The current version of VLC by default will deinterlace during playback. You can turn this on/off and select various deinterlacing algorithms. E.g, VLC menu Video>Deinterlace>Off/On/Auto, and Video>Deinterlace Mode.

By contrast if the FCP viewer is set to "show both fields" the material may exhibit comb artifacts on moving objects. That is how interlaced video looks if it's not deinterlaced.

If you drop progressive drone footage into a 50i interlaced project in FCP, and if the FCP viewer is set to show one field, there may be aliasing on diagonal edges of that clip. If you export the interlaced timeline and play that clip in VLC with Video>Deinterlace>On and Video>Deinterlace Mode>Yadiff, the diagonal edges of the object in the progressive clip should be smooth. That is because the interlaced video file is being deinterlaced during playback, as intended.

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Last edit: by joema.

Strange Problem after Improving Aliasing on Drone Footage 02 Aug 2021 09:01 #115611

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Many thanks.

I'd forgotten about the "Show Both Fields" option in the View menu. Ticking this has made all the difference (shame FCPX doesn't remember the setting and you have to do this every time you switch the laptop back on). The drone footage on an interlaced timeline now looks ok. I would say the 4K 25p clip looks better than the 1080 50p clip on the interlaced timeline - less aliasing on the roof of the buildings - but it is a closer shot.

But the main thing is this looks like a solution to my initial problem.

Many thanks

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