Combing artifact when video broadcast?

[Winsordawson]

Recently, the videos I have submitted to the local public access station (NTSC) have been broadcast with bad, large combing artifacts. None of these appear on my interlaced version which has the correct field order. It only happens when there is movement.

I want to tell them about it to avoid this in the future. It this as simple as the broadcast department not choosing the right field order, or something worse? (They are supposed to be upside down).

combing artifact.jpg

Thanks

[lordsmurf]

What is their process? How do they handle the videos?

- interlace field order chosen?
- deinterlace at any step, then reinterlaced later?
- resolution, upscale?

[Winsordawson]

Thanks, I don't know which field order they use but probably lower since that is most common. But my video is also BFF.

I don't think they reinterlace, but from what little I know they may combine all of the videos for that day into one stream to broadcast.

They broadcast it as 480i, 4:3, 29.97 fps. My videos have the same native settings.

[latreche34]

De-interlace it first from now on, The generation that work in studios now don't know how to handle old interlaced videos. If your videos come from modern equipment don't interlace them just send them the way they are, Their equipment can handle downscaling just fine.

[Winsordawson]

Thanks, I will ask them next week if they take progressive video. My videos were originally interlaced, but I create a de-interlaced version for YT anyway. But I never saw combing artifacts so large.

[lordsmurf]

- BFF is only DV
- TFF is everything else

Large artifacts like that can be a mix of wrong settings, often due to upscale interlace, then deinterlacing it badly.

The working generation now is too often poorly educated, and barely grasp modern standards.

[Winsordawson]

Thanks, that's a comment relevant to society at large, too.

I have Pro Res video captured from a third party (U-Matic) that says BFF in MediaInfo. It also appears that because it looks wrong when assuming TFF in Avisynth. So the field order can also be determined by the player irrespective of the codec?

If so, perhaps the department just looked at my h.264 interlaced video and assumed it was TFF because most are that way (I doubt they even have MediaInfo on their PCs ). Although even if true, the output wouldn't look this bad....

-- merged --

I just noticed that although I set BFF in Avisynth and FFMPEG (like in the original video), MediaInfo says that the video is TFF. I read that MediaInfo can sometimes be wrong, but perhaps this could be part of the issue.

My FFMPEG code is:

ffmpeg -i video.avs -c:a mp3 -qscale:a 0 -c:v libx264 -flags +ilme+ildct -preset slower -crf 18 -profile:v high -pix_fmt yuv420p -tune grain -vf setfield=bff video_FINAL.mp4

[hodgey]

You may also need

-top 0

somewhere in there to make it encode as bff.

[Winsordawson]

Thanks, but now I am confused. If I setfield=bff, I want the bottom/lower fields (the second, fourth, sixth line etc.) to be first. Followed by the top fields (the first, third, fifth lines, etc.), if my understanding is correct.

So why would I use -top? Would I not use something like "-bottom 0"