Interlaced video saved as progressive scan, how to convert to interlaced?

Started 2 months ago | Discussions thread
OP toughluck Veteran Member • Posts: 3,713
Re: Interlaced video saved as progressive scan, how to convert to interlaced?

Gary3000 wrote:

Sean Nelson wrote:

Gary3000 wrote:

Sean Nelson wrote:

Gary3000 wrote:

Sean Nelson wrote:

The OP's problem is that he's got a video marked as 25p where each frame has both the odd and even fields combined into a single image, and because these fields were originally captured 1/50th of a second apart any motion in them results in combing artifacts like this (from the Wikipedia article):

Honestly, it sounds like the OP has never worked with interlaced video. The above image is what a frame of interlaced (50/60i) video looks like

NO, that is NOT what a frame of interlaced video looks like. The picture above is a single image. In an interlaced video, there are two separate "fields" that store the even and odd scan lines of the image. This is a critical distinction, it's the crux of the problem that the OP has.

WRONG. Sounds like you've never worked/manipulated INTERLACED video before as well. how else do you think they arrived at the term INTERLACED?
Open up ANY footage, in any codec, QT Player, or VLC player, ..or drop into After Effects, and that is EXACTLY what a properly encoded frame of INTERLACED video looks like. The only way to view without the interlacing is to DE-Interlace!

Spoken like someone who's never watched video on a CRT.

There's a difference between what you see on a progressive screen and what's stored in the file. For a discussion of interlaced file encoding, look up "Picture-Level Frame/Field Coding" or "Macroblock-Adaptive Frame/Field Coding".

The player software you use makes a difference too, some players do a much better job of deinterlacing than others. Decent software would NOT show the kinds of artifacts that you see in the image above because it analyzes the even and odd fields and compensates for the positional differences between them.

And that's the crux of the matter: because the OP's video is encoded as progressive, the player cannot perform deinterlacing and artifact removal. That's exactly why he wants to find a way to reencode it as interlaced.

I've been working in Broadcast television, at the Network level (NBC), for over 25 years, and using After Effects the same amount of time as well (v1.0), so pretty sure I have significantly more experience "dealing" with interlaced video issues than most people here.

Listen, that's nice, but it has literally zero bearing on my problem. You can expect your co-workers to do it right.

So the cameraman won't play with his camera settings. Before HD days, you didn't suddenly get video delivered in PAL 25 fps at 576 lines, you always got a neat NTSC video at 30 fps at 480 lines.

The person in charge of collecting and tagging the original footage won't fool around converting them to random formats with incorrect metadata, but will always convert them to a format that's expected next.

The most important thing here is you have people responsible for their part of the production pipeline.

But outside the broadcasting industry, there are tons of people doing professional video who don't know everything, but need to do the entire workflow. The same person films the footage, drops it into some NLE, does editing, renders it out and records it to disc (okay, used to record it, hardly anybody does anymore). They're bound to not know everything and to make blunders.

I always render out QT ProRes, and regardless of if it's interlaced, progressive, or contains 24fps video that's got 3:2 pulldown, it ALL goes out as a 29.97 QT movie. it's not "encoded" progressive or interlaced. Nor is there an option to "encode" progressive - that all depends on the image. - not the encoding.

Okay, but the video I had wasn't rendered in QT ProRes.

Now how software decides to deal with it, is all up to the software.
but no, this doesn't sound like the OP is having trouble with playing back interlaced footage, sound like something far more confusing to the OP, or someone like yourself could have provided a better answer than "try FFMPEG"

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