Flickering, pulsating after deinterlace with QTGMC in AviSynth+?
 

I'm working on old VHS-C camcorder footage, that was digitized using a HDD/DVD recorder. I use OTGMC for deinterlacing, which works well, but I do have a problem. I'm hoping someone might have a suggestion about how to fix it. The problem is this: after deinterlacing, the resulting video has a very annoying flickering / pulsating effect in dark areas (especially in the top corners). This is not an artifact produced by QTGMC, since it can be clearly observed after simply applying SeparateFields() to the original video. Apparently the bottom fields are somehow slightly darker (in the top area) than the top fields. This off course results in the odd frames in the deinterlaced video to be somewhat darker than the even frames, which produces the flickering / pulsating.
Obviously, I can simply discard all the odd frames by applying SelectEven() after deinterlacing. This solves the flickering / pulsating problem, but also makes the motion much more jerky. So, I don't want to do that.
Another thing I tried is the ReduceFlicker plugin (with strength=1). This gets rid of most of the flickering / pulsating, but it produces horrible artifacts in scenes where there's lots of motion.
So, do you have any idea how I can get rid of the flickering / pulsating, without sacrificing smooth motion and without these artifacts? Does QTGMC itself by chance have a way of addressing this issue with its many, many parameters? Or do you know another method that might do the job?

apply a brigthness reduction/increase in odd/even fields with AviSynth, then deinterlace

I am digitizing VHS-C and I am trying to figure out the same thing. I did notice that when I turned my line TBC on in my Panasonic 1980p ag it helped a lot. It’s not really that bad now. When I look at my captures on certain parts the tint alternates.

Yes, I thought about that as well. But not the entire picture is affected. it's mostly the top third of the screen, and especially in the top corners. If, for example, I would selectively increase the brightness, or reduce the contrast on the bottom fields before deinterlacing, so that the top corners no longer flicker, that would most likely introduce a flickering effect on the rest of the picture, effectively making things worse instead of better. For this to work, I would need some kind of masking function to only apply the correction to the affected areas.

Better hardware helps a lot on this.

Unfortunately I cannot go back in time and ask my dad to buy a different camcorder... :D

Maybe try FluxSmoothT? On only the affected area:

Thanks! That does look much better on the sample clip. I'll need to check how well it performs on the rest of the footage, of course.

Yea I can’t go back in time to tell my mom to get something better either but ow well. At least they cared enough to record this stuff.

Here’s my flicker problem with VHS-C. https://www.digitalfaq.com/forum/vid...ore-after.html. I have noticed that my line TBC pretty well completely gets rid of the flicker on my tapes that I have captured so far. That one spot is just bad.

Have you tried these yet?

- the wheels
- the gadget

For those prices, you'd expect it to work as seen on screen. :woot:

Well, in my case everything (about 40 hours of footage) has been digitized already, and I'm not planning to go through that process again. Besides, the tapes I have are second generation video, since dad always used to copy the VHS-C recordings to regular VHS tapes and then reuse the VHS-C cassettes. So I doubt another piece of hardware would do all that much to improve the image quality. So, I'm just going to work with the captures I have and try to correct any flaws as well as I can using AviSynth and plugins.

I found that FluxSmoothT does a pretty decent job of getting rid of the flickering, except in extreme cases where the image is way too dark and the contrast needs to be increased significantly. But those are rare, and I can live with some remaining flickering there. And it looks like that filter doesn't introduce any horrible artifacts either. So, I'm quite happy! I don't expect those old videos from the 80's to ever look like modern digital video... :P

Haha good idea.

Great.

For me the VCR was a big quality improvement then my proc amp helps a lot. Before the VCR they were absolute trash. At the same time you’re right. They’re still VHS-C and mine are in EP. That’s why I’m thinking well these are probably just going to be only a YouTube upload so what well I be able to notice after YouTube has its way with them? My project is about the full size tapes after these anyways.

With a bunch of mine they just aren’t shot well. That depends on who was behind the camera but the ones that are shot well look pretty good.

I am going to recapture mine that was flickering with the saturation turned down a little and the hue changed and the sharpness on the middle notch. That capture was before I messed with that. I might call it good after that.

ReduceFlicker works fine to remove the luma flickering.

Yes, as I said in my original post it does remove the flickering. But it also introduces horrible artifacts on scenes with lots of motion. Pay close attention to people's faces.... :eek:

Using the Vapoursynth version of ReduceFlicker with: 'ReduceFlicker(clip=clip, strength=3, aggressive=1)'
I didn't spot anything,...

You're right. Because that clip contains very little motion. Try using it on a clip with fast panning motion, and see what happens. I used it with strength=1 and aggressive=false (in AviSynth) and was quite satisfied with the results at first, until I came across the artifacts in other scenes.

Ah, okay, without a sample of such a scene which allows reproducing the problem you are on your own then. ;)

I don't have access to my videos at the moment. Maybe I'll upload a sample tomorrow. But I'm using FluxSmoothT now. It doesn't get rid of the flickering completely, but it has the advantage of not creating artifacts. So, I'm happy!

Here is an example of what ReduceFlicker does to scenes with fast panning motion, and a comparison to FluxSmoothT.