When Are Debancing and Dithering Needed?

[MysteryX]

I'm still confused about the whole Debanding/Dithering thing.

I wrote a software that contains a Media Encoder (https://www.spiritualselftransformation.com/blog/conscious-business/conscious-ressources/natural-grounding-player-v1-1-released-on-source-forge/) that allows upscaling SD content into HD with just a few clicks; GREATLY simplifying the process, especially if you need to convert 50 videos.

Here's a sample video before (https://www.spiritualselftransformation.com/files/media-encoder-old.mpg) and after (https://www.spiritualselftransformation.com/files/media-encoder-new.mkv).

Now my question is: would this video benefit from any debanding and/or dithering? What difference do they make? When are those needed?

[creaothceann]

When are those needed?

Recent example I did on a wallpaper (possibly nsfw)...

original: http://i.imgur.com/gQVFk5W.jpg
fixed: http://i.imgur.com/UwRFR8K.jpg

script:
ImageSource("source.png", 0, 0)
ConvertToYV12
GradFun3(smode=2, thr=0.35*2, thrc=0.35*2, radius=16, radiusc=16)

[MysteryX]

Yes I know what debanding is, but I honestly don't notice any of it in most videos.

[wonkey_monkey]

Recent example I did on a wallpaper (possibly nsfw)...

I'm truly shocked by those images. She's not wearing a crash helmet!

[vivan]

Debanding is the process of removing banding. Usually it's performed by reconstructing gradients to a higher bitdepth.
Imagine having a gradient that goes from 0 to 10 in 20 pixels - you need a >8 bit colorspace to store it.

Dithering is the process of lowering bitdepth. Just dithering makes on sense - you can't lower 8 bits to 8 bits.
After debanding you have 16-bit image - so you have to lower bitdepth at some point. Most debanding filters (if not all) have built-in dithering. Some have an option to output 16-bit image, so you can process it further (read about dither tools) and dither it down to 8/10 only at the end.

Will your video benefit from debanding? Probably just a bit. But you'll need way higher bitrate to encode all noise it adds. Or 10 bits.

[foxyshadis]

You left enough grain in these videos that there's no appreciable banding -- banding noticeably occurs when a video is too clean, not when it's dirty. Of course you won't get any use out of debanding.

There's a much bigger problem though: The after video exhibits severe judder, so something about your 25->60 frame rate conversion is incorrect. It's producing very jerky video that appears to skip frames several times a second or double up frames too many times, I'm not sure.

[MysteryX]

You left enough grain in these videos that there's no appreciable banding -- banding noticeably occurs when a video is too clean, not when it's dirty. Of course you won't get any use out of debanding.

There's a much bigger problem though: The after video exhibits severe judder, so something about your 25->60 frame rate conversion is incorrect. It's producing very jerky video that appears to skip frames several times a second or double up frames too many times, I'm not sure.
I'm using the "Smooth" preset, could that be it? It can cause artifacts.

[MysteryX]

I looked again more carefully at the clip frame by frame and don't see what you're referring to. The only thing I see is "1 frame repeat every 16 seconds"

[osgZach]

You left enough grain in these videos that there's no appreciable banding -- banding noticeably occurs when a video is too clean, not when it's dirty. Of course you won't get any use out of debanding.

There's a much bigger problem though: The after video exhibits severe judder, so something about your 25->60 frame rate conversion is incorrect. It's producing very jerky video that appears to skip frames several times a second or double up frames too many times, I'm not sure.


I'm not really seeing the judder either. Maybe my eyes are getting crap with age, all I see is ocassional crap camera-work :D

I did see one slight jerk in the beginning but that was about it. Couldn't tell after that if it was frame repeats / or shitty camera man when watching in real-time.

[foxyshadis]

My bad, I watched one with MPC and one with MPDN. The new one looks smooth on MPC. I'm not sure why MPDN failed with this when it's fine with 1080p, but I'll have to remember that from now on....