Creating artifacts,....

[Selur]

Just a thought:
Are there Avisynth/Vapoursynth filters to create artifacts? Like ringing, banding, makroblocking, drop-outs, blending, all those.

Why?
a. Because I was wondering why there are not that many machine learning stuff out there that can handle most of these 'usual' artifacts from bad captures or morons doing video editing&co and one reason might be that they simply lack content to train their networks against. From what I gather you usually use a 'good' source, then manhandle it and try to get your network to produce the good source out of the manhandled one. So I think it would help if one could produce such manhandled content from good sources.

b. Because someone might want to create old/manhandled looking content for some other reason.

Cu Selur

Ps.: may be I'm just missing the right search terms to find such filters.

[Cornucopia]

Some of those are due to faultily set and/or quite low bitrate encoding, so a "filter" would have to consist of a complete set of encode+decode. Possible to do, but lots of work to code for such a niche purpose when one could just as or even more easily just export to known encoder & decoder suites.
In the past I have seen some similar things under the heading "convolving" filter...


Scott

[rrats]

Create them yourelf by mishandling the footage across multiple video editors. I do this all the time out of the boredom

[rrats]

Technically all of these are possible to do in Avisynth. I might try to create a script that does it

[Selur]

@s-mp: the point is to do it in an automated fashion not manually.

[jagabo]

I've seen references in these forums to AviSynth scripts that make clean video look like VHS recordings. There are youtube videos about this too. Those may not accurately reflect real VHS artifacts though. Training an AI with them may not work for real VHS recordings

[rrats]

I've seen references in these forums to AviSynth scripts that make clean video look like VHS recordings. There are youtube videos about this too. Those may not accurately reflect real VHS artifacts though. Training an AI with them may not work for real VHS recordings

This man talked about destroyed digital video, not destroyed analogue video

[rrats]

ChangeFPS(60, 1)
AssumeFieldBased()
weave()
BicubicResize(320,240)
BicubicResize(640,480)



Then render with high compression

[rrats]

Does this work, Selur?

[Selur]

@s-mp: That causes some blended frames and blur + it resizes the input to 640x480. If that is what you intended, then yes it is something that could be used.

[rrats]

I think changing colour settings or messing with contrast can cause banding. I am not sure tho

[jagabo]

If you're starting with RGB you can create banding simply by converting to YUV and back.

# RGB 24source
ConvertToYV12()
ConvertToRGB24()

Or you can convert to YUV, reduce the bit depth, the bring the bit depth back up.

# RGB24 source
ConvertToYV24()
#ColorYUV(cont_y=-128, cont_u=-128, cont_v=-128).ColorYUV(cont_y=256, cont_u=256, cont_v=256) # 7 bits
#ColorYUV(cont_y=-192, cont_u=-192, cont_v=-192).ColorYUV(cont_y=768, cont_u=768, cont_v=768) # 6 bits
ColorYUV(cont_y=-224, cont_u=-224, cont_v=-224).ColorYUV(cont_y=1792, cont_u=1792, cont_v=1792) # 5 bits
ConvertToRGB24()

But this type of reduction doesn't fully emulate the type of banding you get from over-compession. It would be better to just compress and decompress the video.

[_Al_]

for some kind of artificial banding, where resize function in vapoursynth does not allow lower than 8bit could be used:

BITS = 6  # 1 to 7
v = {7:4, 6:8, 5:16, 4:32, 3:64, 2:128, 1:256}
downbits =           clip.std.Expr(f'x {v[BITS]} /')
up_8bits_again = downbits.std.Expr(f'x {v[BITS]} *')
up_8bits_again.set_output()

[rrats]

you can do haloing by sharpening footage a little bit

[Selur]

Had a look at https://gitlab.com/bg123/vapoursynth-vhs-fx/-/tree/master since I was wondering how they got the drop outs.
Sadly the simply overlay an existing clip that is black and contains the drop-outs. :/

[rrats]

VHS filters are never accurate.

[Selur]

Can you eleborate what you mean by that?

[rrats]

Real VHS artefacts are random. VHS filters are not

[Selur]

There really isn't a reason why there can't be, both Avisynth and Vapoursynth provide random numbers/functions.

[rrats]

There really isn't a reason why there can't be, both Avisynth and Vapoursynth provide random numbers/functions.

Because effect comes from an overlay that just repeats itself

[Selur]

Because effect comes from an overlay that just repeats itself

In the script I mentioned above: Yes, but like I wrote there isn't a reason why it could only be solved this way.

Cu Selur