Handbrake artifcat with fine parallel lines

[uvhp]

For mpeg2 (dvd) to h.264 conversion with handbrake, scenes that have fine parallel lines (example the window blinds, or some sort of a fine grid) end up bad with very visible artifacts even at high RF quality settings like 16-18 (the rest settings being just same as built in preset like 'Fast 480p30'). The output instead of a still window image is something like a gif with some kind of motion happening. Is there some setting that will avoid this? I tried a RF10 value (placebo quality) but that doesn't address this. Thanks!

[manono]

'Fast 480p30'? Meaning 30fps? Is it a movie? Do you have an unreencoded short 10-second sample made from the DVD? One with steady movement? An M2V perhaps created in DGIndex?

[uvhp]

"Fast 480p30' is the name of a preset in handbrake. The src is 30fps.

[jagabo]

Are you resizing, deinterlacing, or sharpening? That causes moire artifacts like those you are describing, not the encoding.

[manono]

"Fast 480p30' is the name of a preset in handbrake. The src is 30fps.

I repeat:

Is it a movie? Do you have an unreencoded short 10-second sample made from the DVD? One with steady movement? An M2V perhaps created in DGIndex?

[uvhp]

I am attaching a sample (source and output mp4). Notice the grid pattern behind the person.

[LMotlow]

You didn't say you cropped the frame to mod2 dimensions and inverse telecined it.

[uvhp]

It is from a default setting in handbrake. I did not use any explicit cropping settings. What is mod2, inverse telecine? IMO this artifact seems to be unrelated to the dimension/crop and happens regardless.

[poisondeathray]

Those coarse lines in the background from deinterlacing post processing after fieldmatching. The fine patterns are detected as "combing" by handbrake . If you can disable that in handbrake it will "less bad" . If you were using avisynth , it would be TFM(pp=0).TDecimate() to IVTC but disable the post processing. Not sure of what the equivalent would be in handbrake . Maybe --no-decomb ?

https://handbrake.fr/docs/en/latest/cli/command-line-reference.html

But some of it is unavoidable - fine lines and patterns will always cause moire patterns, especially from dvd.

eg. (not cropped or resized)

[jagabo]

Another way with TFM is to increase the post processing combing threshold from the default of 9 up to 11 -- TFM(cthresh=11).

In Handbrake Set Detelecine to Default and Deinterlace to Off. Set the frame rate to constant, 23.976.

[uvhp]

Changing the Deinterlace option (in the filters tab) from Default to Off makes the output a lot better. With so many settings I did not know which one to experiment with. Thank you people so much for your directions.

Now that makes me wonder what the downside is if I turn that filter off? That filter is ON at default in all the presets. There must be a reason. What does it do anyway? Does it do more good than harm? I will try to read some information about it as well.

Thanks again.

[jagabo]

Now that makes me wonder what the downside is if I turn that filter off?

True interlaced material won't be rendered correctly -- comb artifacts will appear in the output file.

[uvhp]

What is a good way to decide to keep the decomb filter on or off or keep at some intermediate setting? How do we find if the source is interlaced or not?

Also you suggested "Set the frame rate to constant, 23.976". Should I do that or set it to "same as source"? The dvd is 2.97 fps.