August 14, 2020, 02:15:17 pm



Resize Filter UI Improvement

Started by butterw, July 23, 2020, 08:28:06 pm

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1. Should round to mod8 by default (vs only mod16). 1080p is mod8 not mod16 !
2. Should display the output Aspect Ratio (ex: 1.778 - 16/9, 4/3, 9/16, 21/9)
and display the mod level ex: mod16, especially if it is too low (mod-4, mod-2)

(Improvements to resize functionality:)
3. More/updated options for resize: more Algorithms + parameters, bicubic should be default (for downscaling) ?


Spline36Resize seems to be the current go-to resizer in avisynth:
Mitchell-Netravali family Bicubic(B, C) can also be used.
Lanczos is not recommended for downsizing compressed sources.

Regarding the mod setting:
mod-16 is best, but modern codecs can all handle mod-8 (because 1080 is mod-8)
Say you had to crop the source video and want to resize down, the GUI doesn't give you enough help in determining the right resize dimensions.   


At the codec level, 1920x1080 is in most cases not really 1920x1080, it is 1920x1088 with 8 lines at the bottom cropped. I realize that with 16 as roundup value, it is impossible to input 1920x1080, which is IMHO a minor inconvenience.

This "Resize" filter provides GUI access to some features offered by libswscale in FFmpeg, other providers should be exposed in dedicated plugins. In any case, code contributions are welcome, but further work on swsResize plugin in not on my todo list.

Thank you for your input.