What are the conversion options for ffmpeg?
Below is an example of converting 720p to 4K (300%) in Proteus.
-vf veai_up=model=prob-3:scale=0:w=3840:h=2160:preblur=0:noise=0:details=0:halo=0:blur=0:compression=0:estimate=20:device=-2:vram=0.5:threads=0,scale=w=3840:h=2160:flags=lanczos
VEAI can only be set to 1x, 2x, or 4x, so any other magnification is scaled down from a magnification larger than the desired size by ffmpeg’s built-in lanchos. 4x and larger would have been scaled up by lanchos.
In previous versions, the GUI would calculate the scaling factor from the specified size, using scale=2, scale=4, and set it in ffmpeg.
However, in recent versions, if scale=0 is specified and w and h are specified, the magnification is calculated internally and replaced with scale.
In other words, the options are the same as below, with the image scaled up by a factor of 4 and reduced by Lanczos.
-vf veai_up=model=prob-3:scale=4:preblur=0:noise=0:details=0:halo=0:blur=0:compression=0:estimate=20:device=-2:vram=0.5:threads=0,scale=w=3840:h=2160:flags=lanczos
However, depending on the screen size, the magnification calculation may not be performed correctly, and the image may be enlarged from 2x when it should be reduced from 4x, and so on.
I do not like the w,h option because it is not easy to tell at a glance how many times the image has been enlarged.
