Sinc filter does not work with videos

[lextra2]

Command used to test:
ffmpeg -y -benchmark -init_hw_device vulkan -i "input" -vf "libplacebo=w=iw*2:h=ih*2:upscaler=sinc" -c:v libx264 -preset ultrafast -qp 0 -g 1 -an test123.mkv

Some comparisons:

Spline36 (Avisynth)

Sinc (Avisynth) How it is supposed to look

Bilinear (Avisynth)

Sinc (libplacebo) Looks blurrier then Bilinear

The same thing happens with gpu-next in MPV: mpv-player/mpv#13672

[Chipcraft]

Can you provide the same source frame you used, as a reference?

Avisynth is using four taps for Sinc, whereas libplacebo uses three taps however, that is unlikely to cause the difference.
Within libplacebo itself, Sinc is clearly superior to bilinear.

[lextra2]

Can you provide the same source frame you used, as a reference?

Within libplacebo itself, Sinc is clearly superior to bilinear.

I've only included bilinear for sharpness comparison

[Chipcraft]

Cannot replicate the output with libplacebo e987124 and ffmpeg master ab2173c0a5.

ffmpeg -init_hw_device vulkan -i 313426824-3cc2ca8e-7c87-44b7-978d-e7531ea335e3.png -vf libplacebo=upscaler=sinc:w=iw*2:h=ih*2 -pix_fmt rgb24 Sinc_Out.png

https://nle-chipcraft.com/Git/Sinc_Out.png

[lextra2]

Cannot replicate the output with libplacebo e987124 and ffmpeg master ab2173c0a5.

ffmpeg -init_hw_device vulkan -i 313426824-3cc2ca8e-7c87-44b7-978d-e7531ea335e3.png -vf libplacebo=upscaler=sinc:w=iw*2:h=ih*2 -pix_fmt rgb24 Sinc_Out.png

https://nle-chipcraft.com/Git/Sinc_Out.png

Yeah weird. That works.
And
ffmpeg -loop 1 -init_hw_device vulkan -i input.png -c:v libx264 -qp 0 -t 15 -vf libplacebo=upscaler=sinc:w=iw*2:h=ih*2 -pix_fmt yuv420p test.mp4
works too.

But this code
ffmpeg -init_hw_device vulkan -i input.mkv -vf "libplacebo=w=iw*2:h=ih*2:upscaler=sinc" -c:v libx264 -preset ultrafast -qp 0 -an test567.mkv
does not work.

[lextra2]

Here, try this 30 seconds snippet.
Reference frame is at 0:25.025 (Frame 600)

And this time, encode it as video.

Edit: My guess is it only works with RGB inputs, and YUV fails. Pure speculation. Can't test right now.