Sinc filter does not work with videos

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: https://github.com/mpv-player/mpv/issues/13672

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.

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

Cannot replicate the output with libplacebo e987124b 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

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.

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.

fixed in https://github.com/haasn/libplacebo/commit/76bb971847a5c7f5a40596edcb071de5ab8b7446