FFmpeg: Ultimate film grain

ffmpeg film grain

ffmpeg -i "HD Splice 1080p No Grain.mkv" -i "HD Splice 1080p No Grain.mkv" -filter_complex "
        color=black:d=3006.57:s=3840x2160:r=24000/1001,
          geq=lum_expr=random(1)*256:cb=128:cr=128,
          deflate=threshold0=15,
          dilation=threshold0=10,
          eq=contrast=3,
          scale=1920x1080 [n];
    [0] eq=saturation=0,geq=lum='0.15*(182-abs(75-lum(X,Y)))':cb=128:cr=128 [o];
 [n][o] blend=c0_mode=multiply,negate [a];
        color=c=black:d=3006.57:s=1920x1080:r=24000/1001 [b];
 [1][a] alphamerge [c];
 [b][c] overlay,ass=Subs.ass"
       -c:a copy -c:v libx264 -tune grain -preset veryslow -crf 12 -y Output-1080p-Grain.mkv

I suspect the only way to really achieve what you're looking for will be to add film grain only if the bitrate is high enough to eliminate macroblocking. But, perhaps judiciously applying a denoise filter before encoding could allow a lower bitrate to do a good job conveying smooth frames, and then that would be a suitable thing to add fake film grain to at playback time.

I am trying to beautify a tv series with this. But in every episode after 50 mins and 6 secs (movie length) ffmpeg throws "EOF timestamp not reliable" and from now on the grain is not changing anymore between the frames (like not temporal). Any idea what could cause this?

OP, what is your goal?

kocoten1992, this is similar to what AV1 is trying to do. I am unsure how well it works in real-world tests.

https://norkin.org/research/film_grain/index.html

My goal is simulated film grain that looks more like the real thing than just per-pixel noise.