Using deface on 10 Bit HDR Videos
Posted on :: Linux Scripts deface

deface is a script to automatically blur faces. Its underlying engines onnxrt and opencv are limited to 8-bit processing. It took me way too long to figure out how to use deface’s capabilities while preserving the full 10-bit color information (I admit, it’s very niche).

That’s why I just want to briefly mention the result here.

cat cat

uv tool install deface --with onnx --with onnxruntime

Faces
Original
faces blurred
deface <image/video>
Using deface – as far as I can see – there is no way to preserve the 10-bit color information. But we can use a trick and generate an 8-bit binary mask that we can use with ffmpeg to manually blur the regions.
faces blacked
deface --replacewith solid <infile>
We can use the above starting point and inject ffmpeg postprocessing arguments (--ffmpeg-config) to replace every non-black color with white.

Let’s construct the command. Using the lossless codec ffv1, the raw command looks like this:

ffmpeg -i <infile> -vf "geq=\
    r='if(bitand(eq(r(X,Y),0),bitand(eq(g(X,Y),0),eq(b(X,Y),0))),0,255)':\
    g='if(bitand(eq(r(X,Y),0),bitand(eq(g(X,Y),0),eq(b(X,Y),0))),0,255)':\
    b='if(bitand(eq(r(X,Y),0),bitand(eq(g(X,Y),0),eq(b(X,Y),0))),0,255)',\
    negate" -c:v ffv1 <outfile>.mkv

This converts to:

deface --replacewith solid --ffmpeg-config '{
    "codec": "ffv1",
    "ffmpeg_params": [ "-vf", "geq='\
'r='\''if(bitand(eq(r(X,Y),0),bitand(eq(g(X,Y),0),eq(b(X,Y),0))),0,255)'\'':'\
'g='\''if(bitand(eq(r(X,Y),0),bitand(eq(g(X,Y),0),eq(b(X,Y),0))),0,255)'\'':'\
'b='\''if(bitand(eq(r(X,Y),0),bitand(eq(g(X,Y),0),eq(b(X,Y),0))),0,255)'\'',negate"]}' \
  -o binary.mkv <infile>

The output is a lossless binary video:

faces blacked

We can now manually blur the video and use this mask to stamp out parts of it that we subsequently overlay onto the original. Assuming we have a file in yuv420p10le:

ffmpeg -y -i <infile> -i binary.mkv -filter_complex \
    "[0:v]gblur=sigma=15[blur];\
     [blur][1:v]alphamerge[merge];\
     [0:v][merge]overlay=format=yuv420p10" <outfile>
faces blacked