APNG encoder AVOptions:
-dpi <int> E..V...... Set image resolution (in dots per inch) (from 0 to 65536) (default 0)
-dpm <int> E..V...... Set image resolution (in dots per meter) (from 0 to 65536) (default 0)
-pred <int> E..V...... Prediction method (from 0 to 5) (default none)
none 0 E..V......
sub 1 E..V......
up 2 E..V......
avg 3 E..V......
paeth 4 E..V......
mixed 5 E..V......