[FFmpeg-devel] [PATCH 2/2] doc/utils/eval: clarify meaning of random* seed value

Michael Koch astroelectronic at t-online.de
Wed Jan 3 13:20:12 EET 2024


 > Possible address trac issue:

> http://trac.ffmpeg.org/ticket/10763

I don't like the random generator as it is, because the first two random numbers
are very close to zero, as can be shown with this command line:
ffmpeg -loglevel repeat -f lavfi -i nullsrc=size=1x1,format=gray -vf 
"geq=lum='print(random(0));print(random(0));print(random(0));print(random(0))'" 
-frames 1 -y out.png 0.000000 0.000091 0.285346 0.929202 This behaviour 
can be improved by inizializing the generator with a large number as 
seed value. I'm not sure if it's a good idea to share the same variables 
for ld() and st() (as double) and random() (as unsigned int). Wouldn't 
it be better to use separate variables for random()? Michael



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