[FFmpeg-user] -crf ignored

[Paul Gardiner]

Hi,
I've been using this command:

ffmpeg -i <input file> -f mp4 -vcodec libx264 -crf 18.0 -acodec ac3 -ab 
160k <output file>

and it works to some extent, but the report on stdout/stderr says
that it is using crf=23.0. The results support 23.0 being used,
plus if I change the value I pass in, it has no effect on the file
size or quality. Can anyone tell me what I'm doing wrongly? I
can easily supply more info if that helps.

Paul.