[FFmpeg-user] ocr howto set whitelist

[Thomas Seilund]

Hi all

I run this command as webcam connected at /dev/video2 points a piece of 
paper with the text "123a".

FFREPORT=file=ffreport.log:level=32 ffmpeg -y -loglevel debug -f v4l2 
-input_format mjpeg -s hd480 -r 30 -i /dev/video2 -filter_complex 
"[0:0]fps=1,ocr=language=eng:whitelist=0123456789,metadata=print:key=lavfi.ocr.text,null[X]" 
-map '[X]' -pix_fmt yuv420p -f xv Title

Above I set whitelist to "0123456789" but still I see 
"[Parsed_metadata_2 @ 0x55fb2537b9c0] lavfi.ocr.text=123a" in log file 
ffreport.log

Why is the letter "a" recognized when the letter "a" is not in the 
whitelist?

It is difficult to find ex. of ffmpeg with the ocr filter - any hints?

Thanks in advance

Thomas S