I think that finally found it if anyone need it this is it:
this will find all your .srt files in the specific directory and then change utf 8 to utf 8 with bom

Maybe like this?

find /volume2/Disk.2/Downloads/ -name '*.srt' -type f -exec sed -i '1s/^/\xef\xbb\xbf/'

Is that right?

find . -name '*.srt' -type f -exec sed -i '1s/^/\xef\xbb\xbf/'

but how i ll make find to look to specific file?

Can i make sed to search all the .srt in folder Downloads and make them utf8 with bom?

I m running this via a task on my synology

filebot -script fn:suball /volume2/Disk.2/Downloads/ --lang el -non-strict

the thing is because of greek language the best is to have a utf8 with bom can i write a script at the end of the task? Do you have any idea how to do that?

Thanks.

Greetings, I also have this problem the thing is that some devices cant recognize the characters of the .srt file which is UTF-8 but can recognise UTF-8 with BOM or an ANSI. I used the windows-1253 for encoding and working perfectly but only to get subtitles for one file. Can you please be more ...