How do I convert a hdmv_pgs_subtitle (which is image based) to a text based subtitle in a MKV file?
I have tried ffmpeg -i in.mkv -c:v copy -c:a copy -c:s mov_text out.mkv
but that results with the following error:
Stream mapping:
Stream #0:0 -> #0:0 (copy)
Stream #0:1 -> #0:1 (copy)
Stream #0:2 -> #0:2 (hdmv_pgs_subtitle (pgssub) -> mov_text (native))
Error while opening encoder for output stream #0:2 - maybe incorrect > parameters such as bit_rate, rate, width or height
Best Answer
Converting image based subtitles to text is a nontrivial process, as you will need some kind of OCR system to interpret the bitmaps and figure out what the corresponding text is.
ffmpeg
alone will not do that for you.I am not aware of any app that will do the whole process in one go, for Linux/UNIX. However, this process should work:
mkvextract
orffmpeg
mkvmerge
orffmpeg