Let us start by analyzing our input files and what we expect to find
- A video stream, the obvious
- Audio streams for different languages
- Audio streams that should play together
- dvd_subtitle
dvd_subtitle
Let us start with the subtitles, the encoder/decoder for dvd_subtitle stream is either dvdsub or dvbsub.
According to documentation, This codec decodes the bitmap subtitles used in DVDs; the same subtitles can also be found in VobSub file pairs and in some Matroska files.
Metroska uses VobSub, vobsub is basically the same as the stream in DVD but in a file with the extension “*.sub”.
So, I have a stream with “dvd_subtitle” on stream 0:3, to extract, I will probably use a command such as
Extracting the subtitle files
ffmpeg -i input.VOB -c copy -map 0:3 subtitles.sub
Now, at this stage, if you want to convert them to srt for example (Or a text base subtitle system), you will need to use a tool that has OCR !! Such a tool is VobSub2SRT =>
Another method after extracting is using an online service such as this one (https://subtitletools.com/convert-to-srt-online) to turn subtitles into SRT