[FFmpeg-user] MP4 with 9 subtitle streams

[Mark Filipak]

On Sat, Sep 23, 2023 at 1:58 PM Ferdi Scholten <ferdi at sttc-nlp.nl> wrote:
> >    Stream #0:2[0x3](eng): Subtitle: mov_text (tx3g / 0x67337874),
> > 1920x162, 0 kb/s (default)
> >
> That is not an srt subtitle, it has been transcoded by handbrake to an
> mp4 text stream (which should work as subtitle when playing the video
> with a video player that supports them). If you want srt, use another
> container that does support them, like mkv.

What is "an mp4 text stream"? Do you mean private packets? MP4
implements MPEG formatted streams (which includes private packets... I
think there's type 1 and type 2) and are where all subtitles reside.
There are nav packets, video packets, audio packets, and private
packets. That's on DVD. I don't know how BD streams are organized
because I don't know how to parse BD headers.