Multiple subtitle tracks: trying to understand

[djcv]

This can be considered the opposite of troubleshooting: vlc is working correctly and the other software seems not to. I'm here for possible help figuring out what's going on and what I can do about it.

I have a soft-subtitled video file on my hands, and I want to extract its subtitles. Ffmpeg indicates the file has three streams -- 0 = video, 1 = audio, and 2 = subtitles (English) in tx3g format -- and it can extract that third stream in SRT format. Or I can also open the video in SubtitleEdit and save that same subtitle stream. So far so good.

But when I play it with vlc, vlc indicates that it has FOUR subtitle streams, and by god, it does! vlc identifies stream 2 as

Stream 2
Codec: tx3g
Language: English
Type: Subtitle

and streams 3, 4, and 5 as

Codec: Text subtitles with various tags (subt)
Type: Subtitle

(3, 4, and 5 show as French text.) I'd like to extract all of them, but only vlc seems able to recognize the last three.

So my real question is: how can the file have three subtitle streams that even ffmpeg doesn't recognize, but vlc does?

And what can I do to extract all the subtitle streams?

Puzzled.

[mederi]

Aren't they external srt subtitle files autoloaded by VLC?

[djcv]

I gave up on that earlier attempt. (No, they weren't external SubRip files; they were streams in the file.) But I've encountered another peculiar MP4 file with embedded tx3g subtitles. For this one, vlc plays the video with subtitles and identifies 3 streams, one of which is

Stream 2
Codec: tx3g
Language: English
Type: Subtitle

When I load the file in SubtitleEdit, it shows what appears to be chapter definitions. I can't see how to make FFMPEG extract stream 0:2 (as MP4box identifies it), nor MP4box itself.

Perhaps the structure of this file is screwed up, but vlc can play it with subtitles quite nicely. So how can I extract the text:tx3g stream? Since vlc seems to be the only software that can use that stream, is there some way for me to politely invite vlc to extract it?

[InTheWings]

try Nightly Build of VLC