Re: Extract subtitles from a video created with VDH

[Wild Willy]

This is a little bit off topic. VDH doesn't handle subtitles at all. If, as in the case
of this little video, the captions are burned into the file, VDH doesn't download the
captions. It downloads the video & oh by the way, the captions are simply embedded
within the video track. I am attaching the ffprobe I ran on your little video. It shows
that the captions are not a separate entity in the file. There is only the video track &
the audio track. The captions are just part of the video track, not a separate entity.
Just as an aside, this points out why I very much prefer my captions to start out as a
separate WebVTT file & I never burn captions into a video. If you leave captions
separate, you can edit them & even translate them. A vtt file is just plain text & you
can edit it with any text editor.

If you want to extract the captions, you need to go look for tools that do that. Do web
searches & you will find suitable applications. I have a program called Subtitle Edit.
Not very original but that's its name. It is freeware. Really. Free. The guy who
wrote it & maintains it does it pretty much as a hobby. There is a very active user help
forum for the program, & the application is under very active development. The support
for it is truly phenomenal. I don't think I've ever seen software that has such good
support. And it's free! I have not used SE for extracting captions, but it is my
understanding that it can do it. But like I say, you will probably find many tools out
there that do what you want. VDH is not among them.

[Wild Willy]

Thanks for you comments. By the way, I saw your post on the SE forum. I am quite
interested to see what response you get from anybody there.

I did try to get the subtitles in your video out of SE after I posted & I also failed
completely. I also was able to play the video in VLC & display the closed captions.
They are closed captions. The ffrpobe report I posted upthread shows they are closed
captions. You have to explicitly turn on the captions in VLC (the v command) to get them
to display. At least, when I played the video, that's what I had to do. VLC starts
playing the clip with the captions turned off by default. It took a bit of persistence
to turn them on because the clip is so short & VLC has an annoying habit of hesitating a
bit before displaying captions.

But I need to correct some of your terminology. VDH did not create this video. Some
author on the web created this video with burned in closed captions. VDH merely
downloaded what was there. Like I said earlier, VDH does not recognize that there are
captions there. VDH actually has no captions processing whatsoever. People regularly
have asked for that to be added to VDH but so far, nothing doing. The captions are just
part of the bits that constitute the video track. VDH read the bits. That's all. VDH
didn't add the captions. They were already there. And like I say, VDH doesn't recognize
captions anyway. There is no video anywhere on the planet for which VDH would create a
captions track, to use your words. And even if VDH were enhanced to support captions, I
would totally support Michel's decision to do nothing about closed captions. Closed
captions are always just part of the video track. That is a decision made by the author
of the content, not VDH, not SE, not ffmpeg, not any software. The author makes that
decision. VDH downloads videos. Separating closed captions from a video track seems to
me to be something VDH should never bother to do.

The enhancement VDH should add is to support captions files. Those are files separate
from the video. Alternatively, captions can be burned into the video as a separate
track. Those are recognized by ffmpeg. I haven't seen much of that. Captions are
usually side files in vtt or srt format. Those seem to be the types of captions you
encounter most often. My opinion is vtt is the superior format. Since vtt & srt files
are just plain text, you can edit them with any text editor, like Notepad. If a word is
misspelled, or the caption doesn't match what the people in the video are actually
saying, or if the caption displays too early, too late, for too long, for not long
enough, you can correct those things with a text editor. Of course, SE is really the
tool you should use for any of that, but if you are diligent, you can do it in Notepad.
For me, the possibility of easily editing captions is a no-brainer argument for keeping
captions in a separate file, for never burning them into the video. But I believe (I
haven't actually done this myself) that when ffmpeg merges a captions side file with a
video, the captions become a track. In ffmpeg parlance, it's called a Stream. This is
completely different from your video, which has closed captions, a totally different data
structure. I have seen so few videos with non-closed captions tracks, like maybe none, I
do not know what VDH does with such content. I expect either it ignores the captions or
it just entirely fails to download the content. It would be a wonderful enhancement to
VDH to get captions support. Maybe it will happen some day.