[FFmpeg-devel] Status and Plans for Subtitle Filters

[Nicolas George]

Michael Niedermayer (12020-02-24):
> > No, they can't: being the same subtitle or not is part of the semantic.

> Does anyone else share this oppinion ?
> 
> iam asking because we need to resolve such differences of oppinion to
> move forward.
> Theres no way to design an API if such relativly fundamental things
> have disagreements on them

It's not a matter of opinion, it is actually quite obvious:

# 1
# 00:00:10,000 --> 00:00:11,000
# Hello.
# 
# 2
# 00:00:11,000 --> 00:00:12,000
# Hello.

… means that two people said Hello in quick succession while:

# 1
# 00:00:10,000 --> 00:00:12,000
# Hello.

… means that Hello was said only once, slowly.

And it has practical consequences: Clément suggested a voice synthesis
filter, that would change its output.

Some subtitles have overlap all over the place. I am thinking in
particular of some animé fansub, with on-screen signs and onomatopoeia
translated and cultural notes, all along with dialogue. De-overlapping
would increase their size considerably, and cause actual dialogue to be
split, which results in the problems I have explained above.

But I don't know why you are so focussed on this. Overlapping is not a
problem, it's just something to keep in mind while designing the API,
like the fact that bitmap subtitles have several rectangles. It's
actually quite easy to handle.

Regards,

-- 
  Nicolas George
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