[FFmpeg-user] Questions about `-to` parameter

[Pan Lee]

Thanks for your reply, Vincent. It's very helpful and clarify.

I still have one question:
Is there any chance that ffmpeg developer might implement this?

Because it's not intuitive for user to compute the duration when
cropping the video. And as the wiki said, `-t` and `-to` is duplicate
in this case.

Thanks,
lp

Vincent Deconinck <vdeconinck at gmail.com> 于2024年11月15日周五 17:56写道：

> >
> > I look up the ffmpeg document
>
>
> You have probably missed the part of https://trac.ffmpeg.org/wiki/Seeking
> that
> says 'Note when "-ss" used before "-i" only: ("-ss" as input option) the
> timestamps will be reset according to 0.͏ So "-t" and "-to" shall be the
> same.' :-)
>
> [Q1] Is this really intentional? If it is, can anyone share the thought of
> > this design?
> >
>
> There is a logic, at least.
> Think "-ss before -i" as two separate ffmpeg operations:
> 1 : create a new file without the start
> 2 : truncate the new file at a certain time
> Operation 2 has no idea what the original file was, as an "input seeking"
> (step1) was applied before, so it doesn't know how much was removed.
>
>
> > [Q2] Is there a way to make the second command works like the first
> > command?
> >
>
> Not that I know of.
> You should just compute the desired duration (as end-start) before calling
> ffmpeg, and I suggest you use -t instead of -to in that case. They behave
> the same and that removes any ambiguity for the reader.
>
> Vincent
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