[FFmpeg-user] Syntax of ffmpeg -t and -to

[Alexander Strasser]

On 2013-09-11 08:37 +0200, Robert Krüger wrote:
> On Wed, Sep 11, 2013 at 5:14 AM, Timothy Gu <timothygu99 at gmail.com> wrote:
> > Nicolas George <nicolas.george <at> normalesup.org> writes:
> >
> >> It just means that av_parse_time() can parse a negative duration. This is
> >> not very useful for the -t and -to options, but there is certainly some
> >> piece of code where it can be handy.
> >
> > What is an example? Sorry for being so dumb, but I really cannot think of any
> > use case with negative duration.
> >
> Just think of specifying an offset, e.g. move something in a stream
> two seconds and three frames back. Being able to parse "-00:00:02:03"
> is certainly a nice thing for that use case. It would even seem weird
> to me, not to be able to parse a negative value in such a general
> library function.

  Please Nicolas or anyone else with more intimate knowledge of the
matter correct me, but IIRC it is quite possible for some formats to
start at a "negative" point in time? Maybe I am just misremembering
things though...

  Alexander
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