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

[Robert Krüger]

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.