[FFmpeg-devel] On libavfilter: A Summary of Issues

[Michael Niedermayer]

On Fri, Oct 19, 2012 at 02:07:21AM +0200, Stefano Sabatini wrote:
[...]
> > a = movie('input', :from => 10:00, :to => 10:30)
> 
> movie="input:sp='10:00':t=30" [v1];
> 
> (the time option is not yet implemented, or we could implement an
> "upto" option)
> 
> > b = movie('input2')
> 
> movie="input2" [v2];
> 
> > c = fade_in(a, b, :seconds => 10, :overlap => 5)
> 
> we have no fade in at this point, also I don't know how this really
> works, but it could be something like:
> [v1][v2] fadein=??? [tmp1];
> 
> > d = add_overlay(c, :from => 1:00 => to: 200)
> 
> again I don't know what this means, but what we lack in this case is
> an enable parameter, which could be:

> overlay=...:enable=gte(t,60)*lt(200)

what is needed in this specific case is not different trick in each
filter. What is needed is a 100% consistent and for a normal user
intuitive way to apply _any_ filter to timespans

example:
timespan=
    from=12:22:
    to=14:07:
    overlay=
        ...

keep the syntax intuitiv for an english speaking average user.
He knows for example what "to" and "from" mean, he does not know that
gte means greater than or equal nor can you count on him knowing that
multiplying these has the effect of a logical "and".

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Opposition brings concord. Out of discord comes the fairest harmony.
-- Heraclitus
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