[FFmpeg-devel] Output to text file from filter

Reimar Döffinger Reimar.Doeffinger at gmx.de
Tue Jul 10 20:36:30 CEST 2012

On Tue, Jul 10, 2012 at 06:48:53PM +0200, Nicolas George wrote:
> Le tridi 23 messidor, an CCXX, Clément Bœsch a écrit :
> > Did you look at how the scene cut is made in the select filter?
> > http://ffmpeg.org/libavfilter.html#select
> Since you speak of it, I must say I am really not fond of that approach.
> Of course, having the feature right now is better than waiting forever for
> the perfect design, so you were quite right to just go ahead, and it was
> probably the most useful way of doing it. But now that we have time, we
> should be looking for generic solutions to that issue.
> My main concern is that the scene change test can be useful for other things
> than just selecting the frame: segmenting, updating on-screen text,
> inserting another program, etc.
> A solution that just came to my mind: let the filters attach arbitrary
> key=value pairs to the frames. And, of course, let the select expressions
> use any of these variables.

Please do not make it filter-specific. Something like this is needed to
add proper decode support for ATSC closed-caption subtitling, since
there the data needs to be reorder together with the frames.
However in this case IMHO you could just as well have the filter
create a data stream with that information, I don't think there
is any particular need for it to be in the AVFrame.

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