[FFmpeg-devel] [PATCHv2 5/5] lavfi/select: add support for concatdec_select option

Stefano Sabatini stefasab at gmail.com
Fri Nov 20 16:43:34 CET 2015

On date Friday 2015-11-20 13:54:26 +0100, Marton Balint encoded:
> This option can be used to select useful frames from an ffconcat file which is
> using inpoints and outpoints but where the source files are not intra frame
> only.
> Signed-off-by: Marton Balint <cus at passwd.hu>
> ---
>  doc/filters.texi       | 20 ++++++++++++++++++++
>  libavfilter/f_select.c | 27 +++++++++++++++++++++++++++
>  2 files changed, 47 insertions(+)
> diff --git a/doc/filters.texi b/doc/filters.texi
> index 471ec3f..c886976 100644
> --- a/doc/filters.texi
> +++ b/doc/filters.texi
> @@ -13196,6 +13196,19 @@ value between 0 and 1 to indicate a new scene; a low value reflects a low
>  probability for the current frame to introduce a new scene, while a higher
>  value means the current frame is more likely to be one (see the example below)
> + at item concatdec_select
> +The concat demuxer can set the @var{lavf.concat.start_time} and the
> + at var{lavf.concat.duration} packet metadata values which are also present in the
> +decoded frames.

Maybe here you could elaborate. Something like:

The concat demuxer can select only part of a concat input file by
setting an inpoint and an outpoint, but the output packets may not be
entirely contained in the selected interval. By using this variable,
it is possible to skip frames generated by the concat demuxer which
are not exactly contained in the selected interval.

> +
> +The @var{concatdec_select} variable is -1 if the frame pts is at least
> +start_time and either the duration metadata is missing or the frame pts is less
> +than start_time + duration, 0 otherwise, and NaN if the start_time metadata is
> +missing.
> +
> +That basically means that an input frame is selected if its pts is within the
> +interval set by the concat demuxer.

Looks good otherwise.
FFmpeg = Fanciful Free Merciless Proud Erroneous Ghost

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