[FFmpeg-devel] [PATCH] avfilter/select: add metadata detection function

[Tobias Rapp]

On 18.06.2021 14:50, Timo Rothenpieler wrote:
 > [...]
 >
 > + at item detected(kind)
 > +Evaluates the metadata added to frames by various detection filters.
 > +Returns -1 if the respective filter has detected what it was looking 
for,
 > +0 otherwise.
 > +
 > +Possible values for the @var{kind} parameter:
 > + at table @option
 > + at item SILENCE (audio only)
 > +Looks for metadata added by @ref{silencedetect}.
 > + at item FREEZE (video only)
 > +Looks for metadata added by @ref{freezedetect}.
 > + at item BLACK (video only)
 > +Looks for metadata added by @ref{blackdetect}.
 > + at end table
 > +
 >   @end table

If I understand that description correctly a filter line like 
"aselect=detected(SILENCE)" kill keep the silence and remove the rest? 
So for most use cases a wrapping not() shall be used? Adding an example 
in the docs might clarify this.

I think it is a bit unfortunate that the new syntax differs from the 
existing "concatdec_select" which is similar in concept. In my very 
personal opinion using variables like "silence_detected" would have been 
more consistent, but take this as a suggestion - not objection.

Regards,
Tobias