[FFmpeg-devel] [PATCH] lavfi: add showspectrum filter.

Nicolas George nicolas.george at normalesup.org
Sun Aug 12 09:50:14 CEST 2012

Le sextidi 26 thermidor, an CCXX, Nicolas George a écrit :
> PRESERVE on top of WRITE would mean that the previous filters, who may still
> hold a reference to the same frame with WRITE permissions, do not intend to
> use it in the future.
> But now that I think of it, once a filter has given write permissions to the
> next, writing on the same buffer makes no sense: it would possibly overwrite
> the work of the next. So yes, I guess PRESERVE is indeed redundant in
> practical circumstances

Hum, strike that. PRESERVE is relevant when you do not have write perms. It
distinguishes between "some previous filter wants to keep the buffer for
itself to write in it" and "all previous filters have renounced to their
write privileges".


  Nicolas George
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