[FFmpeg-devel] [PATCH] lavfi: add duration field to AVFilterBufferRef

Clément Bœsch ubitux at gmail.com
Tue Jul 31 21:39:53 CEST 2012

On Tue, Jul 31, 2012 at 03:05:42PM +0200, Nicolas George wrote:
> > Same semantic as the pkt_duration field in AVFrame, a duration of 0
> > means unspecified, a negative value should be regarded as invalid
> > (unless we have some use for a negative duration??). I'll update the
> > patch accordingly.
> Clément had expressed concerns with that convention: there may be situations
> where duration=0 makes senses. I do not remember the specifics,
> unfortunately.

duration=0 might be an "empty stopping subtitle" (see tx3g subtitles for
example). duration=-1 might make sense for subtitle lasting up the the
next one (but that shouldn't happen at that level since the decode step
would have set the correct timestamp).

Also we might expect duration=0 in various situation (let's say after a
timestamp rescaling for instance).

Clément B.
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