GST_BUFFER_FLAG_DROPPABLE to detect keyframes?

[Nicolas Dufresne]

Le lun. 17 févr. 2020 12 h 45, Olivier Crête <olivier.crete at collabora.com>
a écrit :

> Hi,
>
> DROPPABLE isn't related to keyframes.. !DELTA is all you need. A
> keyframe could even be droppable.
>

Be aware though that not all keyframes are synchronization point. It all
depends on the use case. In some use case we track the header flag.


> Olivier
>
> On Mon, 2020-02-17 at 17:26 +0100, Juan Navarro wrote:
> > Should GST_BUFFER_FLAG_DROPPABLE be considered when trying to identify
> > video keyframes?
> >
> > Docs on buffer flags are a bit too precise about what each flag does,
> > but tend to be vague about what it actually _means_ in the more general
> > sense, so I haven't been able to discern if this is enough to classify a
> > buffer as keyframe:
> >
> > !GST_BUFFER_FLAG_IS_SET (buffer, GST_BUFFER_FLAG_DELTA_UNIT)
> >
> > or if this would be a better / more robust choice:
> >
> > !( GST_BUFFER_FLAG_IS_SET (buffer, GST_BUFFER_FLAG_DELTA_UNIT)
> >      || GST_BUFFER_FLAG_IS_SET (buffer, GST_BUFFER_FLAG_DROPPABLE) )
> >
> > or if these two flags are related in such way that they will always come
> > together when the frame is indeed a keyframe, and thus this expression
> > would be better:
> >
> > !( GST_BUFFER_FLAG_IS_SET (buffer, GST_BUFFER_FLAG_DELTA_UNIT)
> >      && GST_BUFFER_FLAG_IS_SET (buffer, GST_BUFFER_FLAG_DROPPABLE) )
> >
> > Here they say "maybe" it's a good idea checking for "DROPPABLE":
> > https://stackoverflow.com/a/52873803
> >
> > And here it is mentioned that "NON_DROPPABLE" might mean keyframe, so I
> > guess by extension we should assume that "DROPPABLE" might mean
> > non-keyframe:
> > https://gstreamer.freedesktop.org/releases/1.14/ (under "New RTP
> > features and improvements")
> >
> > But I'm missing a more concrete piece of text talking about the
> > implications of DELTA_UNIT, DROPPABLE / NON_DROPPABLE, and the meaning
> > of their possible combinations, if any.
> >
> > Could someone that knows about this share a bit of know-how?
> >
> > Thanks :)
> > Juan
> > _______________________________________________
> > gstreamer-devel mailing list
> > gstreamer-devel at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel
> --
> Olivier Crête
> olivier.crete at collabora.com
>
> _______________________________________________
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>
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