[vlc-devel] [PATCH 3/3] snapshot: fix copy of opaque pictures
remi at remlab.net
Mon Jun 5 18:50:06 CEST 2017
Le maanantaina 5. kesäkuuta 2017, 18.19.13 EEST Thomas Guillem a écrit :
> On Mon, Jun 5, 2017, at 18:10, Rémi Denis-Courmont wrote:
> > Le maanantaina 5. kesäkuuta 2017, 19.02.22 EEST Rémi Denis-Courmont a
> > écrit :
> > > Stating the obvious here, but the patch does not do what the commit
> > > title
> > > implies.
> > >
> > > AFAICT, there are essentially only two way to handle copying of pictures
> > > with an opaque context: the very obvious but very slow way and the
> > > rather
> > > obvious and very fast way. And that means either adding a copy callback
> > > (slow), or replacing the destroy callback with a pair hold/release
> > > callbacks.
> > (The "correct" way is to perform a shallow copy of the context. A pure
> > reference counter would interfere with context changes in VDPAU filters.)
> This means that the same context will be used simultaneously by the
> video output and by a video filter (via the video converter needed for
> the image encoder).
> This will create issues with some hardwares.
No. The picture context has always had reference counting internally. It just
was never exposed to the core.
In other words, a back-end without reference counting can´t use the picture
context trick. And it has always been but a trick to make up for the lack of
converter, filter and splitter pools.
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