[FFmpeg-devel] [PATCH v4 03/11] libavutil/hwcontext_d3d11va: adding more texture information to the D3D11 hwcontext API

[Hendrik Leppkes]

On Sat, May 9, 2020 at 7:41 PM Soft Works <softworkz at hotmail.com> wrote:
>
> > -----Original Message-----
> > From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On Behalf Of
> > Hendrik Leppkes
> > Sent: Saturday, May 9, 2020 9:08 AM
> > To: FFmpeg development discussions and patches <ffmpeg-
> > devel at ffmpeg.org>
> > Subject: Re: [FFmpeg-devel] [PATCH v4 03/11] libavutil/hwcontext_d3d11va:
> > adding more texture information to the D3D11 hwcontext API
> >
>
> > > >
> > > > I'm not really a fan of this. Only supporting array textures was an
> > > > intentional design decision back when D3D11VA was defined, because
> > > > it greatly simplified the entire design - and as far as I know the
> > > > d3d11va decoder, for example, doesnt even support decoding into
> > anything else.
> > > >
> > > > - Hendrik
> > >
> > > It's not like there would be a choice. The Intel MSDK uses an
> > > allocator mechanism and when it asks for a non-array DX11 texture it has to
> > be given one.
> > >
> >
> > Of course there is a choice. Only support the new stuff. Afterall we havent
> > supported it at all for years now, so only supporting it on newer drivers isn't
> > the end of the world.
>
> It _IS_ the end of the world when at the same time, the default will be
> switched to DX11 because this will automatically create many cases
> where things will fail which have been working previously.
>
> An automatic fallback is not a good alternative either because that would
> break specific adapter selection by adapter number because the numbering
> is different between D3D9 and DX11.
>
> Assuming that everybody would have the latest driver is not matching the
> situation in the real world. See here for an example:
> https://github.com/softworkz/ffmpeg_dx11/issues/1
>

According to your own documentation, even the proposed DX11 version
will still fail on various systems (only bullet point 3 is solved from
the list in issue 2, leaving 1 and 2)
So either you have a fallback, or DX11 should probably just not be the
default at all then.

- Hendrik