[FFmpeg-devel] [PATCH v3 4/4] libavutil/qsv: enabling d3d11va support

[Max Dmitrichenko]

On Sun, Apr 26, 2020 at 10:00 PM Soft Works <softworkz at hotmail.com> wrote:

> > -----Original Message-----
> > From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On Behalf Of
> > Mark Thompson
> > Sent: Sunday, April 26, 2020 8:54 PM
> > To: ffmpeg-devel at ffmpeg.org
> > Subject: Re: [FFmpeg-devel] [PATCH v3 4/4] libavutil/qsv: enabling
> d3d11va
> > support
> >
> > On 24/04/2020 15:52, artem.galin at gmail.com wrote:
> > > From: Artem Galin <artem.galin at intel.com>
> > >
> > > Makes selection of d3d11va device type by default and over DirectX 9,
> > > which is still supported but requires explicit selection.
> >
> > ... which might break users with older drivers/systems.  Some comment on
> > exactly which setups are broken would be helpful here.
>
> I have done some investigation on this question:
> https://github.com/softworkz/ffmpeg_dx11/issues/1
>
> A short summary:
>
> - D3D11 will fail for Gen 3 Intel CPUs
>


DX9 is still possible to use,
this patch is not about DX9 removing


>
> - D3D11 will fail for Gen 4 and Gen 5 Intel CPUs as long as DX11 array
> textures are used
>   (to get these working, the D3D11 hw context needs to be extended to
> support non-array textures)
>
>

Feel free to share a patch with support of non-array textures


> - For all newer CPUs: For all drivers that are older than 14-16 months,
> D3D11 may fail
>   (except when implementing support for non-array DX11 textures)
>
>

Windows DCH Drivers allow to install latest drivers,
even on OEM devices


> Note: by "working" or "fail" I'm considering the full set of hw features
> including VPP filters.
> Simple decoding or encoding might still work in cases where I wrote "fail".
>
>

Feel free to share a patch with support



>
> An additional objection I have is about the non-deterministic selection
> between D3D9 and DX11.
> The -qsv_device parameter allows to specify the device numer/Index of a
> graphics adapter to use.
>
> On Windows, the numbering graphic adapters is very different between D3D9
> and DX11 (=> DXGI).
> You could roughly say that D3D9 is counting by connected displays while
> DXGI is counting by
> Physical device.
>
> As long as there is no way to specify whether to enforce D3D9 or DX11, it
> is impossible to know
> which adapter ID should be specified when the implementation makes an
> internal decision whether
> to select D3D9 or DX11. In that context, defaulting to DX11 will break
> applications that are
> specifying D3D9 adapter IDs.
>
> There needs to be a deterministic and reliable behavior which can be
> controlled from the
> command line. The proposed method for selecting D3D9 is not sufficient
> from my point of view
> because the QSV codecs are standalone codecs and intended to work without
> dealing with explicit
> hw context creation. For the other half, there should also be a way to
> explicitly select "DX11-or-fail".
>
> IMO there should be a global command line option to explicitly choose
> between D3D9 or DX11.
> (global, because there's no way to mix the two).
>
>

Usage examples describe explicit selection.

DX11 has certain advantages, already described, over DX9
and should be used by default,
this also helps to end-customers which are not (dont want to be?) very
familiar with DX details and limitations.
it is not possible to avoid such fact of switching.


> softworkz
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regards
Max