[vlc-devel] [PATCH] DxVA2: allow NV12 pixel format all the way to the D3D texture

[Steve Lhomme]

On Wed, Apr 1, 2015 at 3:40 PM, Jean-Baptiste Kempf <jb at videolan.org> wrote:
> On 01 Apr, Steve Lhomme wrote :
>> On Wed, Apr 1, 2015 at 3:16 PM, Jean-Baptiste Kempf <jb at videolan.org> wrote:
>> > On 01 Apr, Steve Lhomme wrote :
>> >> j-b mentioned that a custom VLC_CODEC_DXVA pixel format could be used
>> >> for hardware acceleration, like it's done in Android. But if we want
>> >> to use filters that means the DXVA format cannot be opaque.
>> >
>> > Well, one idea is that the DxVA decoder always outputs
>> > VLC_CODEC_D3D9_OPAQUE or VLC_CODEC_D3D11_OPAQUE and we create a fiter
>> > that can do VLC_CODEC_D3D9_OPAQUE -> NV12 and one VLC_CODEC_D3D9_OPAQUE
>> > -> YV12.
>>
>> As NV12 is a requirement of DxVA there's a good chance that any GPU
>> that comes with support for it and outputs NV12 will support NV12
>> input format.
>
> So what?
>
>> > Therefore we can do all the format negotiation in the vfilter chain.
>> >
>> > And of course, we can have the D3D or D3D11 video output to render
>> > directly the VLC_CODEC_D3D9_OPAQUE or VLC_CODEC_D3D11_OPAQUE
>> > (respectively)
>>
>> In the end what's the difference in having VLC_CODEC_DXVA_OPAQUE just
>> being VLC_CODEC_NV12 ? It gives the same problem with filters that
>> only handle I420.
>
> No. VLC_CODEC_DXVA_OPAQUE would be just the handle to Direct3D9 surface
> ref.
>
>> It's not that opaque if we want to able to convert it. So let's not
>
> Of course, but we already have the conversion between Direct3D9 and NV12
> or YV12 in the decoder
>
>> using an opaque format at all.
>
> It is. Because it's a way to have GPU 0-copy like on VDPAU and
> MediaCodec.
>
>> A real opaque format would make sense in the case the user doesn't
>> want to bother with filters. It could be handled by the matching vout.
>> It might be useful to support formats that cannot be accessed at all
>> by the CPU (DRM).
>
> I'm sorry, but I think you are mistaken.
>
> The solution I propose would allow to have:
>  - 0 copy (full opaque)
>  - NV12 output for Direct3D output
>  - I420 for filters and the rest.
>
> And all that could be autonegotiated.


OK, that's easy enough to try to see if it works (the negotiation and
using filters).