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

[Rémi Denis-Courmont]

Le 2015-04-01 14:19, Steve Lhomme a écrit :
> Do not force YV12 out of DxVA using the costly SplitPlanes as NV12 is 
> the
> preferred format and will always comes with DxVA and the renderers
> 
> https://msdn.microsoft.com/en-us/library/windows/desktop/dd206750%28v=vs.85%29.aspx#nv12

With the current architecture, the decoder cannot know what is 
downstream. You cannot assume that it is the Direct3D 11 video output. 
It could be a filter (as JB already noted), it could be another video 
output, it could be video splitter or it could even be an encoder (in 
principles).

> "NV12 is the preferred 4:2:0 pixel format for DirectX VA. It is
> expected to be an intermediate-term requirement for DirectX VA
> accelerators supporting 4:2:0 video."

I think the preferred texture format for any reasonable video 
acceleration is "opaque". If you want to optimize the data path from the 
DX VA decoder to the DX 3D video output, you should not copy the data 
back to CPU memory at all. The issue of NV12 vs YV12 is thus moot.

(And any modern video DSP or GPU will prefer a vendor-specific tiled 
texture format over NV12.)

-- 
Rémi Denis-Courmont