[FFmpeg-devel] [PATCH v2 1/5] avutil/hwcontext_d3d11va: fix the uninitialized texture bindflag

[Xiang, Haihao]

On Sat, 2022-04-30 at 13:59 +0000, Soft Works wrote:
> > -----Original Message-----
> > From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On Behalf Of
> > Hendrik Leppkes
> > Sent: Saturday, April 30, 2022 12:02 AM
> > To: FFmpeg development discussions and patches <ffmpeg-
> > devel at ffmpeg.org>
> > Subject: Re: [FFmpeg-devel] [PATCH v2 1/5] avutil/hwcontext_d3d11va:
> > fix the uninitialized texture bindflag
> > 
> > On Fri, Apr 29, 2022 at 12:45 PM Tong Wu
> > <tong1.wu-at-intel.com at ffmpeg.org> wrote:
> > > 
> > > When uploading rawvideos using d3d11va hardware framecontext, the
> > 
> > bindflag
> > > is not initialized and will cause creating texture failure. Now fix
> > 
> > it,
> > > assign it the value of D3D11_BIND_RENDER_TARGET.
> > > 
> > 
> > As with similar fixes of this nature, this implicit behavior to fix
> > one particular bug does not seem fitting inside the hwcontext itself.
> > There can be a large list of usages of the hwcontext that all require
> > different BindFlags, but we can only define one default - why this one
> > specifically?
> 
> I agree that this change is not ideal. On one side, it is "safe" in a way 
> that a texture is practically unusable for video processing without having 
> at least one of the flags (decoder, encoder or render_target),
> so this wouldn't "hurt" anybody.
> 
> > So rather:
> > 
> > Where is the context created?
> 
> Looking at the command line in the commit message, this is about 
> standalone D3D11 context creation. 
> 
> > Why is a required flag not set there? That would be better, because
> > that knows what flags it needs.
> 
> There doesn't really exist an appropriate "there". I see two options
> 
> 1. Add a generic internal device creation parameter to the dictionary
>    in ffmpeg_hw.c like "standalone=1" 
>    (for all devices created via init_hw_device)
> 
> Some time ago, I had another case where I thought this could be useful.
> Then, this could be used in d3d11va_device_create() to set an internal
> field 'default_bindflags' which would be used as condition in 
> d3d11va_frames_init. The situation would remain similar though, as that
> when the device is used by a decoder (which sets the decoder flag)
> this needs to override the default.
> 
> 2. Use a device parameter specific to the D3D11
> hwcontextD3D11_BIND_RENDER_TARGET
> 
> This would need to be specified in the command line.
> Everything else like in #1
> 
> What do you think?

There aren't extra parameters for other standalone hwcontext creation. May we
take BindFlags=0 as the default setting and set texDesc.BindFlags to
D3D11_BIND_RENDER_TARGET directly ?

Thanks
Haihao