[FFmpeg-devel] [PATCH v3 1/2] dxva: wait until D3D11 buffer copies are done before submitting them

[Steve Lhomme]

On 2020-08-11 13:08, Soft Works wrote:
> 
> 
>> -----Original Message-----
>> From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On Behalf Of
>> Steve Lhomme
>> Sent: Tuesday, August 11, 2020 12:44 PM
>> To: ffmpeg-devel at ffmpeg.org
>> Subject: Re: [FFmpeg-devel] [PATCH v3 1/2] dxva: wait until D3D11 buffer
>> copies are done before submitting them
> 
> 
>> Even though the discussion is heated (fitting with the weather here) I don't
>> mind. I learned some stuff and it pushed me to dig deeper. I can't just accept
>> your word for it. I need something solid if I'm going to remove a lock that
>> helped me so far.
> 
> You're not supposed to accept my word. I wouldn’t do either. You could have
> just valued it as a possibility..that's all.
> 
>> So I'm currently tooling VLC to be able to bring the decoder to its knees and
>> find out what it can and cannot do safely. So far I can still see decoding
>> artifacts when I don't a lock, which would mean I still need the mutex, for the
>> reasons given in the previous mail.
> 
> Are you actually using D3D11 staging textures? I'm still not clear about
> that "old-api" way.

No. I render the texture slices on the screen straight from the decoder. 
In a separate thread from the libavcodec thread(s).

> I'm curious: what's your motivation for using D3D11 over D3D9?

At first for UWP apps (no other way except for D3D12). But now also 
because it supports HDR.

> I mean, we are always transcoding without rendering a video to any surface.
> Our reasons to use D3D11 are these two:
> 
> 1. Works headless (without connected display)
> 2. Works without user session (like inside a Windows service)
> 
> What's yours?
> 
> When implementing D3D11 for QuickSync I managed to get very close to
> DXVA2 performance eventually, but I hardly ever have been able to exceed it..

Same here, especially because I never managed to make it work without 
copying first to another texture. But I might give it another try in 
light of all this.

> PS: Yes, it's damn hot here as well! :-)
> 
> Kind regards,
> softworkz
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