[vlc-devel] [PATCH] avcodec VA: reuse the VA if possible disable thread safe buffer pool on WIN32

Sean McGovern gseanmcg at gmail.com
Wed Apr 8 15:00:15 CEST 2015

I'm sorry if my comment seemed like a "shot across the bow". It was not intended as such.

-- Sean McG.
-----Original Message-----
From: Rémi Denis-Courmont <remi at remlab.net>
Sender: "vlc-devel" <vlc-devel-bounces at videolan.org>Date: Wed, 08 Apr 2015 10:19:31 
To: Mailing list for VLC media player developers<vlc-devel at videolan.org>
Reply-To: Mailing list for VLC media player developers <vlc-devel at videolan.org>
Subject: Re: [vlc-devel] [PATCH] avcodec VA: reuse the VA if possible
 disable thread safe buffer pool on WIN32

Le 2015-04-08 08:46, Steve Lhomme a écrit :
> On Tue, Apr 7, 2015 at 5:33 PM, Rémi Denis-Courmont <remi at remlab.net> 
> wrote:
>> Le 2015-04-07 16:49, Sean McGovern a écrit :
>>> Is there a way to blacklist this on machines where we know it 
>>> doesn't
>>> work? Would that be desirable?
>> How about following the (DXVA) specification instead of relying on 
>> undefined
>> behaviours and blaming the drivers?
> Because the real world is never following specifications fully. It
> doesn't matter what a document says if noone is following it.

On the one hand, I wrote nothing about following or not following 
defined behaviour. If you do not understand the meanining of undefined 
behaviour, then please get a (good) book, and come back when you do. On 
the other hand, like Sean, if you have proof that one driver is not 
following the spec, you should explain how and why. You cannot just 
blame third parties on a public mailing list without backing.

> I have looked at a lot of docs about DXVA lately and I have found
> nothing about threading.

But that is the point. I very doubt that the GPU would care about CPU 
threads; it will however care about memory synchronization and 
protection. If threading breaks your code, then the code is probably 
wrong. It might well be pure luck that it does not break in a single 

Rémi Denis-Courmont
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