[Interest] Utilizing the GPU, how to start?

Jason H jhihn at gmx.com
Fri Jul 8 21:23:34 CEST 2016

> Sent: Friday, July 08, 2016 at 1:11 PM
> From: "Giuseppe D'Angelo" <giuseppe.dangelo at kdab.com>
> To: interest at qt-project.org
> Subject: Re: [Interest] Utilizing the GPU, how to start?
> Il 06/07/2016 18:19, Jason H ha scritto:
> > What others have not said:
> > I did extensive testing of Qt Quick1 with video playback.
> This is a chapter on its own. (By the way, Qt Quick 1 is still 
> widget-based...)
> In case of video playback, there's much more going on than using the GPU 
> for displaying the video. You want to use the GPU also to decode the 
> video stream (using whatever native APIs you have on your system) and, 
> in order to display it, it's not guaranteed at all the using OpenGL is 
> actually the best way.
> Other overlaying solutions are usually much, much better 
> performance-wise (e.g. VDPAU). But: they don't allow you to embed the 
> video in arbitrary UI hierarchies. Media players usually have very 
> complex setups in order to be able to switch between presentation 
> backends when f.i. you set a videoplayer full screen rather than windowed.

I'm not sure if I am agreeing or conflicting with you, but Anything that can't be overlaid today is going to be an issue. You might get minimal CPU on a direct render situation, but that's a horrible approach I hope does with the old DirectX backends. I much more value the ability to embed video in arbitrary hierarchies with alpha-blended overlays.

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