Re: [Qemu-devel] [PATCH] opengl rendering in the sdl window

[Stefano Stabellini <stefano.stabellini@eu.citrix.com>]

Jamie Lokier wrote:

> 
> Fwiw, in my experience with Xine and mplayer, drawing video updates to
> the screen using OpenGL was quite a lot slower than drawing them with
> XShmImage.  That needs colour conversion as video doesn't even use RGB.
> 
> Probably OpenGL is faster on some hardware, and slower on some hardware.
> Don't assume it's always faster.


Yes, good point.

 
> Yes it very much depends on the drivers and opengl implementation.  It
> isn't always possible to map the guest framebuffer into video
> (texture) memory, and also some opengl implementations are not
> particularly fast at copying textures from CPU memory to texture memory.


This is also true.

 
> Another way to map guest framebuffer to video memory is the XF86DGA
> extension, which is great when you can use it.  I think VMware uses it
> in full-screen mode.

I went with OpenGL because I wanted the accelerated window resize
feature, and because I think it will give us more opportunities for
further improvements (for example using PBOs as soon as they are
supported by at least one open source graphic card driver).