[mythtv-users] Nvidia CUDA / HD decoding

Todd Ignasiak ignasiak at gmail.com
Mon Feb 19 16:33:08 UTC 2007

On 2/19/07, Michael T. Dean <mtdean at thirdcontact.com> wrote:
> On 02/18/2007 03:53 PM, Todd Ignasiak wrote:
> > On 2/18/07, Michael T. Dean <mtdean at thirdcontact.com> wrote:
> >
> >> Yep.  And, with OpenGL and OpenGL Shading Language (GLSL)--which is a
> >> mandatory part of OpenGL 2.0+, and, therefore, supported by ATI and
> >> NVIDIA drivers--and a sufficiently new video card (i.e. GeForce 6800+ or
> >> Radeon R520 (don't remember which cards use that chip)), you can program
> >> the programmable shaders to do 100% of the decoding on the GPU (rather
> >> than just motion compensation and inverse discrete cosine transform, as
> >> with XvMC).  You have to have a pretty new card to get support for
> >> sufficiently complex programming to allow decoding on GPU.
> >>
> > That sounds excellent.    Since it's part of OpenGL, does this mean
> > that it will be more open, and definitely be available in Linux (and
> > Mac OS X)?
> It would be available wherever OpenGL 2.0+ or OpenGL 1.4 with GLSL
> support is available.  Are there any GLSL-compliant drivers available
> for OS X?

I assume Mac OS and the drivers must support this, because there was a
session on using GLSL at last year's Mac developer conference.

> > As we all know, hardware capabilities have not always
> > translated into usable features..
> GLSL gives direct access to programming the programmable pixel shaders
> of modern GPU's.  So, it doesn't depend on drivers providing specific
> support for specific functions--only that drivers support GLSL.  You
> then program the shaders to do what you want (i.e. iDCT and MC, decode,
> whatever).

Sounds fantastic.  Finally a reason to get rid of my aging Nvidia 5200
and XvMC.

> > Radeons have been doing MPEG2 accel
> > for over a decade, but you still can't use it in Linux.
> That's what XvMC is--MPEG-2 accel.  XvMC allows using the video card to
> do Motion Compensation (MC) and inverse Discrete Cosine Transform
> (iDCT)--which are required mathematical operations for decoding MPEG-2.
> It could also be implemented to accelerate MPEG-4 and some other
> CODEC's, but isn't worth the driver vendor's time in most
> cases--especially now that they've opened up much more ("unlimited")
> capability with GLSL (as unlimited as the hardware's programmable shader
> implementation, that is).

Yeah, I know about XvMC,  my point was that even though ATI offered
had the capability to do this for over a decade, they never provided a
way (driver or spec's) so that Linux users could take advantage of it.
   The situation in Mac OS is arguably worse.  Apple uses it in their
DVD Player app, but provides no method for third parties to use it.
At least in Linux there is the NVidia closed driver or the OpenChrome

If GLSL provides an avenue to the raw capabilities of the hardware, it
sounds like a great way to go.     Hopefully we'll have an option for
a GPU with open drivers that can support this, maybe the Intel X3000 /

Thanks for the info.   This sounds like an exciting time for Linux
video.   My first HD card was a MyHD MDP-100 card in Windows, with an
excellent hardware MPEG2-HD decoder.  I've been looking for a Linux
option to rival that for a long time.

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