[ltcommander.data]

http://www.apple.com/macosx/specs.html

If you check Apple's Snow Leopards specs the following GPUs are supported for OpenCL and h.264:

Quote

QuickTime H.264 hardware acceleration
requires a Mac with a NVIDIA 9400M graphics processor.

OpenCL
NVIDIA Geforce 8600M GT, GeForce 8800 GT, GeForce 8800 GTS, Geforce 9400M, GeForce 9600M GT, GeForce GT 120, GeForce GT 130.
ATI Radeon 4850, Radeon 4870

The most glaring omission for OpenCL is for desktops with ATI GPUs, namely the HD 2400XT, HD 2600Pro, HD2600XT, and HD3870. Now it's not like these GPUs can't support GPGPU operation since they already do so in Windows under ATI's own CTM and Brook+ language. ATI's OpenCL drivers for Windows should be available soon, they were promised for H1, and if it turns out the HD2xxx and HD3xxx series are capable of supporting OpenCL but only in Windows and not OS X it'd be very disappointing. Somehow I don't think Apple envisions iMac users having to use Boot Camp to use OpenCL accelerated apps.

I'm hopeful that the list is still incomplete since the Quadro FX 5600 isn't included even though is the same architecture as the result of the nVidia 8xxx and 9xxx series and is Apple shipped and supported. I can understand Apple not listing the HD3870 and upcoming GTX 285 and Quadro FX 4800 since they are third-party aftermarket parts even if they may well work.

The other thing is that Apple lists the 9400M as required for h.264 acceleration in QuickTime X. I'm assuming the higher 9600M GT, GT 120, and GT 130 are also supported since they were released after. But what about the 8600M GT, 8800GS, and 8800GT which have the same PureVideo 2 video processing engine? And what about other GPUs? The Unified Video Decoder in the HD2600 has feature parity with PureVideo 2 even though it was released earlier and even the ATI X1600 and X1900 and the nVidia 7000 series have partial h.264 hardware acceleration capabilities. And you'd think these older Macs would benefit more from having GPU accelerated decoding than newer Macs anyways. Certainly, the HD4850 and HD4870 should be supported. With ATI GPUs seemingly having the advantage in terms of price/performance and execution, it doesn't seem like a good time to be too nVidia centric.

I'm bringing this up because I'd encourage everyone who cares to bring the issue of OpenCL and h.264 GPU support up with Apple. Apple retracted on removing the Firewire port from the 13" MacBook (Pro) due to user reaction so it's certainly possible and they'd be most receptive now that Windows 7 is shaping up pretty well. It'd be great if Apple could support OpenCL and h.264 acceleration back to the HD2xxx series and maybe even the ATI X1xxx and nVidia 7xxx series for h.264. Apple should also consider supporting GPU acceleration not just for h.264 but also VC-1/WMV and MPEG4/DIVX/XVID since it's the same video processing unit being used. Maybe I'm being naive, but I can still hope and there is still some time before Snow Leopard is released for an about face.

http://www.apple.com...ack/macosx.html

[mattw]

ltcommander.data, on June 9th 2009, 04:12 AM, said:

The other thing is that Apple lists the 9400M as required for h.264 acceleration in QuickTime X.

I read that and my immediate reaction was that surely it can't be only that model can it?

I imagine it may be more beneficial than on models with more CPU power available but I'd sure like to see the hardware utilised where possible and I'm pretty sure my Radeon 4870 can help with H.264 playback if the software is in place.

[bobbob]

ltcommander.data, on June 8th 2009, 08:12 PM, said:

somehow I don't think Apple envisions iMac users having to use Boot Camp to use OpenCL accelerated apps

I sure hope OpenCL has a CPU fallback, since there are things that would be faster on the CPU even with GPU acceleration.

Quote

you'd think these older Macs would benefit more from having GPU accelerated decoding than newer Macs anyways

And that G5's would benefit more from an optimized Snow Leopard over 10.5.

Quote

Apple retracted on removing the Firewire port from the 13" MacBook (Pro)

And replaced the ExpressCard slot that could hold an n-way memory card reader or (say) an eSATA port with a fixed SD slot. It's Apple. They're don't respond well to pressure, logic, or aspiration.

Quote

Apple should also consider supporting GPU acceleration not just for h.264 but also VC-1/WMV and MPEG4/DIVX/XVID

They don't support VC1 and the DIVX/XVID variants at all, do they? It's not like them to have a performant decoder, either, so what else is new.

[teflon]

OpenCL is an optional thing for using the GPU as if it were a CPU (in some cases). The threads that will run faster on a CPU obviously wont be assigned to the GPU, which is at the developer's discretion, and then only when there's an OpenCL capable GPU present. So if not, then yeah, itll default back to run on the CPU.

Also, getting GPU assisted decoding of VC-1 is pretty vital to getting Blu-Ray up and running in OSX... Perhaps theres a hitch here?

[Janichsan]

There aren't that many applications for OpenCL for a "normal" user in the first place, mainly video and audio processing to some extent. Most other uses are in the area of really high end number crunching like scientific applications. For games, it won't be of any use anyway, since the GPU will usually be busy with other things. That could change when Apple would offer Macs with more than one at the same time usable GPU.

[teflon]

Well, thats what Apple will be pushing anyway. Using OpenCL to help with video encoding and decoding, and it could be useful when it comes to Garageband.
But with games, OpenCL would open the door for GPU accelerated physics to make their way over to the mac, which would be nice.

[ltcommander.data]

As a follow-on, after contacting someone in the know, the reason why Snow Leopard doesn't support pre-HD4xxx series ATI GPUs is due to hardware limitations. I didn't ask for specific clarification, but speculating, one the major differences in Stream Processing Unit organization in the HD4xxx series compared to the HD3xxx and HD2xxx series is that the HD48xx organizes 80 Stream Processing Units together in a SIMD core with a shared local data store. This local data store is something that nVidia has had since the 8xxx series and among other things can avoid polling the CPU for data and the lack of it has been identified as a major reason why Folding@home performance in the HD2xxx and HD3xxx series is so poor compared to nVidia GPUs. I'm not familiar with the technical details of OpenCL requirements, but I wouldn't be surprised if OpenCL was written with local data store between groups of execution units in mind. In any case, I'm told that the forthcoming Windows/Linux OpenCL drivers won't support the HD2xxx or HD3xxx either.