I'd like to share my experience on codecs/gpu acceleration of various video formats.
I recently discovered that older codecs for the mkv format, doesn't support acceleration for h264/x264 encoded files. This means that most HD/Bluray mkv compressed videos arent fully utilizing your GPU's capability, whats more is that it putting huge loads on your cpu.
I first noticed this when i plugged an Asus M70 into a 32" HDTV. I was shocked to see the 1080p movie dropping frames, and stuttering. Upon checking the CPU utilization, it as running 80-90%. This may not be an issue with newer desktop PC's, as the cpu power available is more than adequate. This, was still totally ridiculous as the notebook has a dedicated 512mb 9600 GT GPU unit. After reading various forums, and researching various codecs, i discovered that until last month most if not all codecs relied on software to decode the 1080p video.The Klite codec pack, containing all the imanginable codecs on the planet, didn't help. Searching for other alternatives, i came across CoreAVC, which is currently the best software decoder in the market. Which was still unacceptable, as it was still using the cpu to decode h264 videos, albeit they are saying that one with GPU and CUDA support is coming soon. Even with those promises, bottom line was: it wasn't free.
Finally after reading all the bruhaha, theories in other forums, i came across shark007's Vista Codec pack (don't let the name scare you, as it does work with XP). Im seeing the CPU loads of the m70 now at 10%-15% which is quite acceptable. And yep it has GPU acceleration via HAALI media splitter coupled with DXVA (Direct X video Acceleration). And whats more is that, its slimmer than the klite codec pack.
To sum it all up: Before, i thought that having all the bells and whistles, or rather all the imaginable codec available (yep i mean klite, xp codec pack, and the other codec packs that comes with everything but the kitchen sink) for video decoding was the best way to go. Until i tried to customize/adjust the setting of the installed codecs. I was spending so much time tweaking/figuring out stuff, when what i really wanted was to go and enjoy my movie. Well at least because of that experience, im now better informed. And now i will atest, that when it comes to codecs/codec packs less is definitely more
Shark007's Codecs Homepage
Accelerate x.264 1080p movies over the GPU Guide
Watching h.264 videos using DirectX Video Acceleration (DXVA). | My collection of short anime reviews
The Green Button - How to setup 1080p MKV h264 playback using hardware acceleration - PLZ HELP
MKV and ATI HD2X00 GPU Acceleration - AVS Forum
MKV and 8500 Full Hardware Acceleration [Archive] - Doom9's Forum
CoreAVC.com: World's Fastest High Definition H.264 Video Software Decoder
*rechecked m70's cpu util when i got home..