CPU Load at HD Video Playback
Blu-Ray/HD DVD Playback
With a single exception, ATI Radeon GPUs have lower CPU load than Nvidia’s GeForce GPUs due to the hardware deficiencies of the latter (they lack bitstream processing for the VC-1 codec).
Our testbed has a fast CPU. If you’ve got a slower model, you should choose your graphics card carefully: where our CPU needed 40% of time to help decode VC-1, a weaker CPU may take much more time, which may result in the loss of frames in complex dynamic scenes, especially when you enable Picture-in-Picture mode/Bonus View.
As opposed to VC-1, there are no clear winners or losers when it comes to decoding MPEG4 AVC/H.264. The average CPU load varies within 20-25%, which is rather low.
Interestingly, for many GPUs that offer hardware acceleration for two streams simultaneously, the task of decoding a scene from The Day After Tomorrow with a very high bit rate (a distinguishing feature of all movies from Fox Home Entertainment) proved to be more difficult than the reproduction of the last scene from Beowulf with Picture-in-Picture mode enabled.
We did not test the CPU load when playing MPEG2 video although Blu-ray movies encoded with MPEG2 HD are available on the market. If you’ve got such discs, you may be interested to know the CPU load when decoding MPEG2 stream at 20-25Mbps (a free clip from NASA showing a space shuttle launch).