Blu-ray HD video decoding and playback
One of the things that buying a new graphics card will get you that an older card or integrated graphics solution might not have is decode and playback acceleration for HD video, including Blu-ray discs. The latest GPUs include dedicated logic blocks that offload from the CPU much of the work of decoding the most common video compression formats. To test how well these cards perform that function, we used CyberLink's new release 8 of PowerDVD, a Lite-ON BD-ROM drive, and the Blu-ray disc version of Live Free or Die Hard. Besides having the "I'm a Mac" guy in it, this movie is encoded in the AVC format (which includes H.264 video compression) at a 28Mbps bit rate.

Video decode acceleration is particularly important for the miserly among us, because budget CPUs sometimes have trouble playing back compressed HD video without a little bit of help. Most of today's dual-core processors can still handle it, but they won't have many extra cycles left over to do anything else. Compounding the problem, we've found in the past that low-end video cards sometimes run into bandwidth limitations when assisting with HD video decoding, playback, and image scaling.

In order to really stress these cards, we installed a lowly Core 2 Duo E4300 processor (a dual-core 1.8GHz CPU) in our test rig, and we asked the cards to scale up our 1080p movie to fit the native 2560x1600 resolution of our Dell 30" monitor. We then recorded CPU utilization over a duration of 100 seconds while playing back chapter four of our movie.

Good news all around here. None of the video cards had any trouble playing our movie, with no apparent dropped frames or other playback glitches. As you can see, the Radeons tended to do a little bit better job of unburdening the CPU than the GeForces, but all of the cards proved to be more than capable—even the lowly GeForce 9500 GT.

We considered also testing image quality using the HD HQV benchmark, but we decided against it for a number of reasons. HQV tests the efficacy of post-processing algorithms like noise reduction and edge enhancement, but the reality is that on a properly mastered Blu-ray disc, you really won't need such things. In fact, Nvidia's drivers leave both noise reduction and edge enhance off by default. AMD's do have noise reduction enabled, but not at a very aggressive setting. Nvidia suggests the reviewer should tune his video card's noise reduction slider manually in order to achieve the best score in HQV, but I have a hard time imagining that many users would tune their video cards' noise reduction algorithms on a per-video basis.

The big thing to take away from these tests is that even the least capable video card in the bunch is more than adequate at accelerating HD video playback.