2. Digging Into DHCAT

Here we take two passes over the assessments that DHCAT makes as it runs from start to finish. First, we provide a 10,000-foot overview of the kinds of things that DHCAT does and how it does them, sometimes individually and sometimes in tandem, to perform its many and varied assessments. It's probably worthwhile noting here and now that DHCAT usually takes somewhere between one and two hours to complete. Many of the individual assessments are worth watching nevertheless, because they can provide useful (and even telling) demonstrations of how well a system performs under various usage scenarios.

DHCAT At 10,000 Feet

Basically, DHCAT seeks various ways to exercise the media handling capabilities of a PC system, subject to some well-thought-out virtualizations (which we'll explain shortly). DHCAT looks for the following components in any system that it attempts to assess:

DivX Pro 6.4 codec or newer: We used the DivX Pro 6.5 codec in our testing, because it's the latest, most readily available version. SDTV and HDTV tuners: We used single or dual tuner Hauppauge SDTV tuners, in either PVR-150MCE single or PVR-500MCE dual tuner configurations; we used the AverMedia AVerTVHD MCE A180 single-tuner HDTV tuner card. We do, however, wish we'd had the new AverMedia M780 AverTV Combo card, which combines an HDTV and an SDTV tuner on a single TV capture card that plugs into a PCI-E x1 slot. HD Audio: We used RealTek ALC8XX models for all tests, including the ALC882M 7.1 for the Intel CPUs, the ALC883 5.1 for the Asus AMD motherboards, and the ALC888 5.1 for the Gigabyte motherboard; all chipsets met DHCAT's requirements for high-definition audio. A UPnP media server that complies with criteria set by the Digital Living Network Alliance (to which both Intel and AMD belong), and that also includes the ability to transcode Windows Media Video (WMV) and DivX to MPEG2 format.

As it goes through its paces, DHCAT tests a media PC's abilities to perform the following kinds of tasks:

Encode, play, record, and transcode standard TV and HDTV video. Synchronize and edit digital photos. Serve, stream, and transcode media to one or two devices across a network, with or without compression - this is where the DLNA Media Server comes into play.

Rather than actually use real hardware-based SDTV and HDTV tuners, or interact with other machines across a network, Intel chose to stub these activities out to virtual devices and interfaces so as to keep its testing entirely focused on the machine under assessment. We followed that reasoning to its logical conclusion by also installing UPnP media server software on those same machines as well.

What makes Intel's assessments interesting, and its results at least potentially relevant to those who might wish to use the results to compare one system against another, are the combinations of individual activities that Intel puts into various scenarios for testing. The company also invested in some useful automated Mean Opinion Score (MOS) based video quality assessments. These allow a pristine source video to be compared to a degraded copy of the same video, so as to observe how well a system does when playing back noisy or otherwise imperfect video source material.

In the next section we'll step through all six scenarios in the complete DHCAT suite, and explain the individual assessments, which number from three to five per scenario, that go into each one.