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DIGITAL HOME CAPABILITIES ASSESSMENT TOOL
The purpose of the DH-CAT is to evaluate the
performance of a digital media system.
Although
most any modern system is powerful enough to handle simple DVD playback, the
recording and playing of HDTV footage is more demanding.
The perceptual science behind DH-CAT isnÂ’t based on market research, per se; it is based on the opinions of many end-users (thousands in some case). Their tool uses a video quality assessment tool developed by Psytechnics, a leading firm in this area. Intel's User-Centered Design group in Oregon was also instrumental in providing video quality assessment tools in other usage scenarios (playback/streaming).
DH-CAT evaluates a system based on which tasks
it can perform with adequate performance. Because the tool is designed to test
a system's suitability for use as a Media Center / Home Theater PC, it is
obvious what tasks it must be capable of: Playing, recording, and streaming
various audio and video formats. The exact capabilities that it tests are shown
below in a slide from Intel's presentation about the tool.
Different tasks are tested for capability in different ways.
Each of these tasks is tested in a different way. Some are straightforward;
either the system can handle the task, or it can't. Others are based on video
quality; the system must maintain a certain threshold of video
quality to pass the test. Finally, some tasks are based on response time,
meaning that the system must complete the task in a certain amount
of time.
These core tasks are grouped into three standard
levels of capability:
- Basic (level 1)
- HD (level 2)
- Connected
(level 3)
Most systems should be able to hand the Basic level, which
requires playing, recording, and transcoding standard definition TV and DVD
content. The next level is HD capability, which requires the same tasks to be
done using HDTV footage. Level three adds the ability to stream media as a DLNA
compliant stream — guaranteeing compatibility with other DLNA compliant devices.
Three basic levels of capability are tested.
The way that core tasks are divided into the three levels is complex. Each level of capability
contains a number of mandatory and optional "scenarios", which themselves contain
one or more core capabilities. The most difficult capability tests involve multitasking:
Two, three, four or more core capabilities are tested simultaneously, and if
any of them cannot be completed to a satisfactory level of quality, the system
is considered incapable of performing that scenario. A system must be able to
complete all mandatory scenarios to be considered capable of a given level.
In addition, optional "extra credit" scenarios not considered
in the capability levels are used to differentiate between systems that are
otherwise equally capable. These scenarios may be mandatory for a higher level,
or simply an unusual (or especially system-intensive) pattern of core tasks.
Extra credit scenarios contribute to the "Overall Capability Level Score". A more detailed table
of how well the system performed each scenario can also be viewed, which makes
it possible to tell at a glance exactly which capabilities the system is — and
isn't — capable of.
The hierarchy of capabilities: Individual tasks ("usage primitives") are
combined into scenarios,
which must all be completed for compliance with a particular level of capability.
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