For years ATI has held the reputation for industry-leading video acceleration. It seems that each successive generation has ushered in a new video feature for their competition to try to match. Nearly every new high-end OEM system ships with a DVD drive, enabling MPEG-2 video playback for an increasing number of households.

Video features are most easily understood if they are split into two categories: Quality and Performance.

Performance features assist the CPU in the decoding process, leaving the CPU free to handle other applications. System requirements are also lowered, since powerful processors aren’t needed for full-frame decoding. Motion compensation is the first of these features, decreasing CPU load by about 25%. Also integrated into the Radeon core is an iDCT engine, which complements the motion compensation unit. iDCT accounts for roughly 15% of the decoding process, so a machine boasting both of these features will enjoy roughly 40% less CPU utilization while engaged in video playback than a system lacking them.

Some of the performance features may also bleed into the quality category. For instance, motion compensation uses a 9-bit error term that may be truncated to 8-bits by some engines, resulting in a loss of quality. ATI’s motion compensation engine uses the full 9-bits to maintain video integrity and thus does not suffer the loss. In addition, the Radeon also supports alpha subpicture blending. This is another quality-targeted feature that takes a menu or subtitle and blends it to the background in hardware to avoid stressing the CPU with the signal processing that is associated with alpha blending.

Perhaps the biggest addition to ATI’s video repertoire for the Radeon is adaptive deinterlacing, a quality feature that blends bob and weave deinterlacing on a per-pixel level for a smoother image. If motion is detected on any given pixel, bob interlacing is used, if there is no motion on the pixel, weave interlacing is used instead. Unfortunately, adaptive deinterlacing isn’t recognized by Video 2000, so although we’d love to run MadOnion’s video benchmark on the Radeon, the numbers that are returned don’t represent actual performance.

As HDTV broadcasts become more common, Radeon’s DTV support will become more important. Until we see a product that offers more than just “support for HDTV,” the only claim that matters is that the Radeon fully supports all 18 DTV broadcast formats.