Moreover, one of the attractions of the more recent ATI & NVIDIA chipsets is their support for video decoding. Does this work under Linux, I wonder?
Sadly no VC-1 or H264 decoding capabilities yet in either chipset (so far as I am aware). For an HTPC setup using those codecs, hardware acceleration could mean the difference between a 2GHz and 1GHz CPU... which would be very significant on a m-ITX board like the KI690.
You are correct, and this is the only beef I have with this board, although it is currently the best onboard GPU, so you have to give them credit.
I believe the first onboard solution with the HW decoding ability will be Intel's G35 with the X3500 GPU
. Let's hop Albatron can do something similar with it.
The G35 will be based on Intel's next-generation X3500 Graphics Media Accelerator. Full DX10 support is claimed, including support for Shader Model 4.0. For backwards compatibility X3500 also will support Shader Model 3.0 and Hardware Transform and Lighting (T&L). High Resolution DVD playback is also featured, with support for both HD-DVD and Blu-Ray playback. X3500 also is said to support HDMI and DVI. MPEG2 and VC1 1080i/p are also supported by the Intel Clear Video feature of X3500.
Just for reference, here is some info on the 690G video decoding abilities from anandtech
For video acceleration features, the X1250 is capable of hardware acceleration of MPEG2 and WMV playback. MPEG4 playback decode is not hardware accelerated, but it is supported in software via the driver. DVD and TV (both SD and HD resolution) playback can be offloaded from the CPU, but we have seen some severe choppiness or blank screen issues with HD media formats at 1080p - although 720p worked fine. AMD has indicated that this issue will be addressed in a future driver and the chipset is fully capable of 1080p output with an upper end CPU and proper software support.
And here is some info on nVidia's newest solution, the 7050PV
The PureVideo standard incorporates a hardware accelerator for the afore mentioned MPEG-2/DVD, and Microsoft Windows Media High Definition Video standards (WMV9 HD).
The 1080P version of the Discoverers video chews up a bit more system resources between 15-20%. That's still peanuts compared to what a non-accelerated high definition video would use, and you have a ton of resources free for whatever else you're doing.