As mentioned in the past I got a new TV this year. It's an LG 32LCD2DB with a native panel resolution of 1366x768. As well as the usual SCART/component inputs it has VGA and HDMI. Currently my homebrew PVR outputs to the TV via a full featured DVB card with onboard MPEG2 decoder, but this limits me to 720x576 output and a basic OSD. My current box is a PIII-800 with a basic onboard SiS graphics chipset, so it's not got the grunt to drive the TV directly itself. I'm thus on the lookout for an upgrade.
Let's start with my constraints. I have a Silverstone LC-02 case. I'd previously planned to upgrade to something bigger, but the discovery that LinITX can provide a variety of riser cards to suit PCI-E/PCI as needed means I don't have to. The LC-02 will take a MicroATX board and provide me with 2 slots, one of which is taken up by the PCI DVB card. This box lives in my living room, so it needs to be quiet - the current incarnation is a bit too loud but I believe that's mainly due to using a standard heatsink+fan assembly, so I'm hoping that something specifically designed to be quiet will be better. An lirc dongle and wireless keyboard/mouse are already sorted.
I'd like to expand the use of the PVR to be a more general PC as well; up until now it's just been a PVR, but being able to check email/IRC would be nice, as would the ability to play games. Up until now I've run VDR, which takes full advantage of the MPEG2 decoder, but I'd like to give MythTV a decent try. All of this points to wanting more than just a HD hardware MPEG2/MPEG4 decoder.
First lets start with the graphics chipset options. The contenders seem to be ATI, Intel, nVidia and Via. From my reading ATI lack any form of XvMC support in both their Free and binary blob drivers, so we can discount them. nVidia have support, but only in their binary drivers. The Nouveau project have support on their TODO list, but I can't see any sign of it yet. I'd really rather avoid non-free drivers, so that leaves us with just Intel and Via.
I really like the look of the Intel G965/X3000. They've opened up their driver development and it seems to be quite active from reading the Xorg mailing lists. However they don't have any XvMC support; Keith Packard on the xorg list in February says "For media purposes, the current drivers aren't taking full advantage of the hardware yet", though later on does say "XvMC is on several of our lists; I don't know when someone will pick it up and implement it". Unfortunately I get the feeling it's not a high priority; I've seen/heard several comments about the fact that any processor that'll get hooked up to this chipset will be more than fast enough to cope without the assistance. That may be true, but I don't want my CPU to be spending all its time trying to decode MPEG2 or MPEG4 at 1920x1080i while the GPU sits mostly unused. I'd much rather the GPU was used to the full giving me spare CPU cycles, or perhaps the ability to clock it a bit slower for common use cases, reducing power and heat. I'm keeping Intel on my list because I hope they do get round to proper support sooner rather than later. They've also talked about the fact the GPU is programmable which would make it perfectly possible to add MPEG4 acceleration to the chipset; that would be pretty sweet.
It's a bit odd to end up with Via on the list. I mainly think of them as associated with MiniITX boards, but they do also produce various motherboards for Intel/AMD CPUs with integrated graphics. They managed to shoot themselves in the foot for a period of time by limiting the maximum accelerated resolution to 1024x1024, but recently they've released the CX700M /P4M900 chipsets which appear to do 2048x2048. The OpenChrome project have these up and running to a basic level from what I can tell, but work on XvMC support appears to be progressing with various patches and reports flying about on the list.
So currently it looks like Via has the best option (albeit through the Free software community, rather than a concerted effort on their part), while Intel has something that could be very appealing if the driver was more complete.
The other factor is the CPU. 3 contenders this time; AMD Intel and Via. My current PIII-800 is rated at 20.8W TDP. Modern processors are in general a lot hotter, but I need to keep in mind that I'm looking for a quiet machine, and that the case doesn't have a huge amount of room for big cooling systems. AMD's dual core chips all start at 89W or more, though some of their single core lower end CPUs are more like 67W. Of course the Intel graphics won't work with it and I'm not 100% sure Via has a suitable Athlon chipset at present either (the 2 I found were for Intel/Via). Intel's P4 offerings aren't much better for power consumption, with many of the highest end chips being over 100W. Core 2 Duo looks promising; 65W, so more than the current CPU, but a lot more grunt. Via come out tops here; 20W for their 2GHz top end processor. However this is only single core and compares poorly to the equivalent clock speed of Core 2 Duo.
A MiniITX board with a 2GHz C7 and a CX700M would probably make a fine PVR, but I'm not convinced about there being enough grunt for anything else. The Via chipsets appear to have more active in-progress support for media acceleration, which suggests a P4M900 + Core 2 Duo. That's contrasted with what looks to be the more powerful X3000, that actually has a manufacturer who seems to want to get full Free support out there.
I'm probably a couple of months off actually making a decision; partly because I want to watch how it all plays out in the hope that the Intel chipset will get some more support, or that the Via chipset will be proven to be reliable in operation. And assuming I do make a video chipset/CPU decision I then get the joys of trying to find a motherboard with DVI + SP/DIF. I know the G965 can do DVI out with an ADD2 card in the PCI-E slot, but I don't know if the P4M900 supports the same thing. I can't see an Intel MicroATX 965 board with SP/DIF out - there's an HD audio header, but this doesn't seem to be a direct mapping. Can I get a converter?