A Better HTPC Card: MPEG-4 ASP Decoding & LPCM Audio

Along with the addition of DirectX 10.1 functionality, the latest members of NVIDIA’s GPU lineup have picked up a couple of new tricks specifically geared towards HTPC use.

The first of these is a newer video decoding engine. Officially NVIDIA is moving away from the VP* moniker, but for the time being we’re sticking to it as we don’t have a better way of easily differentiating the feature sets of various video decoding engines. NVIDIA’s vendors are calling this VP4, and so are we.

Successive VPs have focused on adding support for additional video formats. VP2 had full H.264 decoding, and VP3 (which never made it into a GTX 200 series part) added VC-1 decoding. For VP4, NVIDIA has added support for full decoding of MPEG-4 (Advanced) Simple Profile, better known as DivX or XviD. With this addition, NVIDIA can now offload the decoding of most of the MPEG formats – the only thing not supported is MPEG-1, which as the oldest codec is trivial to decode on a CPU anyhow.

To be frank, we’re a bit puzzled by this latest addition. By no means are we unhappy (we’ll always take more acceleration!), but MPEG-4 ASP isn’t particularly hard to decode. Even an underclocked Nehalem with only a single core (and no HT) enabled can handle HD-resolution MPEG-4 ASP with ease; never mind what even a low-end dual-core Pentium or Celeron can do. This would be a good match for the Atom, but those almost always use integrated graphics (and Ion isn’t slated to get VP4 any time soon). So while this addition is nice to have, it’s not the kind of game changer that adding H.264 and VC-1 were.

The unfortunate news here is that while the hardware is ready, the software is not, and this is something that caught us off-guard since these parts have been going to OEMs since July. NVIDIA has yet to enable MPEG-4 ASP acceleration in their drivers, and won’t be doing so until the release 195 drivers. So at this point we can’t even tell you how well this feature works. We’re not pleased with this, but we’re also not particularly broken up about it since as we just mentioned the cost of CPU decoding isn’t very much in the first place.

On a final note with video decoding, one of NVIDIA’s marketing pushes with this launch is touting the fact that they have been working with Adobe to bring video decode acceleration to Adobe Flash 10.1, and that the GT 220/G 210 series are well suited for this. This is going to be absolutely fantastic to have since Flash Video is a CPU-hog, but Flash 10.1 is still 6 months (or more) away from being released. More to the point, as far as we know this is being implemented via DXVA, which means everyone else will get acceleration too. And notably, this is only for H.264, as VP6 (the older Flash Video codec) is not supported in hardware on any card.

Moving on, the other new HTPC feature is that NVIDIA has finally stepped up their game with respect to HDMI audio on cards with discrete GPUs. Gone is the S/PDIF cable to connect a card to an audio codec, which means NVIDIA is no longer limited to 2-channel LPCM or 5.1 channel DD/DTS for audio. Now they are passing audio over the PCIe bus, which gives them the ability to support additional formats. 8 channel LPCM is in, as are the lossy formats DD+ and 6 channel AAC. However Dolby TrueHD and DTS Master Audio bitstreaming are not supported, so it’s not quite the perfect HTPC card. Lossless audio is possible through LPCM, but there won’t be any lossless audio bitstreaming.

Finally, we’re still waiting to see someone do a passive cooled design for the GT 220. The power usage is low enough that it should be possible with a dual-slot heatsink, but the only cards we’ve seen thus far are actively cooled single-slot solutions with the heatsink sticking out some.

DirectX 10.1 on an NVIDIA GPU? Palit’s GT 220 Sonic Edition


View All Comments

  • Ryan Smith - Monday, October 12, 2009 - link

    I don't have that information at this moment. However this is very much the wrong card if you're going scientific work for performance reasons. Reply
  • apple3feet - Wednesday, October 14, 2009 - link

    Well, as a developer, I just need it to work. Other machines here have TESLAs and GTX280s, but a low end cool running card would be very useful for development machines.

    I believe that the answer to my question is that it's 1.2 (i.e. everything except double precision), so no good for me.
  • jma - Monday, October 12, 2009 - link

    Ryan, if you run 'deviceQuery' from the Cuda SDK, it will tell you all there is to know.

    Another goodie would be 'bandwidthTest' for those of us who can't figure out the differences between various DDR and GDDR's and what the quoted clocks are supposed to imply ...
  • vlado08 - Monday, October 12, 2009 - link

    My HD 4670 idles in 165MHz core and 249,8MHz memoy clock and GPU temps 36-45 degrees(passively cooled) as reported by GPU-Z 0.3.5 Is there a possibility that your card didn't lower it's clock during idle? Reply
  • vlado08 - Monday, October 12, 2009 - link

    My question is to Ryian of course. Reply
  • Ryan Smith - Monday, October 12, 2009 - link

    Yes, it was idling correctly. Reply
  • KaarlisK - Monday, October 12, 2009 - link

    The HD4670 cards differ.
    I've bought three:



    The first one would idle at 0.9v.
    The second would idle at 1.1v. When I edited the BIOS for lover idle voltages, I could not get it to be stable.

    The third one turned out to have a much cheaper design - not only did it have slower memory, it had no voltage adjustments and idles at 1.25v (but the correct idle frequency).
  • vlado08 - Monday, October 12, 2009 - link

    Are GT 220 capable of DXVA decoding of h.264 at High Profile Level 5.1?
    And videos wiht more than 5 reference frames. Because ATI HD4670 can only do High Profile (HiP) Level 4.1 Blu-ray compatible.
    Also what is the deinterlacing on GT 220 if you have monitor and TV in extended mode? Is it vector adaptive deinterlacing?
    These questions are important for this video card because it is obvious that it is not for gamer but for HTPC.
    On HD 4670 when you have one monitor then you have vector adaptive deinterlacing but if you have two monitors or monitor and TV and they are in extended mode then you only have "bob" deinterlacing.
    I'm not sure if this is driver bug or hardware limitation.
  • Ryan Smith - Monday, October 12, 2009 - link

    I have another GT 220 card due this week or early next. Drop me an email; if you have something I can use to test it, I will gladly try it out. I have yet to encounter anything above 4.1 though; it seems largely academic. Reply
  • MadMan007 - Monday, October 12, 2009 - link

    So my inner nerd that just has to know is confused. Are these truly GT200-based or G9x-based? Different sources say different things. In a way the GT200 series was an improvement on G9x anyway but with enough significant low level changes to make it different. The article calls these GT200 *series* but that could be in name only. It's not clear if that means smaller process cut down die GT200-based or added feature G9x-based.

    Inquiring nerds want to know!

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