The New Video Decode Pipeline: UVD

UPDATE: Since the launch of the HD 2900 XT, we've learned that all HD 2000 series parts except the high end R600 based parts will have UVD. This means that the HD 2900 XT will feature the same video decode acceleration offered on the R5xx hardware. As higher end cards are usually paired with faster CPUs, AMD feels that UVD on R600 is unnecessary.

This comes as a bit of a surprise to us and to certain board partners who's box art claims UVD as a feature of the HD 2900 XT. We do apologize for any confusion we may have caused at launch.

NVIDIA beat AMD to the punch with their full H.264 decode acceleration on G86/G84. Of course, AMD is one upping NVIDIA this time around, as their UVD (Unified Video Decode) architecture is also capable of decoding VLC bitstreams on all three HD media codecs. This means that there are no cases where AMD hardware will not handle 100% of the video decode process (after the CPU has dealt with pulling the encrypted content off the disk and preparing it to send to the GPU that is).

Here's a diagram of the landscape as it stands now. Notice that G80 is not capable of the bitstream decode or the inverse transformation (either iDCT or otherwise), but G84/G86 come very close to matching AMD's capabilities.

At the same time, we should remember that bitstream decode is only really heavy under H.264. Certainly VC-1 and MPEG-2 will see some benefit, but they are already fairly manageable. NVIDIA stated that building the hardware to handle VLC bitstreams wouldn't have a high enough return on investment. AMD, however, indicated that their bitstream processors are at least a little bit adaptable and it wasn't that difficult to include VLC decode.

Either way, the best way to figure out what's going on is to take a look at performance and see if there really is any advantage to R600 over G86. Unfortunately, try as we might, we could not get UVD to work with the current drivers provided by AMD and the PowerDVD release that is supposed to enable the hardware acceleration on HD 2000 series parts. We will have to take a second look at hardware decode when AMD and CyberLink or Intervideo get their software in order.

For now, our information leads us to believe that performance won't be hugely improved over G84/G86 in MPEG-2 and VC-1 CPU offloading. Where we might start to see a difference is in AMD's 65nm HD 2000 and mobility series parts. These have the potential to decrease power consumption by large amounts and provide quiet running systems for HTPCs, or longer battery life for notebooks. We will have to wait to get our hands on the higher volume R6xx based parts though. Also worth nothing is that AMD's high-end hardware does something that NVIDIA's 8800 series cards currently don't, so NVIDIA users that want fast H.264 decoding support are stuck with slower 3D performance.

Tesselation and the Future AMD CFAA Performance and Image Quality
POST A COMMENT

86 Comments

View All Comments

  • wjmbsd - Monday, July 02, 2007 - link

    What is the latest on the so-called Dragonhead 2 project (aka, HD 2900 XTX)? I heard it was just for OEMs at first...anyone know if the project is still going and how the part is benchmarking with newest drivers? Reply
  • teainthesahara - Monday, May 21, 2007 - link

    After this failure of the R600 and likely overrated(and probably late) Barcelona/Agena processors I think that Intel will finally bury AMD. Paul Ottelini is rubbing his hands with glee at the moment and rightfully so. AMD now stands for mediocrity.Oh dear what a fall from grace.... To be honest Nvidia don't have any real competition on the DX10 front at any price points.I cannot see AMD processors besting Intel's Core 2 Quad lineup in the future especially when 45nm and 32 nm become the norm and they don't have a chance in hell of beating Nvidia. Intel and Nvidia are turning the screws on Hector Ruiz.Shame AMD brought down such a great company like ATI. Reply
  • DerekWilson - Thursday, May 24, 2007 - link

    To be fair, we really don't have any clue how these cards compete on the DX10 front as there are no final, real DX10 games on the market to test.

    We will try really hard to get a good idea of what DX10 will look like on the HD 2000 series and the GeForce 8 Series using game demos, pre-release code, and SDK samples. It won't be a real reflection of what users will experience, but we will certainly hope to get a glimpse at performance.

    It is fair to say that NVIDIA bests AMD in current game performance. But really there are so many possibilities with DX10 that we can't call it yet.
    Reply
  • spinportal - Friday, May 18, 2007 - link

    From the last posting of results for the GTS 320MB round-up
    http://www.anandtech.com/video/showdoc.aspx?i=2953...">Prey @ AnandTech - 8800GTS320
    we see that the 2900XT review chart pushes the nVidia cards down about 15% across the board.
    http://www.anandtech.com/video/showdoc.aspx?i=2988...">Prey @ AnandTech - ATI2900XT
    The only difference in systems is software drivers as the cpu / mobo / mem are the same.

    Does this mean ATI should be getting a BIGGER THRASHING BEAT-DOWN than the reviewer is stating?
    400$ ATI 2900XT performing as good as a 300$ nVidia 8800 GTS 320MB?

    Its 100$ short and 6 months late along with 100W of extra fuel.

    This is not your uncle's 9700 Pro...
    Reply
  • DerekWilson - Sunday, May 20, 2007 - link

    We switched Prey demos -- I updated our benchmark.

    Both numbers are accurate for the tests I ran at the time.

    Our current timedemo is more stressful and thus we see lower scores with this test.
    Reply
  • Yawgm0th - Wednesday, May 16, 2007 - link

    The prices listed in this article are way off.

    Currently, 8800GTS 640MB retails for $350-380, $400+ for OC or special versions. 2900XT retails for $430+. In the article, both are listed as $400, and as such the card is given a decent review in the conclusion.

    Realistically, this card provides slightly inferior performance to the 8800GTS 640MB at a considerably higher price point -- $80-$100 more than the 8800GTS. I mean, it's not like the 8800Ultra, but for the most part this card has little use outside of AMD and/or ATI fanboys. I'd love for this card to do better as AMD needs to be competing with Nvidia and Intel right now, but I just can't see how this is even worth looking at, given current prices.
    Reply
  • DerekWilson - Thursday, May 17, 2007 - link

    really, this article focuses on architechture more than product, and we went with MSRP prices...

    we will absolutly look closer at price and price/performance when we review retail products.
    Reply
  • quanta - Tuesday, May 15, 2007 - link

    As I recalled, the Radeon HD 2900 only has DVI ports, but nowhere in DVI documentation specifies it can carry audio signals. Unless the card comes with adapter that accepts audio input, it seems the audio portion of R600 is rendered useless. Reply
  • DerekWilson - Wednesday, May 16, 2007 - link

    the card does come with an adapter of sorts, but the audio input is from the dvi port.

    you can't use a standard DVI to HDMI converter for this task.

    when using AMD's HDMI converter the data sent out over the DVI port does not follow the DVI specification.

    the bottom line is that the DVI port is just a physical connector carrying data. i could take a DVI port and solder it to a stereo and use it to carry 5.1 audio if I wanted to ... wouldn't be very useful, but I could do it :-)

    While connected to a DVI device, the card operates the port according to the DVI specification. When connected to an HDMI device through the special converter (which is not technically "dvi to hdmi" -- it's amd proprietry to hdmi), the card sends out data that follows the HDMI spec.

    you can look at it another way -- when the HDMI converter is connected, just think of the dvi port as an internal connector between an I/O port and the TMDS + audio device.
    Reply
  • ShaunO - Tuesday, May 15, 2007 - link

    I was at an AMD movie night last night where they discussed the technical details of the HD 2900 XT and also showed the Ruby Whiteout DX10 Demo rendered using the card. It looked amazing and I had high hopes until I checked out the benchmark scores. They're going to need more than free food and popcorn to convince me to buy an obsolete card.

    However there is room for improvement of course. Driver updates, DX10 and whatnot. The main thing for me personally will be driver updates, I will be interested to see how well the card improves over time while I save my pennies for my next new machine.

    Everyone keeps saying "DX10 performance will be better, yadda yadda" but I also want to be able to play the games I have now and older games without having to rely on DX10 games to give me better performance. Nothing like totally underperforming in DX9 games and then only being equal or slightly better in DX10 games compared to the competition. I would rather have a decent performer all-round. Even saying that we don't even know for sure if DX10 games are even going to bring any performance increases of the competition, it's all speculation right now and that's all we can do, speculate.

    Shaun.
    Reply

Log in

Don't have an account? Sign up now