Seeing the Present: HDMI 1.4a, UVD3, and Display Correction

DisplayPort wasn’t the only aspect of AMD’s display controller that got an overhaul however, AMD’s HDMI capabilities have also been brought up to modern standards. Coming from Cypress with support for HDMI 1.3, AMD now supports HDMI 1.4a on the Barts based 6800 series and presumably they will do so on the rest of the 6800 series too. With HDMI 1.4a support AMD can now support full resolution (1080p) 3D stereoscopy for movies, and 720p for games and other material that require 60Hz/eye, along with 4k x 2k resolution for monitors and TVs that have equivalent support. Unlike DP this has less to do with monitors and more to do with TVs, so the importance of this will be seen more on future AMD cards when AMD refreshes their lower-end parts that we normally use with HTPCs.

Launching alongside support for displaying full resolution 3D stereoscopic video is the hardware necessary to decode such video, in the form of the latest version of AMD’s Unified Video Decoder: UVD3. The last time UVD received a major update was with UVD2, which launched alongside the Radeon HD 4000 series and added partial MPEG-2 decoding support by moving IDCT and MoComp from shaders in to the UVD fixed function hardware.


Click to enlarge

With the Radeon 6800 series AMD is releasing UVD3, which like UVD2 before it builds on the existing UVD feature set. UVD3 is adding support for 3 more-or-less new codecs: MPEG-2, MVC, and MPEG-4 ASP (better known as DivX/XviD). Starting with MPEG-4 ASP, it’s the only new codec in supported by UVD3 that’s actually new, as previously all MPEG-4 ASP decoding was done in software when it came to AMD GPUs. With UVD3 AMD can now completely offload MPEG-4 ASP decoding to the GPU, bringing forth the usual advantages of greatly reducing the amount of work the CPU needs to do and ideally reducing power consumption in the process.

AMD adding MPEG-4 ASP support gives us an interesting chance to compare and contrast them to NVIDIA, who added similar support a year ago in the GT21x GPUs. AMD  is a good bit behind NVIDIA here, but they’re making up for it by launching with much better software support for this feature than NVIDIA did; NVIDIA still does not expose their MPEG-4 ASP decoder in most situations, and overall did a poor job of advertising it. When we talked with DivX (who is AMD’s launch partner for this feature) they didn’t even know that NVIDIA had MPEG-4 ASP support. Meanwhile AMD is launching with DivX and had a beta version of the DivX codec with UVD3 support ready to test, and furthermore AMD is fully exposing their MPEG-4 ASP capabilities in their drivers as we see in this DXVA Checker screenshot.

The only downside at this time is that even with Microsoft’s greater focus on codecs for Windows 7, Windows 7 doesn’t know what to do with DXVA acceleration of MPEG-4 ASP. So while Win7 can play MPEG-4 ASP in software, you’re still going to need a 3rd party codec like the DivX codec to get hardware support for MPEG-4 ASP.

The other bit worth mentioning is that while AMD is launching support for MPEG-4 ASP decoding here on the 6800 series, much like HDMI 1.4a it’s not going to be a big deal for the 6800 series market. MPEG-4 ASP is a fairly lightweight codec, so support for it is going to be a bigger deal on low-end products, particularly AMD’s APUs if Llano and Bobcat end up using UVD3, as MPEG-4 ASP decoding in software requires a much greater share of resources on those products.

Up next is MPEG-2, which has been a codec stuck in limbo for quite some time over at AMD. MPEG-2 is even older and easier to decode than MPEG-4 ASP, and while GPUs have supported MPEG-2 decode acceleration as early as last decade, CPUs quickly became fast enough that when combined with low levels of hardware decode acceleration (inverse discrete cosine transform) was more than enough to play MPEG-2 content. Thus AMD hasn’t done much with MPEG-2 over the years other than moving IDCT/MoComp from the shaders to UVD for UVD2.

Because of the similarities between MPEG-4 ASP and MPEG-2, when AMD added support for full MPEG-4 ASP decode acceleration they were able to easily add support for full MPEG-2 decode acceleration, as they were able to reuse the MPEG-4 ASP entropy decode block for MPEG-2. As a result of including full MPEG-4 ASP decode acceleration, AMD now supports full MPEG-2 decode acceleration. Even more so than MPEG-4 ASP however, the benefits for this are going to lie with AMD’s low-end products where getting MPEG-2 off of the CPU should be a boon for battery life.

The final addition to UVD3 is support for Multiview Video Coding, which isn’t a new codec per se, but rather is an extension to H.264 for 3D stereoscopy. H.264 needed to be amended to support the packed frame formats used to store and transmit 3D stereoscopic videos, so with UVD3 AMD is adding support for MVC so that UVD can handle Blu-Ray 3D.

Finally, coupled with support for new codecs and new display outputs in AMD’s display controller is a refinement of AMD’s existing color correction capabilities in their display controller. Cypress and the rest of the 5000 series could do color correction directly on their display controllers, but they could only do so after gamma correction was applied, meaning they had to work in the non-linear gamma color space. Technically speaking this worked, but color accuracy suffered as a result. With the 6800 series’ new display controller, AMD can now perform color calibration in linear space by converting the image from gamma to linear color space for the color correction, before converting it back to gamma color space for display purposes.

As color correction is being used to correct for wide-gamut monitors the importance of this change won’t be seen right away for most users, but as wide-gamut monitors become more widespread color correction becomes increasingly important since wide-gamut monitors will misinterpret the normal sRGB colorspace that most rendering is done in.


Click to enlarge

Seeing the Future: DisplayPort 1.2 High IQ: AMD Fixes Texture Filtering and Adds Morphological AA
POST A COMMENT

197 Comments

View All Comments

  • Ryan Smith - Friday, October 22, 2010 - link

    Quality is unchanged. UVD 3 adds a few fixed function blocks, but quality is a matter of post-processing and hence affected by the drivers once you have sufficient shader power to do all the post-processing. Reply
  • Pastuch - Friday, October 22, 2010 - link

    I posted about this earlier but my post was deleted.

    Ryan there is a ton of HTPC users on this site.

    1. Exactly how long is the Radeon 6870/6850 vs the GTX 460?

    2. How does the GTX460 compare to the Radeon 6 series regarding bitstreaming high def audio?

    3. How UVD3 post-processing compare to Nvidias?
    Reply
  • Ryan Smith - Friday, October 22, 2010 - link

    It's exactly the same as this: http://www.anandtech.com/show/3973/nvidias-geforce... Reply
  • HigherGround - Friday, October 22, 2010 - link

    Why was EVGA card included in this test? The rest of the field is generic (non OC, no brand), so why included an OC card, which skews the readers perspective? Pretty sure EVGA paid you to included its top OC card in this review ... Reply
  • Parhel - Friday, October 22, 2010 - link

    No, NVidia paid them to include it. NVidia sends "guidelines" to all the hardware review sites, telling them what settings to use and which cards to use in the comparison. In the guidelines for today's review was to use the EVGA GTX 460 FTW, and and site you see using it is essentially a paid NVidia shill.

    I could care less about ATI vs NVidia, as I'm not really a gamer, but I'm very disappointed today to see my long time favorite hardware site stooping to this level. In the end, it gives consumers bad information, which should be antithetical to the purpose of a site like this.
    Reply
  • AtwaterFS - Friday, October 22, 2010 - link

    I agree, this site is typically class-leading, but this article give AnandTech a bit of a black eye and the results dont particularly jive with "un-biased" sites like HardOCP. Reply
  • DrKlahn - Friday, October 22, 2010 - link

    I was going to post the same thing. As a long time reader of this site, I was very disappointed with the decision to include the overclocked card. Either the ATI cards should have been overclocked and their results provided in every test or it should have been excluded as per the normal benchmarking guidelines.

    I would have no issue with a followup or side article comparing factory overclocked offerings. But this is clearly bowing to pressure from Nvidia and I expected better of this site.
    Reply
  • aungee - Saturday, October 23, 2010 - link

    To Include the EVGA GTX 460 FTW was unfair and whether intentional or not it did spoil the launch party for AMD on this site to some degree. It would have been more appropriate to make a small mention of it's existence and to benchmark it in the future against any factory OC 6800 cards.

    After getting your head around the naming, AMD needs to be credited for bringing such a performance on only a 255 mm2 package (it even caused the price drop for the 530mm2 GTX 470) . AMD has headroom to drop the price of the 6800 cards so lets hope they do soon.
    Reply
  • tigersty1e - Friday, October 22, 2010 - link

    I couldn't find the clocks, but if you do include an OC'd card in your benches, you should give us the clocks. Reply
  • dertechie - Friday, October 22, 2010 - link

    850 MHz Core, 1700 MHz shaders, 4 GHz Memory, up from 675 MHz Core, 1350 MHz shaders, 3.6 GHz Memory.

    That's a 26% Core OC and an 11% Memory OC. However, the cost has been OC'd too, the FTW card costs the same $240 as the stock Radeon 6870.
    Reply

Log in

Don't have an account? Sign up now