AMD Radeon HD 7970 Review: 28nm And Graphics Core Next, Together As Oneby Ryan Smith on December 22, 2011 12:00 AM EST
- Posted in
- Radeon HD 7000
Video & Movies: The Video Codec Engine, UVD3, & Steady Video 2.0
When Intel introduced the Sandy Bridge architecture one of their big additions was Quick Sync, their name for their hardware H.264 encoder. By combining a specialized fixed function encoder with some GPU-based processing Intel was able to create a small, highly efficient H.264 encoder that had quality that was as good as or better than AMD and NVIDIA’s GPU based encoders that at the same time was 2x to 4x faster and consumed a fraction of the power. Quick Sync made real-time H.264 encoding practical on even low-power devices, and made GPU encoding redundant at the time. AMD of course isn’t one to sit idle, and they have been hard at work at their own implementation of that technology: the Video Codec Engine (VCE).
The introduction of VCE brings up a very interesting point for discussing the organization of AMD. As both a CPU and a GPU company the line between the two divisions and their technologies often blurs, and Fusion has practically made this mandatory. When AMD wants to implement a feature, is it a GPU feature, a CPU feature, or perhaps it’s both? Intel implemented Quick Sync as a CPU company, but does that mean hardware H.264 encoders are a CPU feature? AMD says no. Hardware H.264 encoders are a GPU feature.
As such VCE is being added to the mix from the GPU side, meaning it shows up first here on the Southern Islands series. Fundamentally VCE is very similar to Quick Sync – it’s based on what you can accomplish with the addition of a fixed function encoder – but AMD takes the concept much further to take full advantage of what the compute side of GCN can do. In “Full Mode” VCE behaves exactly like Quick Sync, in which virtually every step of the H.264 encoding process is handled by fixed function hardware. Just like Quick Sync Full Mode is fast and energy efficient. But it doesn’t make significant use of the rest of the GPU.
Hybrid Mode is where AMD takes things a step further, by throwing the compute resources of the GPU back into the mix. In Hybrid Mode only Entropy Encode is handled by fixed function hardware (this being a highly serial process that was ill suited to a GPU) with all the other steps being handled by the flexible hardware of the GPU. The end goal of Hybrid Mode is that as these other steps are well suited to being done on a GPU, Hybrid Mode will be much faster than even the highly optimized fixed function hardware of Full Mode. Full Mode is already faster than real time – Hybrid Mode should be faster yet.
With VCE AMD is also targeting Quick Sync’s weaknesses regardless of the mode used. Quick Sync has limited tuning capabilities which impacts the quality of the resulting encode. AMD is going to offer more tuning capabilities to allow for a wider range of compression quality. We don’t expect that it will be up to the quality standards of X264 and other pure-software encoders that can generate archival quality encodes, but if AMD is right it should be closer to archival quality than Quick Sync was.
The catch right now is that VCE is so new that we can’t test it. The hardware is there and we’re told it works, but the software support for it is lacking as none of AMD’s partners have added support for it yet. On the positive side this means we’ll be able to test it in-depth once the software is ready as opposed to quickly testing it in time for this review, however the downside is that we cannot comment on the speed or quality at this time. Though with the 7970 not launching until next year, there’s time for software support to be worked out before the first Southern Islands card ever goes on sale.
Moving on, while encoding has been significantly overhauled decoding will remain largely the same. AMD doesn’t refer to the Universal Video Decoder on Tahiti as UVD3, but the specifications match UVD3 as we’ve seen on Cayman so we believe it to be the same decoder. The quality may have been slightly improved as AMD is telling us they’ve scored 200 on HQV 2.0 – the last time we scored them they were at 197 – but HQV is a partially subjective benchmark.
Finally, with Southern Islands AMD is introducing Steady Video 2.0, thesuccessor to Steady Video that was introduced with the Llano APU last year. Steady Video 2.0 adds support for interlaced and letter/pillar boxed content, along with a general increase in the effectiveness of the steadying effect. What makes this particularly interesting is that Steady Video implements a new GCN architecture instruction, Quad Sum of Absolute Differences (QSAD), which combines regular SAD operations with alignment operations into a single instruction. As a result AMD can now execute SADs at a much higher rate so long as they can be organized into QSADs, which is one of the principle reasons that AMD was able to improve Steady Video as it’s a SAD-heavy operation. QSAD extends to more than just Steady Video (AMD noted that it’s also good for other image analysis operations), but Steady Video is going to be the premiere use for it.
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Wreckage - Thursday, December 22, 2011 - linkThat's kind of disappointing.
atticus14 - Thursday, December 22, 2011 - linkoh look its that guy that was banned from the forums for being an overboard nvidia zealot.
medi01 - Tuesday, January 3, 2012 - linkMaybe he meant "somebody @ anandtech is again pissing on AMDs cookies"?
I mean "oh, it's fastest and coolest single GPU card on the market, it is slightly more expensive than competitor's, but it kinda sucks since AMD didn't go "significantly cheaper than nVidia" route" is hard to call unbiased, eh?
Kind of disappointing conclusion, indeed.
ddarko - Thursday, December 22, 2011 - linkTo each their own but I think this is undeniable impressive:
"Even with the same number of ROPs and a similar theoretical performance limit (29.6 vs 28.16), 7970 is pushing 51% more pixels than 6970 is" and
"it’s clear that AMD’s tessellation efficiency improvements are quite real, and that with Tahiti AMD can deliver much better tessellation performance than Cayman even at virtually the same theoretical triangle throughput rate."
Samus - Thursday, December 22, 2011 - linkI prefer nVidia products, mostly because the games I play (EA/DICE Battlefield-series) are heavily sponsered by nVidia, giving them a developement-edge.
That out of the way, nVidia has had their problems just like this card is going to experience. Remember when Fermi came out, it was a performance joke, not because it was slow, but because it used a ridiculous amount of power to do the same thing as an ATI card while costing substantially more.
Fermi wasn't successful until second-generation products were released, most obviously the GTX460 and GT430, reasonably priced cards with quality drivers and low power consumption. But it took over a year for nVidia to release those, and it will take over a year for ATI to make this architecture shine.
kyuu - Thursday, December 22, 2011 - linkWat? The only thing there might be an issue with is drivers. As far as power consumption goes, this should be better than Cayman.
CeriseCogburn - Sunday, March 11, 2012 - linkHe's saying the 28mn node will have further power improvements. Take it as an amd compliment - rather you should have.
StriderTR - Thursday, December 22, 2011 - linkEA/Dice are just as heavily sponsored by AMD, more in fact. Not sure where your getting your information, but its .. well ... wrong. Nvidia bought the rights to advertize the game with their hardware, AMD is heavily sponsoring BF3 and related material. Example, The Controller.
Also, the GTX 580 and HD 6970 perform within a few FPS of each other on BF3. I run dual 6970's, by buddy runs dual 580's, we are almost always within 2 FPS of one and other at any given time.
AMD will have the new architecture "shining" in far under a year. They have been focused on it for a long time already.
Simple bottom line, both Nvidia and AMD make world class cards these days. No matter your preference, you have cards to choose from that will rock any games on the planet for a long time to come.
deaner - Thursday, December 22, 2011 - linkUmm, yea no. Not so much with nvidia and EA/DICE Batttlefield series giving nvidia a development edge. (if it does, the results are yet to be seen)
Facts are facts, the 5 series to our current review today, the 7970, do and again continue to edge the Nvidia lines. The AMD Catalyst performance of particular note, BF3, has been far superior.
RussianSensation - Thursday, December 22, 2011 - link."..most obviously the GTX460 and GT430, reasonably priced cards with quality drivers and low power consumption. But it took over a year for nVidia to release those"
GTX470/480 launched March 26, 2010
GTX460 launched July 12, 2010
GT430 launched October 11, 2010
Also, Fermi's performance at launch was not a joke. GTX470 delivered performance between HD5850 and HD5870, priced in the middle. Looking now, GTX480 ~ HD6970. So again, both of those cards did relatively well at the time. Once you consider overclocking of the 470/480, they did extremely well, both easily surprassing the 5870 in performance in overclocked states.
Sure power consumption was high, but that's the nature of the game for highest-end GPUs.