Quick Sync Image Quality & Performance

Intel obviously focused on increasing GPU performance with Ivy Bridge, but a side effect of that increased GPU performance is more compute available for Quick Sync. As you may recall, Sandy Bridge's secret weapon was an on-die hardware video transcode engine (Quick Sync), designed to keep Intel's CPUs competitive when faced with the onslaught of GPU computing applications. At the time, video transcode seemed to be the most likely candidate for significant GPU acceleration so the move made sense. Plus it doesn't hurt that video transcoding is an extremely popular activity to do with one's PC these days.

The power of Quick Sync was how it leveraged fixed function decode (and some encode) hardware with the on-die GPU's EU array. The combination of the two resulted in some pretty incredible performance gains not only over traditional software based transcoding, but also over the fastest GPU based solutions as well.

Intel put to rest any concerns about image quality when Quick Sync launched, and thankfully the situation hasn't changed today with Ivy Bridge. In fact, you get a bit more flexibility than you had a year ago.

Intel's latest drivers now allow for a selectable tradeoff between image quality and performance when transcoding using Quick Sync. The option is exposed in Media Espresso and ultimately corresponds to an increase in average bitrate. To test image quality and performance, I took the last Harry Potter Blu-ray, stripped it of its DRM and used Media Espresso to make it playable on an iPad 2 (1024 x 768 preset).

In the case of our Harry Potter transcode, selecting the Better Quality option increased average bitrate from to 3.86Mbps to 5.83Mbps. The resulting file size for the entire movie increased from 3.78GB to 5.71GB. Both options produced a good quality transcode, picking one over the other really depends on how much time (and space) you have as well as the screen size of the device you'll be watching it on. For most phone/tablet use I'd say the faster performing option is ideal.

Intel Core i7 3770K (x86) Intel Quick Sync (SNB) Intel Quick Sync (IVB) Intel Quick Sync, Better (IVB) NVIDIA GeForce GTX 680 AMD Radeon HD 7970
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While AMD has yet to enable VCE in any publicly available software, NVIDIA's hardware encoder built into Kepler is alive and well. Cyberlink Media Espresso 6.5 will take advantage of the 680's NVENC engine which is why we standardized on it here for these tests. Once again, Quick Sync's transcoding abilities are limited to applications like Media Espresso or ArcSoft's Media Converter—there's still no support in open source applications like Handbrake.

Compared to the output from Quick Sync, NVENC appears to produce a softer image. However, if you compare the NVENC output to what we got from the software/x86 path you'll see that the two are quite similar. It seems that Quick Sync, at least in this case, is sharpening/adding more noise beyond what you'd normally expect. I'm not sure I'd call it bad, but I need to do some more testing before I know whether or not it's a good thing.

The good news is that NVENC doesn't pose any of the horrible image quality issues that NVIDIA's CUDA transcoding path gave us last year. For getting videos onto your phone, tablet or game console I'd say the output of either of these options, NVENC or Quick Sync, is good enough.

Unfortunately AMD's solution hasn't improved. The washed out images we saw last year, particularly in dark scenes prior to a significant change in brightness are back again. While NVENC delivers acceptable image quality, AMD does not.

The performance story is unfortunately not much different from last year either. The chart below is average frame rate over the entire encode process.

CyberLink Media Espresso 6.5—Harry Potter 8 Transcode

Just as we saw with Sandy Bridge, Quick Sync continues to be an incredible way to get video content onto devices other than your PC. One thing I wanted to make sure of was that Media Espresso wasn't somehow holding x86 performance back to make the GPU accelerated transcodes seem much better than they actually are. I asked our resident video expert, Ganesh, to clone Media Espresso's settings in a Handbrake profile. We took the profile and performed the same transcode, the result is listed above as the Core i7 3770K (Handbrake). You will notice that the Handbrake x86/x264 path is definitely faster than Cyberlink's software path, by over 50% to be exact. However even using Handbrake as a reference, Quick Sync transcodes over 2x faster.

In the tests below I took the same source and varied the output quality with some custom profiles. I targeted 1080p, 720p and 480p at decreasing average bitrates to illustrate the relationship between compression demands and performance:

CyberLink Media Espresso 6.5—Harry Potter 8 Transcode

CyberLink Media Espresso 6.5—Harry Potter 8 Transcode

CyberLink Media Espresso 6.5—Harry Potter 8 Transcode

Unfortunately NVENC performance does not scale like Quick Sync. When asked to preserve a good amount of data, both NVENC and Quick Sync perform similarly in our 1080p/13Mbps test. However ask for more aggressive compression ratios for lower resolution/bitrate targets, and the Intel solution quickly distances itself from NVIDIA. One theory is that NVIDIA's entropy encode block could be the limiting factor here.

Ivy Bridge's improved Quick Sync appears to be aided both by an improved decoder and the HD 4000's faster/larger EU array. The graph below helps illustrate:

If we rely on software decoding but use Intel's hardware encode engine, Ivy Bridge is 18% faster than Sandy Bridge in this test (1080p 13Mbps output from BD source, same as above). If we turn on both hardware decode and encode, the advantage grows to 29%. More than half of the performance advantage in this case is due to the faster decode engine on Ivy Bridge.

Power Consumption Final Words
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  • dagamer34 - Monday, April 23, 2012 - link

    I see them just killing off the 13" MacBook Pro entirely, and upgrading the SSD base size to 256GB. There's little reason for the Pro to live on anymore when the Air is far superior in everything except for CPU. Reply
  • gorash - Monday, April 23, 2012 - link

    Really... the Air's screen is terrible. Plus Air is basically not user upgradeable. Reply
  • Breach1337 - Monday, April 23, 2012 - link

    Yeah, I view mine as a consumable. And I love it. Reply
  • tipoo - Monday, April 23, 2012 - link

    That would be a shame, even without the optical drive they could differentiate the 13" pro from the Air with the mentioned 35w quad core CPU, or a discreet GPU in all the space they saved from ditching the ODD, and have more space for battery to offset it. Reply
  • jaydee - Monday, April 23, 2012 - link

    If I'm buying a system for onboard GPU gaming, I'm going AMD. If I'm buying a system for cpu performance with overclocking, I'm buying Sandy Bridge. I'm not sure what the point of this launch is. Reply
  • A5 - Monday, April 23, 2012 - link

    Notebooks/ultrabooks and debugging the new process node. Reply
  • 8steve8 - Monday, April 23, 2012 - link

    I've seen so many negative comments like this about Ivy Bridge all over the web... so I'll respond to them all here:

    I'd rather have higher energy efficiency and stability (and less noise), which comes with running at stock voltage/clock speeds. I am not alone there... Plus with turbo boost, why bother OCing, when it has the thermal headroom, it boosts the clock...

    If you think that you can find a significantly better sweat spot of performance, power consumption, and reliability/lifespan of the average high-end (K) CPU from intel, then I have to call BS on that. If you agree that intel knows their cpus better than you, but are purposely under-clocking them (the highest clocked models), then I would ask why.

    I may say that given significantly more exotic/larger/louder coolers, maybe you can dissipate more heat than the processors were designed to dissipate, and you have some headroom to raise the voltage, which may yield higher stable frequencies, but keep in mind power is roughly proportional to voltage^2, so energy efficiency goes out the window real fast...

    I'm not saying no one should play around with their CPUs, have fun... but to say ivy bridge is pointless just because you can't over-volt/over-clock it to the same extent as sandy bridge is foolish when it's clearly a significant step forward, and the best solution for the vast majority x86 PCs.

    For those of us who want an energy efficient, high performance computer, some variant of ivy bridge will be the best option, probably until haswell/2013.

    Thanks intel, and thanks Anand for the review.
    Reply
  • jaydee - Monday, April 23, 2012 - link

    But it's really not that much more efficient. In fact at idle, the difference is negligible by all benchmarks I've seen, which for most users is the most important area. At full power, a difference of 25 watts is practically nothing given how much time most cpu's are spent at that load. It really shouldn't affect power supply sizing either. I'm just talking about desktop usage here, we don't really have a good look at the notebook chips yet.

    I'm not sure what Intel thinks it's pulling by calling this "tick+" instead of a regular "tick". I don't see anything here that's really that appealing. If helps Intel "debug the process node for 22nm", that's great for Intel, but it doesn't sway me as a consumer to buy one.
    Reply
  • JarredWalton - Monday, April 23, 2012 - link

    Idle power quickly hits a limit based on everything else in the system. It's hardly surprising that the highly efficient Sandy Bridge does just as well at idle as Ivy Bridge. Power gating allows Intel to basically shut down everything that's not being used, and the result is that low loads have pretty much hit their limits. What's impressive is the big drop in power use under heavier loads.

    As for the "tick+", it's all in the GPU. They went from DX10 12EU in SNB to DX11 and 16EU in IVB. As a percentage of total die size, the GPU in IVB is much larger than the one in SNB. But as Anand notes, we still would have liked more (e.g. a 24 EU GT3 would have been awesome for IGP performance).
    Reply
  • owan - Monday, April 23, 2012 - link

    Marginal improvement over Sandy Bridge that can be compensated for by SB's significantly better overclocking ability. Why so much praise for the IGP when 95% of desktop users don't care AND its still vastly inferior to Llano? With so much focus on mobile I'm not even sure why they bothered releasing a high-end desktop SKU Reply

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