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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  • DanNeely - Monday, April 23, 2012 - link

    Isn't the net OC performance roughly a wash? You're losing ~10% off the top in clock speed, but getting it back by the CPU doing ~10% more per clock.

    I'm curious what the power gap for the OCed IB is vs SB. For a system kept running at full load, the stock power gap would give a decent amount of yearly savings on the utility bills. If the gap opens even more under OC it'd be a decent upgrade for anyone running CPU farms.
    Reply
  • Shadow_k - Monday, April 23, 2012 - link

    Very nice igp improvements

    An also when will anandtech do a review on the i5 3570k because igp is underclocked
    Reply
  • Ram21 - Monday, April 23, 2012 - link

    Ultraoboks Reply
  • Ram21 - Monday, April 23, 2012 - link

    Page 11 has the incorrect title or chart of Starcraft II - GPU Bench on the Dirt 3 page Reply
  • Anand Lal Shimpi - Monday, April 23, 2012 - link

    Fixed both of these, thank you! Reply
  • ltcommanderdata - Monday, April 23, 2012 - link

    I don't have a comment on this Ivy Bridge review itself since it's thorough as always from Anandtech and Ivy Bridge seems pretty much what was expected. I do want to suggest a new benchmark for the eventual OpenCL followup when Intel releases new GPU drivers. As AMD mentioned as part of heir HD7000 series launches, WinZip 16.5 has finally been released with OpenCL acceleration in collaboration with AMD. Since fluid simulations won't be a common use case for most consumers and video encoding seems better suited to fixed function hardware like QuickSync, this OpenCL accelerated file compression/decompression will probably be the first and most popular use of GPGPU by consumers. It'll be interesting to see how much of a benefit GPU acceleration brings and whether AMD's collaboration results in better performance from AMD GPUs compared to Intel and nVidia GPUs then raw hardware specs would suggest. Other interesting tests would be to see if the acceleration is more pronounced with 1x1GB compressed file versus many compressed files adding up to 1GB. How well acceleration scales with between different GPU performance classes and whether it'll be bottlenecked by PCIe bandwidth, CPU setup time, system memory transfers or more likely HDD I/O. Whether tightly coupled CPU/GPUs like Llano and Ivy Bridge gives a performance advantage compared to otherwise similar specced discrete GPUs. Whether GPU acceleration is worthwhile on older GPU generations like the AMD HD5000/6000 and nVidia 8000/9000/100/200 series which aren't as compute optimized as the latest AMD HD7000 and nVidia 400/500 series. Whether WinZip 16.5 supports the HD4000 series which is OpenCL 1.0 or whether it requires OpenCL 1.1. Does WinZip 16.5 use OpenCL to help improve performance scaling on high core count CPUs (such as 8 or more cores).

    If GPU accelerated file compression/decompression is effective hopefully Microsoft and Apple will consider adding it to their native OS .zip handler.
    Reply
  • Ryan Smith - Monday, April 23, 2012 - link

    Rest assured it's on our list of things to look at, though I haven't seen it yet. Reply
  • mgoldshteyn - Monday, April 23, 2012 - link

    The graphics engine still cannot support 10-bit per color IPS displays, as can be found on quality modern laptops from Dell and HP. That means that one is forced to get an overpriced mobile video card from ATI or NVidia to compensate, lowering the laptops power on hours by requiring an external card to be used with these displays. On non-IPS displays, one can choose to use the Intel built in graphics engine to save battery life. No such choice on high quality IPS displays since they are incompatible with the graphics engine of even Ivy Bridge. Reply
  • zaccun - Monday, April 23, 2012 - link

    The workstation class laptops you are referring to are only offered with discrete graphics cards. No other machine has a 10 bit IPS panel. There is zero sense in dell or HP offering a machine aimed at professionals doing 3d modeling/CAD/video editing/etc without also putting the graphics horsepower in the laptop to support it.

    While I personally would love the option of getting a machine with the awesome panels that those notebooks use, without also paying for the $$$$ quadro cards that pros need, neither Dell nor HP offer anything like that.
    Reply
  • Arnulf - Tuesday, April 24, 2012 - link

    Neither can you eyes distinguish 1 073 741 824 different colors so why would you care ? Reply

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