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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  • Tujan - Tuesday, April 24, 2012 - link

    cause how I see it :
    " If you're constantly transcoding movies to get them onto your smartphone or tablet, you need Ivy Bridge. In less than 7 minutes, and with no impact to CPU usage, I was able to transcode a complete 130 minute 1080p video to an iPad friendly format—that's over 15x real time."

    The majority of trancoding is going the other way- from an ipad friendly format to another friendly type format (device or not). Cell phone to pc,ipad to youtube etc.
    I like the concept of the transcode,encode,but as much as with the bandwidth necesary to utilize them they are as they are 'bandwidth hungry'. And here is the first I have noticed that of telling there is hardware to facilitate the h.264 type encoding. "Hardware" to do this.
    The screens from all of those cell phones in high resolution 'still'require bandwidth to utilize them. .. and so on.

    I dont understand it completely but I'll attempt to stay tuned.
    Reply
  • androticus - Tuesday, April 24, 2012 - link

    I find this review enormously confusing. You mix IB and SB parts/sku's throughout, without clearly highlighting which is which. On page 2, at first I thought the chart was of IB CPUs, but then realized it was a mishmash of both. Likewise on all the benchmark charts, and I couldn't even distinguish various SB/IB/core counts apart.

    Was this article written solely for people who have a PhD in Intel sku's ???
    Reply
  • Dudenell - Tuesday, April 24, 2012 - link

    Could we actually see comparison with the i7-920 or i7-950 in there? Reply
  • Pjotr - Wednesday, April 25, 2012 - link

    Thanks for the Compile test, this is all I look at to decide purchases at work. Reply
  • sld - Wednesday, April 25, 2012 - link

    The A8 is conspicuously missing from the 2 charts showing idle and load system consumption. Why is this so? Reply
  • greggm2000 - Wednesday, April 25, 2012 - link

    Anand/Ryan,

    According to the article linked below from today, it seems that Intel may be using TIM paste instead of fluxless solder in the IB chips, and if so, does this seem like a reasonable explanation for the high temperatures that people are seeing?

    I'm interested in your thoughts on this... and if it's true, and if the article is correct, then Intel deliberately handicapping their chips (to possibly preserve SB-E sales?) is quite troubling to me.

    http://www.overclockers.com/ivy-bridge-temperature...
    Reply
  • slickr - Thursday, April 26, 2012 - link

    Hi, is this good enough of an upgrade over a Pentium 4 for office, internet and movies?

    And will the HD4000 beat a ATI x1650XT?
    Reply
  • Death666Angel - Friday, April 27, 2012 - link

    Hey guys!
    Good review overall, thanks for that!
    But the Quicksync section was kinda strange. No way that an x86 software solution generates worse IQ than any accelerated stuff. Unless you were comparing IQ with settings that have the x86 do recode the file in the same time it takes the other solutions. Anyway, I don't understand what you did in that section. :-)
    Reply
  • kevith - Friday, April 27, 2012 - link

    Great review.

    Would it be interesting to see how it fared in a series 6 motherboard, now that it actually is backwards compatible?
    Reply
  • pwnsweet - Saturday, April 28, 2012 - link

    The only thing I care about is how much faster this new slab of silicon will power though my x264 encoding and that's the one part of the review that was left out!

    Why anand, why!?
    Reply

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