The Kaby Lake-U/Y GPU - Media Capabilities
Written by Ganesh

While from a feature standpoint Kaby Lake is not a massive shift from Skylake, when it comes to GPU matters it none the less brings across some improvements that are directly visible to the end-user. As with the CPU cores, Intel’s 14nm+ process will allow for higher GPU frequencies and overall better GPU performance, but arguably the more impressive change with Kaby Lake is the updated media capabilities. To be clear, Kaby Lake is still an Intel Gen9 GPU – the core GPU architecture has not changed – but Intel has revised the video processing blocks to add further functionality and improve their performance for Kaby Lake.

The media capabilities of the Skylake GPU were analyzed in great detail in our 2015 IDF coverage. The updates to Kaby Lake-U/Y should be analyzed while keeping those features in mind. The major feature change in the Kaby Lake-U/Y media engine is the availability of full hardware acceleration for encode and decode of 4K HEVC Main10 profile videos. This is in contrast to Skylake, which can support HEVC Main10 decode up to 4Kp30, but does so using a “hybrid” process that spreads out the workload over the CPU, the GPU’s media processors, and the GPU’s shader cores. As a result, not only can Kaby Lake process more HEVC profiles in fixed function hardware than before, but it can do so at a fraction of the power and with much better throughput.

Also along these lines, Kaby Lake has implemented full fixed function 8-bit encode and 8/10-bit decode support for Google’s VP9 codec. Skylake offered hybrid decode support for the codec, which is useful from a feature standpoint, but is a bit more problematic in real-world use since it’s not as power-efficient to use VP9 a codec implemented in fixed function hardware. Google has proven eager to serve up VP9 to its YouTube users, so they can now much more efficiently decode the codec. Meanwhile, on the encode side, brand-new to Kaby Lake is VP9 encoding support, to go with the aforementioned HEVC encode support.

An overview of the GPU engine in Kaby Lake-U/Y is presented in the slide below.

The new circuitry for hardware accelerating HEVC Main10 and VP9 are part of the MFX block. The MFX block can now handle 8b/10b HEVC and VP9 decode and 10b HEVC / 8b VP9 encode. The QuickSync block also gets a few updates to improve quality further, and AVC encode performance also receives a boost.

The Video Quality Engine also receives some tweaks for HDR and Wide Color Gamut (Rec.2020) support.  Skylake's VQE brought in RAW image processing support with a 16-bit image pipeline for selected filters. While Intel has not discussed the exact updates that enable Rec.2020 support, we suspect that more components in the VQE can now handle higher bit-widths. Intel pointed out that the HDR capabilities involve usage of both the VQE and the EUs in the GPU. So, there is still scope for further hardware acceleration and lower power consumption in this particular use-case.

Intel claims that Kaby Lake-U/Y can handle up to eight 4Kp30 AVC and HEVC decodes simultaneously. HEVC decode support is rated at 4Kp60 up to 120 Mbps (especially helpful for premium content playback and Ultra HD Blu-ray). With Kaby Lake-U/Y's process improvements, even the 4.5W TDP Y-series processors can handle real-time HEVC 4Kp30 encode.

On the subject of premium content, in their presentation Intel rather explicitly mentioned that the improved decode capabilities were, in part, for “premium content playback.” When we pushed Intel a bit on the matter – and specifically on 4K Netflix support – they didn’t have much to say beyond the fact that to play 4K Netflix, you need certification. Based on what was said and what was not said (and what we know about the certification process) our educated guess is that the updates in Kaby Lake-U/Y include some new DRM requirements for 4K content, and 4K Netflix should hopefully be good to go with the new platform. However on that note, because of those DRM requirements and that this is being pitched as a new feature for Kaby Lake, we suspect that when 4K Netflix streaming does come to the PC platform, Skylake owners are going to be out of luck.

It must be kept in mind that all the encode / decode aspects discussed above are for 4:2:0 streams. This is definitely acceptable for consumer applications, as even Blu-ray video streams (that have plenty of bandwidth at their disposal) are encoded in 4:2:0. However, if Intel wants to use the new media engine in professional broadcast and datacenter applications, 4:2:2, and, to a much lesser extent, even 4:4:4 support might become necessary. For the purpose of the Kaby Lake-U/Y consumer platforms being introduced today, this is not an issue at all.

Moving on, like the GPU core itself, Kaby Lake-U/Y's display pipeline is the same as that of Skylake. This means the iGPU can support up to three simultaneous displays.

One of the disappointing aspects from Skylake that has still not been addressed in Kaby Lake-U/Y is the absence of a native HDMI 2.0 port with HDCP 2.2 support. Intel has been advocating the addition of an LSPCon (Level Shifter - Protocol Converter) in the DP 1.2 path. This approach has been used in multiple motherboards and even SFF PCs like the Intel Skull Canyon NUC (NUC6i7KYK) and the ASRock Beebox-S series. Hopefully, future iterations of Kaby Lake (such as the desktop and high-performance mobile parts coming in January) address this issue to simplify BOM cost for system vendors.

In summary, Kaby Lake-U/Y resolves one of the major complaints we had about Skylake's media engine: the absence of hardware-accelerated 4Kp60 HEVC Main10 decode. There are a few other improvements under the hood that enable a more satisfying multimedia experience for consumers. The software and content-delivery ecosystems have plenty of catching up to do when it comes to taking full advantage of Kaby Lake-U/Y's media capabilities.

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  • Rampart - Friday, January 6, 2017 - link

    I would say that silicon is hitting its physical limit as we can see with the yields. But that doesn't mean that we won't see some different exotic compounds taking its place.
  • Nagorak - Thursday, January 5, 2017 - link

    Based on my 2500K I'd say you're going to get at least 5 years of use out of these boards! I'd say that's pretty good for longevity!

    Oh, wait, that's not what you were asking?
  • tomi1 - Tuesday, January 3, 2017 - link

    Any idea why 7820HK, 7280HQ and 7700HQ are the same msrp $340?
    Who in the right mind will choose 7700HQ when the HK is clearly better at the same prices.
  • MrSpadge - Tuesday, January 3, 2017 - link

    The mobile prices don't make much sense, as in the previous generations. If there were no further discounts for the slower models, OEMs wouldn't use them at all.
  • slideruler - Tuesday, January 3, 2017 - link

    That thing Intel does is becoming a problem. As usual, the trouble lies with all the software. OSes are having trouble keeping up with all those minor tweaks (both Windows and Linux.) The worst part is that at the end of the day, with all that effort of wring new power management drivers, there is not much to show for it...
  • MrSpadge - Tuesday, January 3, 2017 - link

    Are you talking about Speed Shift v2? If so: did you miss the part about it requiring no new drivers? If not: I have no idea what you're complaining about. Is it that Linux and OSX don't have Speed Shift drivers yet? In that case Intel should never introduce any new features...
  • yannigr2 - Tuesday, January 3, 2017 - link

    The i3 7350K looks like a trolling joke. $157 for 4.2GHz? And how high can it go? 4.8GHz? Wow! 14% improvement. What would have been nice, would have been an unlocked 7100 at $110.
  • Shadowmaster625 - Tuesday, January 3, 2017 - link

    I'm hoping somebody delids one and pushes it to 5.5GHz.
  • zepi - Tuesday, January 3, 2017 - link

    Display resolution support is a disgrace. Year 2017 and they are stil stuck with dp1.2. World needs to move on. Should have moved on already long time ago so that we could actually use the high-dpi displays in bigger then 24" sizes.
  • jjj - Tuesday, January 3, 2017 - link

    So now the question is how how low does AMD go with quad Zen.

    From a cost perspective they can go to 49$ and up -they need to address the budget market and a quad CPU or a dual core APU are about the same area.
    From a business perspective it would be better for quad Zen to start at 99$ and they would still make a killing.

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