HD4000: Quick Sync Transcoding

While gamers sneer (justifiably) at the performance of integrated GPUs in general and Intel's "HD Graphics" in particular, Sandy Bridge CPUs introduced a new feature: Quick Sync video transcoding. Portions of the iGPU were optimized for video transcoding tasks, and programs that took advantage of this feature could transcode video faster than all but the very best discrete video cards.

Quick Sync was slow to take off, since the original P67 desktop chipset didn't support it: the iGPU of these new processors was disabled in P67 based desktop motherboards. If you had a system based on the H67 chipset, you could use Quick Sync, but were prevented from overclocking your system. Intel finally removed these artificial restrictions with the Z68 chipset, which allows systems to both overclock and use the integrated GPU. Lucid Logix' Virtu GPU virtualization software added the cherry to the sundae by enabling users to fine-tune how the Sandy Bridge iGPU was used in conjunction with a separate graphics card.

With the Ivy Bridge CPUs, Intel has moved from the HD 3000 graphics to HD 4000. The specifications of this new iGPU are spotty: we know that it has 16 "execution units" as opposed to the HD 30f00's 12, but not much more than that. Still Intel says users will see a dramatic performance increase, so I decided to check out Quick Sync performance on the 3770K to see how it compared.

This chart shows the results from transcoding a video (the same Family Guy episode I use for my Handbrake testing) to the "iPad" presets in Arcsoft Media Converter. The output video is an MP4 at 1280x720 (720p) resolution with a bit rate of 4Mbps. I ran the transcode five times: first using the CPU coding of the 2600K and 3770K, then using the Radeon HD5770 card, then using the iGPUs of the 2600K and 3770K. It is important to note that each "code path" through the transcoding process is different and that the output video for each version, although it adheres to the settings made in the program, is not pixel-per-pixel identical.

In this test, at least, we see that although Quick Sync is dramatically faster than pure CPU-based transcoding and the extra boost provided by the HD5770 card, the HD4000 iGPU is not significantly faster than the HD3000. The difference is a mere 13%.

But maybe we'll see more impressive results from video performance tests in the next section.

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