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MillimeterTest Drive: Nvidia Quadro CX and Adobe CS4, Part 2
Jan 26, 2009 12:00 PM, By Jan Ozer
Figure 2. This suite of After Effects projects revealed several unique advantages of the Quadro CX.
On to After Effects
As mentioned, the Nvidia rep did identify several scenarios where the Quadro CX supported specific After Effects operations that the 1700 didn't, including depth of field and cartoon effects, and he supplied tests that confirmed the advantage. In these tests, I timed how long it took to preview each project using the 1700 and then the CX. Table 1 shows the details.
Table 1. After Effects performance.
As you can see, the benefit when previewing the popular cartoon effect was quite profound, with a noticeable boost in the preview speed of the bilateral blur. I'll note that in the reviewer's guide, Nvidia cited a 38X performance boost for the cartoon operation, but again, that was the difference between running the test with the CX and rendering without OpenGL and relying solely upon the CPU, not the CX vs. a different graphics card with OpenGL support.
Figure 3. Encoding trials with Elemental Technologies RapiHD. I'll take mine shaken, not stirred.
Premiere Pro
With Premiere Pro, OpenGL support is limited, and it doesn't appear to leverage any hardware-specific features of the CX over those of other OpenGL cards. For this reason, I didn't compare the 1700 to the CX with any OpenGL-specific tests. Rather, I focused on H.264 encoding, which the Quadro CX accelerates with a technology called Elemental Technologies (ETI) RapiHD.
From a workflow perspective, Adobe Media Encoder simply has another format option called ETI RapiHD. When you select that option, you encode using the CX; when you encode using any other format, such as H.264-Blu-ray, you encode using Adobe's own codecs driven solely by the computer's CPU. Nvidia supplied a sample 4-minute project, consisting of two 2-minute trailers for the latest James Bond movie, Quantum of Solace.
Table 2. Premiere Pro performance, encoding H.264 for Blu-ray.
I started out on with the full eight cores on the HP xw8600, and I found a reduction of encoding time of 29 percent, from 5:14 to 3:43. I then removed one processor and tested again. Encoding time for the MainConcept encode jumped to 6:33, while RapiHD took about the same time, reducing encoding time by 44 percent. I produced at 25Mbps, and all encoded streams looked great.
In my discussions with the Nvidia rep, he had mentioned that performance times would, to some degree, depend upon the type of effects being rendered on the timeline. That's because if significant effects were involved, Premiere Pro would have to render the effects, then hand off the frames to either encoder for transcoding to H.264. If Premiere Pro's rendering was a bottleneck, it would slow both encoders and erode some of RapiHD's competitive advantage. In effect, since no rendering was involved, my initial tests were a best-case presentation.
Accordingly, I added three effects to the Bond previews—color correction, dust and scratches, and camera view—and I used keyframes to shift the camera view over the course of the video. This boosted overall rendering time significantly, and as anticipated, it abridged the CX's performance advantage down to 24 percent. Running all eight cores on the xw8600 speeded both operations, and the performance advantage afforded by the CX rose to 35 percent.
Table 3. Premiere Pro performance, encoding H.264 streaming.
The Nvidia press materials didn't focus on encoding H.264 for streaming. However, since many producers care more about H.264 for streaming than for Blu-ray, I ran some trials, again encoding with RapiHD and MainConcept and timing the results, which are shown in Table 3.
I tested by encoding files directly in Adobe Media Encoder, which means no effects on the Premiere Pro timeline, again the best-case test scenario for the CX. With 640x480 files, RapiHD shaved almost 49 percent off the encoding time when using four cores, and 32 percent with eight cores.
However, the results were anomalous with a 720p file encoded to the same 1Mbps, Here, when running eight cores, RapiHD actually took longer than MainConcept, which made no sense, though I tested twice. Bumping down to four cores proved much more efficient, and the CX produced time savings in the 51-percent range. I compared the quality of the RapiHD and MainConcept 720p files and found them very similar—a good result for RapiHD since Premiere Pro's Main Concept encoder is a very high-quality producer.
Continue the discussion on “Crosstalk” the Millimeter Forum.