How Much Video Processing Performance Boost Do the Latest PC Processors Deliver?
Now that Intel has launched Ivy Bridge-based CPUs that triple the core count of early Nehalem-based workstations from four to 12, can video editors expect significant performance gains? In this article we'll assess the performance gain from the 12-core HP Z800 to the 24-core HP Z820 with respect to both editing and streaming encoding.
Which CPU?
Like many workstations, you can configure the Z820 with different CPUs of different speeds. Choosing the optimal CPU depends upon the type of activity and whether it’s performed standalone or with other CPU intensive applications running in the background. To flesh this out, HP supplied three sets of CPUs for the Z820, as shown in Table 3 (below). Note that the CPU speed for all cores is roughly the equivalent, so the comparisons really focus on the value of the additional cores.
Table 3. Three CPUs tested in the Z820
The tests that I performed for this analysis were similar to those performed above, but not identical, primarily because I couldn’t get Episode Engine running on the Z800. Figure 5 (below) shows the results for rendering Premiere Pro projects within the Adobe Media Encoder. The numbers show the cumulative rendering time for all projects in the trial, with dedicated rendering on left, and rendering while producing a Blu-ray Disc in the background on the right.
Figure 5. Testing CPUs while rendering with Adobe Media Encoder
For those editing in dedicated mode (on the left), the 2680 V2 produced about 12% faster performance than the older 2680 V1, but the 2697 V2 delivered no performance improvement at all. On the right in Figure 5, with a Blu-ray Disc being produced in the background, the 2680 V1 delivered about 14% better performance than the V1, to which the 2697 delivered another 5%. Given these results, in both types of applications, I would choose a faster CPU over one that delivered additional cores.
Figure 6 (below) shows the results achieved with the batch-encoding programs when encoding multiple files to multiple outputs. As you can see, Carbon was the clear star of the show, with performance improvements that were nearly proportional with the additional cores. For example, the 2680 V2-equipped system had 25% more cores than the 2680 V1 system, and Carbon delivered a 22% speed improvement. With 48 cores, the 2697 V2-equipped system had 50% more cores than the base 2680 V1 system; here Rhozet delivered a 46% speed boost.
Figure 6. Testing many-to-many encodes with the listed programs
Though Squeeze and Episode Engine also benefited from the additional cores, the performance enhancement didn’t conform as proportionally to the increase in processor powe as with ProMedia. However, note that all programs achieved much less benefit in one-to-many trials, where a single file was encoded to multiple outputs (Figure 7, below). Since only a single file was involved, it was much more difficult for all three programs to load balance and keep all CPU cores active.
Figure 7. Testing one-to-many encodes with the listed programs
In a server farm environment, which will be continuously encoding files throughout the day, I would prioritize the number of cores over clock speed, particularly with an encoder as efficient as ProMedia Carbon. On the other hand, for sporadic encoding, I would prioritize clock speed over the number of cores.