- Baseline (no capture): 100 fps, 45% CPU usage.
I loaded a unit test map and spawned enough units to give me a nice stable 100 fps on my i5 2500k with an NVIDIA GTX 560 Ti, 1680x1050, medium graphics.
- XSplit screen region (1680x1050): 90 fps, 60% CPU usage.
As expected, CPU use within xsplit jumped once adding the screen region. I was actually surprised how low the FPS hit was though, if you have the spare CPU this seems like a good (and free) method to use.
- XSplit game source: 62 fps, 66% CPU usage.
Pretty terrible. Would not recommend, it maxed out XSplit's CPU usage across a single core and caused a 40% FPS drop in SC2. Despite SplitMedia's claims that game source is ready for prime time, it clearly has a long way to go.
- DXTory (with scaling): 82fps, 55% CPU usage.
Was surprised again by the FPS hit, I thought DXTory would cause the lowest FPS drop prior to these tests. This test involved scaling options set in DXTory to match the XSplit window size (1152 x 720).
- DXTory (no scaling): 82fps, 50% CPU.
Same as above, but with no scaling set so that XSplit has to do the scaling. The CPU hit from this is very low, which seems to indicate something else is causing the FPS drop as there is clearly a lot of CPU to spare.
- DXTory (Synchronous Surface Lock): 92fps, 55% CPU.
Enabling the advanced option 'Synchronous Surface Lock' seems to increase FPS considerably with a minor CPU hit. This option may be video card dependent, so do your own testing do determine whether this helps or not.
You might look at the results and think you'd be fine using the built in screen region in XSplit. Several pro-gamers have complained that even on high end PCs, streaming makes their game feel laggy. I tried to quantify this lag and found that screen region does indeed cause frame lag. If you capture your game using the screen region feature, expect to see a few frames of input lag.
You can tell if there is frame lag by dragging your mouse around the mini-map very fast and observing if the white rectangle keeps up with your mouse cursor. I shot video of my screen at 60fps and reduced it to 1fps to show the results here:
No Capture (regular SC2):
XSplit Screen Region:
(If the above images no longer work due to bandwidth use, you can download the test videos here).
You can clearly see that the XSplit screen region method introduces frame lag that is not present with no capture or DXTory. Another interesting thing I noticed is that screen region will still cause increased CPU use and frame lag even if it is disabled in the xsplit sources window. I strongly recommend removing all unused screen regions for this reason.
Update: Disabling Aero seemed to remove the frame lag issue with screen capture for me. Your results may vary as this is probably video card dependent.
DXTory Worth It?
DXTory isn't free and costs around $50. Whether this is worth it to you depends on whether you are sensitive enough to notice the frame lag caused by xsplit screen capture. If you want the best gameplay experience when you stream, then DXTory is a must. If you aren't at the level where frame lag is affecting your game, then xsplit's screen region is surprisingly efficient, if a little CPU hungry. Another benefit of DXTory is being able to capture in Fullscreen mode, which some pro-gamers prefer to use instead of Windowed Fullscreen.