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Handbrake
This conversion utility differs greatly from the other two apps we tested. It costs nothing, and though it does include a number of presets for mobile devices, its interface isn't really designed with the computer illiterate in mind. All kinds of encoding and conversion settings are at at your disposal right there in the main window. To be honest, it took a little digging in the documentation to figure out what some of the settings do.

The publicly available version of Handbrake lacks hardware acceleration support entirely. The pre-release build we used, as we noted earlier, features a beta, OpenCL-accelerated version of the x264 encoder. During a presentation at AMD's Fusion Developer Forum last month, x264 lead developer Jason Garrett-Glaser said he expected to release the source code "in a couple of months"—so, by mid-August or thereabouts. He added that a public build would likely be out before then.

One more thing: this build of Handbrake doesn't have a setting to disable OpenCL acceleration. Fiddling with the x264 config file in the program directory didn't help, either. In the end, we used the latest public release available from the Handbrake website (0.9.8) to test raw CPU performance. That may not have been the most scientific approach, but it was the only option available.

  Core
i7-3770K
Core
i7-3770K
(OpenCL)
HD Graphics
4000
(OpenCL)
Radeon
HD 7750
(OpenCL)
GeForce
GT 640
(OpenCL)
Measured time 34 34 42 31 33
Reported FPS 126.0 123.5 124.4 138.3 131.9
Idle wattage 37 W 37 W 37 W 43 W 46 W
Peak wattage 88 W 87 W 87 W 114 W 113 W
File size 77.5MB 78.2MB 78.2MB 78.3MB 78.2MB
Actual bitrate 4093 4131 4131 4138 4129

One would expect the OpenCL encoding process to work identically regardless of the hardware used, so it's a little surprising to see bitrate and file size differences. (Yes, we tried re-testing and came up with the same results.) In any case, the Radeon achieves the quickest encoding time, with Intel's HD 4000 integrated graphics coming in last—behind the unaccelerated build running in software mode, in fact.

We can probably chalk up that last result to insufficient optimization. Our own testing gives no indication that the HD 4000 has poor OpenCL performance in general; in LuxMark, we saw a mobile incarnation of the HD 4000 slightly outpace the integrated graphics inside AMD's A10-4600M APU. So, perhaps this version of the x264 encoder just isn't properly optimized to take advantage of the HD 4000. For what it's worth, the x264 developers recorded fairly substantial performance gains running their accelerated encoder on an AMD A10 APU's integrated graphics.



Aside from slight variations in artifact patterns, it's hard to discern much of a difference between the different solutions here. That's good news. It means the OpenCL acceleration doesn't degrade image quality in a noticeable way, regardless of the hardware used.

Handbrake is the only one of our three test apps that doesn't mess with color saturation, too. Really, I'd say it has the best output, hands down.