Optimizing Handbrake for Faster Video Conversion

Handbrake converts DVD video to formats that can be played on the computer, the iPod/iPad/etc or any conventional player.

While Handbrake makes far better usage of multiple cores than most programs, it doesn’t scale much beyond 9 cores (as of August 30, 2010). Perhaps a future release will address this limitation.

Duplicate the application and run two copies.

This approach makes sense on the 12-core Mac Pro, with its ample CPU core reserves. It will likely show little or no advantage on 4-core machines, or might even be slower (not investigated, an exercise for the reader).

Shown below are timed results encoding the same four movies totaling about 3 hours of video, using these settings. The faster results for each Mac Pro used two copies of the Handbrake application running at the same time. Surprisingly, even the 6-core machine benefits from this approach, though not as much.

For a big queue of jobs, the 26% time savings is very attractive (640 vs 874).

Results will vary somewhat with the settings and material chosen for conversion, but both the 12-core and 6-core Mac Pro show clear benefits; 28% for the 12-core and 12% for the 6-core.

With dual apps, the 12-core machine cuts the runtime by 40% as compared to the 6-core.

Two Handbrake applications simultaneous compared to one.
Using the Handbrake beta build as of August 30, 2010.

How to do it

Here’s how:

1. Duplicate the Handbrake application;
2. Launch both copies of Handbrake;
3. Add video to be converted to the queue in each Handbrake program, balancing the material between them so that both queues have approximately the same work to be processed.
4. Start both copies running.

CPU core usage

Shown below are two copies of Handbrake running simultaneously on the 12-core.

This is what you want to see on a 12-core system. The less than helpful display of all 24 virtual cores suggests that there is untapped CPU power, but that’s not really true; there are twelve hardware cores, and they are being fully used; virtual cores (hyperthreading) are slightly better than useless.

CPU core usage with Handbrake, two applications simultaneously
2010 Mac Pro 12-core @ 3.33GHz

Settings

Settings used for encoding the video.

Setting used for testing Handbrake