Apple Compressor: Make the most of unused cores and nearby Macs

If you have lots of video to transcode and tight deadlines, sometimes even Apple Compressor isn’t fast enough for the job. If you have a Mac with multiple cores and lots of RAM or a network of Macs going to spare, you can use this power to speed up video conversions and transcodes.

Using more cores on your Mac

If you have many CPU cores and enough RAM, you can have multiple copies (‘instances’) of Compressor run on your iMac or Mac Pro at the same time. Each copy works on a different frames of the source video.

The number of Compressor instances you can set up on a Mac depends on the number of cores and the amount of RAM installed. You need to have at least 8 cores and 4GB of RAM to have at least one additional instance of Compressor run on your Mac.

Maximum number of additional instances of Compressor that can run on a Mac:

GB RAM: 2 4 6 8 12 16 32 64
4 Cores 0 0 0 0 0 0 0 0
8 Cores 0 1 1 1 1 1 1 1
12 Cores 0 1 2 2 2 2 2 2
16 Cores 0 1 2 3 3 3 3 3
24 Cores 0 1 2 3 5 5 5 5

This means that your Mac needs to have a minimum of 8 cores and 4GB of RAM to have two instances of Compressor running at the same time. MacBook Pros (as of Spring 2018) have a maximum of 4 cores – described as ‘quad-core’ CPUs.

From Apple’s support document: Compressor: Create additional instances of Compressor:

To enable instances of Compressor

  1. Choose Compressor > Preferences (or press Command-Comma).
  2. Click Advanced.
  3. Select the “Enable additional Compressor instances” checkbox, then choose a number of instances from the pop-up menu.

Important: If you don’t have enough cores or memory, the “Enable additional Compressor instances” checkbox in the Advanced preferences pane is dimmed.

Using using additional Macs on your network

Once you install Compressor on your other Macs, you can use those Macs to help with video transcoding tasks.

To create a group of computers to transcode your videos:

  1. Set the preferences in Compressor on each Mac in the network to “Allow other computers to process batches on my computer” (in the ‘My Computer’ tab of the preferences dialog).
  2. On the Mac you want to use to control the video transcoding, use the ‘Shared Computers’ section of Compressor preferences to make a group of shared computers.
  3. Add a new untitled group (using the ‘+’ button)
  4. Name it by double-clicking it and replacing ‘Untitled’ and pressing Return.
  5. In the list of available computers (on the right), select the checkbox next to each computer that you want to add to the group.

Once this group is set up, use Compressor to set up a transcode as normal. Before clicking the Start button, click the “Process on” pop-up menu and choose the group of computers that you want to use to process your batch.

There are more details in Apple’s support document: Compressor: Transcode batches with multiple computers.

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