Compressor 2, which is included with Apple’s Final Cut Studio and DVD Studio Pro 4, lets you convert between PAL and NTSC video standards without having to hand off your video—and your hard earned money—to a professional conversion service. But it isn’t quick about it. The process can require as much as 40 minutes to convert a single minute of video. Not looking forward to tying up your Mac for an entire weekend just to convert a 90-minute movie? Well, if you have some spare Macs lying around the house, you can significantly trim the conversion time by building a cluster—a group of networked computers that share the processing burden.
Professional—also know as optimized —Compressor clusters typically use a combination of shared storage, Xserves, G5 PowerMacs, and fibre channel drives to maximize the cluster’s processing power. And if you’re working with high-definition or uncompressed standard-definition video, having this kind of high-end equipment is essential. But if you’re working with compressed video formats, such as DV, DV50, or DVCPRO HD video, you can still get a significant speed boost by building a non-optimized compression cluster. This cluster can consist of anything from an iMac G5 to a PowerBook to even a simple Mac Mini.
Equipment
Here’s what you’ll need to get the most video-processing pop out of your existing equipment:
• Recent Macs: To be a part of the cluster, your Macs will need to have a G4 or G5 processor and be running Mac OS X 10.3.9 or higher. You’ll get the best results by making sure all of your clustered computers have the same processing power (using all Dual G5s, for example). However, that’s not required. You can build a cluster with computers of varying power and still achieve significant timesaving.
• Wired Router: You’ll need a 100 Base-T or faster Ethernet router with enough ports to accommodate all of the clustered computers. While many consumer-level Macs top out at 100 Base-T, professional level Macs and newer iMac models support 1000 Base-T, and would therefore benefit from a faster router. Whatever you do, however, do not use a wireless router. It’s essential that you have a stable connection.
Step 1: Network the Computers
Network together the assembled computers via the Ethernet router. All computers should be on the same internal network.
Step 2: Install Qmaster
Most ad-hoc Compressor clusters rely on a master computer to run Compressor and distribute the jobs. This is typically the computer that you do most of your editing on. The master computer interacts with the rest of the machines in the cluster via the Qmaster application, which is included with Final Cut Studio and DVD Studio Pro 4. This means you’ll need to install Qmaster on every machine in the cluster.
On each computer, insert the Final Cut Studio or DVD Studio Pro 4 install disc, locate the AppleQmasterNode.mpkg installer package (it’s usually found in the Extras folder), and double-click on it. Follow the instructions to install the program.
Step 3: Configure Qmaster on all cluster machines
Once you’ve installed Qmaster, open up the System preferences and select the Apple Qmaster preference option listed under Other.
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In the Apple Qmaster preference pane, click on the Setup Tab. If this is the computer you plan to use as your master computer, turn on the Services And Cluster Controller option (A). For all other computers in the cluster, turn on the Services Only option.
Under the Services heading, enable the Share and Manage options for Compressor on all your machines (B). Unless you also run Shake 4, leave the Rendering settings turned off.
Next, open the Advanced tab. Here you’ll set options for storing and sharing files. In the Shared Cluster Storage section (C), click on the Set button to specify where Qmaster should copy the work media while it’s compressing. The default location for this storage is /var/spool/qmaster. This exists on the Unix side of the Mac, not easily accessible via OS X’s graphical interface. You can change this location if you like (in professional XSan environments, the shared storage would be the optimal location for the cluster).
You can also define how long the media will be kept in this location. Video can take up a lot of space on your hard drive so purging the media when the job is done is usually a good idea. Otherwise you might find that your computer’s hard drive is very full after a compression job. The default is 7 days for deleting the work media; you can lower this value if you wish.
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In the Network section, set the Use Network Interface menu to Built-in Ethernet (D). In the Extra’s section, select the Show Qmaster Status In The Menu Bar option. In the text field (E), give the computer a name. This is what Qadministrator will use to identify this machine later on. All of the computers in your cluster should have a unique name. When you’re done, click on Start Sharing.
Repeat this step for all the computers in the cluster.
Step 4: Set up Qadministrator
To set up a Compression cluster, use Qadministrator (which is installed by the QMaster program). When you launch the program, you should see your available shared computers in the Qmaster Service Browser at the bottom of window (F). (If for some reason, Qadministrator doesn’t see a computer that you’ve set up, you may need to reset the Qmaster preferences on the errant computer and repeat Step 3. To reset a computer’s Qmaster preferences, hold down the option key and bring your cursor over the Start Sharing button. It will change to Reset Services.)
In Qadministrator, click on the plus (+) sign under the Cluster column (G) to create a new cluster, and then give it a name (I’ll use the name “Local Cluster” for this example). In the services tab, open the Controller pull-down menu (H) and select the name of the computer you assigned as the Services and Cluster Controller in Step 3.
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Once the Controller is set, drag the available shared computers from the Qmaster Service Browser at the bottom of the window into the Services window for the Controller (I). These are the computers that will become your cluster. You can create multiple clusters if you like, just remember: a computer can be assigned to only one cluster at a time. In the case above, I have a 1.5 GHz G4 PowerBook, combined with two Dual 2.5 G5 PowerMacs. Click on Apply and your Compressor cluster is built.
TIP: If you haven’t downloaded the latest update for Compressor (version 2.0.1, at press time), you should do so before sending any jobs to your cluster. The 2.0.1 update improves how the controller divides the work between computers—making more efficient use of its resources. In our example cluster, the 1.5 GHz PowerBook, has far less processing power than the Dual G5s. In Compressor 2.0, the PowerBook would greatly diminish the speed of the overall cluster because the work would be distributed evenly between the computers regardless of their strength. With the 2.0.1 update, the cluster will instead give more of the workload to the G5s.
Step 5: Send a job to the cluster
To send a Compressor job to the cluster, simply launch Compressor, drag the file you want to compress to the Batch window, and then choose a setting (J) for Compressor to use—in this case NTSCtoPAL. (For a step-by-step guide to setting up your Compressor settings correctly, see “Send Video Abroad” in the March issue) Next, choose your cluster from the Cluster pull-down menu (K).
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When you click on Submit, Compressor will send the job to all the computers in the cluster. Because our non-optimized cluster doesn’t include shared media storage, video segments will have to be copied to each computer via Ethernet. This results in a small performance hit while the media copies, however, the combined processing power of the cluster will more than compensate for this.