View Full Version : Get Compressor to Multitask


Robert Lane
November 5th, 2007, 10:33 AM
One feature available to multi-core Macs is the ability to have Compressor use it's segmenting/multi-threading capabilities which dramatically speeds up crunch time.

Below are screenshots of a current job being encoded; without job segmenting this 1-hour project was originally going to take appx 10 hours to encode from DVCPRO-HD to MPEG2 SD-DVD (2-pass VBR, best motion estimating); with Qmaster setup properly and the job being split up between cores it's now taking less than 6.

You can see that the job is being split up into separate threads; the trick is to use half of the available CPU cores on your machine to accomplish the task. On this machine I've allowed Compressor to grab 4 cores, but look at the CPU status bars and you'll notice all cores are actively crunching away.

There's a wierd thing where in Activity Monitor each thread of Compressor is showing "not responding", but the job is actively crunching away. I've noticed this on all multi-segmented jobs and have a ticket into Apple about it.

Read the book, Compressor 3 Quick Reference Guide, Brain Gary, about how to set this up on your machine.

Nate Weaver
November 5th, 2007, 01:59 PM
I'm pretty sure the new kernel in 10.5 solved the core problem, which was that the 10.4 kernel had no idea how to distribute the compressord thread.

Anyway, I've noticed higher processor usage in 10.5 without having reconfigure to use a virtual cluster, something I had just gotten going on 10.4 weeks before 10.5 came out.

Robert Lane
November 6th, 2007, 08:44 AM
You're right Nate, Leopard does make more efficient use of Compressor's built-in ability to multi-thread without setting up a v-cluster. But until AJA releases Leopard-compatible drivers we're stuck on 10.4 for our main edit machine.

The other thing I forgot to mention is that this v-cluster really only benefits those codecs that are by default *not* multi-threaded or would not allow job segmenting such as H.264. MPEG2 doesn't really see a speed increase with a v-cluster in fact, part of the issue of the "compressord not responding" is related to that issue.

Hopefully AJA will get the ".5" drivers going and we can get off this memory-tired Tiger.

Nate Weaver
November 8th, 2007, 12:35 PM
I'm having one issue with 10.5 and FCP6, but it's not anything to do with video output...it's the Motion template issue.

My LHe is working fine with the 4.0 drivers in 10.5

Chris Harris
November 8th, 2007, 01:04 PM
Is Compressor 2 supposed to see a speed gain under Leopard or is it just Compressor 3? Because I did some H.264 encoding of a relatively short sequence in Compressor 2 and didn't see a significant difference, if there was one at all.

Robert Lane
November 9th, 2007, 08:28 PM
Chris,

H.264 is not a multi-segmented codec, which means if you want to get faster encodes you'll need to get FCS2 and use the virtual-clustering available in Compressor 3.

Alex Humphrey
February 9th, 2009, 10:51 AM
so Compressor 2 does not have virtual clustering with QMaster? Might make sense to upgrade from FCS 1. I still believe FCS3 is around the corner, though I thought that 6 months ago.

Mathieu Ghekiere
February 9th, 2009, 05:35 PM
so Compressor 2 does not have virtual clustering with QMaster? Might make sense to upgrade from FCS 1. I still believe FCS3 is around the corner, though I thought that 6 months ago.

Apple has updates Final Cut a lot around April, at NAB.
So I wouldn't upgrade now, just wait a bit.