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Where’s the bottleneck?
Hi all,
I’m rendering a 1.5 hour video from Final Cut Pro X. The source footage is unoptimized “1080p” AVCHD and I’m exporting at 720p to ProRes 422. The export takes about 1.5 hours and during the export I see the following:
The specs on my machine are:
No resource (CPU, RAM, Hard Drive) seems to be taxed at all. It seems like the export should be happening at least 3-4 times faster than it is.
Since, as I mentioned, I was using straight AVCHD without “optimization”, I thought perhaps there’s a lot of intense processing going on on the AMD Radeon card decoding the H.264, and so the CPU doesn’t look like it’s getting a workout. But I did a test where I optimized 3 minutes of footage (which pre-converts the AVCHD to ProRes 422) and the export still took about 3 minutes and the CPU, HD, etc. don’t see much utilization.
I suppose RAM access speed could be a bottleneck, but it seems a bit unlikely to me.
I’m wondering if anyone has tried something similar and gotten the same or different results? I’m worried there’s something wrong with my system.
Thanks in advance!
-Matt
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7 Replies
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You have an hour and a half video, and it took you an hour and half to export? I wish I got performance like that.
All the best,
Tom
“Final Cut Pro X for iMovie and Final Cut Express Users” from Focal Press
Class on Demand DVDs “Complete Training for FCP7,” “Basic Training for FCS” and “Final Cut Express Made Easy”
Coming in 2012 “Complete Training for FCPX” from Class on Demand -
I use Compressor with Qmaster! I’ve a 12 core MacPro… using Qmaster you can manage the entire resources of your processors and increase 5/6 times the speed of rendering. When I open “use CPU” window I see the power at 100%. 🙂 Honestly I don’t know how and if it works with your iMAC
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I’m using a mid-2009 thirteen-inch MacBook Pro with 8GB RAM but otherwise its stock; three LaCie D2 1.5 TB firewire drives; and if I export directly from the project in FCPX (i.e. “Share”)to a QT ProRes 422 file, its slow, but if I use Compressor 4.0.3 to do the same file to the same resolution, its glacial–like, five times as slow as a direct export. Now, of course, I have a slow graphics card, but the original events are QT ProRes 422, so other than some titles and some color correction, there’s not a lot of extra stuff going on. I know, my computer is woefully inadequate for the job, but its what I have for now. I just don’t understand what makes Compressor so much slower than a direct export considering the instructions are identical.
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Looks like you RAM is pegged.
15.71 of 16GB is “used”
Jeremy
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Exports via Compressor are slower because Compressor doesn’t yet use the GPU. On the other hand exports direct from FCP X the GPU is utilized and you should see a nice speedup.
Also, tell me a bit more about your project. Do you have background rendering turned on, i.e. are you exporting unrendered?
What type of filters, color correction do you have applied to the footage, or is it just simple cuts?
What results to you get with your 3 minute test with optimized if you export ProRes 1080p directly from FCP X?
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T. Payton
OneCreative, Albuquerque -
OK, deleting the Final Cut Projects and Final Cut Events folders has restored my FCPX. I can now export 1080P projects to ProRes 422 faster than real-time on my mid-2011 iMac Core i7 with 2GB NVIDIA card. Also, my CPU cores are now utilized during the export (whereas they mostly sat idle when I was having the performance problem).
When FCPX works correctly, the performance really is amazing on a new iMac. My test sequences included “Bad TV” effect, transitions, and a color correction and I can preview with no rendering (background render is pointless, turn it off!!!) and export to ProRes faster than real-time.
At one point before I deleted everything, the problem got so bad that FCPX claimed it would take 9 hours to export my 1 hour project to ProRes. This has got to be a bug in FCP.
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Great to hear things are going well now.
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T. Payton
OneCreative, Albuquerque
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