• Blogs
• Forums
• Tradeshows
• Partners
• White Papers
• Podcast Show Notes
• Events

Optimizing Encoding Performance with Apple Final Cut Pro, Part 1

Oct 20, 2009 12:00 PM, By Jan Ozer

We've had a fun time so far with this column, digging inside an Apple Mac Pro to install a Blu-ray recorder and benchmarking Snow Leopard. Now it's time to get serious and get some real work done.

Specifically, over the next two issues, I'll detail the factors to consider when choosing and configuring a Final Cut Pro sequence setting, identify the alternatives for rendering from Final Cut Pro and their pros and cons, and detail how to enable and use Qmaster for accelerating encoding with Compressor. Dreadfully boring stuff for most Final Cut Pro editors (though I find it fascinating), but once you know it, you know it, and understanding these under-the-hood machinations can help preserve quality and dramatically improve encoding performance.

Configuring a sequence setting

Let's start with choosing and configuring your sequence setting. Sounds pretty simple, right? If you're working in DV, HDV, or XDCAM HD, you just choose that Sequence Preset and start ingesting and editing.

Well, here's the thing: If you plan to export a QuickTime reference movie to input into Compressor (and you likely will as you'll read below), any changes to the source video files—including simple color or brightness correction and sophisticated layering effects—will force a recompression of the affected frames back into the codec selected in the sequence setting, causing another generation of compression-related quality loss.

What's the alternative? Change the Compressor setting in the Sequence Settings dialog to the desired version of Apple ProRes (I typically use ProRes 422 [HQ] or ProRes 422). That way, when you create your QuickTime reference movie, Final Cut Pro will use ProRes rather than Motion JPEG (for DV source video footage) or MPEG-2 (for HDV or XDCAM HD).

Related Links

Optimizing Encoding Performance with Apple Final Cut Pro, Part 2 If you have a multiple-processor computer, you can use Apple Qmaster to help spread the encoding load over those multiple processors, which can dramatically boost encoding performance... Blu-ray Creation with the New Apple Final Cut Studio This issue of Final Cut Pro Insider finds me—well, inside an Apple computer, appropriately enough, specifically to add a Blu-ray drive to a Mac Pro... Apple Snow Leopard for Video Producers, Part 1 Apple's new Snow Leopard (or OS X 10.6) is the type of release that delivers incremental advancements on the surface, but exponential enhancements below the waterline--though many will take months, if not years, to truly start bearing fruit... Apple Mac Pro vs. MacBook Pro Test Drive, Part 2 Back again, comparing the performance of an Apple MacBook Pro (3.06GHz Intel Core 2 Duo processor, 8GB of 1067MHz DDR3 RAM) with a Mac Pro (2.93GHz quad-core Nehalem Xeon CPUs with 18GB of 1067MHz DDR3 RAM) in a range of editing and encoding chores...

How much quality difference will it make? Well, ProRes is technically a lossy codec that discards information during the conversion process, just like Motion-JPEG and MPEG-2. But with all lossy codecs, the amount of information discarded determines the amount of quality loss—the more you compress, the more you lose.

DV and HDV are both stored at 25Mbps, while XDCAM HD is 50Mbps. In contrast, Apple's ProRes come in multiple flavors with different data rates—including ProRes 4444 (330Mbps), ProRes 422 (HQ) (220Mbps), ProRes 422 (147Mbps), ProRes 422 (LT) (102Mbps), and ProRes 422 (Proxy) (45Mbps)—all at 1080i with no alpha channel. If you use ProRes 422 (HQ), you have nearly nine times the data rate of DV/HDV and more than four times the data rate of XDCAM HD.

Again, how much difference will this make? I'd probably have to guess that most of the time, you probably couldn't tell the difference, especially when working with XDCAM HD because the data rate is so high. But with highly detailed footage or extremely delicate effects, the extra layer of compression could cause visible multiblock artifacts and the like—especially with HDV, which is very highly compressed.

Look at it this way: You'd never recommend encoding your video into 25Mbps MPEG-2 format before rendering a file for Blu-ray or web output. But that's just what you're doing when you leave HDV as the Compressor configuration and create a QuickTime reference movie. So change the Compressor configuration option to ProRes instead.

A couple of notes. Why no mention of AVCHD? Because Final Cut Pro ingests that as ProRes from the start. What about DVCPRO HD? I'd switch to ProRes there as well. Though DVCPRO HD is 100Mbps, it's essentially four DV streams for four times the pixels, so the compression rate is the same.

Can't you just select a ProRes sequence setting from the start rather than choosing your capture format and then switch over? Certainly, but be careful. For example, would you know to select a 1440x1080 60i ProRes preset for HDV? Which would you select for DVCPRO HD, which has a 1280x1080i native resolution? In contrast, you can't go wrong if you choose a preset that matches your camcorder format and then switch the codec in the setting to ProRes.

Continue the discussion on “Crosstalk” the Millimeter Forum.
© 2009 Penton Media, Inc.