On video editing codecs

Video compression is something of a black art. I’ve become something of a compression nerd over the past few months, partly because I was helping to plan the 2010 NPPA Multimedia Immersion, and partly because I’m a giant geek. I’m going to concentrate on editing codecs today. I don’t want to get into final output and compression.

For the workshop we settled on Apple Intermediate as an editing codec. We were bringing in footage from a wide variety of cameras, mostly Canon and Nikon SLRs, but a handful of dedicated video cameras too. We wanted everyone to be on the same page.

For the Canon and AVCHD folks it was easy, we just set up the plugins for Apple Intermediate, then did a standard Log and Transfer. For the Nikon shooters, it was a little bit more complicated. There isn’t a Nikon plugin, so they had to use Compressor (or MPEG Streamclip) to transcode from Motion JPEG to Apple Intermediate.

So … why not ProRes 422?

The most obvious reason is storage. We had people using a wide variety of hard drives. Some were USB, some FireWire. Some were big, some were small. Apple Intermediate gave us good quality at reasonable file sizes. The main drive of the workshop was creating content for the web, which means it’s going to get compressed down quite a bit anyway. We weren’t going to be doing heavy color work, and we didn’t need alpha channels. So there you have it, Apple Intermediate. We could’ve very easily landed on ProRes LT (which has a similar data rate), but there were a handful of people using Final Cut Express, which uses Intermediate exclusively.

Like I said earlier, a lot of it comes down to storage and use. For HD video, ProRes 422 averages around 66GB per hour. The same footage encoded using Apple Intermediate comes in around 49GB per hour, and the quality is still excellent. When Apple released Final Cut 7, they also introduced several new ProRes flavors, including ProRes LT, which comes in at 46GB per hour. Intermediate and LT are also much nicer to laptops.

I haven’t done much experimenting with it, but I may start using LT for future projects. Apple designed the ProRes family with multicore Intel systems in mind, so you can go longer between renders, and footage renders faster. The advantage of LT over Apple Intermediate is the extra color information (4:2:2 vs. 4:2:0). The big caveat here is that Final Cut 6 can’t handle the new codecs, so you’re better off using Intermediate (or normal 422) if you’ve got to go back and forth.

For web use, ProRes 422 is generally overkill, especially if you’re not doing color work. If you need an alpha channel, however, then 422 it is.

If you’re mastering Blu-ray, then by all means, use 422, otherwise, save some drive space for your next project.

For more info about ProRes and other codecs, check out Larry Jordan’s site and Apple’s ProRes page.

This entry was posted on Saturday, May 29th, 2010 at 9:52 am. It is filed under final cut, multimedia and tagged with codecs, compression, final cut, prores, video. You can follow any responses to this entry through the RSS 2.0 feed.