Apple’s new ProRes codecs
Today Apple released it’s new version of Final Cut Studio which also includes a new version of the ProRes codec family. I was involved in a comparison test (analytically and subjective) with DNxHD (also a DCT-based codec for post-production by Avid) about a year ago, and ProRes won in nearly every aspect. It really has been amazingly difficult or even impossible to see the difference between an uncompressed image (for example from a film scanner) and the ProRes encoded image for most of the samples we used.
More flavors
The original version of ProRes only had two variants: ProRes and ProRes HQ, both 10-bit color depth Y’CbCr 422 codecs, the ProRes HQ with a slightly higher bitrate.
Now there are 5 flavors, adding new applications and workflows:
- ProRes 4444 (33 MB/sec for HD 1920x1080 at 24p): 12-bit color depth, optional alpha channel for very high quality RGB(A) image data
- ProRes 422 HQ (22 MB/sec): 10-bit color depth for very high quality video (Y’CbCr) image data
- ProRes 422 (15 MB/sec): 10-bit color depth with better real time support than ProRes HQ
- ProRes 422 (LT) (10 MB/sec): Great performance for already compressed video image data (for example AVCHD)
- ProRes 422 (Proxy) (5 MB/sec): For preview or offline editing with reduced disk capacity (for example 60 minutes material is only 41 GB).
New Alpha channel
The ProRes 4444 codec has an optional alpha channel, which is mathematically lossless in 16-bit color depth for exact reproduction of mattes in compositing. The cool thing is: The high precision alpha channel only increases bandwidth about 10% in common scenarios, as mattes have lots of white and black areas that are cheap to compress. Now ProRes 4444 is a real successor of the clumsy Animation codec.
Performance
The codecs’ multi-threading implementation hugely benefits from lots of cores on new MacPros, your decoding/encoding time nearly drops to half with twice the number of processor cores. For example a recent MacPro can playback 16 ProRes (LT) streams (full HD 1920x1080) with appropriate disk performance available. And there is still the “Reduced Resolution Decoding” (half width and half height) that again increases speed from 20% up to 45% in Final Cut Pro.
Conclusion
Final Cut Studio dropped in price (now $999 USD instead of $1299 USD) but with the new codecs Apple again will be able to motivate users from pro-consumers to high-end post-production facilities to get even more new Mac Pros and Macbook Pros. But nonetheless: Highest quality movie post-production is as cheap as never before with Apple’s new software products - only the film crew and a good story is not included in the box yet.
More information
More details (also on chroma sampling and bit depth) are available in the Apple ProRes White Paper 2009.
