updated 12:30 pm EDT, Wed April 18, 2007
Apple details ProRes 422
Apple has posted a white paper on its new Apple ProRes 422 video format, which the company says is designed to reproduce as much of an artist's original vision on the screen as possible. "With ProRes 422 inside Final Cut Studio 2, there is now a better choice for ensuring that all creative work maintains its original, pristine color and detail -- from capture all the way to final viewing," Apple writes. The document describes some history of video editing on the Mac platform, and highlights features of the new format. Apple ProRes 422 features uncompressed HD quality at data and storage rates lower than uncompressed SD, and boasts performance comparable to or better than the existing HD codecs in Final Cut Pro.
"For years now, Final Cut Pro editors have relied on HD formats such as DVCPRO-HD and HDV for native, real-time multistream editing. The efficiency and image quality of these workflows are excellent for content that originates with and can be finished natively in these formats. But such formats were designed under significant camcorder engineering constraints, so they limit the full quality that can be carried in an HD signal."
As noted by AppleInsider, Apple's new format is said to work with HD on slower drives, and with more users on shared storage. Quality is indistinguishable from most pristine sources, according to Apple, even after multiple encoding/decoding generations. The format offers full width of 1920x1080 and 1280x720 resolution alongside 4:2:2 chroma sampling to provide precise compositing and blending at sharp saturated color boundaries.
A 10-bit sample depth preserves subtle gradients of 10-bit sources such as sunsets or graphics with no visible banding artifacts, and I frame-only encoding ensures consistent quality in every frame with no artifacts from complex motion, according to the Cupertino-based company.
Apple ProRes 422 features variable bit-rate (VBR) encoding which analyzes the image and allocates more bits to complex frames, increasing efficiency by not wasting excess bits on simple frames. The format offers two target HD bit rates with normal quality targeted at 145Mbps and high quality (HD) targeted at 220Mbps. Apple notes that low bit rates increase the affordability of equipment, enabling users to edit more streams with more real-time effects on slower drives or have more users accessing the same media over Xsan.
The format is designed for speed, according to Apple, with full-size and 1/2-by-1/2-size decoding speed for more effects and more streams. Additionally, users can capture ProRes 422 in real time from any HD-SDI source with improved encoding speed.