ARRI Alexa 3.2K ProRes for UHD

ARRI will offer no codec before its time. That time is when the image and color scientists on Tuerkenstrasse declare picture perfection. In an upgrade announcement reminiscent of the famous Orson Welles line (“we will serve no wine before its time”), ARRI Alexa cameras will soon be able to record 3.2K ProRes for seamless up-rez to UHD/4K in post.

FDTimes readers recently sent a salvo of emails asking why Amira could do it and why not Alexa?

ProRes 3.2K for Alexa cameras will be available in a software update (presumably SUP 11) scheduled early next year. ProRes 3.2K allows a similar up-sampling in post to UHD as Arriraw Open Gate does to 4K.

For TV productions working in UHD,  Alexa XT cameras and Classic cameras with an XR Module will be able to record ProRes 3.2K. The data rates will be well below uncompressed Arriraw (ProRes 4444 3.2K is expected to be around 700 Mbit/s, which is 1/3 of Arriraw Open Gate’s 2.17 Gbit/s).

The ARRI Amira upgrade announced last week offers ProRes UHD recording in-camera and in real time to CFast 2.0 cards up to 60 fps. This  in-camera up-rez is possible because Amira has a powerful processor. Amira’s UHD uses the same 1.2x up-sample filter that Alexa’s Open Gate mode employs to up-rez in post for 4K distribution.

Alexa ProRes 3.2K is a 16:9 format. Image diagonal is 29.74 — so almost all 35mm cine lenses will cover. Where do the extra pixels come from? The Alexa HD image area is 2880 x 1620. The additional width comes from the 5% extra surround view area of the sensor, which is also used in Open Gate.

Numbers, Facts and Figures

  • Alexa ProRes 3.2K is 3168 x 1720
  • Amira UHD is 3200 x 1800
  • UHD is 3820 x 2160
  • Arriraw Open Gate is 3.4K
  • ProRes 3.2K for Alexa XR and XT cameras will be available in ProRes 422, 422 HQ, 4444 and 4444 XQ.

Official information on the ARRI website.



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