The ARRI Alexa has proven to be a wonderful camera system from top to bottom — DPs and ACs love it for it’s beautiful imagery and ease of use. And at the end of the day you get compatible ProRes MOV files that both your editors and creative staff can easily view on Mac’s and PC’s simply by using Quicktime Player. Even so, there are still post-production facilities out there that insist on working with Avid DNxHD. As a Producer, it’s your job to make that happen.
Record directly to Avid DNxHD from the camera
Beginning with version 6.0 or higher, Alexa’s Software Update Packet will let you record Avid DNxHD directly to the internal SxS cards. Although Moving Picture knows that this is clearly the simplest solution to implement, there are some real world drawbacks to this approach. Your creative team won’t have viewing access to the material recorded on DNxHD MXF files unless helper software or additional codecs have been installed on their computers. So, to avoid these types of headaches, you may want to seek an alternative approach.
Record Avid DNxHD with an external video recorder
One solution is to record directly from the ALEXA to DNxHD or ProRes using a PIX recorder.
There are many external recorders on the market right now, and they range drastically in price range and feature set. However, for this simple live transcoding task, I recommend the Sound Devices PIX-240 recorder with the v3.0 Aurora firmware update. With the new v3.0 firmware, this $200/day recorder can accept 3G HDSDI 12bit 4:4:4 LOG C video from the Alexa, and real-time transcode to DNXHD 220x 10bit.
However, reversing the settings will produce better quality video. If you allow the Alexa to record the DNxHD files to the SxS cards, the PIX-240 can record ProRes 4444 12bit at 330Mb/s for your creative team’s review. Another alternative that saves on drive space would be to provide lower resolution “proxy” files to your team. Simply set your PIX recorder to save ProRes 422Proxy 8bit 36Mb/s files.
There are additional options, but suffice it to say that this approach is the most versatile way to tackle the transcoding problem.