ARRI ALEXA post, part 3

Post Workflow – Avid Media Composer 5

Thanks to Avid Media Access (AMA), the Media Composer application starting with version 5 can natively handle Apple ProRes media. This means you can bring in files from an ARRI ALEXA and immediately start editing. But ProRes 422 (HQ) or ProRes 4444 might be more taxing than you want to deal with on a long project, so I’m going to outline a suggested workflow for an ALEXA project using Avid Media Composer 5.

Step 1. Same as step 1 in the previous FCP post – clone your media files for protection. Standard archiving solutions include LTO data tape, redundant copies on hard drive or burning media to Blu-ray discs (BR-ROM).

Step 2. Import the camera masters (ProRes HQ or ProRes 4444) into a Media Composer project, using “Link to AMA Files (or Volume)”.

Step 3. Determine the selected takes you plan to edit with and transcode these AMA clips to Avid media. If you intend to use these for just rough cut, creative editing, then select the DNxHD 36 resolution. Move the transcoded files to a separate bin. Close the bin with the AMA clips and do not use these as sources in your edit.

Step 4. Edit as you normally would with the DNxHD 36 clips. Feel free to change clip names as appropriate. I am going to assume that the ALEXA clips used the Log C profile, which means that they are low-contrast in appearance. For the purpose of client/producer viewing, you may need to apply a basic color effect filter to an upper track in order to provide a basic adjustment to make these clips appear more like “normal” video. Edit until the cut is locked and approved.

Step 5. Once the cut is locked, hide the transcoded media by moving the corresponding Avid media files out of the MXF folder on your media hard drive. This will cause the clips in your sequence to be offline.

Step 6. Open the AMA bins (with the ProRes files) and relink the edited sequence to the AMA clips. When relinking is complete, the sequence will be repopulated with AMA media, which will be the native files.

Step 7. Consolidate/transcode your sequence. Select a higher resolution, such as DNxHD 175X. This will create new Avid media clips at full quality for all clips in your timeline.

Click on the image for an enlarged view. (Alexa clip courtesy of ARRI.)

Step 8. Remove any temporary color effect you might have added before. Enter the Avid color correction mode for final grading. As I previously discussed with Color, one approach is to use the auto-contrast controls to change black and white points. Apply this first and increase the master saturation to 150 as a basic starting point. Then proceed to do your creative grading using the hue offset and curve controls. Just as in Color, this automatic control is only calculated on the parked frame, so tweak as needed.

An interesting hybrid approach to posting ALEXA files is to combine elements of these Final Cut and Media Composer workflows. For example, you could use FCP and the Nick Shaw LUT plug-in to create editing proxy files. Export one set of files from FCP with the LUT and timecode burned-in. Bring those in via AMA and follow the steps outlined above for the rough cut.

Then, when it comes to the finishing steps, use AMA to import the original camera files and link your sequence to those clips instead of the ones with the LUT and burn-in. The one caveat to proper relinking is to make sure the source file names match, including extensions. Both the original files and the exported “baked” files need to match with regards to the presence or absence of the .mov file extension. It may take a bit up trial-and-error for you to get the hang of it, but this hybrid solution will work just fine!

©2010 Oliver Peters

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