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Working with 5D3 Magic Lantern raw footage on OSX

Magic Lantern is the one free software add-on for the Canon 5D3 that offers the incredible possibility to record full-frame film in uncompressed 14bit raw. Explained in short this means the information from the 5D3’s bayer sensor is directly recorded, bypassing the shortcomings of the standard h264 recording codec of the camera. We’ll end up with much sharper, detailed material that doesn’t fall apart when being graded. Apart from that there are more features that come with the Magic Lantern add-on, for example Zebra, Peaking or the possibility of “cropping” the sensor readout (3x magnification without any loss in pixel resolution).
In case you’re interested in the details, visit the Magic Lantern homepage and / or check out the DVXUser guide to Magic Lantern raw.

Even though the Magic Lantern software add-on is for free (but you’re invited to tip those extremely talented programmers via Bitcoin), it still comes at a certain price concerning storage and workflow:

As the data rate of raw video is way higher than the usual h264, reliable raw recording of full HD (1920×1080) material at 24 or 25 frames per second will only be possible by using really fast CF cards. After trying out a variety of UDMA7-compatible types of CF cards (Lexar, SanDisk, Komputerbay), I found the (rather expensive) SanDisk Extreme Pro 160MB/s the most reliable option for my camera, at least at the size of 128 GB.
That being said, even those cards delivered some drop frame errors when being formatted as ExFAT, but with the camera-internal FAT formatting, they proved to be a reliable option (don’t worry, the raw video files will be split to overcome the 4GB-per-file limit of FAT).

There are two different file formats that Magic Lantern offers to record raw video, RAW (only video information) and MLV (video & audio information). As I always need sound as sync source on my jobs, I only record in MLV.

Once the recording is finished, the MLV files will be transferred to my Apple workstation. Don’t forget, we are recording raw information directly from the Bayer sensor inside the camera (kinda like REDRaw, but without the 1:2 compression), these visual informations need to debayered before they can be taken to the NLE of your choice. The cool thing is: we’re dealing with raw information, so white balance, tint etc. can all be set after the actual recording has taken place. I would call that “recording without a picture profile”.

There are a couple of tools available on the OSX platform to process MLV files:

The MlRawViewer makes it possible to watch MLV files directly from the Finder without prior debayering. A very nifty solution on set, as it is impossible to play back the recorded files directly on camera in real time (but they can be watched in non-realtime to check the framing etc.). MLRawViewer can also be used to debayer the images properly and export them either as DNGs (single raw image sequences) or Apple PRORES files (set white balance first!), but at the moment, this process is CPU-based and takes quite a while.
The option I am using at the moment to debayer my recorded videos is decoding the MLV files as DNG sequences via MLV Mystic and then importing these into Blackmagicdesign’s DaVinci Resolve Lite 10. This free version of the popular color grading solution is able to perform a GPU-based debayering of the raw image sequences in realtime on my workstation. In conjunction with the awesome Cinelog LUTs for DaVinci Resolve, which will help to interpret the color information from the 5D3 sensor properly, we have the possibility to obtain proper PRORES422 or PRORES4444 video files for hassle-free editing (or further grading) within the NLE of choice.
For quick jobs, we can choose to debayer directly to REC709, while staying on the Cinelog profile or exporting as Arri Alex Log C gives us the freedom to further grade the footage to our likes.
While the method mentioned above is my personal preferred path to deal with DNG sequences out of MLV, there are other options to debayer the recorded 5D3 sensor information. ACR (Adobe Camera Raw that comes with Photoshop or Lightroom) does probably the best job in interpreting this data, but it is not really batch-able and takes a longer time. As a sidenote, the Cinelog profile mentioned before is also available for ACR.
Some NLEs can also interpret CDNG (Cinema DNG) sequences directly, but the lack of possible white balancing within FCPX makes it a lesser option in my case.
Here’s a quick comparison between the different debayering possibilities (no color change applied) while we can also see how much resolution is being “taken away” when using the internal h264 recording:

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Posted on May 13, 2014, in Filmtools and tagged , , , . Bookmark the permalink. Leave a comment.

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