RAW and CinemaDNG Wrapper Workflow

RAW/CinemaDNG Wrappers are a way to load RAW and CinemaDNG files in Premiere Pro and After Effects. As the video above shows, there are 3 basic steps in the workflow.

  1. Run the Merger.
  2. Create a GNR file.
  3. Import the GNR file into After Effects or Premiere Pro

To create a GNR file that points to a set of EXRs, you have two options:

  • RAW/CinemaDNG Wrapper
  • RAW/CinemaDNG Wrapper (Batch)

The Merger expects each shot to be in its own directory with the files numbered sequentially. If you have one shot then you should use the non-batch option which will create a single GNR file. If you have multiple shots then you should use the batch option. You will enter the first directory (alphabetically) and the last directory. Then each individual directory will get its own GNR file.

There are several other options available to you:

  1. Resolution: Allows the GNR file to interpret the file as a different size. For example, if your source files are very large but you are outputting at 1080p then After Effects and Premiere Pro will think of the files as 1080p, which in some cases will speed up playback and rendering.
  2. Frame Rate: Specifies the Frame Rate that the footage will be interpreted as.
  3. Naming: There are two naming conventions. Let’s say that you have a directory Foo with a sequence of EXRs starting with Cam0001.EXR.
    • Base Directory: Your output file will be called Foo.GNR
    • First File: Your output file will be called Cam0001.GNR
  4. Resample Sharpness: If you are going to change your resolution then you have the option to do some sharpening during the resize. 1.0 is usually a good value. For no sharpening, set it to 0.0. If your Resolution is set to “Full Size” then this slider has no effect.
  5. Full Debayer: Option of which debayering algorithm when displaying an image that is Full Size. You will almost always want to set this to High.
  6. Half Debayer: Option of which debayering algorithm to use when displaying an image that is half size or smaller.
  7. Ignore Crop: This is a special option designed for the BMC Camera.

Debayer High vs. Debayer Low

When using the High option it performs a full debayer and then scales it down. Using the Low is a bit more complicated.

The Bayer pattern means that for every 2×2 block of pixels you will have 1 red, 1 blue, and 2 green pixels. With the Low option it averages the two green values and uses the red and blue directly. The advantage is that it is fast. The disadvantage is that your image is half size and tends to be “too sharp” and is prone to aliasing.

In our experience most editors would prefer to use a low-resolution proxy for faster playback during editing, and then want to render the sequence as high quality. With the Half Debayer setting set to Low you can achieve the same effect by just switching the preview resolution.

Ignore Crop

Many camera formats record at a higher resolution but often the edges are not usable. Those cameras use the Crop metadata information to tell the importers to only load the cropped data.

The BMC camera has some special behavior though. The RAW file has a crop size of 2400×1350 but the original data size is 2432×1366. However the extra data seems perfectly usable. So by enabling the Ignore Crop parameter you can squeeze out a slightly wider FOV. It’s not much bet every bit helps.