CinemaDNG File Format
The CinemaDNG file format is designed to store high-resolution video streams in camera raw format and typically adds less than 1 KB overhead per image. CinemaDNG files typically require half the storage space of corresponding DPX files. Each video frame is independently encoded using the DNG (Digital Negative) image format. The video stream is stored either as a picture track in an MXF (Material Exchange Format) file or as a sequence of individual frame files.
CinemaDNG uses fully-documented, vendor-neutral, standard formats for video and imaging – DNG, TIFF/EP, and MXF. The format is unencrypted and free from intellectual property encumbrances or license requirements. Several SDKs are available for each of the components of the format.
The CinemaDNG format allows vendors to add functionality on set or in post, for example, by extending the decoder SDKs with additional image processing or metadata processing.
The DNG Format
The camera sensor output can be stored directly into the DNG image file, without in-camera pixel processing or repackaging of the sensor data. The DNG image format is widely used to capture and archive camera raw images. Tools are available to convert images from over 200 proprietary camera raw file formats to the DNG format. The DNG format specification is now being incorporated into the ISO 12234-2 standard as TIFF/EP Profile 2.
DNG options in CinemaDNG include:
- Image data from a single-chip image sensor (with color filter array) or a multi-chip image sensor (without color filter array)
- Sensor values of any bit depth from 8 to 32 bits
- Arbitrary-size color filter arrays with up to seven different filter colors
- Arbitrary image height and width
- Lossless compression
- Black level, white level, and linearization parameters for decoding and scaling of sensor values
- Color-processing parameters for mapping sensor values to CIE XYZ color space
The MXF Format
For a high level of compatibility with existing tools, CinemaDNG images can be stored in a directory structure, in an MXF wrapper, or transformed between these wrapping formats. SMPTE standard 377M defines MXF for the interchange of audiovisual material. The MXF file wraps multiple streams of essence, such as DNG, and includes metadata that describes the material contained within the MXF file.