CinemaDNG is the result of an Adobe-led initiative to define an industry-wide open file format for digital cinema files. [1] CinemaDNG caters for sets of movie clips, each of which is a sequence of raw video images, accompanied by audio and metadata. CinemaDNG supports stereoscopic cameras and multiple audio channels. CinemaDNG specifies directory structures containing one or more video clips, and specifies requirements and constraints for the open format files, (DNG, TIFF, XMP, and/or MXF), within those directories, that contain the content of those clips. [2]
CinemaDNG is different from the Adobe DNG (Digital Negative) format that is primarily used as a raw image format for still cameras. However, each CinemaDNG image is encoded using that DNG image format. The image stream can then be stored in one of two formats: either as video essence using frame-based wrapping in an MXF file, or as a sequence of DNG image files in a specified file directory. Each clip uses just one of these formats, but the set of clips in a movie may use both.
CinemaDNG has become an accepted file format in its brief history:
All of these are free and freely available; [27] however, at November 2009 the products are prerelease versions:
There does not appear to be any commitment from Adobe (or any other company) to submit CinemaDNG to a standards body such as ISO. However, they have repeatedly emphasized that it will be an open format, and Adobe has stated "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". [30] It is reasonable to speculate that eventually CinemaDNG will become a formal standard, based on the history of DNG itself which has been submitted to ISO for use in the revision of ISO 12234-2 (TIFF/EP).
Rather than creating entirely new file formats, the strategy for CinemaDNG is primarily to specify how to package files and other data-sets, of existing open and/or standard formats, in consistent ways, so that not only can individual components of a movie be interchanged and archived, but so can sets of clips with all their associated video, audio, and metadata files. [2] The emphasis is on having a systematic structure that supports the very complicated workflows, involving many stages and suppliers and software and hardware components, of movie development. [28] The CinemaDNG specification is largely about this systematic directory structure and the requirements and constraints that ensure that individual files fit within it.
If CinemaDNG follows the same sort of path to standardization as DNG, (or indeed, PDF), there will first be a period while the specification is tested in the marketplace to ensure that it works in practise as well as theory. It will then be revised accordingly, so that whatever is standardized will be credible, well supported by products, and ready for immediate use.
In November 2014 Blackmagic Design introduced an extension to the CinemaDNG format in the form of a lossy compression scheme used in their URSA cameras. [31] This format uses a 12-bit Huffman Coding by patching jpeg-9a for 12-bit support. These CinemaDNG files are supported by Blackmagic Design's own DaVinci Resolve software, slimRAW and Fast CinemaDNG Processor.
The adoption of compressed CinemaDNG among camera manufacturers appears to be hindered by Red Digital Camera’s patent US9245314, which covers in-camera recording of compressed raw video. There had been an unsuccessful attempt to invalidate the patent. [32] [33]