A Digital Cinema Distribution Master / DCDM
is a prestage format in the process of creating a DCP / Digital Cinema Package. The DCDM is mostly archived alongside with the DCP, to act as a source format for future purposes (remastering / ancilliary markets, localised versions…)
A DCDM contains all data needed for the creation of a Digital Cinema Package / DCP (picture, sound, subtitles, metadata) in uncompressed and unencrypted form.
Picture and sound data must be formatted according to DCI Specs .
Picture:
Flat: 1,85:1 = 1998:1080 Pixel
Cinemascope: 2,35:1 = 2048:858 Pixel
Sound:
Broadcast Wave file format (.wav), see ITU Tech 3285
version 1 (PCM WAVE) 24bit 48 or 96 kHz 5.1.
In exact terms:
A set of DCDM files (image, audio, subtitles, etc.) contains all of the content required to provide a
Digital Cinema presentation. The DCDM provides two functions, an interchange file format, and a
playback format that is directly sent from the Media Block to the projector (this is referred to as
DCDM*). For use in interchange, the encoding process can be performed in real time or non
-real time. For use in playback, the DCDM* is logically required to playback in real time.
Metadata within the DCDM provides a method to synchronize image, audio and subtitles. This
method is used to synchronize the tracks in order to maintain frame -based lip sync from the
beginning to the end of a presentation. This is different from the requirement to synchronize the
system clocks of different pieces of equipment to run at consistent frequencies. The first part
addresses the packaging of the picture, sound and subtitles in such a way as to establish and
maintain a timing relationship between all these tracks of essence.
