There are 2 options for subtitling in digital cinema:
1 . Subtitles as text information
To minimize the space consumed by a Digital Cinema Package it is possible to store subtitles as text information. This text information is then rendered and displayed by the projector during runtime. There is a special .xml format and scheme in which the text information is stored (for Interop and SMPTE there are two different .xml schemes, CineCanvas™ and SMPTE 429-5 which differ slightly). The text information is stored together with the meta data (e.g. in and out points, text effects like italic or bold, and the text position and direction). It is also possible to use a custom font for the subtitles (TrueType format .ttf)
2. Additional picture version with burned – in subtitles
Another possibility is to master a second picture track with the subtitles in the picture (brun-in). This increases the size of the DCP as a seperate picture version is needed. For 3D Films this is until now (September 2015) the most reliable option. There will be an SMPTE standard for 3D subtitling (with depth information) in text format, but until now it is not yet completely adopted.
It is possible to convert nearly any given subtitle text format into the needed .xml format or make a picture version with subtitles burned in. Please contact us if you need further information.