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Access to Digital Cinema Systems

A subcommittee of the Society of Motion Picture and Television Engineers/SMPTE has worked for many years now to develop a standard for the inclusion of subtitling/captioning data in digital cinema packages (DCP), as well as inclusion of description as an audio track in the DCP. The Media Access Group at WGBH has participated from the beginning in this committee work. WGBH's work on this effort was funded by the U.S. Department of Education from September of 2003 to August 2006. WGBH continues to work on ensuring access to digital cinema, and will do so until the nation's transition to digital cinema is complete.

In October of 2009, the standard was finalized for open and closed caption, and open and closed subtitle data in the DCP (how to insert it into the DCP and how it will play out with external devices.) In April, 2010, a movie industry standard for how to recognize and play out captioning files from DCPs across various brands of digital cinema servers was finalized, and a demonstration of beginning support for the standard took place. While there is still some work to be done before all the manufacturers support the new standards, support has been rolling out and should be completed by April 2011.

Among the server manufacturers that already enable processing of closed captioning from DCPs inlcude Doremi, GDC and Qube. These companies implemented their solution in response to market demand. We continue to work with Sony, Dolby and other server manufacturers on their implementation of access features, and will update this page to reflect current equipment in the marketplace.

Additionally, there are now middleware boxes designed to bridge the closed caption/subtitle data from the DCP to the specific display devices (for example the Rear Window® Caption display) in the theaters. One such manufacturer, USL, Inc., now supports the Rear Window Captioning display from their equipment. Digital cinema servers from Dolby and Sony now play out closed captioning via the Rear Window system with the aide of the USL device. Additional companies are pursuing alternative caption display and description delivery technologies for in-theater use.

There are currently theaters using an interim method of direct closed caption support, and theaters are deploying cinema servers and middleware boxes like the USL equipment, supporting the SMPTE standard for closed captions/subtitles. Inclusion of audio description data in the DCP, and identification and play out of the track via cinema servers and FM or infrared systems in theaters, continues and should be completed by April 2011.

SMPTE committees working on standards for access features in digital cinema, and to which NCAM contributes expertise, are:

  • SMPTE 21DC - the parent committee for Digital Cinema

    and two technical committees within 21DC
  • TC-21DC10 SG Stereoscopic Subtitles (Study Group within the Mastering
  • TC-21DC30 AHG Closed Captions (Ad-Hoc Group within the Exhibition– or theater chain owners'– subgroup)