DCI Specs - Digital Cinema Initiatives

3.3.4. File Format3.3.4.1. GeneralThe audio file format shall comply with the Broadcast Wave file format (.wav), per [ITUTech 3285 version 1 (PCM WAVE coding)], is extended and constrained as furtherdescribed here.The audio file shall remain uncompressed throughout the Digital Cinema system. Thisshall include packaging, distribution and storage.3.3.4.2. SynchronizationThe Broadcast Wave (.wav) file is required to contain metadata that indicates the firstsample of audio data. The metadata is also required to contain a continuous frame countrelative to the image as well as the sample rate.3.4. Text Rendering3.4.1. Text Rendering Concepts and RequirementsDigital Cinema has a subtitling system that can convey multiple languages. Along withsubtitling, there are text localizations, titling and captioning that may also be a part of thenew Digital Cinema experience. However, captioning and subtitling are identified as twoseparate systems having different roles in the presentation of content and may havedifferent methods of rendering.Traditionally, the audience for captioning is the deaf and hard of hearing (D/HOH). Thedelivery can be done in different ways. These include closed systems that are optional-tothe-viewerdelivery and are usually displayed on a personal device (such as a wirelessreceiver), or delivery to an obscured device that is viewable with an appliance (such as arear-wall display viewed through a mirror).Subtitling is generally associated with a foreign language translation for localizing a movie ina particular geographic territory. Subtitles are typically open or displayed on the screen aspart of the movie, without option. Subtitling and localizations are generally designed for aparticular look with creatively chosen fonts and drop shadows.With captioning, the source language (what is spoken in the movie) and the target language(what appears as captions) are most often, as in the case of English, the same. Forsubtitling, the source language and target language are different because the goal ofsubtitling is to translate the movie.Subtitles and captions, if supplied, may be one or more of the following:• Pre-composited into the Digital Cinema image files (burned-in)• Pre-rendered PNG bitmaps (subpicture), or• Documents containing text and attributes for:o Rendering in a specified font (Timed Text) and overlaid by the server, an inlineprocessor or the Digital Cinema projectorooLED displays driven by a captioning processor receiving data from the DigitalCinema server, orSeparate projection systems driven by a captioning processor receiving dataDCI Digital Cinema System Specification v.1.2 Page 34