Subtitle 2014 __TOP__
This document specifies two profiles of [TTML1]: a text-only profile and an image-only profile. These profiles are intended to be used across subtitle and caption delivery applications worldwide, thereby simplifying interoperability, consistent rendering and conversion to other subtitling and captioning formats. The text profile is a superset of [SDPUS].
This document specifies two profiles of [TTML1]: a text-only profile and an image-only profile. These profiles are intended for subtitle and caption delivery worldwide, including dialog language translation, content description, captions for deaf and hard of hearing, etc.
In applications that require subtitle/caption content in image form to be simultaneously available in text form, two distinct subtitle documents, one conforming to the Text Profile and the other conforming to the Image Profile, SHOULD be offered. In addition, the Text Profile subtitle document SHOULD be associated with the Image Profile subtitle document such that, when image content is encountered, assistive technologies have access to its corresponding text form.
A subtitle document MAY contain elements and attributes that are neither specifically permitted nor forbidden by a profile. Such elements and attributes MAY be ignored by the presentation processor or transformation processor.
A subtitle document MAY be associated with a related video object, which SHALL consist of a sequence of image frames, each a rectangular array of pixels, and SHALL be considered the Related Media Object.
When mapping a media time expression M to a frame F of a related video object, e.g. for the purpose of rendering a subtitle document onto the related video object, the presentation processor SHALL map M to the frame F with the presentation time that is the closest to, but not less, than M.
Otherwise, the root container of a subtitle document SHALL be mapped to the related video object frame in its entirety. If tts:extent is present on the tt element, the extents of the root container SHALL be equal to the dimensions of the related video object frame.
A progressively decodable subtitle document is structured to facilitate presentation before the document is received in its entirety, and can be identified using ittp:progressivelyDecodable attribute.