What is a DTB?
The DAISY DTB is a collection of digital files. These files may contain digital audio recordings of human or synthetic speech, marked up text, and a range of machine-readable files.
The structure of the book is created using XML tags and is accessible via a browser or a playback device. The DAISY DTB utilizes commonly used web technologies with some additional specialized applications.
Three basic types of DAISY DTBs:
- Audio with NCX: DTB with structure. The NCX is the Navigation Control Center, a file containing all points in the book to which the user may navigate. The XML textual content file, if present, contains the structure of the book. It may also contain links to features such as narrated footnotes, etc. Some DTBs may also contain additional textual components, for example, index or glossary, supporting keyword searching.
- Audio and full text: DTB with structure and complete text and audio. This form of a DTB is the most complete and provides the richest reading experience. The XML textual content file contains the structure and the full text of the book. Audio and text are synchronized.
- Text and no audio: DTB without audio. The XML textual content file contains the structure and full text of the book. There are no audio files. This type of DAISY DTB may, for example, be rendered with synthetic speech or with a refreshable braille display.
XML provides the producer with the ability to structure a book in great detail. Compared to HTML markup, XML increases markup options making more detailed structure and proper nesting possible.
A DTB produced to the DAISY Standard consists of some or all of the following files:
- A Package File (drawn from the Open eBook Forum (OEBF) Publication Structure Specification 1.2), containing administrative information about the DTB, the files that comprise it, and how these files relate to each other.
- A textual content file containing some or all of the text of the book with appropriate markup.
- Audio files containing the human voice recording and/or synthetic speech rendering of the book.
- SMIL (Synchronized Multimedia Integration Language) file(s) containing information linking the audio and textual content files.
- NCX - a file containing all points in the book to which the user may navigate.
DTBs produced according to the DAISY Structure Guidelines are not dependent of distribution medium. The digital master file can be archived and may also be distributed using media such as SD cards, USB flash drives, CDs or DVDs. Patrons can also access these books using apps - utilizing the DAISY Online Delivery Protocol.