DAISY Technology

What is a DTB?

A traditional talking book is an analog representation of a print publication. A Digital Talking Book (DTB) is a multimedia representation of a print publication.

At very early stages in the development of the DAISY Standard, talking book readers from many countries were surveyed regarding their reading requirements and their vision of a fully accessible audio book. Those who provided input made it very clear that analog recordings did not meet their reading and information needs. Access to different sections within a book, sound quality plus numerous other issues that were mentioned, indicated that producers of talking books had to begin the move to a digital platform. However, a digitally produced human voice talking book in itself would not resolve all of the issues, particularly the issues of accessibility and navigation from point to point within a book.

The DAISY DTB is a collection of digital files (from this point onward referred to simply as "files") that provides an accessible representation of the printed book for individuals who are blind, visually-impaired, or print-disabled. 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 designated by the XML tags and is accessible to the reader by use of a browser or a playback device. The DAISY DTB utilizes the technology of the Internet with some specialized applications added to provide greatly improved access to the information.

There are 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 and may contain links to features such as narrated footnotes, etc. Some DTBs of this type 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, multimedia reading experience and the greatest level of access. The XML textual content file contains the structure and the full text of the book. The audio and the 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 and makes 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 current Open eBook Forum (OEBF) Publication Structure Specification 1.2), containing administrative information about the DTB, the files that comprise it, and how these files interrelate.
  • 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.

XML provides the producer with the ability to structure a book in great detail. Compared to HTML markup, XML increases markup options and makes more detailed structure and proper nesting possible.

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 on currently available media such as SD cards, USB flash drives, CDs or DVDs. More importantly, as technology advances and digital media distribution methods evolve, these same books can be distributed via the newly developed media or system.