Sustainability of Digital Formats
 Planning for Library of Congress Collections

Introduction | Sustainability Factors | Content Categories | Format Descriptions | Contact
Format Description Categories >> Browse Alphabetical List

DTB (Digital Talking Book), 2002

>> Back
Table of Contents
Format Description Properties Explanation of format description terms

Identification and description Explanation of format description terms

Full name Digital Talking Book. ANSI/NISO Z39.86-2002
Description

The NISO Digital Talking Book Standard, ANSI/NISO Z39.86-2002, defines the format and content of the electronic file set that comprises a digital talking book (DTB) and establishes a limited set of requirements for DTB playback devices. It uses established and new specifications to delineate the structure of DTBs whose content can range from XML text only, to text with corresponding spoken audio, to audio with little or no text. DTBs are designed to make print material accessible and navigable for blind or otherwise print-disabled persons.

The standard comprises a set of files, including a mandatory package file, which incorporates a manifest listing all the other component files and a spine, which indicates logical reading order. Component files can be of several types, including: textual content (in XML); audio files; image files; synchronization files (in SMIL); navigation control files (in XML); bookmark/highlight files (in XML).

Production phase This bundle of files is likely to be used primarily as a middle-state format, with dissemination to end-users managed through publishers or aggregators who provide in a form appropriate for viewers/players that enforce limitations on access and use consistent with terms imposed by copyright holders.
Relationship to other formats
    Contains OEBPS_1_0, OEBPS, Open Ebook Forum Publication Structure 1.0.1
    Defined via XML_DTD, XML Document Type Definition (DTD)
    May contain WAVE_LPCM, WAVE Audio File with LPCM Audio
    May contain MP3_ENC, MP3 Audio Encoding
    May contain AAC_MP4, Advanced Audio Coding (MPEG-4)
    Has modified version DTB_2002_NLS, Digital Talking Book, NLS extension for AMR-WB+ Speech Codec. NLS is the National Library Service for the Blind and Physically Handicapped, a part of the Library of Congress. The NLS variant of DTB_2002 permits a restricted set of features and uses an audio codec that is not allowed for in the base standard.
    Has later version DTB_2005, DTB (Digital Talking Book), 2005

Local use Explanation of format description terms

LC experience or existing holdings The National Library Service for the Blind and Physically Handicapped (NLS), which is part of LC, has been actively involved in the development of this standard. The unit employs an extended version, DTB_2002_NLS.
LC preference Preferred format for digital talking books. A DTB_2002 or DTB_2002_NLS incorporating the full text of a work is among the acceptable XML-based formats for textual works, assuming no encryption or DRM is applied.

Sustainability factors Explanation of format description terms

Disclosure Open standard
    Documentation ANSI/NISO Z39.86-2002. Specifications for the Digital Talking Book. ISSN: 1041-5653
Adoption

The National Library Service for the Blind and Physically Handicapped (NLS) is using DTB_2002_NLS, the extended version of the standard for the production of NLS talking books. As of April 2009, none of the NLS talking books include full text and there are no plans to produce books with full text.

Bookshare.Org, which provides full-text books to print-handicapped users, makes the full text (without audio) of books available in several formats, including the NISO DTB standard (aka DAISY 3).

A forty-member panel representing educators, publishers, technology specialists, and advocacy groups, sponsored by Office of Special Education Programs at the U. S. Department of Education recommended, in a report released in July 2004, that a specific application (or profile) of the NISO DTB standard be adopted as version 1 of the National Instructional Materials Accessibility Standard (NIMAS). The National Center on Accessible Instructional Materials provides a list of hardware and software supporting DTB and DAISY specifications.

    Licensing and patents None
Transparency See information on the encoding formats employed for the files that comprise a DTB file set: XML, LPCM, MP3, AAC_MP4. XML and LPCM both rate highly for transparency.
Self-documentation The Package file can include Dublin Core metadata and an extended set of elements intended to record information about rights and the provenance and generation of the talking book from a source text.
External dependencies None. The format is designed to support effective use of special hardware and software players for the visually impaired, but does not require them.
Technical protection considerations None in relation to the sets of files that comply with the ANSI/NISO Z39.86-2002 specification. Digital Talking Books are likely to be distributed to end users via mechanisms that do impose technical protections. Hence it is probable that LC will need to receive such files direct from publisher or aggregator by a special transmittal process rather than by harvesting as if an end user.

Quality and functionality factors Explanation of format description terms

Sound
Normal rendering Good support.
Fidelity (high audio resolution) Not intended for audio quality beyond CD quality. DTB players must support sample rates of 44.1, 22.05, and 11.025 kHz at a depth of 16 bits per sample. Compressed audio must be encoded such that the output sampling rate is restricted to one of the above three rates and uses a constant bit rate.
Multiple channels DTB Players are not required to support multiple channels, but must recognize stereo and render at least as monaural.
Support for user-defined sounds, samples, and patches Not investigated at this time.
Functionality beyond normal rendering Synchronization with text transcription.
Text
Normal rendering Good support.
Integrity of document structure The logical structure of a document is an important part of a DTB with textual content. See DAISY Structure Guidelines.
Integrity of layout and display This standard focuses on the textual content, the logical structure, and the synchronization of text with audio of the text being read. Layout is not of primary significance in rendering for the visually impaired.
Support for mathematics, formulae, etc. Not supported
Functionality beyond normal rendering Supports embedding of audio, images, and synchronization of text with audio of the text being read.

File type signifiers Explanation of format description terms

Tag Value Note
Filename extension opf
For the required Package file. Documented in NISO standard.
Filename extension xml
For textual content files. Documented in NISO standard.
Filename extension ncx
For navigation control files. Documented in NISO standard.
Filename extension aac
For AAC_MP4 audio files. Documented in NISO standard.
Filename extension mp3
For MP3 audio files. Documented in NISO standard.
Filename extension wav
For WAVE_LPCM audio files. Documented in NISO standard.

Notes Explanation of format description terms

General The standard supports any of the following classes of digital talking book:
  • Audio with Title element only: DTB without structure. This is the simplest class of DTB and is used for books where structure will not be applied. The XML textual content file may not be present, or if it is, contains only the title of the book, and other required notation. The book must be read linearly. Direct access to points within the DTB is not possible.
  • Audio with NCX only (Navigation Control): DTB with structure. The XML textual content file, if present, contains only the structure of the book and may contain links to features such as narrated footnotes, etc. This is the most common form of DTB and is ideal for stand-alone players.
  • Audio with NCX and partial text: DTB with structure and some additional text. The XML textual content file contains only the structure of the book and the text of components where keyword searching and direct access to the text would be beneficial, e.g., index, glossary, etc.
  • Audio and full text: DTB with structure and complete text and audio. This form of a DTB is the most complex but provides 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.
  • Full text and some audio: DTB with structure, complete text and limited audio. The XML textual content file contains the structure and the text of the book. The audio files contain recordings of parts of the text. This type of DTB could be used for a dictionary where only pronunciations were provided in audio form.
  • Text and no audio: E-text with structure. The XML textual content file contains the structure and text of the book. There are no audio files.
History This format is also known as DAISY 3, being the third in a sequence of talking book formats. From the point of view of long-term sustainability, the earlier DAISY formats are less likely to be appropriate for LC collections. The previous version was Daisy 2.02, which was based on XHTML rather than XML.

Format specifications Explanation of format description terms


Useful references

URLs


Last Updated: 02/27/2015