How good is EPUB 3 – Is it the best choice of format for eBook?
EPUB 3 is the recent / current version of the most acceptable eBook file format, the ePUB that has been approved by the IDPF membership as the ultimate ‘Recommended Specification’ which comprises of four sets namely: EPUB Publications 3.0, EPUB Content Documents 3.0, ePUB Open Container Format (OCF) 3.0 and EPUB Media Overlays 3.0. EPUB 3, which stands third among the major three major releases (after EPUB 1.0 and EPUB 2.0.1) of the EPUB standard and it surpasses the preceding version – EPUB 2.0.1.
- EPUB Publications 3.0 – Characterizes publication-level semantics as well as the predominant conformance requisites for Publications in EPUB format.
- EPUB Content Documents 3.0 – Characterizes XHTML, SVG and CSS profiles that are to be used in the structure of EPUB Publications.
- EPUB Open Container Format (OCF) 3.0 – Characterizes a file format as well as the processing model to sum up a set of correlated resources into a single ZIP file EPUB Container.
- EPUB Media Overlays 3.0 – Characterizes a format together with a processing model to synchronize text as well as audio.
The above mentioned new specifications of EPUB increases the EPUB format’s potential considerably, enabling additional support to many more publication needs for features like complex layouts, overall font as well as rich media and communication. EPUB 3 is expected to be well utilized for a wide range of publications including magazines, academic publications as well as professional and scientific publications apart from other books.
The main features of EPUB 3 are as follows:
(1) Embedding of Audio and Video:
EPUB 3 supports embedding of audio and video within the content in the document with the functionality and features relevant to audio and video provided through the elements of HTML 5. EPUB 3 also allows adding of ‘Media Overlay Documents’, which are XML documents that partners with the XHTML Content Document containing pre-recorded audio narration intended to provide an in line playback experience. The TTS (Text-to-speech) facilities in order to control pronunciation, voice distinctiveness including prosody too are provided by EPUB 3.
(2) Support for CSS3:
EPUB 3 supports the recent CSS3 modules thus enabling typescript for a number of languages as follows:
- Enables vertical writing, allowing the users to toggle direction by providing this feature in the Reading Systems.
- Handling of emphasis is made well.
- Enhanced control over hyphenation as well as line breaking – enabling breaks to take place at the character level in the cases of those languages that do not use space between words.
(3) Font support:
Complicated as well as regular font resources supported by EPUB 3 for both ‘OpenType’ and WOFF,’ – two interrelated font formats, houses traditional as well as digital publishing workflows. Global distribution of publications is improved by EPUB 3 that supports alternate representations of entire text metadata items within the package metadata segment
EPUB 3 format books could be read in any Reading System without any trouble with the fonts as EPUB 3 facilitates embedding of fonts and thus enables rendering of the book (text) content as intended. This feature is very much helping to have the special characters of the book to be retained as such.
EPUB is able to reach its main goal of ‘facilitating content accessibility’, through its EPUB 3 version.