Audiobook Manifest

Example

{
  "metadata": {
    "@type": "http://bib.schema.org/Audiobook",
    "identifier": "urn:isbn:9780000000001",
    "title": "Moby-Dick",
    "author": "Herman Melville",
    "narrator": ["Joe Speaker", "Lucy Narrator"],
    "language": "en",
    "publisher": "Whale Publishing Ltd.",
    "published": "2016-02-01",
    "modified": "2016-02-18T10:32:18Z",
    "duration": 4320,
    "type": "audio/mpeg",
    "bitrate": 128
  },

  "links": [
    {"rel": "self", "href": "http://example.org/manifest.audiobook-manifest", "type": "application/audiobook+json"},
    {"rel": "cover", "href": "http://example.org/cover.jpeg", "type": "image/jpeg", "height": 300, "width": 300},
    {"rel": "alternate", "href": "http://example.org/audiobook.m3u", "type": "audio/mpegurl", "bitrate": 64}
  ],

  "spine": [
    {"href": "http://example.org/part1.mp3", "type": "audio/mpeg", "bitrate": 128, "duration": 1980, "title": "Part 1"}, 
    {"href": "http://example.org/part2.mp3", "type": "audio/mpeg", "bitrate": 128, "duration": 1200, "title": "Part 2"}, 
    {"href": "http://example.org/part3.mp3", "type": "audio/mpeg", "bitrate": 128, "duration": 1140, "title": "Part 3"}
  ],
  
  "timeline": [
    {"href": "http://example.org/part1.mp3#t=0,299", "title": "Introduction"},
    {"href": "http://example.org/part1.mp3#t=300", "title": "Part 1", "children": [
      {"href": "http://example.org/part1.mp3#t=300,1319", "title": "Chapter 1"},
      {"href": "http://example.org/part1.mp3#t=1320", "title": "Chapter 2"}
    ]},
    {"href": "http://example.org/part2.mp3", "title": "Part 2", "children": [
      {"href": "http://example.org/part2.mp3#t=0,539", "title": "Chapter 3"},
      {"href": "http://example.org/part2.mp3#t=540,839", "title": "Chapter 4"},
      {"href": "http://example.org/part2.mp3#t=840", "title": "Chapter 5"}
    ]},
    {"href": "http://example.org/part3.mp3", "title": "Part 3", "children": [
      {"href": "http://example.org/part3.mp3#t=0,599", "title": "Chapter 6"},
      {"href": "http://example.org/part3.mp3#t=600", "title": "Chapter 7"}
    ]}
  ]
}

Introduction

There is no single dominant format for audiobooks and so far IDPF/W3C hasn't shown any particular interest in them.

The goal of this document is to provide an audiobook profile for the Readium Web Publication Manifest that will cover the following requirements:

• provide metadata
• list the different components of an audiobook
• support multiple audio formats and means of accessing an audiobook (streaming or downloads)

While the Audiobook Manifest is technically a profile of the Web Publication Manifest, it has its own media type and file extension in order to maximize compatibilty with audio apps:

• its media type is application/audiobook+json
• its file extension is .audiobook-manifest

Metadata

The core metadata for the audiobook manifest are based on the default context for the Readium Web Publication Manifest with the following additional requirements:

• it must include a @type element that identifies the manifest as an audiobook using the bib extension to schema.org: http://bib.schema.org/Audiobook
• it must include a duration element that provides the total duration of the audiobook
• it must also include the narrator element

While the format and bitrate of each audio file that constitute the audiobook are provided in the spine, it is also recommended to include:

• the main media type used for the audio files using the type element
• the bitrate for those files using the bitrate element

Listing Audio Files

An audiobook is divided into one or more audio files, which are all listed in the spine of the manifest, in reading order.

In addition to the normal requirements of a spine, all link objects have the following additional requirements:

• all link objects must point strictly to audio files
• every link object must include a duration that provides the duration of each individual audio file

In addition, all link objects should also include the bitrate whenever possible.

Cover

A manifest can also specify the cover of an audiobook using the cover relationship in links:

"links": [{
  "rel": "cover", 
  "href": "http://example.org/cover.jpeg", 
  "type": "image/jpeg", 
  "height": 300, "width": 300}]

Timeline

A manifest can also provide additional navigation through a timeline collection.

A timeline is a list of labels pointing to specific timestamps in an audiobook.

Each link object in a timeline collection has the following requirements:

• it must point to an audio file listed in the spine and use a media fragment to point to a specific timestamp
• it must provide a title
• it must not use type, duration or bitrate to avoid duplication with the spine

Container

In order to facilitate distribution, both manifest and audio files can also be distributed using a container.

In this case, all files (individual audio files and manifest) must be contained in a ZIP where the manifest is at the root of the zip and named manifest.json.

The container also has the following properties:

• its file extension must be .audiobook
• its media type must be application/audiobook+zip

When an audiobook is distributed in a container (instead of simply as a manifest), the manifest has the following additional restrictions:

• the spine must strictly reference audio files that are present in the container
• to reference such files, all URIs in the spine must be relative to the manifest (at the root of the container)

Live Demo

An Audiobook Manifest based on the Librivox edition of Flatland is available at: https://hadriengardeur.github.io/audiobook-manifest/examples/flatland.audiobook-manifest

A proof of concept for an audiobook player is also available at: https://hadriengardeur.github.io/audiobook-manifest/examples/player/