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Audiobook Profile

Editors:

  • Hadrien Gardeur

Participate:

Example

{
  "@context": "http://readium.org/webpub-manifest/context.jsonld",
  
  "metadata": {
    "@type": "http://schema.org/Audiobook",
    "conformsTo": "https://readium.org/webpub-manifest/profiles/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
  },

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

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

Introduction

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 Readium Web Publication Manifest, it has its own media type in order to maximize compatibilty with audio apps: application/audiobook+json.

1. 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 conformsTo element that identifies the manifest as an audiobook: https://readium.org/webpub-manifest/profiles/audiobook
  • it must include a duration element that provides the total duration of the audiobook in seconds

The duration of an audiobook as expressed in metadata is purely a hint and must not be used by the User Agent for anything else than informing the user.

In addition to its duration, an audiobook may indicate that it's an abridged edition using the abridged element.

2. Listing Audio Resources

An audiobook is divided into one or more audio resources, which are all listed in the readingOrder of the manifest.

In addition to the normal requirements of a readingOrder, all Link Objects have the following additional requirements:

  • they must point strictly to audio resources, with no fragment identifier.
  • they must include a duration term that provides the duration in seconds of each individual audio resource

In addition, all Link Objects should also include the bitrate (in kbps) whenever possible.

3. Alternate Audio Resources

In order to support multiple variants of the same audiobook (using a different format or bitrate for instance), Link Objects in the readingOrder may rely on the alternate key:

{
  "href": "http://example.org/part1.mp3", 
  "type": "audio/mpeg", 
  "bitrate": 128, 
  "duration": 1980, 
  "title": "Part 1",
  "alternate": [
    {
      "href": "http://example.org/part1.opus", 
      "type": "audio/ogg", 
      "bitrate": 32
    }
  ]
}

All Link Objects present in the alternate array:

  • must indicate their media-type using type
  • should indicate their bitrate using bitrate
  • must reference audio resources of the same duration as the top-level Link Object
  • must not include the following keys: title, duration or templated

4. Packaging

An Audiobook publication may be distributed unpackaged on the Web, but it may also be packaged for easy distribution as a single file. To achieve this goal, this specification defines the Readium Packaging Format (RPF).

To maximize compatibility with dedicated apps, such a package has its own file extension and media-type:

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

Appendix A - Examples

A full example based on the LibriVox edition of Flatland is available at: https://readium.org/webpub-manifest/examples/Flatland/manifest.json

Over 10,000+ audiobooks are also available in this format through the Internet Archive OPDS Catalog.

Appendix B - Demo

A demo of the Flatland example is also available through a Web App developed by De Marque.