This specification describes the requirements for the creation of audiobooks, using a profile of the Publication Manifest specification.
An Audiobook is a collection of audio resources grouped together by a reading order, metadata, and resources, all contained in a manifest. This Audiobook can live on the Open Web Platform, or as a packaged entity.
This specification is intended to standardize the audiobooks distribution model on the web and between businesses. It should facilitate different user agent architectures for the consumption of Audiobooks. The primary goal is to bring clarity to a part of the publishing industry currently underserved by standards, while opening Audiobooks to the Open Web Platform and new user agents. This specification does not outline what file types or formats should be used by content creators, only a manifest format for delivering them.
This specification does not define how user agents are expected to render Audiobooks. Details about the types of affordances that user agents can provide to enhance the reading experience for users are instead defined in [[pwp-ucr]].
Terms with meanings specific to the publishing industry are capitalized in this document (e.g., "Reading System"). A complete list of these terms and definitions is provided in [[pub-manifest]].
Only the first instance of a term in a section is linked to its definition.
In addition, the following terminology is defined for use in this specification:
Supplemental content is any content relating to the audiobook content but not required for the full experience of the publication. Examples of supplemental content include photographs, charts, or data relating to topics mentioned in the audiobook.
The primary entry page is an HTML resource that represents the preferred starting resource of an Audiobook and enables discovery of its manifest. It typically introduces the audiobook and provides access to the content.
The primary entry page MUST include either a link to the manifest or embed the manifest [[!pub-manifest]]. It also SHOULD contain the table of contents.
An Audiobook MUST include a primary entry page except when packaging allows alternative discovery of the manifest. When present, the page MUST be included in the resource list.
The table of contents provides a hierarchical list of links that reflects the structural outline of the major sections of the Audiobook and any supplemental content it may contain.
The table of contents is expressed via an [[html]] element (typically a nav element) in one of the
resources. This element MUST be identified by the role attribute [[html]] value
"doc-toc" [[dpub-aria-1.0]].
If the table of contents is located in the primary entry page, the table of contents MUST be the first element in the document — in document tree order [[dom]] — with that role value. Otherwise, the manifest SHOULD identify the resource that contains the structure.
If the table of contents is not located in the primary entry page, the manifest SHOULD identify the resource that contains the structure.
When an Audiobook contains audio resources that include multiple chapters or parts, or if the audiobook contains supplemental content:
a table of contents SHOULD be included;
the table of contents SHOULD include a link to any of the resources; and
all links SHOULD refer to publication resources [[!pub-manifest]].
Some Audiobooks may have audio resources that contain more than one chapter or section of the book content. It is strongly recommended that content creators provide a table of contents using media fragments [[media-frags]] to provide the user with access to the structure of the Audiobook.
When including supplemental content, be aware that users might not have access to this content unless it is linked to from the table of contents. It is strongly advised to provide links to all content that is not in the default reading order.
For more guidance on the structure and formatting for tables of contents, consult Publication Manifest - Machine-Processable Table of Contents [[pub-manifest]].
The Audiobook manifest is defined by a set of properties that describe the basic information a user agent requires to process and render an Audiobook. These properties are categorized in the Publication Manifest [[pub-manifest]]. Where these properties are extended from the Publication Manifest is specified in this section.
The Audiobook manifest is defined as a specific "shape" of [[json-ld11]]. This shape is also defined, informally, through a JSON schema [[json-schema]] that expresses the constraints defined in this specification. This schema is maintained at https://www.w3.org/ns/pub-schema/audiobooks/.
The requirements for the expression of Audiobook properties and resource relations are defined as follows:
The list of properties uses the formal names for each property as described in [[schema.org]] and [[pub-manifest]]. A descriptive label is included in parentheses where the purpose of these properties might be unclear.
conformsTo
@context
readingOrder
name
(publication title) abridged
accessibilityFeature
accessibilityHazard
accessibilitySummary
accessMode
accessModeSufficient
author
cover
duration
dateModified
datePublished
id
(canonical identifier) inLanguage
(publication language) readBy
readingProgression
resources
type
url (address)
Some properties are implicitly required, as they are compiled from alternative
information when not explicitly authored. Refer to the internal representation
data models [[pub-manifest]] for more information (the Audiobooks representation only
differs in the default value for the type term).
An Audiobook manifest has to start by setting the JSON-LD context [[!json-ld]]. The context has the following two major components:
https://schema.orghttps://www.w3.org/ns/pub-context
{
"@context" : ["https://schema.org", "https://www.w3.org/ns/pub-context"],
…
}
To add the global language and direction of the manifest metadata, language and direction declaration [[!pub-manifest]] can also be added to the context:
{
"@context" : [
"https://schema.org",
"https://www.w3.org/ns/pub-context",
{"language":"fr"}
]
…
}
The conformance URL expressed in the conformsTo
term [[!pub-manifest]] MUST be "https://www.w3.org/TR/audiobooks/".
{
"@context" : ["https://schema.org", "https://www.w3.org/ns/pub-context"],
"conformsTo" : "https://www.w3.org/TR/audiobooks/"
…
}
The Publication Type is defined using the type
term [[!pub-manifest]].
{
"@context" : ["https://schema.org", "https://www.w3.org/ns/pub-context"],
"type" : "Audiobook"
…
}
If a type is not specified, Audiobook [[!schema.org]] is assumed as the default.
A creator is an individual or entity responsible for the creation of the Audiobook. The Audiobooks profile can use the full list of creators defined in [[!pub-manifest]].
The creators list includes two recommended creators for Audiobooks:
{
"conformsTo" : "https://www.w3.org/TR/audiobooks/",
"@context" : ["https://schema.org","https://www.w3.org/ns/pub-context"],
"type" : "Audiobook",
…
"url" : "https://publisher.example.org/janeeyre",
"author" : {
"type" : "Person",
"name" : "Charlotte Bronte"
}
}
{
"conformsTo" : "https://www.w3.org/TR/audiobooks/";
"@context": ["https://schema.org", "https://www.w3.org/ns/pub-context"],
…
"url" : "https://publisher.example.org/janeeyre",
"author" : {
"type": "Person",
"name": "Charlotte Bronte"
}
"readBy" : {
"type": "Person",
"name": "Ivan Herman",
"id" : "https://www.w3.org/People/Ivan/"
}
}
A duration is the length of the audio resources in an Audiobook. The duration property is fully defined in Publication Manifest [[!pub-manifest]].
Duration SHOULD be expressed for the entirety of the audiobook as part of the manifest, and SHOULD be present at the item level in the default reading order.
When a content creator specifies both the duration for the audiobook and item-level duration in the default reading order the resource-level duration SHOULD be equal to the sum of the durations of the items in the reading order.
{
"conformsTo" : "https://www.w3.org/TR/audiobooks/",
"@context" : ["https://schema.org","https://www.w3.org/ns/pub-context"],
…
"url" : "https://publisher.example.org/janeeyre",
"author" : {
"type" : "Person",
"name" : "Charlotte Bronte"
},
"duration" : "PT12345.235S"
}
The default reading order [[!pub-manifest]] is a specific progression through the audio resources in the audiobook.
The default reading order MUST contain at least one audio resource, which MAY be identified by the
type of LinkedResource [[!pub-manifest]]. The default reading order MUST NOT
contain non-audio resources.
An audio resource can be referenced in its entirety via a URL [[url]], or for content where multiple chapters occupy a single file by using media fragments [[media-frags]] to locate the exact starting and end points.
It is important to note that a resource cannot be referenced more than once in the reading order. In the case where an audio file represents the content of multiple chapters or sections of the book, the table of contents can be used to specify the starting and ending points of those chapters in the larger audio file, as demonstrated in this example.
Annotations can also use media fragments to identify the location of the annotation in the resource, and are compatible with the Web Annotations model. This method will only apply to audiobook manifests that are not packaged.
{
"@context" : ["https://schema.org", "https://www.w3.org/ns/pub-context"],
"conformsTo" : "https://www.w3.org/TR/audiobooks/",
"url" : "https://publisher.example.org/janeeyre",
"name" : "Jane Eyre",
"readingOrder" : [{
"type" : "LinkedResource",
"url" : "audio/janeeyre.mp3",
"encodingFormat" : "audio/mp3",
"name" : "Jane Eyre",
"duration" : "PT124503.123S"
}]
}
{
"@context" : ["https://schema.org", "https://www.w3.org/ns/pub-context"],
"conformsTo" : "https://www.w3.org/TR/audiobooks/",
"url" : "https://publisher.example.org/janeeyre",
"name" : "Jane Eyre",
"readingOrder" : [{
"type": "LinkedResource",
"url" : "audio/part001.wav#t=0,457.931",
"encodingFormat" : "audio/vnd-wav",
"name" : "Chapter 1",
"duration" : "PT457.931S"
}, {
"type" : "LinkedResource",
"url" : "audio/part002.wav#t=12.741",
"encodingFormat" : "audio/vnd-wav",
"name" : "Chapter 2",
"duration" : "PT234.245S"
}]
}
The resource list enumerates any additional resources used in the processing and rendering
of an audiobook that are not listed in the reading order. It is expressed using the
resources property.
If an audiobook includes supplemental content it MUST be referenced in the resource list.
{
"@context" : ["https://schema.org", "https://www.w3.org/ns/pub-context"],
"conformsTo" : "https://www.w3.org/TR/audiobooks/",
"url" : "https://publisher.example.org/janeeyre",
"name" : "Jane Eyre",
"resources" : [
"cover.jpg",
"portrait_CB.jpg",
"supplement.pdf"
]
}
Previews are a common way to provide users an experience of the full content before purchasing or downloading the full audiobook.
A preview is identified using the
preview link relation, as defined in [[!pub-manifest]].
Previews MAY be located externally or included as a resource of the audiobook.
{
"@context" : ["https://schema.org", "https://www.w3.org/ns/pub-context"],
"conformsTo" : "https://www.w3.org/TR/audiobooks/",
"url" : "https://publisher.example.org/janeeyre",
"name" : "Jane Eyre",
"resources" : [{
"type" : "LinkedResource",
"url" : "https://publisher.example.org/jane-eyre-preview.wav",
"encodingFormat" : "audio/wav",
"rel" : "preview"
}]
}
{
"@context" : ["https://schema.org", "https://www.w3.org/ns/pub-context"],
"conformsTo" : "https://www.w3.org/TR/audiobooks/",
"url" : "https://publisher.example.org/janeeyre",
"name" : "Jane Eyre",
"resources" : [{
"type" : "LinkedResource",
"url" : "preview.wav",
"encodingFormat" : "audio/wav",
"rel" : "preview"
}]
}
Audiobooks will be packaged using the method described in the Lightweight Packaging Format [[lpf]] note.
The history of the audiobook is rooted in the world of accessibility. Both purely audio publications and publications that synchronize text and audio playback have long been used to assist users with alternative reading needs and preferences.
An approach for accessible synchronized media in publications is currently being done by the Synchronized Multimedia for Publications Community Group. Refer to the work of that group for more information about creating such content and incorporating it into an Audiobook.
Alternatively, a content creator can provide the text equivalent as HTML [[html]] resources in the resources.
{
"@context" : ["https://schema.org", "https://www.w3.org/ns/pub-context"],
"conformsTo" : "https://www.w3.org/TR/audiobooks/",
"url" : "https://publisher.example.org/janeeyre",
"name" : "Jane Eyre",
"readingOrder" : {
"type" : "LinkedResource",
"url" : "audio/part001.wav#t=0",
"encodingFormat" : "audio/vnd-wav",
"name" : "Chapter 1",
"duration" : "PT457.931S",
"alternate" : {
"type" : "LinkedResource",
"url" : "text/part001-1.html",
"encodingFormat" : "text/html"},
},
"resources" : [{
"type": "LinkedResource",
"url": "text/part001-1.html",
"encodingFormat" : "text/html"
}…
]
}
This section depends on the Infra Standard [[!infra]].
The specification extends the Publication Manifest processing algorithms [[!pub-manifest]] as follows:
The following extension steps are added for Audiobook manifests:
() Check the duration of the publication as follows:
Let resourceDuration hold the total duration of individual resources.
For each resource of data["readingOrder"]:
if resource["duration"] is not defined, validation error.
otherwise, if resource["duration"], add resource["duration"] to resourceDuration.
If the values cannot be compared because data["duration"] is not set, validation error.
Otherwise, if resourceDuration does not specify the same total duration as data["duration"], validation error.
This step checks both that all resources in the reading order specify a duration and that the sum of all those durations matches the total duration for the publication.
A validation error is only emitted while checking each resource if the resource does not specify a duration. The validity of the durations [[pub-manifest]] is already checked in the publication manifest algorithm so does not need to be repeated.
The following extension steps are added for Audiobook manifests:
() Check the reading order as follows:
If data["readingOrder"] is not set, fatal error.
For each resource in data["readingOrder"], if resource is not an audio resource, validation error, remove resource from data["readingOrder"].
If data["readingOrder"] is an empty list, fatal error.
This step ensures that only audio resources are listed in the reading order and removes any that are not.
If the reading order does not contain any entries after checking each resource, a fatal error is returned as the publication is not a valid audiobook.
() If data["type"] is not set or is an empty list, validation
error, set to « "Audiobook" ».
This step sets the default type of the publication to Audiobook when a
type property has not been specified.
() Check that each of the following properties is set. If not, issue a validation error for each one.
() If no resource in data["readingOrder"] or
data["resources"] has a rel
entry that contains the relation
cover, validation
error.
This step checks the reading order and resource list to verify that a cover has been
specified (i.e., an resource has the value cover in its
rel property).
This specification extends the Publication Manifest’s User Agent Processing Algorithm for Machine-Processable Table of Contents [[pub-manifest]] to locate a table of content element as follows:
As Audiobooks is a profile of Publication Manifest [[pub-manifest]], all security and privacy considerations detailed in that specification are applicable to this profile.
This profile acknowledges the following considerations:
This section outlines the expected user agent behaviors for implementation of audiobooks. For processing
instructions, user agents should refer to the Processing a
Manifest section of the Publication Manifest [[pub-manifest]] specification, and conform
to any behavior described there.
All user agent behaviors described in this section are intended to provide implementors with guidance, not strict requirements. Behaviors in this document are taken mainly from the Use Cases and Requirements [[pwp-ucr]] note published by the working group.
As outlined in the Use Cases and Requirements [[pwp-ucr]] note, an audiobook must be navigable in the User Agent. This means that a User Agent must provide methods for the user to move through the audiobook in a linear or non-linear fashion by either moving through the Reading Order seamlessly or by accessing the Table of Contents. The User Agent should also allow the user to move through individual audio files in short time increments.
For an audiobook, the User Agent should provide a player interface [[pwp-ucr]] that will allow the user to navigate, play, or pause the audiobook. This interface can be represented to the user in any way (i.e. physical buttons, visual interface, keyboard input, or voice commands), but should be accessible at any point in the listening experience.
The Use Cases and Requirements [[pwp-ucr]] note recommends that content be available offline and that any packaged formats should not affect the iterations of the publications. This means that even if the content is copied many times to many users via multiple User Agents, the core manifest and its identifier are never changed.
This specification recommends the Lightweight Packaging Format [[lpf]] for packaging audiobook content, but this is not a requirement. Audiobook User Agents should be able to ingest LPF files for play, and should display content according to the requirements and recommendations in this document.
If a User Agent is serving the content directly from their service (i.e. as a retailer or repository of content), it is recommended that they provide a method for offlining or downloading the content to the user. This can be in any format they choose, but the audiobook should be complete and valid and the contents listed in the manifest should be served in their entirety. Even if a User Agent does not support the display of a certain resource (i.e. an image file or data table), it should still be available to the user for download.
This specification does not provide a method for content creators to protect or watermark their content, as there are existing methods available in the market today. User Agents who work with content creators that wish to protect or limit the distribution of their content can choose a method that works best for their requirements.
This specification recommends and provides a method for content creators to create fully accessible audiobooks. User Agents should use this information,
in the section on Accessibility, to implement accessible audiobook interfaces. It is recommended
that User Agents provide accessible player interfaces, as well as a method for content creators who
have provided alternate content to have that content displayed.
Substantive changes since the First Public Working Draft:
For a complete list of issues addressed, refer to the GitHub tracker.
A manifest for an audiobook. The canonical version of this manifest is also available.
A manifest for an audiobook with supplemental content.
{
"@context" : ["https://schema.org", "https://www.w3/org/ns/pub-context"],
"conformsTo" : "https://www.w3.org/TR/audiobooks/",
"id" : "https://publisher.example.com/janeeyre",
"url" : "https://publisher.example.com/janeeyre",
"name" : "Jane Eyre",
"author" : "Charlotte Bronte",
"readBy" : "Jane Doe",
"duration" : "PT123456.789S",
"abridged" : false,
"inLanguage" : "en",
"dateModified" : "2019-03-29T15:59:00Z",
"datePublished" : "2019-03-29",
"readingOrder": [
{"url": "audio/chapter001.aac", "encodingFormat": "audio/aac", "name": "Chapter 1", "duration": "PT1234.567S"},
{"url": "audio/chapter002.aac", "encodingFormat": "audio/aac", "name": "Chapter 2", "duration": "PT890.123S"},
{"url": "audio/chapter003.aac", "encodingFormat": "audio/aac", "name": "Chapter 3", "duration": "PT456.789S"},
{"url": "audio/chapter004.aac", "encodingFormat": "audio/aac", "name": "Chapter 4", "duration": "PT987.654S"},
{"url": "audio/chapter005.aac", "encodingFormat": "audio/aac", "name": "Chapter 5", "duration": "PT321.987S"}
],
"resources": [
{"rel": "cover", "url": "images/cover.jpg", "encordingFormat": "image/jpeg"},
{"rel": "contents", "url": "toc.html", "encodingFormat": "text/html"},
{"url": "haworth_house.pdf", "encodingFormat": "application/pdf"}
]
}
A primary entry page with a simple table of contents for an audiobook.
<head>
…
<script type="application/ld+json">
{
"@context" : ["https://schema.org","https://www.w3.org/ns/pub-context"],
"conformsTo" : "https://www.w3.org/TR/audiobooks/",
…
"url" : "https://publisher.example.org/janeeyre",
…
}
</script>
…
</head>
<body>
…
<section role="doc-toc">
<ol>
<li><a href="audio/chapter001.wav">Chapter 1. There was no possibility of taking a walk that day...</a></li>
<li><a href="audio/chapter002.wav">Chapter 2. I resisted all the way:...</a></li>
<li><a href="audio/chapter003.wav">Chapter 3. The next thing I remember is,...</a></li>
…
</ol>
</section>
…
</body>
A table of contents for a simple audiobook.
<nav role="doc-toc"> <h2>JANE EYRE</h2> <ol> <li><a href="audio/chapter001.mp3">Chapter 1. There was no possibility of taking a walk that day...</a></li> <li><a href="audio/chapter002.mp3">Chapter 2. I resisted all the way:...</a></li> <li><a href="audio/chapter003.mp3">Chapter 3. The next thing I remember is,...</a></li> … </ol> </nav>
A table of contents using media fragment references to locations in a single audio track.
<nav role="doc-toc"> <h2>JANE EYRE</h2> <ol> <li><a href="https://example.publisher.org/janeeyre/part001.mp3#t=0,456.788">Chapter 1</a></li> <li><a href="https://example.publisher.org/janeeyre/part001.mp3#t=456.789,1234.566">Chapter 2</a></li> <li><a href="https://example.publisher.org/janeeyre/part001.mp3#t=1234.567">Chapter 3</a></li> </ol> </nav>