Revision as of 16:25, 7 June 2007

hAudio 0.4

hAudio is a simple, open, distributed format, suitable for embedding information about audio recordings in (X)HTML, Atom, RSS, and arbitrary XML. hAudio is one of several microformats open standards.

hAudio Microformat Draft Specification

Editor: Manu Sporny, Bitmunk - Digital Bazaar, Inc.
Contributors: Manu Sporny, Bitmunk - Digital Bazaar, Inc.; Martin McEvoy; Alexandre Van De Sande; Michael Johnson; Dave Longley; Brian Suda; Ben Wiley Sittler; Scott Reynen; Frances Berriman; James Craig; David Janes; Andy Mabbett; Danny Ayers; Rudy Desjardins; Chris Griego; Brad Hafichuk; Tantek Çelik

Microformats #Copyright and #Patents statements apply.

Introduction

It is difficult for a browser to extract semantic information about an audio recording described on a web page. Metadata such as speaker, musician, publisher, label, title of the work, release date, acquisition link, related image artwork and tags provide relevant context for the audio recording.

Having such information marked up can provide a number of benefits to the viewer. If a web browser understands that a particular web page contains a song performed by an artist, it can produce richer interactions. For example, specific searches may be performed for artists and songs via general search services such as Google and Wikipedia. Specific search services may also be queried such as MusicBrainz, The Internet Archive, FreeDB, or Bitmunk. Additionally, classification by crawlers can become more accurate. If there are 20 tracks found on a page done by the same artist, and that content consumes a significant portion of the page, it can be assumed that the page is not only about music, but also about a particular artist.

In order to enable and encourage the sharing, distribution, syndication, and aggregation of audio content, the authors propose the hAudio microformat, an open standard for distributed audio metadata. The authors have researched both numerous audio-info-examples in the wild and earlier attempts at audio-info-formats, and have designed hAudio around a simple minimal schema for audio content. Feedback is encouraged on the hAudio feedback page.

Inspiration and Acknowledgments

Many thanks to the various individuals that did research and proposed ideas and discussion related to media info and audio info in general. Among the many participants are RodBegbie, Dean Hudson, Tantek Çelik, Mary Hodder, Joshua Kinberg, ChrisMessina, and Lisa Rein.

Scope

Audio content consistently share several common fields. Where possible hAudio has been based on this minimal common subset.

Out of scope

Fields that are type-specific have been omitted from hAudio. It is important that hAudio be kept simple and minimal from the start. Additional features can be added as deemed necessary by practical implementation experience.

The concept of a universal audio identifier, that is, how to identify the same audio album, song, speech, or podcast across different music and audio sites, though something very useful to have, is outside the scope of this format.

Semantic XHTML Design Principles

Note: the Semantic XHTML Design Principles were written primarily within the context of developing hCard and hCalendar, thus it may be easier to understand these principles in the context of the hCard design methodology (i.e. read that first). Tantek

XHTML is built on XML, and thus XHTML based formats can be used not only for convenient display presentation, but also for general purpose data exchange. In many ways, XHTML based formats exemplify the best of both HTML and XML worlds. However, when building XHTML based formats, it helps to have a guiding set of principles.

Reuse the schema (names, objects, properties, values, types, hierarchies, constraints) as much as possible from pre-existing, established, well-supported standards by reference. Avoid restating constraints expressed in the source standard. Informative mentions are ok.
1. For types with multiple components, use nested elements with class names equivalent to the names of the components.
2. Plural components are made singular, and thus multiple nested elements are used to represent multiple text values that are comma-delimited.
Use the most accurately precise semantic XHTML building block for each object etc.
Otherwise use a generic structural element (e.g. <span> or <div>), or the appropriate contextual element (e.g. an <li> inside a <ul> or <ol>).
Use class names based on names from the original schema, unless the semantic XHTML building block precisely represents that part of the original schema. If names in the source schema are case-insensitive, then use an all lowercase equivalent. Components names implicit in prose (rather than explicit in the defined schema) should also use lowercase equivalents for ease of use. Spaces in component names become dash '-' characters.
Finally, if the format of the data according to the original schema is too long and/or not human-friendly, use <abbr> instead of a generic structural element, and place the literal data into the 'title' attribute (where abbr expansions go), and the more brief and human readable equivalent into the element itself. Further informative explanation of this use of <abbr>: Human vs. ISO8601 dates problem solved

Format

In General

The hAudio format is based on a set of fields common to numerous audio content sites and formats in use today on the web. Where possible field names have been chosen based on those defined by the related hCard standards.

Schema

The hAudio schema consists of the following:

hAudio (haudio)
- fn (aka formatted name). required. text (re-used from hcard).
- contributor. optional. using hCard.
  - suggested 'role's: speaker, artist, composer, band, publisher
- published-date. optional. using datetime-design-pattern.
- rel-sample. optional. sample file/stream using rel-design-pattern with sample as the mf-rel-value.
- rel-enclosure. optional. full download of file using rel-enclosure.
- rel-payment. optional. link to purchase process using rel-payment.
- image-summary. optional. using HTML and XHTML tag img.
- category. optional. text.
- duration. optional. ISO-8601 time duration using abbr-design-pattern (re-used from hcalendar).
- price. optional. using currency-proposal.

Field details

The fields of the hAudio schema represent the following:

hAudio

An hAudio is used to identify and describe metadata associated with an individual audio recording.

an hAudio element is identified by class name haudio

Formatted Name

The Formatted Name of an audio recording is a short textual description used to identify the work among interested parties. This is also referred to as the title of the work. This can be the title of a speech, song title, or short description regarding a sound effect.

The element is identified by the class name fn.
hAudio MUST have a Formatted Name.

Contributor

A Contributor is any entity that takes part in the creation and distribution of an audio recording. Examples include: artist, publisher, guitarist, vocalist, violinist, lead singer, backup singer, bassist, drummer, manager, and roadie.

The element is identified by the class name contributor.
hAudio MAY include one or more contributors.
The contents of the element must include a valid hCard Microformat.
The role field should be used to specify the Contributor's responsibility related to the audio recording.
If multiple Contributors are specified without role specifications, it may be assumed that the first role mentioned is the creator.

Published Date

The Published Date specifies the date that the audio recording was made available to the public. Examples include: The airing date of a radio broadcast, the day a speech was given, or the day a music album was made available for sale.

The element is identified by the class name published-date.
hAudio MAY include one or more published-dates.
The contents of the element must include a date format compliant with the datetime-design-pattern.

Sample

A Sample URL specifies from where an excerpt of the audio recording may be retrieved.

The element is identified by a URL fitting the rel-design-pattern, the rel content being sample.
hAudio MAY include one or more URL samples.
The URL SHOULD point to a directly accessible stream or file.
The type of the sample MAY be specified by using the type specifier for a URL.

Full Download (Enclosure)

An Full Download URL specifies from where the full version of an audio recording may be retrieved. The URL MUST point to a direct link to a file.

The element is identified by a URL with the class name as enclosure.
hAudio MAY include one or more acquire URLs.
The type of the file MAY be specified by using the type specifier for a URL.

Purchase (Payment)

An Purchase URL specifies from where the full version of an audio recording may be purchased. The URL SHOULD point to a page that contains a purchase process.

The element is identified by a URL with the class name as payment.
hAudio MAY include one or more payment URLs.
The type of the file MAY be specified by using the type specifier for a URL.

Image Summary

An Image Summary specifies an image that should be used to summarize the audio recording. Examples include: the image of a speaker, an audio album cover image, or a picture from a concert.

The element is identified by the class name image-summary.
hAudio MAY include one or more image-summary images.
The element must be an <img> element.

Duration

The Duration specifies the length in time of the audio recording in seconds. Examples include: 104 seconds, 3:23, and 4 minutes.

The element is identified by the class name duration.
hAudio MAY include one duration element.
The contents of the element SHOULD use the abbr-design-pattern whose title attribute contains an ISO-8601 formatted duration, specifically in seconds. This allows us to expand into specifying time slices and other time markup in the future, but keep parsing simple for now. An example of 3:23 (203 seconds) would be "P203S" in ISO 8601 format. Currently, all abbr attributes specifying duration SHOULD be in seconds.

Price

The Price specifies the amount of currency that must be exchanged for acquisition of a full specimen of the audio recording. Examples include: One Dollar, $2, and £4.

The element is identified by the class name price.
hAudio MAY include one or more price elements.
The contents of the element SHOULD use the currency-proposal.

More Semantic Equivalents

For some properties there is a more semantic equivalent, and therefore they get special treatment, e.g.:

For any "url", use <a class="url" href="...">...</a> inside the element with the class name 'haudio' in hAudio.
And for "image-summary", use <img class="image-summary" src="..." alt="Photo of ..." />

Language

To explicitly convey the natural language that an hAudio is written in, use the standard (X)HTML 'lang' attribute on the element with class="haudio", e.g. <div class="haudio" lang="en"> ... </div> If portions of an hAudio (e.g. the item name) are in a different language, use the 'lang' attribute on those portions.
hAudio processors which need to handle the language of reviews MUST process the standard (X)HTML 'lang' attribute as specified.

Human vs. Machine Readable

If an <abbr> element is used for a property, then its 'title' attribute is used for the value of the property, instead of the contents of the element, which can then be used to provide a user-friendly alternate presentation of the value.

Similarly, if an <img /> element is used for one or more properties, it MUST be treated as follows:

For the "image-summary" property and any other property that takes a URL as its value, the src="..." attribute provides the property value.
For other properties, the <img /> element's 'alt' attribute is the value of the property.

Notes

This section is informative.

By marking up audio content with the hAudio microformat, the expectation is communicated that information about the content MAY be indexed. This has no impact on the copyright of the content itself which the publisher may explicitly specify using rel-license as specified above.
The enumerated list of item types is under development and may be extended.
Each type may have custom hAudio fields that follow the common set.
Additional details about a particular item should be specified with the rest of the item's info at the URL provided for the item.

XMDP Profile

<dl class="profile">
 <dt>class</dt>
 <dd><p>
  <a rel="help" href="http://www.w3.org/TR/html401/struct/global.html#adef-class">
   HTML4 definition of the 'class' attribute.</a>
  This meta data profile defines some 'class' attribute values (class names) 
  and their meanings as suggested by a 
  <a href="http://www.w3.org/TR/WD-htmllink-970328#profile">
   draft of "Hypertext Links in HTML"</a>.
  <dl>
   <dt>haudio</dt>
   <dd>
    Used to identify and describe metadata associated with an individual audio recording.
   </dd>
   <dt>fn</dt>
   <dd>
    A short textual description used to identify an audio recording among interested parties.
   </dd>
   <dt>collaborator</dt>
   <dd>
    An entity that takes part in the creation and distribution of an audio recording.
   </dd>
   <dt>published-date</dt>
   <dd>
    The date that the audio recording was made available to the public.
   </dd>
   <dt>image-summary</dt>
   <dd>
    An image that should be used to summarize the audio recording.
   </dd>
   <dt>category</dt>
   <dd>
    The genre or style used to classify the audio recording.
   </dd>
   <dt>duration</dt>
   <dd>
    The length of the audio recording.
   </dd>
   <dt>price</dt>
   <dd>
    The amount of currency that must be exchanged for acquisition of a full specimen of the audio recording.
   </dd>
 </dd>
</dl>

Examples

Here are a few examples of audio content from current web sites, and how they could be easily enhanced to support the hAudio audio metadata microformat.

Want to write valid hAudio? Use the hAudio creator (not implemented yet) to write about audio content and publish it on your blog.

Simple Song Example

Display:

Start Wearing Purple by Gogol Bordello

Microformatted XHTML:

<div class="haudio">
   <span class="fn">Start Wearing Purple</span> by 
   <div class="collaborator">
      <div class="vcard">
         <span class="org fn">Gogol Bordello</span>
      </div>
   </div>
</div>

Speech Example

Display:

I Have a Dream, a speech by Martin Luther King Jr.

Microformatted XHTML:

	 
<div class="haudio">	 
   <span class="fn">I Have a Dream</span>, a 	 
   <span class="category">speech</span> by 	 
   <div class="collaborator">	 
      <div class="vcard">	 
         <span class="fn">Martin Luther King, Jr.</span>	 
      </div>	 
   </div>	 
</div>

Complete Example

An example that uses every element of haudio:

[Image] Sneaking Sally Thru The Alley by Phish
Released: October 31, 2006
Acquire: Sample, Live Recording, Buy High Quality Track
Category: Live
Duration: 7 minutes, 27 seconds
Price: $0.99

Here is the hAudio Microformat markup:

<div class="haudio>
   <img class="image-summary" src="images/sneaking_sally.jpg"/>
   <span class="fn">Sneaking Sally Thru The Alley</span>
   <span class="contributor">
      <span class="vcard">
         <span class="fn org">Phish</span>
      </span>
   </span>
   <br/>
   Released on:
   <abbr class="published-date" title="20063110">October 31, 2006<abbr>
   <br/>
   Acquire: 
   <a rel="sample" href="/samples/sneaking_sally.mp3">Sample</a>, 
   <a rel="enclosure" href="/live/sneaking_sally.mp3">Live Recording</a>,
   <a rel="payment" href="/buy/sneaking_sally">Buy High Quality Track</a>
   Category: <span class="category">live</span>
   Duration: <abbr class="duration" title="447">7 minutes, 27 seconds</abbr>
   Price: <span class="money">
             <abbr class="currency" title="USD">$</abbr>
             <span class="amount">0.99</span>
          </span>
</div>

Examples in the wild

This section is informative.

Implementations

This section is informative.

See hAudio Implementations.

References

Normative References

Informative References

CSS1
ISO.8601.1988
- International Organization for Standardization, "Data elements and interchange formats - Information interchange - Representation of dates and times", ISO Standard 8601, June 1988.
W3C NOTE-datetime-19980827
W3C Patent Policy
Other audio metadata efforts. See audio-info-formats.

Similar Work

Copyright

This document and specification is distributed under a Creative Commons Attribution 3.0 license. It is licensed and can be used royalty-free for any purpose.

The authors intend to submit this specification to a standards body with a liberal copyright/licensing policy such as the GMPG (http://gmpg.org/), IETF (http://ietf.org/), and/or W3C (http://w3.org). Anyone wishing to contribute should read each organizations copyright principles, policies and licenses (e.g. the GMPG Principles (http://gmpg.org/principles)) and agree to them, including licensing of all contributions under all required licenses (e.g. CC-by 1.0 (http://creativecommons.org/licenses/by/1.0/) and later), before contributing.

Patents

The authors of this Microformat have not and will not apply for patents covering any invention covering this Microformat in part or as a whole. There are no claims to any patent in this document. Each author is required to report any known patent issues immediately under this section.

This document and specification is distributed under a royalty free patent policy, e.g. per the W3C Patent Policy (http://www.w3.org/Consortium/Patent-Policy-20040205/), and IETF RFC3667 (http://www.ietf.org/rfc/rfc3667.txt) & RFC3668 (http://www.ietf.org/rfc/rfc3668.txt).

Work in progress

This specification is a work in progress. As additional aspects are discussed, understood, and written, they will be added.

Related Pages

hAudio
hAudio cheatsheet - hAudio properties.
hAudio authoring - learn how to add hAudio markup to your existing web pages.
hAudio issues - issues with the specification.
- Audio info issues - issues with the preparatory work.
hAudio brainstorming - ideas for the specification.
hAudio-history - the history of the research and development of hAudio.

haudio: Difference between revisions