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This is an exploratory page to be used for storage of various multimedia data and metadata profiles, formats, and practices currently in use around the web. As this is a very, very early exploration, we should include as many types of multimedia as possible in the opening discussion - but please be sure to place your information in the correct portion of this page.


Purpose of this exploration (or : The Problem)

The purpose of the studies on this page is to determine the feasibility and demand for a flexible, semantic markup format for multimedia related paradigms.

This includes such things as:

This study aims to make a start at solving this problem.


These folks have contributed real-world examples and research to this document, and are interested in helping with a solution.

If you contribute new real-world examples or research, and wish to help with a solution, please add your name as well.

Examples on the Web today

Below is a list of strawman models based on real work examples. (Links to actual examples have been omitted since many of them have been found on adult sites, and it is believed that it would be inappropriate to list these here. -- Charles)

Show Strawman #1

Single clip with a preview image. The clip is the full show.

    <a href="clip.mpeg"><img src="preview.png" /></a>

Show Strawman #2

Single clip with a preview image. The clip is the teaser of the full show. And there is a link that you can go to pay to see the full show.

    <a href="teaser.mpeg"><img src="preview.png" /></a>

    <a href="">Pay to View</a>

Show Strawman #3

A show divided up in multiple clips, each with a preview image. Together the clips make up the show.

    <a href="clip-1.mpg"><img src="preview-1.png" /></a>

    <a href="clip-2.mpg"><img src="preview-2.png" /></a>

    <a href="clip-3.mpg"><img src="preview-3.png" /></a>

Show Strawman #4

A set of teasers for a show. Together they don't make up the full show. And the may or may not overlap in time. There's a "Pay to View" link there too.

    <a href="clip-blue.mpg"><img src="preview-blue.png" /></a>

    <a href="clip-red.mpg"><img src="preview-red.png" /></a>

    <a href="clip-green.mpg"><img src="preview-green.png" /></a>

    <a href="">Pay to View</a>

Show Strawman #5

A single clip that comes in different formats. (Could be a teaser, a clip, or a full show.)

    <img src="preview.png" />
    <a href="clip.mpg">MPEG</a>
    <a href="clip.ogm">Ogg</a>
    <a href="clip.avi">AVI</a>

Show Strawman #6

A single preview image with the show given in 2 different methods. The first is the show broken up into a series of pieces (which makes it easier to download.) And the second is the full show in one file

    <img src="preview.png" />

    <a href="part-1.mpg">[1]</a>
    <a href="part-2.mpg">[2]</a>
    <a href="part-3.mpg">[3]</a>

    <a href="full.mpg">full</a>

Show Strawman #7

A single clip with a preview image. The title of the show is given with an image (and thus the actual machine-readable title is the alt attribute of the image) and is linked with the main URL for the show. There's also a link to older episodes of the show.

    <a href="..."><img src="the-name-of-the-show-png" alt="The Name of the Show" /></a>

    <a href="episode123-clip.mpeg"><img src="episode123-preview.png" /></a>

    <a href="older-shows">older shows</a>

Show Strawman #8

A series of clips with preview images. The title of the show is given with an image (and thus the actual machine-readable title is the alt attribute of the image) and is linked with the main URL for the show. There's also a links to older and news episodes of the show.

    <a href="..."><img src="the-name-of-the-show-png" alt="The Name of the Show" /></a>

    <a href="episode123-clip.mpeg"><img src="episode123-preview.png" /></a>
    <a href="episode122-clip.mpeg"><img src="episode122-preview.png" /></a>
    <a href="episode121-clip.mpeg"><img src="episode121-preview.png" /></a>
    <a href="episode120-clip.mpeg"><img src="episode120-preview.png" /></a>

    <a href="newer-shows">[next]</a>
    <a href="older-shows">[previous]</a>

Show Strawman #9

A series of preview images. The title of the show is given in text. A link to all the show's files via a torrent. Other metadata is also typically included too, in plain text; some is shown here. Also, sometimes metadata is put in the description.

    The Name of the Show

    <img src="preview1.png" />
    <img src="preview2.png" />

    <a href="show.torrent">...</a>

    Torrent Info Hash: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

    Description: blah blah blah .... here some URLs to previews...
                 blah blah blah .... this is 24 fps
                 blah blah blah

    Content: tag1, tag2, tag3

    Resolution: 320px x 240px

    Run Time: 24mins 57secs

    Size: 125.42 MB (131,509,108 bytes)

    Type: Movie Clip

    Published/Uploaded By: someone

    <a href="...">Link to page with list of files in torrent</a>
    <a href="...">Link to page with list of people on the torrent</a>

Show Strawman #10

An embedded object citing a specific plugin, or simply a link to the media itself, as an object parameter. The rest of the parameters include plugin OR media-specific metadata, and any URIs used are usually unique to the media content.

    width='400' height='326' type='application/x-shockwave-flash'
    <param name='allowScriptAccess' value='never' />
    <param name='movie'
    <param name='quality' value='best'/>
    <param name='bgcolor' value='#ffffff' />
    <param name='scale' value='noScale' />
    <param name='wmode' value='window'/>


    scale="tofit" kioskmode="false" 
    cache="false" controller="true" type="video/quicktime" autoplay="true" height="272" width="320">

Current / Previous Standards

Still image

Audio Metadata Formats


(HTML version of spec: local archive, updated version from Apple Chapter Tool Beta docs, online copy at Apple)

iTunes release 4.9 was widely heralded as an advance for mainstream acceptance of podcasting. However, while some advocates resist even the fragment of a trademarked name in the label for the phenomenon, the use of "itunes:" in the namespace is one of many design decisions in Apple's original specification that became focal points of debate. While Apple has a tradition of working on breakthrough features very quietly, they have been open to public input after its initial release. Many other bloggers have chronicled some of the feedback, as well as some face-to-face discussions.

A mailing list may be coming soon...

Media RSS has been in the works longer, but doesn't have the overnight-adoption advantage of iTunes. However, it has a much broader ambit, including video; and a much broader community of interest.

A Podcasting Microformat?

The best starting point for understanding these two proposals is W3C's summary table, by Karl Dubost.

There are (at least) two paths to consider when 'porting' these proposals into Microformats:

  1. Standalone. What is the most straightforward rendering of each proposal into XHTML? This keeps the interests of the developers of consuming applications foremost: how can the migration be made as painless as possible?
  2. Refactored. Given the existing core of Microformats, what is the minimal (!) necessary to add on to RelLicense, RelTag, hReview, and so forth? This favors (we'd hope) content publishing applications: how can the marginal migration costs of adding media be made as painless as possible.

Mapping the existing specs requires understanding the data definitions set forth in each specification, and finding the optimal equivalents (where available). The following is a partial summary of one possible mapping:

Comparison Table

<th>Microformat?</th> <tr> <td style="background-color:darkorange;color:black;font-weight:bold;">Authorship</td> <td></td> <td></td>
<td style="background-color:#eeeeee;color:black;">

need a way of specifying the role of the author or contributor.

       <td style="background-color:darkorange;color:black;font-weight:bold;">Categorization</td>
<itunes:keywords></td> <td><media:category></td> <td>nothing</td> <td><category></td> <td style="background-color:#eeeeee;color:black;">rel-tag - requires a way to do sub categories?</td> </tr> <tr> <td style="background-color:darkorange;color:black;font-weight:bold;">Description</td> <td><atom:summary>
<atom:content></td> <td><itunes:subtitle>
<itunes:summary></td> <td><media:text></td> <td>nothing</td> <td><description></td> <td style="background-color:#eeeeee;color:black;">XHTML (e.g. <blockquote> )</td> </tr> <tr> <td style="background-color:darkorange;color:black;font-weight:bold;">Licensing</td> <td><atom:copyright>
<atom:rights></td> <td><itunes:block>
<link></td> <td>Not explicitly mentioned</td> <td>nothing</td> <td><ttl></td> <td style="background-color:#eeeeee;color:black;">rel-license</td> </tr> <tr> <td style="background-color:darkorange;color:black;font-weight:bold;">Metadata</td> <td></td> <td><itunes:duration>
<td style="background-color:#eeeeee;color:black;">needs a new microformat
proposal for duration</dt>
<abbr class="duration" title="00:27:35">
27 minutes, 35 seconds

-- jkinberg 11:51, 19 Sept 2005 (PDT)) </dd>


       <td style="background-color:darkorange;color:black;font-weight:bold;">Preview</td>
       <td>For Video Media: 

For Audio Media:
nothing</td> <td>nothing</td> <td>nothing</td> <td style="background-color:#eeeeee;color:black;">need a new microformat for this
proposal for video preview</dt>
<img class="preview" src="..." />

-- Charles </dd>


       <td style="background-color:darkorange;color:black;font-weight:bold;">Rating</td>
       <td><media:adult> <media:rating></td>
       <td style="background-color:#eeeeee;color:black;">rel-tag</td>
       <td style="background-color:darkorange;color:black;font-weight:bold;">Title</td>
<atom:subtitle></td> <td><itunes:subtitle>
<title></td> <td><media:title>
<title></td> <td>nothing</td> <td><title></td> <td style="background-color:#eeeeee;color:black;">
       <td colspan="7"> </td>
       <td style="background-color:darkorange;color:black;font-weight:bold;">Show Concept</td>
<td></td> <td></td> <td></td>
       <td>A M3U file.</td>
       <td style="background-color:#eeeeee;color:black;">need a new microformat</td>
       <td style="background-color:darkorange;color:black;font-weight:bold;">Episode Concept</td>
<td></td> <td></td> <td></td>
       <td>A single URL line.</td>
       <td style="background-color:#eeeeee;color:black;">need a new microformat</td>
       <td style="background-color:darkorange;color:black;font-weight:bold;">Media Concept</td>
       <td>Simply the inclusion of a URL on a line.</td>
       <td style="background-color:#eeeeee;color:black;"><img> 
<a href="">
<embed> </td> </tr>




Offline Media

Printed Publications (books/magazines)



Container Formats

The purpose of container formats is to allow the muxing of multiple codecs into a single file or stream. For example, if you want audio, video, and text (subtitles) combined into a single stream.

The purpose of the muxing is for synchronization and so that you can stream the file and view it without having to jump around -- seek -- in the file.

Container formats include:

Container Format Comparison Table

Aspect Atom iTunes RSS Media RSS M3U</td> <th>RSS 2.0
<th>Microformat?</th> <tr> <td style="background-color:darkorange;color:black;font-weight:bold;">Allows Audio</td> <td>Yes</td> <td>Yes</td> <td>Yes</td> <td>Yes</td> <td style="background-color:#eeeeee;color:black;"></td> </tr> <tr> <td style="background-color:darkorange;color:black;font-weight:bold;">Allows Video</td> <td>Yes</td> <td>Yes</td> <td>Yes</td> <td>Yes</td> <td style="background-color:#eeeeee;color:black;"></td> </tr> <tr> <td style="background-color:darkorange;color:black;font-weight:bold;">Allows Text</td> <td></td> <td></td> <td>Yes</td> <td>Yes</td> <td style="background-color:#eeeeee;color:black;"></td> </tr> <tr> <td style="background-color:darkorange;color:black;font-weight:bold;">Error Detection</td> <td></td> <td></td> <td>Yes</td> <td></td> <td style="background-color:#eeeeee;color:black;"></td> </tr> </table>

Notes for Microformats

One of the problems with container formats is that it is often difficult and sometimes impossible to know the disposition of what they contain ahead of time (without reading the file).

For example, Ogg files use the MIME type application/ogg and generally use the extension .ogg. With only these 2 pieces of information, you cannot tell whether such an Ogg file contains video data or not.

There is room for a microformat to help with this. Perhaps something like:

<a class="moving-image" type="application/ogg" href="my.ogg">...</a>

Although, this can be done in other ways too. For example, using disposition hinting one could do something like:

<a type="application/ogg;disposition-type:moving-image" href="my.ogg">...</a>

Anothing thing for any Microformat to consider is that it may be the case that the data files that are muxed in the container format may also be offered in non-muxed forms. This is important when alternatives are offered.

Audio Formats

Audio formats include:

Audio Format Comparison Table

Aspect AVI MPEG Ogg</td> <th>QuickTime
<th>Vorbis</th> <th>WMA</th> <th>Microformat?</th> <tr> <td style="background-color:darkorange;color:black;font-weight:bold;">Lossless</td> <td>No</td> <td>No</td> <td>Yes</td> <td>Yes</td> <td>No</td> <td></td> <td style="background-color:#eeeeee;color:black;"></td> </tr> <tr> <td style="background-color:darkorange;color:black;font-weight:bold;">Lossy</td> <td>Yes</td> <td>Yes</td> <td>No</td> <td>No</td> <td>Yes</td> <td>Yes</td> <td style="background-color:#eeeeee;color:black;"></td> </tr> <tr> <td style="background-color:darkorange;color:black;font-weight:bold;">Streamable</td> <td>Yes</td> <td>Yes</td> <td></td> <td>Yes</td> <td>Yes</td> <td>Yes</td> <td style="background-color:#eeeeee;color:black;"></td> </tr> </table>

Notes for Microformats

Playing Formats

Playing formats include:

Playing Format Comparison Table

Aspect AAC MP3 PCM WAV</td> <th>Speex
<th>Microformat?</th> <tr> <td style="background-color:darkorange;color:black;font-weight:bold;">Alternatives Playing</td> <td></td> <td>nothing</td> <td></td> <td></td> <td><smil:switch></td> <td></td> <td></td> <td>nothing</td> <td><media:group></td> <td>nothing</td> <td>nothing</td> <td style="background-color:#eeeeee;color:black;">need a new microformat</td> </tr> <tr> <td style="background-color:darkorange;color:black;font-weight:bold;">Parallel Playing</td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td></td> <td style="background-color:#eeeeee;color:black;">need a new microformat</td> </tr> <tr> <td style="background-color:darkorange;color:black;font-weight:bold;">Sequence Playing</td> <td></td> <td>if you consider the Atom file a show, then nothing. if you consider the Atom file an episode, then the list of <atom:entry>'s provides a sequence.</td> <td></td> <td></td> <td><smil:seq></td> <td></td> <td></td> <td>if you consider the RSS file a show, then nothing. if you consider the RSS file an episode, then the list of <item>'s provides a sequence.</td> <td>if you consider the RSS file a show, then nothing. if you consider the RSS file an episode, then the list of <item>'s provides a sequence.</td> <td>if you consider the M3U file a show, then nothing. if you consider the M3U file an episode, then the URL lines provide a sequence.</td> <td>if you consider the RSS file a show, then nothing. if you consider the RSS file an episode, then the list of <item>'s provides a sequence.</td> <td style="background-color:#eeeeee;color:black;">need a new microformat</td> </tr> <tr> <td style="background-color:darkorange;color:black;font-weight:bold;">Pre-Fetching</td> <td></td> <td><link rel="enclosure" href="..." /></td> <td></td>
       <td><link rel="enclosure" href="..." /></td>
       <td>The M3U format is just list of URL's, with each URL on its own line.  Pre-Fetching would be accomplished by just added a URL to the list.</td>
       <td style="background-color:#eeeeee;color:black;">rel-enclosure</td>


Raster Graphic Formats

Raster graphic formats include:

Vector Graphic Formats

Vector graphic formats include:

Formats & Protocols


AAC (Advanced Audio Coding) is a lossy audio format. Like MP3, AAC is part of the MPEG standard. Since April 2003, AAC has become an integral part of Apple's iPod and iTunes products. This association between AAC and Apple has become so strong among some that AAC is also sometimes call Apple Audio Codec.



ASF is an Audio/Video format. ASF files that contain only audio data are typically called WMA files.



Atom is a XML-based syndication format that was developed by certain members of the RSS community.



Atom+SMIL is Atom with SMIL used in the <atom:content>.

(This was originally used by Charles Iliya Krempeaux for "Internet TV". Also see Atomic RSS+SMIL)

Atomic RSS

Atomic RSS is a syndication format that is RSS with Atom used as an extension module.



Atomic RSS+SMIL is Atomic RSS with SMIL use in the <atom:content>.

(This was originally used by Charles Iliya Krempeaux for "Internet TV".)


AVI is a container format for Audio/Video formats.



B4S is a playlist format.



BitTorrent is a P2P protocol.


Creative Commons RDF




Extended M3U



Free Lossless Audio Codec (FLAC)


GIF is a raster graphics format and a movie format.





iTunes Library


iTunes RSS



JPEG is a raster graphics format.




KPL is a playlist format.



M3U is a playlist format.




Media RSS

Media RSS is a syndication format that is RSS with the addition of the Media RSS Module.


Matroska MKV/MKA are video and audio containers, respectively.


MNG is a Video format.


MP3 is an Audio format.


ASF is an Audio/Video format.




Ogg is a media container format.



PLS is a playlist format.



RAM is a playlist format.


RSS 2.0

RSS 2.0 is the defacto standard syndication format.









SVG is a vector graphics format.


Theora is an Audio/Video format/



Vorbis is an Audio format.



WAX is an SGML-based playlist for that looks exactly like ASX and WVX, except that it can only reference to ASF or WMA, but NOT to WMV files.



WMA is an Audio format.



WMV is an Audio/Video format.



WVX is an SGML-based playlist format that looks exactly like ASX and WAX, except that it can reference ASF, WMA, and WMV media files.



See Also

media-metadata-examples was last modified: Wednesday, December 31st, 1969
Aspect ASX Atom Atom+SMIL Atomic RSS Atomic RSS+SMIL Extended M3U HTML+Time iTunes RSS Media RSS M3U</td> <th>RSS 2.0