Tuesday, 6 May 2014

Multimedia in GBIF

We are happy to announce another long awaited improvement to the GBIF portal. Our portal test environment now shows multimedia items and their metadata associated with occurrences. As of today we have nearly 700 thousand occurrences with multimedia indexed. Based on the Dublin Core type vocabulary we distinguish between images, videos and sound files. As has been requested by many people the media type is available as a new filter in the occurrence search and subsequently in downloads. For example you can now easily find all audio recordings of birds.

UAM:Mamm:11470 - Eumetopias jubatus - skull
If you follow to the details page of any of those records you can see that sound files show up as simple links to the media file. We do the same for video files and currently do not have plans to embed any media player in our portal. This is different from images which are shown in a dedicated gallery you might have encountered for species pages before already. On the left you can see an example of a skull specimen with multiple images.

When requested for the first time, GBIF transiently caches the original images and processes them into various standard sizes and formats suitable for the use in the portal.

Publishing multimedia metadata

GBIF indexes multimedia metadata published in different ways within the GBIF network. From a simple URL given as an additional field in Darwin Core via multiple items expressed as ABCD XML or a dedicated multimedia extension in Darwin Core archives the difference usually is in metadata expressiveness.

Simple Darwin Core

Melocactus intortus record in iNaturalist
Whenever we spot the term dwc:associatedMedia in xml or Darwin Core archives as part of the a simple, flat occurrence record we try to extract URLs to media items. As the term officially allows for concatenated lists of URLs we try common delimiters such as comma, semicolon or the pipe symbols. An example of multiple, concatenated image URLs can be found in iNaturalist:

As you can see on the right every extracted link is regarded as a separate media item as there is no standard way to detect that 2 links refer to the same item. In the example above every image has a link to the actual image file and another one to the respective html page where it's metadata is presented. There is also no way to specify additional metadata about a link. As a consequence all images based on dwc:associatedMedia do not have a title, license or any further information. The verbatim data for that record before we extract image links can be seen here: http://www.gbif-uat.org/occurrence/891030819/verbatim

Darwin Core archive multimedia extension

By having a dedicated extension for media items many media items per core occurrence record can be published in a structured way. This is the GBIF recommended way to publish multimedia as it gives you most control over your metadata. Note that the same extension can also be used to publish multimedia for species in checklist datasets. This extension, based entirely on existing Dublin Core terms, allows you to specify the following information about a media item, all of which will make it into the GBIF portal if provided:

  •  dc:type, the kind of media item based on the DCMI Type Vocabulary:  StillImage, MovingImage or Sound
  •  dc:format, MIME type of the multimedia object's format 
  •  dc:identifier, the public URL that identifies and locates the media file directly, not the html page it might be shown on
  •  dc:references, the URL of an html webpage that shows the media item or its metadata. It is recommended to provide this url even if a media file exists as it will be used for linking out
  •  dc:title, the media items title
  •  dc:description, a textual description of the content of the media item
  •  dc:created, the date and time this media item was taken
  •  dc:creator, the person that took the image, recorded the video or sound
  •  dc:contributor, any contributor in addition to the creator that helped in recording the media item
  •  dc:publisher, the name of an entity responsible for making the image available
  •  dc:audience, a class or description for whom the image is intended or useful
  •  dc:source, a reference to the source the media item was derived or taken from. For example a book from which an image was scanned or the original provider of a photo/graphic, such as photography agencies
  •  dc:license, license for this media object. If possible declare it as CC0 to ensure greatest use
  •  dc:rightsHolder, the person or organization owning or managing rights over the media item

Access to Biological Collections Data

As usual we also provide a binding from the TDWG ABCD standard (versions 1.2 and 2.06) mostly used with the BioCASE software.

From ABCD 1.2 we extract media information based on the UnitDigitalImage subelements. In particular information about the file URL (ImageURI), the description (Comment) and the license (TermsOfUse).

In ABCD 2.06 we use the unit MultiMediaObject subelements instead. Here there are distinct file and webpage URLs (FileURI, ProductURI), the description (Comment),  the license (License/Text, TermsOfUseStatements) and also an indication of the mime type (Format). The bird sound example from above comes in as ABCD 2.06 via the Animal Sound Archive dataset. You can see the original details of that ABCD record in it's raw XML fragment. There are also fossil images available through ABCD.

Missing from both ABCD versions is a media title, creator and created element.

Media type interpretation

We derive the media type from either an explicitly given dc:type, the mime type found in dc:format or the media file suffix. In the case of dwc:associatedMedia found in simple Darwin Core we can only rely on the file URL to interpret the kind of media item. If that URL is pointing to some html page instead of an actual static media file with a wellknown suffix the media type remains unknown.

Production deployment

We hope you like this new feature and we are eager to get this out into production within the next weeks. This is the first iteration of this work, and like all GBIF developments we welcome any feedback.


  1. Interesting discussion on implementing this for the Canadensys network: https://groups.google.com/forum/#!topic/canadensys/__oECtImVqs

  2. Note that Darwin Core metadata can be directly imbedded in multimedia files as XMP. Exiftool implemented this in early 2013 and it will be implemented in exiv2 starting with version 0.25.