Article category: Tools
PBCore 1.3 to 2.0 translator ready for review
Dave Rice, with support of the Dance Heritage Coalition’s Secure Media Network managed by Bay Area Video Coalition, has created a PBCore 1.3 to 2.0 XSL translator tool. For valid input PBCore 1.3 records, the tool generates a valid 2.0 records as the output.
This process revealed some difficult mapping challenges that have yet to be fully resolved. The main issue is the move away from elements like genreAuthorityUsed to the @source attribute. At first glance, it makes sense that genreAuthorityUsed would become pbcoreGenre source=“authority” in PBCore 2.0. But wait, there was an @source attribute for genreAuthorityUsed! So if the value of genreAuthorityUsed is now 2.0 pbcoreGenre source=“authority”, what happens to 1.3 genreAuthorityUsed source=“name”? It’s lost!
Given that the definition of @source in PBCore 2.0 is “Attribute source provides the name of the authority used to declare data value of the element,” for this and a few other elements, it appears to be impossible to create a sematically lossless mapping.
We have posted the translator to github for public review. You will see in the header comments of the XSL a number of issues that have come up in the mapping, including the genreAuthorityUsed problem. Issues have been identified for mapping 1.3 titleType, descriptionType, and subjectAuthorityUsed.
You can find the translator here: https://github.com/avpreserve/random-pbcore-metadata-translators/blob/master/13_to_Pbcore2.xsl
We would love to get feedback on this from the PBCore community!
Metadata as media
(As always, I speak only for myself as a media producer and archivist.)
I attended the panel discussion on PBCore at the recent Open Video Conference, and was struck by something that should have been obvious. Those of us pushing development of PBCore have failed to clarify one basic thing: What is PBCore for? I’ve been to workshops and sessions on PBCore over the past six years and have been on metadata panels at the AMIA Conference, the PBS Tech Conference, NETA, and iMA. We often focused on explaining the PBCore elements and why they are useful for cataloging media assets. But at the OVC, the question was raised “Why do we need PBCore to catalog our stuff if we already have a good media database?” The question reveals a conflation of two distinct things: having a media database, and being able to easily interoperate with other databases.
Most of us producers are not, after all, experts in database administration, XML, or programming in general. During the American Archive Pilot Project I talked with people at other public TV and radio stations trying to “use” PBCore without adequate tools, and without understanding why they had to use it in the first place. If the answer is “you need a data model for cataloging your media assets,” there are many other catalog and data models. A better answer is you use PBCore to create shareable metadata. If you have a media collection and you want to combine it with other collections, PBCore provides a machine-readable translation layer between systems.
Some people have asked why use PBCore instead of something simpler like RSS or Atom? I think that’s a really good question.
You can stuff lots of descriptive metadata into RSS or Atom. Their schemas are understood by a wide range of applications, and they are simple to implement. At the other end of the spectrum, MPEG7 provides an exhaustive schema for describing multimedia content…emphasis on the word “exhaustive.”
PBCore is somewhere between the simplicity of RSS and the verbose complexity of MPEG7. It provides a level of detail useful to media archives, without being ridiculous to implement. It’s sort of a “just right” format, allowing simple producers like me to share a great deal of useful metadata about my media assets with any system that can parse PBCore XML.
So in the example of the American Archive Pilot Project, my station used a MySQL-based Content Management System to catalog several hundred media assets. (See my earlier post for details.) With the CMS I could render web pages and an RSS feed, plus PBCore records for each asset. The AAPP project portal could just ingest my PBCore records into the national AAPP database, getting much more detail on each asset than would be provided by RSS.
Audio and video are media that connect human beings. RSS and PBCore are media that connect machines.
You can have a fantastic media database not designed around the PBCore standard. You can create a PBCore representation of that database by exporting XML records based on the PBCore schema. You can create other representations of your data based on RSS, JSON, and other formats. An example of this is the NPR API query generator, which provides multiple output format options including RSS, Atom, HTML, and NPR’s proprietary (and wonderfully detailed and useful) NPRML.
Given the flexibility of today’s tools, we can generate multiple different representations of our media database for different purposes. So what’s the use-case scenario with PBCore? With RSS or Atom, we know that many other systems can ingest our data. What systems can ingest PBCore?
A growing number of systems that speak PBCore have the word “archive” in them. Importantly, I hear the American Archive would adopt PBCore as a primary means for ingesting metadata from contributor collections. This would allow each contributor to use whatever database best suits their local needs, as long as each local system can create shareable metadata in the PBCore format.
PBCore won’t be used by media consumers and consumer-level applications like iTunes. PBCore will be used by media archives and the systems that contribute to them. That’s what PBCore is for.
Making PBCore End User Friendly
Sites using the current beta of the module can now export a node as XML as well as dump of their site specific configurations making it easier to compare how organizations are implementing PBCore in practice.
The PBCore module for Drupal is still rough around the edges, but the structure is now there for anyone with even basic PHP skills to contribute.
PBCore in Drupal Supports Customizing Elements End Users See
Don’t look now, but the PBCore module I added to Drupal.org is now #3 in results for pbcore on Google bumping pbcoreresources.org to #4. That module wasn’t intended to be the definitive PBCore module for Drupal, but a conversation started to help locate users and developers with similar needs. This approach of releasing modules that aren’t ready for users and developing in public has worked really well for the MERCI (Manage Equipment Reservations, Checkout and Inventory) and Creative Commons modules. I’m hoping to find additional Drupal users and developers interested in PBCore so I’m not writing code that only serves our needs… which is basically all the module does so far.
The new PBCore module does 4 things:
1. Populates tables with full list of items genre, rating and language elements that adhere to the PBCore standard. This creates a shared vocabulary required to facilitate sharing content.
2. Allow a each site to enable/disable items within an element to meet there local needs
3. Allow a each site to customize the description of items within an element to meet there local needs
4. Provide functions that can be added to CCK fields to populate the select list with the enabled items. Users see the customized descriptions, but the value stored in the database is the standard PBCore value.
After talking to Andrew Feigenson and Ed Leonard about PBcore 2.0, I’m thinking of adding a 5th feature…
5. An option to report the status and customizations of PBCore items to a centralize location.
I’ve posted a detailed explanation about why we’re customizing PBCore terms, but it can be summed up by the Gay/lesbian genre item. We customize that to Gender/Sexuality everywhere a user would see it, but store the actual PBCore term in the database. This works well to appease our producers creating content in that genre who find limiting the description of their work to a Gay/lesbian insulting. It can’t imagine how would argue that Gay/lesbian shouldn’t be deprecated and Gender/Sexuality added, but in cases where the change is less obvious having data from sites using the PBCore module would be helpful. If hundreds of sites are customizing Gay/lesbian and no one is enabling French, that would be a logical place to start revising genre.
Any thoughts on the approach of allowing customizations? Sharing status and customizations of items?
Generating PBCore Instantiation data
To follow up on the comments in Jack’s last post I posted XSL and workflow information that can translate the XML output of MediaInfo and turn it into a PBCore instantiation element (not the whole record, just the technical side of PBCore).
The XSL and a drag-and-drop Mac application of it are at http://www.avpreserve.com/pbcore-instantiationizer/.
An article about the development and related issues is at http://www.avpreserve.com/pbcore-instantiationizer/pbcore-instantiationizing/.
Overall transforming many of the metadata fields from MediaInfo’s output to PBCore is fairly straightforward (mediainfo:overallbitrate -> pbcore:formatdatarate, mediainfo:filesize -> pbcore:formatFileSize), but fields such as formatTracks and formatChannelConfigurations are a bit of a challenge to automate.
Any feedback on this is appreciated.
Use of PBCore in the American Archive Pilot Project
Illinois Public Media was one of the 20-some public TV and Radio stations in the CPB-funded American Archive Pilot Project. The AAPP required participating stations to use PBCore as a metadata format, at least in principle. I decided to push implementation of PBCore in my AAPP content collection as far as possible using the toolset I used on a previous video archive project (Prairiefire on WILL-TV).
This toolset is based on the website Content Management System called ExpressionEngine, which makes setting up a particular database structure rather easy. I set up the database structure based on PBCore elements, with controlled vocabularies reflecting the AAPP taxonomy and suggested PBCore picklists. I then created xml templates in ExpressionEngine to render my AAPP collection metadata as valid PBCore records. I then went one step further, following discussions with Dan Jacobson and David Rice, and created a PBCoreCollection wrapper containing all 235 of the PBCore item records (each as a PBCoreDescriptionDocument) in my collection. The national portal for the AAPP, being developed and hosted at Oregon Public Broadcasting, was able to simply ingest the PBCoreCollection, demonstrating the viability of this approach to aggregating a large collection from multiple content sources.
This article details the methods used to accomplish this in ExpressionEngine. Similar methods could be used in Drupal, which we’re working on now.
In ExpressionEngine, one can easily define a set of fields to input data. For example a blog would need fields for a Title, a Body, and maybe a separate Image upload field along with a label field for the image (so you could add a caption or an alt tag at least). When you create these fields, you also pick a field type: textarea, dropdown list, file upload, etc. EE has several pre-defined field types and there are dozens of addons from third-party developers to add more.
One of the really great EE addons is FieldFrame, developed by Brandon Kelly. FieldFrame is a framework for developing new EE fieldtypes, and there are a bunch of good ones. The most important for our EE PBCore tool is called FF Matrix, which allows you to bundle several fields in a “row” of related data.
Here’s the way you create an FF Matrix field in ExpressionEngine:
With an FF Matrix field, you can do things like enter a PBCore subject tied to a subjectAuthorityUsed, or title along with titleType. Since most of PBCore elements are wrapped in pairs like this, it’s important to solve this in a straightforward way. With FF Matrix, you can enter as many linked pairs as needed, for example with many subject terms you want to have each term wrapped individually along with its corresponding subjectAuthorityUsed.
Here’s the PBCore Item entry form showing a number of such fields (but not the entire form which is a bit long):
We used this form to enter all the Intellectual Content and Intellectual Property metadata for each media item. Nothing in this Item form relates to the physical or digital Instantiation of that item. For that we used a different form with fields and fieldtypes defined specifically for Instantiation metadata. Here’s the fun part: One of the fieldtypes in the Instantiation form is a “relationship” field, which allows you to select an existing Item to which the Instantiation should be linked. So if you have several Instantations, like a wav file, and mp3, and an analog tape of the same Item, you create Instantiations records for each and link them to the Item.
This proved to be a quick and effective way to link multiple Instantiations with a single Item.
You might be able to see that some of the fields are blank, and their instructions say things like “formatDataRate - If MP3 file don’t enter anything.” Lots of the technical metadata like formatFileSize etc could be extracted automatically from the digital files by the system, so we don’t have to enter that data by hand. EE has a nice addon called MP3 Info + that does most of that work.
David Rice has developed better methods of reading file metadata into his PBCore Records Repository using a free tool called MediaInfo. We should get him to write more about that, as it’s work that could be leveraged and used in different systems I’m sure.
After entering all the metadata for our collection using the two forms above, the payoff is in rendering everything in usable form. Since it’s all in the CMS, it’s a simple matter to make a website displaying everything, and providing media players for the files. In fact we did this initially for the catalogers so they could work remotely and listen to and view the audio and video files.
This site was intended for that purpose: http://will.illinois.edu/metadata/aapp-inventory-all/.
As the catalogers added descriptive metadata, the site became much more interesting! We added as much descriptive stuff as possible, even full tape logs for some of the World War II oral history interviews. I chose not to display all that metadata on the web page, but it is rendered in the PBCore XML record for each item.
For example, here is a web page for one such interview: http://will.illinois.edu/metadata/aapp-inventory-all/WWII_oral_history_WesleyMatthews2008-02-21
And here is the PBCore record for the same interview: http://will.illinois.edu/metadata/pbcoreAAPP/wwii_oral_history_wesleymatthews2008-02-21
The way these are rendered is simple: an html template for the web page, and an xml template for the PBCore record, both drawing from the same database. In ExpressionEngine this is very simple to set up, and once it’s set up, you’re done.
Finally, as mentioned above I chose to try implementing the idea of a PBCoreCollection wrapper element, enclosing all 235 of the individual PBCoreDescriptionDocuments in my AAPP media collection. This is, of course, not a valid wrapper element in any PBCore version to date. This experience suggests that it should be. OPB was able to ingest my entire collection in a single gulp from this URL. Other stations in the AAPP were able to export using the same method (PBcoreCollection) even though they have different local systems. The ability to render a PBCoreCollection is all that matters, not the underlying system that rendered it.
I hope this is useful to anyone who might be looking for systems for cataloging media assets and doing various things with them like creating websites and PBCore records or whatever metadata format. I used ExpressionEngine but the basic method would work with Drupal, Plone, and other CMSs and frameworks. Most importantly, regardless of the system used, I hope this demonstration of the power of PBCoreCollection informs the development of PBCore 2.0, which is now in progress.
PBCore Tool Quest
Back in 2005 I became somewhat obsessed with cataloging media on the job here at WILL Public Media. As the website manager, people would do things like hand me a videotape and say "can you put this on the web?" But what's on the tape? It became clear producers had no clue about the importance of recording actual information about their productions. Meanwhile I started learning about metadata and controlled vocabularies, and some of the cool things we could do with structured data on the web. This lead me directly to PBCore as the theoretical metadata standard for public broadcasting and beyond. If producers and stations could create PBCore-compliant XML records for their content, we could develop tools for automated exchange of deep information about media, and the media essence as well.
But we can't do much if nobody catalogs their stuff. So the question became what tools to use? Working with a graduate assistant from Library Science here at Illinois (the great Jimi Jones!), we embarked on a PBCore tool quest.
As we began digitizing and cataloging 15 years worth of the WILL-TV program Prairie Fire, we wanted a tool that would spit out PBCore XML. Jimi and I tried the free MIC database tool, and sorry MIC, but at least back then it was (ahem) a work in progress. We were somehow unaware of the free PBCore File Maker Pro database, which I guess is pretty OK, and if you've used it feel free to comment. So we tried things like using the open-source Greenstone repository software, which I wouldn't recommend for video unless you like migraines. We even started hand-coding XML using Oxygen, which is enough to make your eyes bleed after a while.
Eventually though I started thinking like a web developer, which after all is my job at WILL. We're using a Content Management System to "catalog" media for web pages. We use the same CMS database to output RSS feeds, which is a flavor of XML. Why not add a PBCore flavor of XML? So I added a bunch of fields reflecting the PBCore elements, and asked our producers to provide...a little more detail when adding their content to the website. The result was the new Prairie Fire website, released in January 2007, featuring among other things PBCore records of every episode and segment for every program over the past 15 years.
Since then we've continued to refine our little home-grown CMS-based cataloging tool. Here are a couple of screen shots that kinda show how it works.
This is a form for entering descriptive and administrative metadata based on the PBCore elements. Mary Miller from the Peabody Archives worked with me on this, and she likes to call it the "Platonic Record" of the media object, as it is purely the intellectual record.
This is the input form for the PBCore Instantiation, which is the actual physical or digital object being cataloged. The Instantiation is then linked to the Platonic Record. The result is a complete PBCore-compliant record which looks exactly like this. (If you hit this with Safari, do a View Source to see the XML.) So our CMS can take metadata directly from the Producer to create web pages, RSS feeds/podcasts, and PBCore XML. Why not?
But here we are now in (almost) 2009, and we need more than my cute little CMS solution. Which is why I'm so excited to see the work of Dave Rice and Mike Castleman, who created a much better online system called PBCore Vermicelli. This is a Ruby app that does everything I had set up, plus a lot more. So I wanted to call more attention to it, and suggest that it's a good starting point for much more powerful things to come. What things? I have a few ideas, but I'll pause here for now. Let's talk about it.
WNET PBCore Record Repository project