RE: Metadata access

> So, I guess, your API will be useful for other applications, but not for Web UAs
But there are MANY OTHER types of UAs that MIGHT want/need to access that information.  

A good example being an EPUB3-based UA.  Since EPUB3 is based on HTML5 and will allow for scripting (to some degree), it would seem that an API for metadata access to media would be a appropriate.

Another use case is authoring tools, where some (all?) of the tool is, itself, written in JavaScript. In order for it to do its job, it will need access to the metadata.


-----Original Message-----
From: Silvia Pfeiffer [] 
Sent: Tuesday, April 26, 2011 4:30 AM
To: Joakim Söderberg
Cc:;; Leonard Rosenthol;;;
Subject: Re: Metadata access

2011/4/26 Joakim Söderberg <>:
> Dear all,
> Recently the Ontology for Media Resources and API has been discussed in your forum. On behalf of the Media Annotations WG, I would like to share our response below.
> We are following the discussion on access to media metadata with high interest, as this problem is central to the scope of the Media Annotations WG. From your discussion, it seems that you are aiming for a simple and flexible solution. This is also what MAWG has in mind, and thus we would like to understand better which of your requirements are not satisfactorily addressed by the MAWG specs.
> First of all, as some of you probably know, MAWG is working on two specs: an Ontology for Media Resources and an API for Media Resources. The ontology is defined informally as a set of basic properties of media items, together with mapping to a number of standards and formats. We are convinced that this approach (what Danny called "upper ontology") is necessary to establish interoperability, i.e., enable the use of the metadata without knowing about the specifics of the source format. Note that the metadata properties defined by MAWG are not at all a required set of properties to be provided - depending on the source format only few of them may be available. In addition, the ontology is defined formally as an RDF ontology. The ontology can thus be used without the API, e.g., included in HTML using RDFa.
> The API builds on top on the ontology, providing a way of querying the set of properties in a homogeneous way independent of the source formats. It seems that most of the criticism in the your discussion actually targets the API, i.e., the fact that getMediaProperty is called with a set of parameters and the complexity of the return structure. Actually, our first draft was more like the .language example in Danny's post, but we got the feedback that (i) browser manufacturers would prefer an API with as few functions as possible and (ii) web developers would rather get a result list and iterate through the results of the different properties than calling distinct functions for each of them (Silvia attended this discussion back at TPAC 2009).

Indeed. And my continuous feedback was that IMHO a name-value-pair
interface would be the most complexity that would be required. I don't
like the complexity of the return structures - never have.

> If an application is just interested by the value of the property, just accessing the .value of the result and ignoring the other attributes would do. Also, implementing a simpler flavor of the API that just offers a function to get a property without parameters (except for the property name, they are all optional) and returns just the value would be quite straight forward.
> We are of course interested that the MAWG specs are suitable for use in HTML, thus we would like to understand which are the obstacles for using in the view of the HTML WG in order to consider appropriate adjustments to our specs.

After the recent discussions, I am not sure any more that we do in
fact need an API in the browser to extract video/audio/image metadata.
Most such uses would indeed be satisfied server-side. In particular
since for cross-site resources, it is not even possible to extract the
metadata for security reasons. So, I guess, your API will be useful
for other applications, but not for Web UAs.


Received on Tuesday, 26 April 2011 12:31:10 UTC