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Uses cases for the Media Gallery API

From: Francois Daoust <fd@w3.org>
Date: Fri, 03 Dec 2010 16:27:44 +0100
Message-ID: <4CF90C70.6000404@w3.org>
To: public-device-apis@w3.org
Hello DAP working group,

Dom took ACTION-296 during DAP F2F in Lyon to provide use cases for the media gallery API. Dom and I have been exchanging ideas about that, which lead to the following list of use cases, starting with the ones already listed in the gallery draft:
  http://dev.w3.org/2009/dap/gallery/#use-cases-and-requirements

For each use case, I've detailed a short user story, highlighted what would be needed, and added one or more comments.

HTH,
Francois.


=========
Use cases
=========


Similar content recommendation
-----
User story
--
See use case 1 in gallery draft:
http://dev.w3.org/2009/dap/gallery/#uc1

What's needed
--
- Media gallery API used as a way to filter out the user's collection based on specific terms

Comment
--
While doable at a lower level through the FileSystem API, having to parse thousands of pictures metadata to filter out the ones that match specific terms is likely to take way too much time for something as simple as a picture submission page. The possibility to maintain an offline local database to speed up further submissions would also be an overkill: there should be only one such database, maintained at the browser (or OS) level, not one per Web site that needs the info.



Access to user categorization
-----
User story
--
See use case 2 in gallery draft:
http://dev.w3.org/2009/dap/gallery/#uc2
(note the use case can be directly adapted to playlists for songs)

What's needed
--
- Access to user-generated metadata to filter out content



Music player
-----
User story
--
Clementine goes to http://example.com/musicplayer and grants the Web site access to her local music repository. The music player lets her browse her library, visualize metadata available (artworks, authors, interpreters), and play songs.

What's needed
--
- The music player needs access to specific content metadata
- Metadata should include author, actor, song type, as well as lyrics or artwork.
- Access to metadata should be high-level. For instance, the artwork of an album is basic stuff and would rather be expose in an "artwork" property, but the Ontology for Media Resources seems to leave it to the generic "ma:relation" property:
    http://www.w3.org/TR/mediaont-10/#core-property-definitions

Comment
--
The use case is obvious for the media gallery API. It will help identify a common list of properties that need to be exposed through the API.



Music manager
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User story
--
Clementine goes to http://example.com/musicmanager and grants the Web site access to her local music repository. The music manager includes a music player as above. Additionally, it lets her manage playlists, maintain her library (add/remove songs, categorize, edit metadata, etc), and sync up with a portable music player with limited storage.

What's needed
--
- same as above for music player part.
- the addition of a "manager" side means a fine-grained access to metadata. While the player could make do with basic properties, a manager will need more precise information. For instance, the possibility to sync up with an external portable music aplayer device probably means that the music player needs to have access to the underlying file size and its encoding parameters.
- ideally, the music manager should also be able to access and maintain statistics (usage statistics) or user ranking to organize the user collection.
- read/write rights are needed, but these rights should be restricted to the media gallery, and can be further restricted (e.g. the application could only be allowed to manage playlists and not be allowed to update content metadata).

Comment
--
The use case is the most complete use case for the media gallery API.
It is the most fertile use case for the API since it will push for the inclusion of more properties that the manager can take advantage of.
While read/write rights are needed to create a complete music manager application, a music manager may still provide useful features with very limited rights, possibly restricted to access to an offline storage (although this would mean the information cannot be exposed back to the media gallery API and "shared" with other application or Web sites).



Cloud-based gallery
-----
User story
--
Clementine manages her pictures collection online on http://example.com/galleriedesglaces/ and wants to let http://example.com/blah access this collection in the context of e.g. the "Access to user categorization" use case already mentioned.

What's needed
--
- The media gallery API as a whole!

Comment
--
This use case highlights the need for a media gallery API as a whole: while other use cases could be emulated using the FileSystem API, it is quite unlikely that online services will expose something similar to the FileSystem API. They may expose a more focused media gallery API to let users access and manage their media content.

In short, the media gallery API can easily be mapped to a cloud-based media gallery, while the FileSystem API is restricted to "local" storage (where "local" may include remote storage, but not online services that provide some other specific functionality).



Multimedia shows
-----
User story 1
--
Ten years after the end of her studies, Clementine invites her old schoolmates to meet for a "good old times" party at home. She has a collection of pictures from that period, tagged with appropriate metadata (caption, people, annotations, places) and would like to run some animation on her connected TV in the background. She browses http://example.com/slideshow and points it out to its collection of pictures. She also makes sure the Web site has access to her music repository.

The Web site uses the media gallery API to extract relevant metadata from the pictures, and order the slideshow consequently. It also searches through Clementine's music collections for music that would best match the pictures. It creates a personalized slideshow out of it.

User story 2
--
Clementine is a 4-year-old little girl who wants to hear a great story before she goes to bed. Her father uses a tablet and browses http://example.com/childrenstories/
The Web site proposes to personalize stories and asks Clementine's father for a few keywords (name of an animal, name of the child, a place or address, etc)
The Web site personalizes the story based on the father's responses and adds illustrations taken from the pictures gallery that match these responses as well as keywords from the story itself.

What's needed
--
- Need to be able to search for specific terms in pictures/songs/movies metadata.
- Searchable metadata should include author, actor, song type, more generic metadata (e.g. persons that appear on a picture), history of a picture (time and location), as well as lyrics (or "subtitles" for movies).

Comment
--
Animoto is a good example of what the service could look like:
   http://animoto.com/
The media gallery API would make it easier to do it using regular Web technologies.



Recommendation engine
-----
User story
--
Clementine wants to buy an electronic book on http://example.com/ebooks but does not know what to select in the myriad of books available. The Web sites browses her electronic books collection and highlights a selection of books that have something in common with the ones she already has in her collection (same authors, similar theme, same edition, etc).

What's needed
--
- Same as above: some ability to search for specific terms in books collection.

Comment
--
The user's local books collection may not adequately represent her taste, but ranking could be taken into account by some other means (left to the search engine) or exposed through the API.

The media gallery service enables lightweight suggestion mechanisms and personalization when a service does not know anything about the user.



Personalized user experience
-----
User story
--
Clementine goes to online magazine http://example.com/magazine/
There she reads short novels, articles on famous artists, fashion, sports, culture, cinema, etc.

The Web site provides contextual information to Clementine's music player through the media gallery API. This contextual information is based on keywords associated with the page the user is currently looking at. Clementine's music player reacts to the contextual information by selecting next song based on the provided context. Thus Clementine gets to read articles while listening to contextual music taken out from her own collection.

What's needed
--
- Need to be able to provide contextual information: keywords and/or possibly qualified information such an author, an artist, a place, a time, ...

Comment
--
In the other use cases, the media gallery API exposes information to a Web page. This use case highlights how the media gallery API could, in turn, let a Web page expose metadata to the user's media gallery.

The main benefit of this approach is that it makes it possible and easy for a Web page to provide a more immersive experience without having to access privacy-sensitive information.

Obviously, the information could be exposed by means of, say, RDFa, without requiring an API. The API would simply make the binding more explicit.



==========
Conclusion
==========

Main benefits of the media gallery API:
- high-level access to metadata (instead of having to ship hundreds of Kb of JavaScript that handle things at a lower level), to allow for the implementation of a complete music player and manager, and to make cloud-based media galleriespossible.
- a standard and efficient search-oriented API to extract content from user's media collection based on specific terms or metadata
- sandboxed write access to media gallery. Write access may not be a requirement to start with. Most use cases and functionalities can be implemented without it.
Received on Friday, 3 December 2010 15:28:13 GMT

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