This document discusses using the Grilo framework to build multimedia applications. Grilo provides a single API to access multimedia content from various sources like YouTube, Flickr, and IMDB. It also handles metadata from sources. The document describes how the Totem media player uses Grilo to browse and search video content, and requests only necessary metadata to improve performance. It also discusses how the GNOME Music player maps Grilo metadata to its own data model and queries sources directly for album art. The closing recommends other Grilo use cases like uploading content and auto-resume playback.

1. static void
_g_digicam_manager_class_init (GDigicamManagerClass
*klass)
{
GObjectClass *object_class = (GObjectClass*) klass;
g_assert (G_DIGICAM_IS_MANAGER_CLASS
(klass));
parent_class = g_type_class_peek_parent (klass);
g_type_class_add_private (klass, sizeof
(GDigicamManagerPrivate));
/* Override virtual functions */
object_class->finalize = _g_digicam_manager_finalize;
/**
* GDigicamManager::focus-done:
* @manager: the gdigicam manager
Juan A. Suárez Romero
jasuarez@igalia.com
Writing multimedia
applications with Grilo

2. Opening

3. Sources

4. Sources

5. Grilo
● Framework focused on making discovery and
browsing easy for application developers
● A single, high-level API for all the sources
● Plugins
● Provides access to multimedia content
● Extendable

6. Grilo
SOURCESOURCESOURCE
SOURCESOURCEMEDIA
SOURCESOURCE
METADATA
KEYS
creates
contains provides
Youtube
Jamendo
Flickr
IMDB
...
Audio
Video
Image
...
Title
Artist
Album
...

7. Totem

8. Totem

9. Requirements
● Define what we need
● Type of content
– Any kind?
– Only video? Music?
● Metadata keys
– URL
– Title
– Thumbnail
– ... 55 metadata keys

10. Content to show
● Ignore any source that does not provide Videos
● In “browse” view, ignore any source that does
not support browsing
● In “search” view, ignore any source that does
not support searching

11. Information to show
- Title
- Author
- Duration
- Thumbnail
- URL
- Title
- Author
- Duration
- Thumbnail
- URL
Browse Search

12. Invoke Grilo
- Title
- Author
- Duration
- Thumbnail
- URL
- Title
- Author
- Duration
- Thumbnail
- URL
Browse Search

13. Problems
● Two problems to solve
● Source not handling some keys
● Too much expensive to retrieve some keys

14. Totem
● Flags to control content retrieval
● Normal: provides the known requested content
– GRL_RESOLVE_NORMAL
● Fast only: provides the known requested content
that does not penalize the operation in terms of
performance
– GRL_RESOLVE_FAST_ONLY
● Full: provides the known requested content using
all the available sources
– GRL_RESOLVE_FULL

15. Reduce the problems
● Request content in chunks
● Request fast only in first iteration
● While current chunk is visible
● Ask for each visible media element the discarded
keys (using full flag)
● URL key case: slow key and not shown in the
UI
● Request it when user wants to play

16. GNOME Music

17. GNOME Music
Cover Art

18. GNOME Music
● Music defines its own structure
● Grilo's one is different
● Does not have concept of “Artist” or “Album”
● They are “boxes”
● Needs to sort the results

19. GNOME Music

20. Approaches
● Request content from Tracker directly
● Create Grilo Media elements to add missing information
(Cover Art)
● Instruct Grilo's Tracker plugin how to construct
the medias
● Use query() function
● Very specific to the plugin
● In case of Tracker plugin, use SPARQL to make the query
– First column is the media to build
– Use alias to map each SPARQL column to specific metadata keys

21. Closing

22. Other use-cases
● Application to upload audio/video content to
web services
● store() function
● Mediaplayer with auto-resume
● “playback-interrupted-time” key
● store_metadata() function
– Metadata Store source handles it

23. Show me a code

24. Resources
● Wiki
● http://live.gnome.org/Grilo
● Source code
● git://git.gnome.org/grilo
● git://git.gnome.org/grilo-plugins
● IRC
● #grilo at irc.gnome.org
● Mailing list
● http://mail.gnome.org/mailman/listinfo/grilo-list