Grilo: Easy Access to Online Multimedia Content (LinuxCon Europe 2012)

Grilo: Easy Access to Online Multimedia Content

LinuxCon Europe 2012, Barcelona
Juan A. Suarez Romero <jasuarez@igalia.com>


Introduction

Grilo: Easy Access to Online Multimedia Content LinuxCon Europe 2012, Barcelona

About me

Juan A. Suárez Romero
Computer engineer, Coruña University
Working at Igalia since 2007
Experience in multimedia
Involved in Maemo and MeeGo
Co-author of MAFW


Outline

1 Current problems

2 Grilo

3 Conclusions

4 Thank you!



Current problems


Many sources of content

Online/ofﬂine sources
Different protocol/API
Sources that do not
provide content
(meta-information)


Many different devices

Different screen sizes
Different hardware
components
Different platforms


Current approach

Develop one application per service
Each application with different UX
Not easily scalable: new sources require new applications
Expensive maintenance
In some cases, one application attending more than one
service
Services of the same type (e.g., Photo storage service)
Deﬁne a common layer between application and the service

Not shared effort! Reinventing the wheel all time


What we need?

Stop reinventing the wheel!

Platform-level solution for accessing multimedia content
Provide homogeneous access to all content
Scalable with new sources of information
Collaboration!
Consistent user experience
Users care about the content, not the provider



Grilo


What is Grilo?

Framework focused on making discovery and browsing
easy for application developers
A single, high-level API for all the sources
A collection plugins that provides access to the sources
An extendable system to provide more plugins

http://live.gnome.org/Grilo


Architecture overview


Media types and Keys

Collection of keys and
values
Several keys provided by
core: title, URL, author, . . .
Plugins can extend them
with new keys
Support for multiple
values
Support for relations
between keys


Plugins and Sources

Key component of the
system
Plugins are dynamically
loaded by core
Plugins create one or more
sources
Sources support multiple
operations
Browse, Search, Store,
Remove, . . .
All operations are optional


Plugins and Sources

Sources perform two main
roles:
Provide new media
content
Enrich already existent
media content
Sources collaborate among
them to solve the requests


Example of collaboration

Developer wants to show content from UPnP server and
play it
They need the url to play, a title and a thumbnail to show
1 Perform the request through core API
2 Core checks if the requested keys are supported by the
source
thumbnail is not supported by UPnP source
3 Checks which sources are able to resolve thumbnail key
CoverArt source is able to
But it requires to know two keys: artist and album


Example of collaboration

4 Core checks if those required keys are supported by
original UPnP source
If not, repeat the process as in the case of thumbnail
5 Perform the request in the UPnP source with the keys
requested plus the new keys
6 When the results arrive, send them to CoverArt source to
include the thumbnail
7 Send the ﬁnal results to application

Developer only needs to deal with one provider


Implementing applications

Main language is C
Other languages supported through gobject introspection
(Python, Javascript, Vala, . . . )
Support for C++ (grilomm)
Some initial support for Qt/QML


Code example

1 # ! / usr / bin / python
2
3 import sys
4 from g i . r e p o s i t o r y import Grl
5
6 def main ( argv ) :
7 i f l e n ( argv ) < 1 :
8 p r i n t " Usage : m a k e _ l i s t . py < s e a r c h _ t e x t > "
9 return 1
10
11 Grl . i n i t ( [ ] )
12 r e g i s t r y = Grl . R e g i s t r y . g e t _ d e f a u l t ( )
13 registry . load_all_plugins ( )
14 keys = [ Grl .METADATA_KEY_DURATION,
15 Grl . METADATA_KEY_TITLE,
16 Grl .METADATA_KEY_URL]
17 o p t i o n s = Grl . OperationOptions . new ( None )
18 options . set_count ( 2 0 0 ) ;
19 r e s u l t s = Grl . m u l t i p l e _ s e a r c h _ s y n c ( None , argv [ 0 ] , keys , o p t i o n s )
20
21 p r i n t " #EXT3MU"
22 f o r media in r e s u l t s :
23 i f i s i n s t a n c e ( media , Grl . MediaAudio ) :
24 p r i n t " #EXT3INF : " + s t r ( media . g e t _ d u r a t i o n ( ) ) + " , " + media . g e t _ t i t l e ( )
25 p r i n t media . g e t _ u r l ( )
26
27 i f __name__ == " __main__ " :
28 main ( sys . argv [ 1 : ] )


Implementing plugins

Plugins must be written in C
Adding support for writing plugins declaratively (in XML)
Adding support for other languages (Lua)



Conclusions


Resources

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

Do not miss our booth in ground ﬂoor (in front of Rossini
room)



Thank you!


Images used in this presentation

Hard Disk Icon by Mazenl77 (CC Attribution)
http://www.iconspedia.com/icon/hard-disk-1600.html
Memory Card Icon by Custom Icon Design Studio
http://www.gettyicons.com/free-icon/103/
pretty-office-2-icon-set/free-memory-card-icon-png
Vimeo, Flickr, Jamendo, YouTube and UpnP logos under copyright of their own
brands


Grilo: Easy Access to Online Multimedia Content (LinuxCon Europe 2012)

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