a media sharing platform built with open source software

A Media Sharing Platform Built With Open Source Software

Karel Braeckman - [email protected]

VRT and VRT-medialab

VRT is the Flemish Public Broadcaster 3 TV-channels, 5 radio channels

VRT-medialab is the research department creation, distribution and management

of media content


VRT and VRT-medialabSome of our projects… EBU EC-M Scaie Media Exchange

platformMedia sharing platform with ground truth metadata to train and test media analysis tools

MediaLoepMedia search engine which employs subtitles and news anchor texts to enhance the search.

MediaMapUse of user-generated content in a professional context.


Need for Media Asset ManagementAll these projects required media management

functionality

Upload – Store – Download media

Transcode high-res to low-res, create thumbnails, …

Metadata / Search


Need for Media Asset ManagementWe created a back-end platform “MAMMIE” which is flexible and based on open-source tools.

MAMMIE

Project1

Project 2

Project 3


• upload – store – download • transcode• metadata

Overview: Problems to tackle

What data model should we use?

How to upload and download huge media files?

How to transcode these media files?

How to link all the tools together?


A Flexible Data modelAs every research project employs its own specific metadata, MAMMIE’s data model should be very generic.

Object 2

Original Media

H264

Flash Video

Thumb frame 200

Thumb frame 300

Dublin Core metadata

NewsML-G2 metadata

MPEG7 metadata

Object 1

Original Media

Mpeg2 video


A unique ID

A number of linked mediastreams

A number of linked XMLmetadatastreams


A Flexible Data modelFedora Commons implements this data model.

REST interface to create, read, delete an object or its data streams.

A data stream is a link to media or embedded XML

More advanced features available in Fedora (not used)SOAP, RDF, transformations using web-services, versioning, ...

Object 1

Original Media

Mpeg2 video



A Flexible Data model: SearchApache Solr is used to search the objects. The Fedora Gsearch plug-in will handle the synchronization.

<xml><datastream1> … </datastream1><datastream2> … </datastream2>…</xml>

Fedora Object

<xml><title> … </title><description> … </description><hires> … </hires>…</xml>

Solr Document

XSLT


configured per application

Uploading and Downloading mediaRestrictions firewall shouldn’t block → HTTP huge files (> 2GB) → no default HTML form in-browser upload → Silverlight / Flash /

Java plug-in


Silverlight Upload Component http://silverlightfileupld.codeplex.com/

http://silverlightfileupld.codeplex.com/

http://silverlightfileupld.codeplex.com/

Uploading and Downloading media

File part 1

File part 2

File part 3

User’s Computer Server

A Silverlight component splits the file in chunks and does a regular HTTP upload per chunk. On the server, a Java servlet accepts these uploads and reassembles the file.


File part 1

File part 2

File part 3


File part 1

File part 2

File part 3


File part 1

File part 2

File part 3


uploadservlet

downloadservlet

regular HTTP DOWNLOAD

Uploading and Downloading media

.progress file contains upload byte position and the file size

A servlet is also used to download the file. The download can start as soon as the upload has started!


Problems to tackle






Transcoding media


FFmpeg, Mplayer and Flvtool2 are used to transcode the media files and generate keyframes.

original media, as uploaded(e.g., MXF DV25, D10)

low-res Flash video (*.flv) keyframes (*.jpg)

FFmpeg and Flvtool2 Mplayer2

Linking everything togetherWe employ a message queue to trigger new tasks at the end of a completed task.

RabbitMQ is used as the message broker, it is an open-source implementation of the Advanced Message Queuing Protocol (AMQP).

A message has a “routing key” and some payload: upload.compl

ete

filename = test.mxfsize = 4.3GBid = 812A Media Sharing Platform Built With Open Source Software

Linking everything together

a Xbc

Task aproduces messages

Exchange routesmessage usingrouting key

Queue stores andforwards messages

Task b and cconsumes messages

Message Broker

upload.complete

transcode.complete

Each task has a queue that subscribes to messages with a certain routing key:


Consecutive messages create a workflow

upload.complete Add a data stream to Fedora objectandStart transcoding of media file

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let

fedo

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lowres.complete Add a (low-res) data stream to Fedora object

Task framework implementation The tasks are implemented using Ruby

A configuration file defines which messages (routing keys) trigger which tasks

A Ruby framework parses the configuration file and configures the task queues in RabbitMQ


def manualStartTranscode(msg) system(“ffmpeg –i #{msg[‘filename’]} …”)end

mapping:

manualStartTranscode: transcode.manualstart

startFlashVideo: flashvideo.manualstart

Future workImprovement is still possible

Error handling can be better… Scaling to different machines and stress

testing Start transcoding during upload


Conclusions It’s open-source!

All tools used are open-source Limited amount of custom code

It’s Flexible! Shot segmentation, metadata transformation, FTP

ingest, … and other tasks were effortlessly integrated.

New applications can use the MAMMIE regardless of the metadata model / media formats they employ.

More info? [email protected]


mailto:[email protected]

Questions


a media sharing platform built with open source software

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