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The Italian CONTENT Local Industry Workshop

Napoli, 29th May 2009

A Standard Framework for Content Adaptation: MediaCtrl

Lorenzo Miniero (CINI-UoN)

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Overview

• Issues– Heterogeneous Networks– Heterogeneous Devices– Encoding/Decoding/Bandwidth

• Protocol Requirements– Signaling of Media Session– Media Delivery– Control and Interactivity

• Standardization efforts– Third Generation Parthership Project (3GPP)– Internet Engineering Task Force (IETF)

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Challenge

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Issues

• Heterogeneous networks and devices– Bandwidth fluctuates– Not the same bandwidth anywhere– Even if it is, devices may have different capabilities

• Dynamic behaviour– Different codecs/resolutions/etc.– Content adaptation– QoS feedback mechanisms

• New Trends– Distributed content– Need for interactivity

• Choosing content• Controlling media• ...

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Signaling

• Session Initiation Protocol (SIP)– IETF RFC 3261 (http://www.ietf.org/rfc/rfc3261.txt)– Negotiates media sessions

• Originally conceived for VoIP only• Subsequently extended to implement any kind of multimedia application

– Has ways to dinamically update sessions

• Session Description Protocol (SDP)– IETF RFC 3264 (http://www.ietf.org/rfc/rfc3264.txt)– Conveyed in SIP payloads– Provides details about media sessions to negotiate

• Transport addresses• Encoding/direction of media streams

• SIP/SDP base protocol for IMS– IP Multimedia Subsystem (3GPP)– Unified access to services from heterogeneous networks

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Media Delivery

• Real-Time Transport Protocol (RTP)– IETF RFC 3550 (http://www.ietf.org/rfc/rfc3550.txt)– Transports media frames in real-time– Opaque to the encoding– Negotiated in SIP/SDP messages

• Real-Time Transport Control Protocol (RTCP)– “Sister” protocol of RTP– Provides feedback on delivery of streams

• Base for QoS mechanisms

• RTP Payload for DTMF Digits– IETF RFC 2833 (http://www.ietf.org/rfc/rfc2833.txt)– Further means for interactivity

• DTMF digits can be associated with actions

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Convergent Applications

• SIP/SDP and RTP/RTCP provide means for end-to-end communication– Need for an additional control layer with business logic– Several protocols can be involved

• SIP, RTP, HTTP, ???

• Separation of responsibilities– Application Server (Business Logic)– Media Server (Content Manipulation and Delivery)– AS and MS need a way to interact

• Media Server Control (IETF MediaCtrl)– Standard Framework for Content Adaptation– Describes architecture and protocols for [UAs-]AS-MS interaction– CINI/UoN deeply involved in standardization process

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Media Server Control (MediaCtrl)

• Functionality– Media Processing– Mixing/Transcoding– Playing/Recording– Storing/Retrieving– Detecting Tones (DTMF)– Interactive Voice Response (IVR)/VoiceXML– Text-to-Speech/Speech Recognition– RTP Streams Manipulation– Monitoring and Auditing– Event Notification (subscription mechanism)

• MRFC/MRFP (interface/container) in IMS– May wrap different specification (e.g. H.248)

Client B

SIP SIP

ApplicationServer

MediaServer

SIP Control

Channel RTPRTP

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Why MediaCtrl?

• Several extant protocols...– ITU H.248.19 (MeGaCo)– RFC 4240– MSCML (Media Server Control Markup Language)– VoiceXML/CCXML– ...

• ... a SIP-aware standard was needed– Completely SIP-based– Specific requirements (e.g. MRF...)– Simpler to work with

• JSR 309 and SIP Servlets

• Media Server Control (MEDIACTRL)– BOF (Birds of a Feather) in November 2006– Work almost completed

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Overview

• Charter– http://www.ietf.org/html.charters/mediactrl-charter.html

• Advanced services– Content Delivery– Interactive Voice Response (IVR)– Mixing/Bridging (Conferencing)

• Several topologies: 1:1 → m:n– Media Resource Broker

• Modular approach– Opaque payloads– Control packages– Transactions

as “bricks”

Header Payload

Header Payload

Control Package 2

Control Package 1

Control Package 3

Protocol Messages

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Architecture (1)

ApplicationApplicationServerServer

MediaMediaServerServer

UserUserAgentAgent

UserSignaling(e.g. SIP) SIP

(MediaDialog)

RTP/SRTP

TCP/TLS(ControlChannel)

SIP(ControlDialog)

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Architecture (2)

• AS uses SIP to establish TCP/TLS connection to MS– SIP dialog called Control Dialog– TCP/TLS connection called Control Channel

• Channel setup: SIP with COMEDIA negotiation• Authentication: SYNC message

• Application Server– Frontend for UA signalling

• SIP 3rd Party Call Control (Media Dialog towards MS)

– Handles business logic and control layer (e.g. HTTP)

• Media Server– Termination of Media Channels– Enforces directives coming from AS and notifies about events– AS and RTCP as QoS mechanisms

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Interactive Content Delivery

• Passive streaming– Playout of pre-recorded multimedia files– Playout of live multimedia streams (e.g. RTSP)– Optional VCR controls (rw, ffw, play, pause, volume, etc.)

• Interactivity

• Active Streaming – Use of hidden conferences to broadcast source– Storing of multimedia contents for future use

• Voice mail• Video messages• Tutorials

• Optimized Delivery– MS can fetch content to delivery from any source– MS in use can be changed dynamically

• Media Resource Brokering (MRB)

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Media Resource Brokering (MRB)

• Generic topology is m:n– Several Application Servers (m) and a pool of Media Servers (n)

• Media Resource Broker– Allows AS to audit pool of MS for capabilities/resources– MS themselves provide MRB with information– MRB tells AS which MS is best according to requirements

• Required functionality• Required encodings• Geographic locations• ...

– UAs can be moved dynamically from a MS to another

• Two different interfaces– Publisher Interface (MS→MRB)

– Consumer Interface (MRB→AS)

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CINI-UoN involvement in MediaCtrl

• draft-ietf-mediactrl-architecture-04– Design Team

• draft-ietf-mediactrl-ivr-control-package-06– Design Team

• draft-ietf-mediactrl-ivr-control-package-06– Design Team

• draft-ietf-mediactrl-call-flows-00– A. Amirante, T. Castaldi, L. Miniero, S.P.Romano

• draft-ietf-mediactrl-mrb-00– C. Boulton, L. Miniero

• Open source prototype implementation– http://mediactrl.sf.net ‒ http://www.comics.unina.it

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MediaCtrl in action

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MediaCtrl in action

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MediaCtrl in action

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Thanks for your attention!

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Acknowledgements