1.4 audio over ip

EBU TECHNICAL

Audio over IP

WBUWBU--ISOGISOGGeneva 30Geneva 30thth November 2009November 2009

Mathias Coinchon

EBU TECHNICAL

European Broadcasting Union

EBU TECHNICAL - your reference in media technology and innovation

Audioover

IP


N/ACIP timeline

2005

ISDN will be phased out from end 2007 !!

What replacement solution for audio contribution ?!


N/ACIP timeline

2005

ISDN will disappear in 2007 !!

What solution for audio contribution ?!

2006

EBU N/ACIP group started. Objective: find replacement solutionGerman broadcasters and manufacturersmeeting for Audio over IPFirst meeting with manufacturers in September (IBC)


N/ACIP timeline

2005



2006 2007

EBU N/ACIP groupstarted. Objective: find replacement solutionGerman broadcasters

and manufacturersmeeting for Audio over IPFirst meeting with

manufacturers at IBC

>15 manufacturersConsensus on interoperabilityEBU TECH3326 standard publicationEarly implementationsTests


N/ACIP timeline

2005



2006 2007





2 Plug test workshops at IRT with manufacturersEBU TECH 3329 tutorial publication


2008-20092008-2009


N/ACIP timeline

2005



2006 2007






2008-2009


Technical overview

Audio over IP application A

IP

TCP

NC

UDP

RTP

Audio stream / Packets

Audio over IP application B

IP

TCP

NC

UDP

RTP

Audio stream / Packets

IP network

Transportprotocol

Encapsulation

Audiocoding

Signaling

In red: standardized elements in EBU TECH3326

CODEC

NETWORK


Audio coding

Minimum set of codecs for compatibilityA: Mandatory codecs (A minimum set, always to be found)– G.711– G.722– MPEG-1/2 Layer II– PCM 16 bits, 20 bits, 24 bits

B: Recommended codecs– MPEG-4 AAC, MPEG-4 AAC-LD– MPEG-1/2 Layer III

C: Optional codecs– Enhanced APT-X, MPEG-4 HE-AACv2, Dolby AC-3...


EBU TECH 3326 specification

Transport protocols– RTP: Realtime Transfer Protocol on top of User Datagram

Protocol (UDP)– TCP (Transmission Control Protocol) is optional

RTP media payload formats according to IETF RFC specifications – IETF: Internet Engineering Task Force

Signalling protocols– SDP : Session Description Protocol (RFC4566)– SIP : Session Initiation Protocol (RFC3261) – SAP : Session Announcement Protocol (RFC2974)– Offer/Answer model for SDP (RFC3264) for codec negotiation

=> Compatibility with Voice over IP systems basedon SIP


SIP interoperability

Firewall

SIPProxy and Registrar

Server

Studio-sideAoIP Codec

IP NETW

Reporter’s AoIP Codec

3G + Wi-FiVoIP Phone

SIP servers associate names with IP addresses and allow a reporter* to be found, whatever the location, whatever the device!

*e.g. - sip:[email protected] or telephone number


2nd plugtest workshop – IRT - May 2009

11 participating manufacturers– AEQ, AETA, APT, AVT, Digigram, Mandozzi, Mayah, Orban, Prodys,

Telos, Tieline– Late/withdrawn: Technica del arte, Comrex

Organisation:– 55 sessions of 1.5 hours: 82.5 hours (cumulated) of testing– 6 measurement tables– Wireshark captures (free/open packet sniffing software)

Tests:– All connection through SIP proxy/registar (provided by WDR)– Codecs tested: G.711, G.722, MPEG LII 256kbps 48kHz stereo, PCM

20 bits 48kHz stereo, MPEG-4 AAC-LC 160kbps, MPEG-4 AAC-LD 160kbps


Plugtest Network


Wireshark packet capture


Wireshark SIP analysis


Plugtest II


Results, main issues

SIP signalling– Ambiguous messages– Incompatibilies with SIP Proxy (Open SER). No SIP proxy reference

exists.

SDP signalling– Wrong parameters signalling– AAC: complex syntax with references to MPEG standards

RTP encapsulation– PCM: big endian/little endian– AAC: many uses LATM, ADTS or LOAS but raw AAC is specified


Audio contribution over IP “devices”

Studio, OBVan Codecs

Software codecs

Reporter codecs


Networks

No real IP network equivalent to ISDN nowadays– ISDN: public international network with Quality of Service

Internet as the only international public IP network– No Quality of Service

Private IP network solution get widespread– Big telecom operators– Inmarsat or DVB-RCS providers

Eurovision development of DVB-RCS solution

IP ≠ INTERNET


Conclusion on ACIP

EBU TECH 3326 implementation soon reaches maturity– Clarifications needed. 4th revision TECH3326 in preparation.– Almost all manufacturers are compatible with mandatory audio coding– First AAC interoperability

IMPORTANT: ASK FOR INTEROPERABILITY TO THE MANUFACTURERS

REMAINING ISSUE: NEED FOR AN INTERNATIONAL IP NETWORK WITH QoS


Other EBU activitieson networks


Other NMC project groups

N/VCIP: Video contribution over IP– Chair: Markus Berg (IRT)– Current work: MXF over IP specification– Liaison with Video Services Forum (VSF, US organisation) for

uncompressed transport, etc

N/I3P: Intercom Interoperability over IP– Chair: Claire Mérienne (France 3)– Current work: specification for intercom (based ACIP spec.)– First meeting with manufacturers during IBC 2009

N/IPM: IP networks measurement and profiling– Chair: Yuan-Xing Zheng (BBC R&D)

N/CNCS : Common Network Control Strategy– Chair: Chris Chambers (BBC R&D)


N/I3P: Intercom Interoperability over IP

N/I3P: Intercom interoperability over IP– TV Intercom (“4 wires”)– Presenter return channel

Subset of TECH3326 done for N/ACIP– SIP signalling (like Voice over IP systems)– RTP transport– Audio voice codecs: G.711, G.722, Speex (free, open source)

First meeting with manufacturers during IBCDraft in preparation


EBU N/VCIP profiles

Profile 1: Uncompressed (SD, HD) over IP– Studio and Inter-studio environments

Profile 2: MPEG TS over IP– Inter-studio, sports, news

Profile 3: MXF streaming over IP– Studio, Inter-studio (JPEG2000 and other production formats)

Profile 4: Low bitrate– News, small offices

EBU TECHNICAL

Thank youQuestions ?

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http://tech.ebu.ch

1.4 audio over ip

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