multimedia networks - protocols, design, and applications€¦ · calculation of rtt using rtcp ......

Multimedia Networks - Protocols, Design,

and Applications

- An Overview for all Chapters -

Hans W. Barz Gregory A. Bassett

Wiley, 2016 ISBN 9781119090137

Chapter 1: Introduction

• The following types of networks (Internet, Telcos, Company, Home) make a difference for their multimedia usage

2016 Copyright: Wiley & Sons

Chapter Overview Barz/Bassett Multimedia Networks

• Main standard organizations in the multimedia context are provided (ITU, IETF, ETSI, DVB, ATSC, W3C, DLNA, Others)

• A market overview is provided

2

Chapter 2: Requirements

The Chapter details the requirements for the following application types:

• Telephony - It is the oldest multimedia application since 1876. The most requirements exist in telco and company networks

• Streaming - Exists since 1993 and uses the most capacities in the Internet today

• IPTV – Regular TV programs started in 1935. IP TV is television over the Internet from 2000 onwards. It uses the most capacities in telcos networks.

• Videoconferences - Exists since 1936. Since 2004 also in HD and named now also “Telepresence”. There exist more and more company networks where Telepresence uses the most capacities.

• Webcast - Multimedia presentations over a network.



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The following table summarizes the requirements per application type



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Chapter 3: Audio, Image, Video Coding, and Transmission

The scope of the Chapter is provided in the following figure:



Audio is treated in sections on • Quantization • Companding • Differential Quantization • Vocoders • Audio MPEG

A D

Microphone

Matrix

A D

A D

A D Camera

red green blue

Digitalization & Compression

Transm

ission

De

com

pre

ssion

&

Pre

sen

tation

5

Audio MPEG is characterized by

• Asymmetric Coding System

• Masking using a psychoacoustic model



“ Smart“ Encoder In

“ Dumb“ Decoder

Out MPEG Compliant Bitstream

Asymmetric Coding System

Complex to Make

Expensive Coder Inexpensive Coder

Easy to Make

0

10

20

30

40

50

60

70

0 4000 8000 12000 16000 20000

dB

kHz

Normal Hearing

Mask

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The scope for video coding is detailed in the following figure:



Y‘

Cr

Cb

Y‘

Cr

Cb

SD: 6.75 (13.5)

SD: 270 Mbit/s HD: 1485 Mbit/s

HD: 37.125 (74.25) MHz Sampling

Matrix

A D

A D

A D Camera

red

green

blue

The overview covers:

• Color models

• Interlaced and progressive output

• Subsampling schemes

• Screen display and their characteristics

7

Compressions methods are treated in separate sections:

• Simple

• Motion Estimation

• Statistical with details on Huffman coding

• Transform functions with details on Discrete Cosine Transform



8

Diverse standards are explained in different sections:

• JPEG as the basis of H.261

• An overview on all MPEG and H.x standards

• Details of MPEG Data Streams

• Details of H.261



Max. 64 kbyte payload (Packetized Elementary Stream (PES) 6 byte header

Optional Header

Prefix 000001

Stream ID (8)

Packet Length (16)

10 Scramb- ling (2)

Flags to show existence of optional fields (12)

Header Length (8)

Optional fields

Stuffing Bytes (F..)

Presentation Time Stamp (33)

Elementary Stream Clock Reference (42)

Decoding Time Stamp (33)

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• Details of H.264 – All

additions to H.261

– Including all relevant profiles

– Network abstraction layer

– Scalable video (Temporal, Spatial)



10

• Details of H.265 – Main

additions to H.264

• Reasons why H.265 will stay for the next generation

• Performance comparison H.261 – H.265



11

34

35

36

37

38

39

40

41

42

43

0 2000 4000 6000 8000 10000 12000 14000

PS

NR

(dB

)

Bit Rate (kbit/sec)

H.261 (Projected)

H.262

H.263

H.264

H.265

• Other Video Compression Standards – VC-1, VC-2

– VP8, VP9

– China’s AVS

– Comparison and arguments why all of them will probably never replace H.265

• Three Dimensional Video – TaB, SbS

• Error Resilience – Decoder techniques to overcome problems

– NEWPRED

• Transcoders in MCU’s – Quality adaptation (Open loop, CPDT)

– Spatial adaptation

– Temporal adaptation



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Entropy

Decoder

Quantizer

Q2

De-

Quant-

izer Q-1

Entropy

Coder

Chapter 4: Underlying Network Functions

The scope of the Chapter are the bold parts of the following protocol stack:



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Shared Applications

RSV

P

IP & Diffserv, IP Multicast, VLAN

TCP UDP UDP

SIP+ H.323/H.248 HTTP

SDP

NTP

Cach

ing

Audio/Video

DASH RTSP

Confer- encing

User Interface

ALC

FLUTE

SCTP

SLP

RTP/RTCP

This stack shows all lower layer protocols which are required to serve multimedia applications.

• All details and options of RTP

• Video Coding & Network Abstraction Layer (NAL)

• Compression

• RTCP: all packets and fields plus interworking. Graphic shows calculation of RTT using RTCP reports



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• Session Description Protocol (SDP) and it‘s Extensions – also JSEP

• Real Time Streaming Protocol (RTSP) and its extensions (Vers 2.0, Media fragments)

• Multicast (Addressing, Types, End Delivery IGMP, Routing Protocols, PIM Sparse in Detail)



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• Quality of Service – Intserv with RVSP

– Diffserv with all types of markings for the Per Hop Behavior (PHB), shapers, Droppers, baseline recommendations

– On the LAN

– Net Neutrality

– In the Real World



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• Network Time Protocol (NTP) inclusive offset (Φ) calculation

• Caching elements (Content, Location, Timing), WCCP, CDN



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Chapter 5 Synchronization and Adaptation

• End-to-End Model showing all elements with their timing influence on the end-to-end transmission

• Transmission timing for RTP and HTTP



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• Jitter

• Packet loss

• Play-Out-Time – Hypothetical Decoder (HRD, VBV)

– Multiple Streams

– Adaptive Play-out

• Congestion Control

• Delay

• Queuing – Steady states TCP flows

– Lumpy traffic

– Bufferbloat (ARED,CoDel,PIE)

• Media Player

• Storage an Retrieval – ISO BMFF storage

• For RTP & MPEG TS

• Integration Scripting Language (SMIL)

• Optimization



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Chapter 6: Session Initiation Protocol

• Basics

• Servers – Client- /Server-Interaction

– Proxy

– Name resolution

• More SIP methods – BYE, CANCEL, UPDATE, PRACK,

INFO, MESSAGE, SUBSCRIBE/NOTIFY, REFER



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• PSTN Interconnection – ENUM

– ENUM-DNS

– SPEERMINT

• Conferencing – Endpoint mixing

– Server & distributed clients

– Bridge

– Multicast

– XCON & SIP‘ING

– Binary Flow Control Protocol (BFCP)

– XCON‘s Centralized Conference Manipulation Protocol

– MCCF

• Presence – SUBSCRIBE/NOTIFY

– XML schemas

– XMPP



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• Network Address Translation – Mapping, Port behavior, Mapping

refresh, Filtering, Hair pinning, ALG

– Full-cone. Address-restricted, Port restricted, Symmetric

– STUN

– Discovery

– Hole punching (ICE)

– PMP, PCP, SIP Outbound

• APIs and Scripting

• Security & Safety – Threats & possible measures

– Typical scenarios in companies

– Stability measures for telephone systems

– Logical versus physical separation



22

• Planning a VOIP company telephony system – Data sources and their flows

– Organizational issues

– Business case

– Dial plan

– Emergency • User input, Cell information, LLDP-MEDELIN,

PSAP

– Network planning • Unified communication, Codec, Packet sizes,

QoS, Erlang, Holding times



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Chapter 7 Other Standard VoIP Protocols

• H.323 VoIP Family – H.225

• Gatekeeper (MCU), Terminal

• ASN.1

• ISDN Q.931

• Base actions

– H.245 • Master/Slave determination

• Capability negotiation

• Logical channels

– Comparing H.323 to SIP

• T.120 Data applications – T.120-T.128

– RDP



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• Gateway control – PSTN connection via Digital Subscriber

Signaling

– H.248 (IETF & ITU) • Controlling media gateways

• Termination, Context, Properties

• Communication examples

– Comparison MGCP and H.248

– Signal control • Q.921, ISDN User Part

• Signaling Gateway

• ISDN Q.921 User Adaptation (IUA)

• Stream Control Transmission Protocol (SCTP)



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– SCTP in Detail • Handshake

• Multiple receivers

• Multiplexed streams

• Reliability

• Mobile VoIP – IP Multimedia System

• Elements

– P/I/S-CSCF

– MGCF/MGW/SGW

– BGCF

– MRFC

– AS

• Examples for REGISTER inclusive message contents explained in detail

• Examples for INVITE with two roaming User Entities inclusive message contents explained in detail



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– VoLTE • Overview of current core and radio access

networks in mobile networks

• Elements of infrastructure explained

• Business case for mobile providers to move to VoIP over LTE

• VoLTE INVITE discussed

• Coexistence and migration options discussed

– Circuit Switched Fallback (CSFB)

– Single Radio Voice Call Continuity (SRVCC)

– Simultaneous Voice and LTE (SVLTE=)

– OTT VoIP

– Voice over LTE with Generic Access (VoLGA)

– Skype • Currently known elements presented



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Chapter 8 WebRTC

• Web Real Time Communication – Adds real time communication to

browsers

– W3C describes additional APIs integrated into HTML5 with main elements

• GetUserMedia

• RTCPeetConnection

• RTCDataChannel

– Include specifications for video- and audio-codec – partially untypical for SIP

– Transport uses STUN (ICE/TURN), Security enhanced transport (SRTP, SRTCP, DTLS), extended SCTP on a single port



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– ICE is compulsory • Testing all possible connection paths plus STUN

and TURN servers, Consolidating all information also incremental for better performance

• Restricting RTP/SDP options to achieve best interoperability

– Interoperability with normal SIP • Requires gateways for other environments



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Chapter 9 Streaming and Over-the-Top TV

• Over-the-Top (OTT) is content provided over the normal Internet

• Provider Live Streaming variants in detail – Apple’s HTTP Live Streaming (HLS)

– Microsoft’s Smooth Streaming

– Adobe’s HTTP Dynamic Streaming (HDS)

• Dynamic Adaptive Streaming over HTTP (DASH) - MPEG – Scalable Video Codec (SVC) layers for

adaption on network conditions


Chapters Overview Barz/Bassett Multimedia Networks

30

• DASH cont’d – Media Presentation Description with

examples • Usage in servers and clients

– Network Interaction • Player reaction on network conditions

• Simultaneous streams interaction

• Bufferbloat re-visited – Smooth Adaptive Bit Rate (SABR)

• Content Delivery Networks (CDN) – CDN Technology

• Loading

• Distribution/Synchronization

• Server selection

• Inter CND connection

• Live streaming

• Akamai



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• CDN cont’d – Future

• Content Centric Networks (CCN)

• Managing multiple CDNs

– Provider and their implementations • Amazon Instant Video

• YouTube

• Netflix - more than 60 million subscribers in minimal 50 countries

• Hulu

• Common issues



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Chapter 10 Home Networks

• IETF Home Standards – Address Assignment

– Name Resolution mDNS

– Service Discovery • Service Location Protocol (SLP), Simple Service

Discovery Protocol (SSDP), DNS-based Service Discovery (DNS-SD)

– Zeroconf implementations • Bonjour, Avahi

• UPnP – Architecture covers areas

• Addressing (DHCP, AutoIP)

• Discovery (SSDP)

• Description (XML with SOAP transport)

• Control (SOAP)

• Event Notification

• Presentation



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• UPnP cont’d – AV Architecture and its elements in detail

with most of their state variables, states and important procedure calls explained for the different services

• Connection manager service

• Rendering control service

• Content directory service

• Transport service



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• UPnP cont’d – Summarizing example with procedure

calls explained

• DLNA – Main devices explained

• Residential Gateways • Other names: Delivery Network Gateway

(DNG), Home Gateway (HG) Customer Network Gateway (CNG) and Customer Premise Equipment (CPE)

– IMS Integration

– Network Separation • Mapping of QoS delivered traffic to home

network



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Chapter 11: High-End IP TV

• Treats the Digital Video Broadcast (DVB) IP TV standard – IP TV has more than 115 million

subscribers in 30 countries – deployed by country telcos

– Deployments started in 2005

– Many (older) implementation do not fulfill newest standards

– Uses multicasts as a base mechanism

– Delivers high quality without any interruption and 100ms channel switching

• Overview architecture and protocol stack – Only shaded protocols treated in this

Chapter. Others were treated before



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• Live Media Broadcast (LMB) – Retransmissions explained in detail

• Possible due to up to seconds delayed delivery

• Uses special LMB RETransmission servers and RTCP feedback messages

• Covers also losses to many clients by multicast send-out

– Channel switch • IGMP Version 3 based switching not fast enough

• Reuse of RET server for Fast Channel Change (FCC)

• Expansion of RTCP feedback are the Rapid Acquisition of Multicast RTP Sessions (RAMS)

• Unicast from RET server delivers temporary the data

• Details plus packets



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• Datacast Protocols – FLUTE

• Unidirectional file transfer protocol on top of multicast

• No feedback of receivers

• Bases on the building blocks of Asynchronous Layer Coding (ALC)

• Each recipient uses a Transport Object Identifier (TOI) to identify incoming packets

– Service Discovery and Selection (SD&S) • Maintaining hierarchically structured

information via multicast

• Hierarchy is typically a service description

– Digital Storage Media – Command and Control (DSM-CC)

• Old protocol created in 1996 by DAVIC using an Object Broker (ORB) structure



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• Management Functions – Service Discovery & Selection

• Service tree maintained by DVB SD&S datacast protocol

– Broadband Content Guide (BCG) • Content of all broadcasts (TV Anytime)

– Remote and Firmware • Uses specification T.69 of Broadband Forum

• Covers all to maintain an infrastructure of million of HNED/Set-top-Boxes at customer side

– Content Download Service • All means and method to distribute content

• Contains special reporting features which scale also in multicast

• Deployments – Highly performing and redundant Head-

End systems

– Typical setup discussed



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• Companion Screen Application (CSA) – This covers also non IP-TV solutions Like

Google’s Chromecast

– Functionality: Screen move, Control after move, Synchronized Content

– DVB specification uses for content Material Resolution Service (MRS) on the Internet

– Protocol elements are • Discovery and Association for connecting devices

to TV set

• Content Identification

• Wall Clock to synchronize time between devices

• Event to start specific actions - e.g. alarm on second device in case of a goal during TV play

• Set-Top-Box Functions • Special functionality like time-shift playing is

handled here

• Integration into other systems – IPTV and IMS

– IPTV and Home Network



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Chapter 12 Solutions and Summary

• Requirements for all solutions in Chapter 2

• Global Webcast Solution – Required production environment

• Coordination, Application adaptation, room support, A/V equipment, Question management

– Transport options • Internet: Unicast with or without caching

• In Companies: Multicast on whole path, indirect Unicast, Caching

– Separate Content management solution



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• Digital Signage Broadcasting Solution – Content is stored at signage manager

– Each screen has dedicated signage player (special hardware exist)

• Communicates with manager – often based on http

– Specific players play playlists which are controlled with signage manager

• Controls time to replay, source, sites to play

• SMIL is typical option for playlist specification

– Caching for repeated played content • WCCP in routers



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• Call Center Solution – Functional elements

• Used incoming or outgoing type of media

• Arrival queues, Routing, Announcements, Waiting Queues, Supervisor, Agent

• Control , tracing, recording of agents and their status

• Wallboard , Interface to Customer Relationship Management using standard APIs

– Technical components • For user interaction W3C speech interface

framework with VoiceXML – also called HTML for non computer-based user interactions

• VoiceXML requires dedicated interpretation environment



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– Technical elements cont’d • Voice gateway acts as PSTN

signaling and media gateway controller (Chapter 7)

• Voice script server maintains VoiceXML elements

• Media gateway maps the medium – controlled by gateway via MGCP

• Call router routes call based on diverse criteria

• Media resource server provides media elements – e.g. music



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• Videoconference and Telepresence Solution – Good value provided by a vivid,

consistent and interactive experience

– Today at best achieved by Telepresence systems

– In addition to transport and network attention required for

• Media mapping: not all systems have three screens and question arises how to map more screens on fewer – special standard model exist

• Slides need to be transported as well

– Cisco Transport specifics • Uses first time in practice bundled RTP sessions

in one connection

• Encoder uses GDR (Chapter 3) avoiding peaks

• BFCP (Chapter 6) for laptop screen control

– Cisco Network Setup in detail • Full redundant paths required with router

redundancy, load balancing, link aggregation

• QoS on the whole path – even on the LAN (Chapter 4). Details of prioritization explained

• Special tracing recommended – e.g. Mediatrace



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Courtesy of Cisco Systems Inc

• Summary of Requirements versus Solutions – Requirements from Chapter 2 translated in required measures



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