Multimedia

T.Sharon-A.Frank1

Multimedia

Various Applications

2T.Sharon-A.Frank

Contents

• E-mail, MM-Mail and Internet Fax

• Voice Response Systems

• Computer Messaging Services

• A/V Streaming

• Video On Demand (VOD)

• Video/Multimedia Conferencing

• Virtual Reality (VR)

3T.Sharon-A.Frank

Download A/V vs. Streaming A/V

Copy to system

Download and then play A/V

View/Listen locally

Special Protocol

Streaming A/VView/Listen while loading

4T.Sharon-A.Frank

Playing media over Web via download

5T.Sharon-A.Frank

Streaming media using Web and Media server

6T.Sharon-A.Frank

Audio/Video Streaming

• A technique for transferring data such that it can be processed as a steady and continuous stream.

• Data can be displayed before entire file has been received.

• If data arrives quicker than display, need a buffer.

• If data arrives slower than display, poor quality, jerky display.

7T.Sharon-A.Frank

Use of buffering with Media server

The media player buffers input from the media server and plays from the buffer rather than directly from the network.

8T.Sharon-A.Frank

Multimedia Streaming

• Delivering a multimedia file from a server to a client – the delivery occurs over a network.

• There are two different types of streaming:1. Progressive download – the client begins

playback of the multimedia file as it is delivered where the file is ultimately stored on the client computer.

2. Real-time streaming – the multimedia file is delivered to – but not stored on – the client’s computer.

9T.Sharon-A.Frank

Real-time Streaming

• There are two types of Real-time streaming:

1. Live streaming – used to deliver a live event while it is occurring.

2. On-demand (stored) streaming – used to deliver media streams such as movies,

archived lectures, etc. The events are not delivered in real-time.

10T.Sharon-A.Frank

Audio/Video Applications

1) Streaming On-demand audio/video:• Famous radio broadcasts, full-length movies

(VOD), prerecorded TV shows, music video clips, archived class lectures, etc…

2) Streaming Live audio/video:• Internet radio talk show, live webcasts, etc…

3) Real-time interactive audio/video:• Internet telephony (VoIP), video conferencing,

MM conferencing, distributed interactive worlds, etc…

11T.Sharon-A.Frank

Video On Demand (VOD)

TV Guide

Set-Top Boxor Desktop

HSN Switches

Video Redistributers

Video Servers

12T.Sharon-A.Frank

VOD using different local distribution technologies

(a )ADSL (b) Cable TV

13T.Sharon-A.Frank

Near Video On Demand (N-VOD)

Near video on demand can have a new stream starting at regular intervals, in this example every 5 minutes (9000 frames).

14T.Sharon-A.Frank

Near Video On Demand (N-VOD)

Time

Movie C

Movie B

Movie A

Tra

nsm

issi

on o

f

A AB B A C B CSubscriber requestsfor movies

15T.Sharon-A.Frank

Content Distribution Networks (CDNs)

• Stream large files (e.g., video, MM presentations) from single origin server in real-time.

• Solution: replicate content at hundreds of servers throughout Internet:– Content downloaded to CDN servers ahead of time.– Placing content “close” to user avoids impairments

(loss, delay) of sending content over long paths.– CDN server typically in edge/access network.– Uses DNS system to re-route requests.

16T.Sharon-A.Frank

How do CDNs work?

• CDN (e.g., Akamai) customer is the content provider (e.g., CNN).

• CDN replicates customers’ content in CDN servers.

• When provider updates content, CDN updates all the servers.

origin server in North America

CDN distribution node

CDN serverin S. America CDN server

in Europe

CDN serverin Asia

17T.Sharon-A.Frank

CDN Distribution Tree

18T.Sharon-A.Frank

Multimedia Conferencing

19T.Sharon-A.Frank

What is it used for?

• Social Encounters

• Job Interviews

• Business Meetings

• Distance Learning

• Medical Consultation

20T.Sharon-A.Frank

Conference Types

• Chat Conference (IRC, Chat)

• Audio Conference (WebPhones)

• Video Conference (VC Tools)– Bi-party Conference

– Multiparty Conference (Reflector, MeetingPoint):» Group Communication» Needs Floor Control

21T.Sharon-A.Frank

Audio Conference

Why use the POTS

when you can get it so

much better

on the Internet?

22T.Sharon-A.Frank

Video Conference

IVS-Rendezvous

23T.Sharon-A.Frank

Multimedia Conference via Skype

24T.Sharon-A.Frank

The Meeting Room Conference

25T.Sharon-A.Frank

VC Hardware

• Cameras

• Screens

• Speakers and Microphones

• Other Aids (Electronic Board, Remote Control)

26T.Sharon-A.Frank

VC Software/Tools

• Chat

• Video/Audio tools

• Whiteboard

• Data/File Transfer

• Application Showing

• Application Sharing

27T.Sharon-A.Frank

Whiteboard

28T.Sharon-A.Frank

TelePresence Conference

• Set of technologies allowing a person to feel as if they were present, at a location other than their own one.

• Requires good lighting and screens installed with speakers.

• Transmits the user's position, movements, and voice to the remote location.

• Enables the same transfer for both ends, allowing interactive dialogue.

• Delivers an 'in person' experience, allowing meetings without travelling.

29T.Sharon-A.Frank

An Example TelePresence Conference

30T.Sharon-A.Frank

Virtual Reality (VR) Usage

Create an illusion of imagined reality or augmented reality:

• Entertainment

• Training

– Flight simulators

– Driving simulators

31T.Sharon-A.Frank

Virtual Reality Examples

32

• Strictly, an immersive sensory experience of a synthetic world– Head-mounted displays, data gloves, haptic

interfaces, etc.

• More modestly, 3D graphics that can be explored:– Draggable panorama, objects that can be

moved round

– VRML, QuickTime VR.

Virtual Reality

33T.Sharon-A.Frank

VR CAVE Example

34T.Sharon-A.Frank

Augmented Reality

35T.Sharon-A.Frank

Mediated Reality

36T.Sharon-A.Frank

Mediated Reality Examples