Digital Media Development - Media Streaming - Prof. Dr. Andreas - - PowerPoint PPT Presentation

▶
digital media development
SMART_READER_LITE
LIVE PREVIEW

Digital Media Development - Media Streaming - Prof. Dr. Andreas - - PowerPoint PPT Presentation

Feb 17, 2024 279 likes •511 views

Digital Media Development - Media Streaming - Prof. Dr. Andreas Schrader ISNM International School of New Media University of Lbeck Willy-Brandt-Allee 31a 23554 Lbeck Germany Schrader@isnm.de 6/16/2004 Media Streaming 1 2

slide-1
SLIDE 1

1 6/16/2004 Media Streaming

Digital Media Development

  • Media Streaming -
  • Prof. Dr. Andreas Schrader

ISNM International School of New Media University of Lübeck

Willy-Brandt-Allee 31a 23554 Lübeck Germany Schrader@isnm.de

slide-2
SLIDE 2

2 6/16/2004 Media Streaming

Introduction

slide-3
SLIDE 3

3 6/16/2004 Media Streaming

Introduction

Digital Multimedia Systems – Networked Multimedia

Stand-alone Multimedia System

  • CBT – Computer-based training
  • CBE – Computer-based education
  • Multimedia authoring systems
  • Gaming

Networked Multimedia System

  • Video-Conferencing
  • Online education
  • Online gaming
  • CSCW – Computer-supported collaborative working

Network

slide-4
SLIDE 4

4 6/16/2004 Media Streaming

Introduction

Multimedia Applications – Typical Examples

IP IP-

  • Telephony

Telephony Online Gaming Online Gaming Internet Television Internet Television Video Distribution Video Distribution Video Video-

  • on
  • n-
  • Demand

Demand Distance Learning Distance Learning Audio/Video Audio/Video-

  • Conferencing

Conferencing

slide-5
SLIDE 5

5 6/16/2004 Media Streaming

Introduction

Multimedia in Networks – Bandwidth Development

Text Card Reader Text Teletext Text CRT Terminal Graphics Bitmap Display Audio CD Video Signal Processor Optical Fibre Bandwidth 1950 1960 1970 1980 1990 2000

slide-6
SLIDE 6

6 6/16/2004 Media Streaming

Introduction

Digital Multimedia Systems – Possibilities and Restriction

Video enough scarce not sufficient Audio Graphic 1990 2000 1980

slide-7
SLIDE 7

7 6/16/2004 Media Streaming

Introduction

Multimedia streaming will be key issue in the future Internet

Number of Number of Streaming End Streaming End-

  • points

points World World-

  • Wide

Wide

Source: Ovum, Streaming Media: Commercial Opportunities, Forecas Source: Ovum, Streaming Media: Commercial Opportunities, Forecast, 2002 t, 2002

slide-8
SLIDE 8

8 6/16/2004 Media Streaming

Introduction

Hugh potential revenues for streaming provider

Residential Market Residential Market Mobile Market Mobile Market

Source: Ovum, Streaming Media: Commercial Opportunities, Forecas Source: Ovum, Streaming Media: Commercial Opportunities, Forecast, 2002 t, 2002

slide-9
SLIDE 9

9 6/16/2004 Media Streaming

Time-Based Media Delivery

slide-10
SLIDE 10

10 6/16/2004 Media Streaming

Introduction

Media Streaming

Transmission of discrete and continuous media data Data is decomposed into units (packets) before transmission Packets are sent from the source (sender) to the sink (receiver) A media stream consists of a (temporal) sequence of packets. It has a time component and a lifetime Asynchronous media streams

  • No coordination between sender and receiver - transmission start at any time
  • Independent clocks
  • Example: keystroke on keyboard

Synchronous media streams

  • Transmission only starts at well defined times
  • Late arriving packets are of no value – bandwidth must be guaranteed
  • Example: audio and video transmission

Isochronous media streams

  • Synchronous stream with periodic arrival times of constant distance
  • No variation of delay possible

Source: Steinmetz, Nahrstedt: Multimedia Fundamentals, Volume 1, Prentice Hall, 2002

slide-11
SLIDE 11

11 6/16/2004 Media Streaming

Introduction

Media Streaming – Packet Timing

Strongly periodic

  • Constant intervals

Weakly periodic

  • Function describes periodicity within certain intervals

Aperiodic

  • No analytic function description

t T t T T T 1 2 3 T T1 2 T t T T1 2 Tn

...

Source: Steinmetz, Nahrstedt: Multimedia Fundamentals, Volume 1, Prentice Hall, 2002

slide-12
SLIDE 12

12 6/16/2004 Media Streaming

Introduction

Media Streaming – Packet Volume

Strongly regular

  • Constant data volume (packet size), typical for umcompressed audio or

video streams

Weakly regular

  • Data quantity varies periodically, typical for some video compression

methods

Irregular

  • Data quantity is neither constant nor changing by a periodic function

t D1 D1 D1 D1 D1

...

t D1 D2 Dn

...

D3

...

t D1 D2 D3 D1 D2 D3 D1 D2 D3

...

T

Source: Steinmetz, Nahrstedt: Multimedia Fundamentals, Volume 1, Prentice Hall, 2002

slide-13
SLIDE 13

13 6/16/2004 Media Streaming

Introduction

Media Streaming – Interrelation of consecutive packets

Coherent stream

  • No gaps between media packets
  • Unit identification information is included in stream
  • Resource is utilized 100%
  • Example: ISDN telephone channel with 64kbps audio stream

Non-coherent stream

  • Possibly gaps occur between consecutive packets
  • Example: irregular data stream over channel with constant bandwidth

t D1 D2 D3 D4 D5 D t D1 D2 D3 D4 D5

...

D

Source: Steinmetz, Nahrstedt: Multimedia Fundamentals, Volume 1, Prentice Hall, 2002

slide-14
SLIDE 14

14 6/16/2004 Media Streaming

Introduction

Media Streaming – Media Units

Logical data units (LDU)

  • Different levels
  • Different granularities

Different types of operations for different LDUs, e.g.:

  • Score shifting
  • Refrain filtering
  • Song compression
  • CD transmission

Movie Clip Frame Area Pixel

Example LDUs for Video

Source: Steinmetz, Nahrstedt: Multimedia Fundamentals, Volume 1, Prentice Hall, 2002

slide-15
SLIDE 15

15 6/16/2004 Media Streaming

Service Quality Parameters

slide-16
SLIDE 16

16 6/16/2004 Media Streaming

Introduction

Bandwidth

Is directly proportional to the possible amount of data transmitted or received per unit time Analog systems: difference between highest-frequency signal component and lowest-frequency signal component (in Hz) Digital systems: possible amount of data transmitted per unit time (in bps, Kbps, or Mbps) Bandwidth

  • raw bits, including synchronization, FEC, etc.

Throughput

  • user data or link layer data

Goodput

  • useful user data excluding re-transmission, errors, etc.
slide-17
SLIDE 17

17 6/16/2004 Media Streaming

Introduction

Latency (or Delay)

Time to send message from point A to point B Delay is difficult to measure Synchronized clocks needed One-way versus round-trip time (RTT – estimated delay): with latency propagation time p, transmit time t, and queing time q

  • p=d/c, with distance d and speed of light c (physics)
  • t=s/b, with size of packet s and bandwidth b of the network (network type

dependent)

  • queuing delay q (load dependent)

λ λ = = p p + + t t + + q q

slide-18
SLIDE 18

18 6/16/2004 Media Streaming

Introduction

Jitter (Delay Variance)

Source 7 7 7 Source delay: 7, 7, 7 Destination 8 5 10 Destination delay: 8, 5, 10 Average: 23/3=7.66 Jitter: [-2.66 ... + 2.33]

slide-19
SLIDE 19

19 6/16/2004 Media Streaming

Introduction

Delay x Bandwidth Product

Amount of data ‚in flight‘ or ‚in the pipe‘ Example: 100ms x 45Mbps = 562.5 KByte

Bandwidth Delay

Loss Ratio

Buffer overflows in router queues Fading in wireless networks Bursty errors are most harmful

slide-20
SLIDE 20

20 6/16/2004 Media Streaming

Introduction

Multimedia Applications – Service Quality Requirements

Varying Quality-of-Service requirements: Interactive/non-interactive, realtime/non-realtime, unicast, multicast

Bandwidth Bandwidth

high high IP IP-

  • Telephony

Telephony Conferencing Conferencing Video Distribution Video Distribution low low

Delay Delay

low low high high

Error Rate Error Rate

low low high high

slide-21
SLIDE 21

21 6/16/2004 Media Streaming

Introduction

Example network values

  • Very heterogeneous constraints
  • Large range of bandwidths:

2.4Kbps : 2Gbps ~ 1:1 million

  • Difficult to decide the

appropriate codec

Technology Bandwidth (bps) Loss Rate

GSM Speech 13K ; Data 2,4K - 9,6K high Modem 9,6K - 56K high ISDN 64K / 132K low UMTS 64K - 2M high xDSL 128K - 5M low DAB 384K medium Token Bus 1,5M - 10M low Wireless LAN 2M / 11M medium Ethernet 10M / 100M low Token Ring 4M / 16M low FDDI 100M 155M - 2G low ATM low