1. SWE 423: Multimedia Systems
Chapter 2: Media and Data Streams

2. The Term Multimedia Multi Media Prefix
From Latin “Multus” meaning numerous
Media
Root
Plural form of the Latin word “Medium”.
“Medium” is a noun meaning middle or center.
Objective: Introduction to the terminology

3. The Term Media Media: A means to distribute and present information
Text
Graphics
Pictures
Voice
Sound
Music

4. Attributes of Media Perception Media Representation Media
Storage Media
Transmission Media
Information Exchange Media
Presentation Spaces and Presentation Values
Presentation Dimensions
Perception Media: Q: How do we perceive the data? What we see vs. what we hear
Representation Media: Q: How do we encode the data?
Text: ASCII.
Picture: CEPT or CAPTAIN standard or the GKS graphics standard
Audio: PCM Encoding (Pulse Code Modulation) & Linear quantization of 16bits per sampling value
Image: JPEG Format
Moving Picture: TV Standard, MPEG
Presentation Media: Q: Which medium is used for output/input? Output: paper, computer monitors, speakers. Input: Keyboards, Cameras, Microphones
Storage Media: Where is the media stored? Magnetic Tapes/disks or digital optical disks.
Transmission Media: Q: Which medium is used to transmit data? Cables, radio towers, satellites, ether.
Information Exchange Media: Q: Which data medium is used to exchange information between different locations? Paper, floppy disks, flash mem
Presentation Spaces and Presentation Values: Visual vs. acoustic presentation space
Presentation Dimensions: 2D: Monitors, 3D: Holography, stereophony, Time is another dimension.
Discrete Media vs. Continuous Media (Correctness of data depends on a time condition.

5. Key Properties of a Multimedia System
Discrete and continuous media
Support of one type does not constitute multimedia (according to authors)
Independent media
Unlike video, one can have more than one type.
Computer-controlled systems
Video recorder is not sufficient
Integration
Integration: Way different media will interact in a meaningful way.

6. Characterizing Data Streams
Distributed networked multimedia systems transmit continuous and discrete data
Data transmission characteristics:
Asynchronous
Synchronous
Isochronous
Source, Sink, packets
Transmission modes available for an end to end delay in the transmission of a single packet. FDDI: Fiber Distributed Data Interface [up to 100MBPS)(FDDI2:Video and Audio in addition to data, FFDT: FDDI Full Duplex Technology (up to 200MBPS).

7. Asynchronous Transmission
The sender and the receiver do not need to coordinate before data can be transmitted.
Two independent clocks (one at the sender and the other at the receiver) determine the start of each bit (bit synchronization)

8. Synchronous Transmission
The beginning of transmission may only take place at well-defined times, matching a clocking signal that runs the synchronism with that of the receiver.

9. Isochronous Transmission
The time interval separating any two corresponding transitions is equal to the unit interval or to a multiple of the unit interval.
Transmission rate “guaranteed” and jitter is minimized.
Significant instants of two or more sequential signals have a constant phase relationship.

10. Characterizing Continuous Data Streams
This is in relation to audio and video transmission
Strongly and Weakly Periodic Data Streams
Variation of the data volume of consecutive information units.
Interrelationship of consecutive packets.

11. Strongly Periodic Data Stream
Constant time interval
Minimum jitter
e.g. PCM encoded voice in telephone systems

12. Weakly Periodic Data Stream
Duration of time intervals between neighboring packets is a function with finite period duration.
Time intervals between neighboring packets is not constant.

13. Non-Periodic Data Streams
Other possibilities
e.g. mouse movement on white boards of the screen in video conferences

14. Variation of the Data Volume of Consecutive Information Units.
Periodically Regular
e.g. MPEG
Strongly Regular
e.g. uncompressed
audio/video

15. Variation of the Data Volume of Consecutive Information Units.
Irregular
e.g. JPEG

16. Connection between consecutive packets: Interrelated
No gaps in between
Maximal throughput and use of resources
e.g. ISDN channel transmitting audio
ISDN (Integrated Services Digital Network)

17. Connection between consecutive packets: Non-Interrelated
Gaps between some packets
e.g. DVI-PLV encoded streams over FDDI
DVI-PLV (Production-level video)
FDDI: Fiber Distributed Data Inetrface

18. Comparison

19. Information Units Logical Data Units E.g. Video Data Clips Scenes
Images
Regions
Pixels