1. Properties of Multimedia

Transcription

1 Conens 1.1 Wha is Mulimedia? 1.2 Classificaion of Media Percepion, Represenaion and Presenaion of Informaion 1.3 Quaniaive and Qualiaive Evaluaion of Mulimedia Sysems Combinaion of Media Level of Independence Compuer-Suppored Inegraion Communicaion Capabiliy 1.4 Daa Sream Characerisics Logical Daa Unis Time Resricions Daa Uni Sizes Coninuiy 1 / 10

2 1.1 Wha is Mulimedia? Simple Definiion of Mulimedia: Any kind of sysems ha suppors more han one kind of media. Quesion: Is Television Mulimedia? Definiion: Mulimedia means he inegraion of coninuous media (e.g., audio, video) and discree media (e.g., ex, graphics, images) hrough which he digial informaion can be conveyed o he user in an appropriae way. Muli: many, much, muliple Medium: An inerleaving subsance hrough which somehing is ransmied or carried on. 2 / 10

3 1.2 Classificaion of media 1. Percepion Medium: How do humans perceive informaion in a compuer environmen? (by seeing, by hearing,...) 2. Represenaion Medium: How is he compuer informaion coded? (ASCII, PCM, MPEG,...) 3. Presenaion Medium: Through which medium is informaion delivered by he compuer or inroduced ino he compuer? Oupu: paper, loudspeaker,... Inpu: keyboard, mouse, camera, Sorage Medium: Where will he informaion be sored? 5. Transmission Medium: Over wha medium will he informaion be ransmied? (coax cable, radio,...) 6. Informaion Exchange Medium (combinaion of sorage and ransm. media): Which informaion carrier will be used for informaion exchange beween differen places? 3 / 10

4 1.2 Classificaion of media Each medium defines Represenaion Values Represenaion Space How: Represenaion values deermine he informaion represenaion of differen media: coninuous represenaion values (e.g., elecro-magneic waves) discree represenaion values (e.g., characers of a ex in digial form) Where: Represenaion space deermines he surrounding where he media are presened. visual represenaion space (e.g., paper, screen) acousic represenaion space (e.g., loudspeaker) 4 / 10

5 1.2 Classificaion of media Represenaion dimensions of a represenaion space are: spaial dimensions: wo dimensional (2D graphics) hree dimensional (holography) emporal dimensions: ime independen (documen) - Discree Media (e.g. ex of a book) ime dependen (movie) - Coninuous Media (e.g. sound, video) 5 / 10

6 1.3 Quaniaive and Qualiaive Evaluaion of Mulimedia Sysems Combinaion of Media coninuous and discree media Level of Independence (levels of) independence of differen media Compuer-Suppored Inegraion compuer conrolled media processing Communicaion Capabiliy inerconneced sysems 6 / 10

7 1.4 Daa Sreams Characerisics Asynchronous Transmission Mode provides for communicaion wih no imely resricions e.g. elecronic mail Synchronous Transmission Mode defines a maximum end-o-end delay for each packe of a daa sream ypically : high daa rae, e.g. 140 Mbis/s relaively high end-o-end delay, e.g. 1 second Isochronous Transmission Mode defines a maximum and a minimum end-o-end delay for each packe of a daa sream (limied jier). 7 / 10

8 1.4 Daa Sreams Characerisics Time Inervals: Srongly periodic daa sreams (idenical inervals) Example: T uncompressed audio Weakly periodic daa sreams (periodic inervals) T 1 T 2 T 3 T 1 T 2 T 3 Example: segmened ransmission Aperiodic daa sreams (arbirary inervals) Example: T 1 T 2 T 3 T 4 T 5 T 6 dialog raffic Periodic sreams: + easier o handle - high degree of redundancy (in general) 8 / 10

9 1.4 Daa Sreams Characerisics Coninuiy: Coninuous daa sreams, packes are ransmied wihou inermediae gaps Discree daa sreams, gaps exis beween packes Packe size: T T D 1 D 1 D 1 D 1 D 1 Srongly regular daa sreams D 1 D 2 D 3 D 1 D 2 D 3 Weakly regular daa sreams... D 1 D 2 D 3 D n Irregular daa sreams 9 / 10

10 1.4 Daa Sreams Characerisics Coninuous media consis of a ime-dependen sequence of individual informaion unis: Logical Daa Unis (LDU) Examples: symphony consiss of independen senences, senence consiss of noes On a CD samples are groups o 1/75 second duraion. Granulariy of LDUs: symphony, senence, individual noes, samples, film, clip, frame, raser, pixel Duraion of LDU: open LDU or closed LDU Film Scenes Frames Blocks Pixels several orders of magniude (concerning ime) 10 / 10