Sismul_jaringanmultimedia 11

Introduction of Multimedia Networking Mata Kuliah Sistem Multimedia

Today’s Internet Video Traffic

Pembagian Sistem Multimedia Sistem Multimedia dapat dibagi menjadi: 1. Sistem Multimedia Stand Alone – Sistem ini berarti merupakan sistem komputer multimedia yang memiliki minimal storage (harddisk, CD-ROM/DVD-ROM/CD-RW/DVD-RW), alat input (keyboard, mouse, scanner, mic), dan output (speaker, monitor, LCD Proyektor), VGA dan Soundcard. 2. Sistem Multimedia Berbasis Jaringan – Sistem ini yang melibatkan transmisi dan distribusi konten multimedia melalui jaringan ( biasanya yang mempunyai bandwidth yang besar). Sample applications: videoconferencing, web video broadcasting, multimedia Email, etc.

Pembagian Sistem Multimedia

What is Multimedia networking?

• User requirements of multimedia applications on the network • Technologies associated with multimedia networking • Overall structure of multimedia networking

What is Multimedia networking?

What is Multimedia networking?

Multimedia over Internet

Consideration of Networked Multimedia

Fundamental Characteristics of multimedia information • Large data volume • Typically delay sensitive • But loss tolerant  infrequent losses cause minor glitches

Consideration of Networked Multimedia

• Suitable for unexpected burst of data no need to establishing an explicit connection

• Limitation of bandwidth Bandwidth is shared statistically so data can be sent at any time Causing Queuing delay, especially when congested

• Best effort network IP network is not reliable, cannot guarantee quality of multimedia applications

• Heterogeneity Different user network conditions

Requirements for Networked Multimedia

Challenges of multimedia networking

• Conflict between media size and bandwidth limit of the network • Conflict between the user requirement of multimedia application and the best-effort network • How to meet different requirements of different users?

Technologies of Multimedia Networking

• Media Compression – reduce the data volume Address the1st challenge • Image compression • Video compression • Audio compression

• Multimedia Transmission Address the 2nd and 3rd challenges • Protocols for real-time transmission • Rate / congestion control • Error control

Characteristics of multimedia • Digital – key concept • Integration of multiple media types, usually includes video or/and audio • May be interactive or non-interactive

Multimedia Networking Systems

• Live media transmission system (Stream)  Capture, compress, and transmit the media on the fly

• Send stored media across the network  Media is pre-compressed and stored at the server. This system delivers the stored media to one or multiple receivers.

• Differences between the two systems  For live media delivery: o Real-time media capture, need hardware support o Real-time compression– speed is important o Compression procedure can be adjusted based on network conditions

 For stored media delivery o Offline compression – better compression result is important o Compression can not be adjusted during transmission

Multimedia networking: 3 application types

• streaming, stored audio, video  streaming: can begin play-out before downloading entire file  stored (at server): can transmit faster than audio/video will be rendered (implies storing/buffering at client)  e.g., YouTube, Netflix, Hulu

• conversational voice/video over IP  Interactive nature of human-to-human conversation limits delay tolerance  e.g., Skype

Media Steaming Media streaming merupakan media digital (berupa video, suara dan data) agar bisa diterima secara terus-menerus (stream). Data tersebut dikirim dari sebuah server aplikasi dan diterima serta ditampilkan secara real-time oleh aplikasi pada komputer klien Streaming sering disebut dengan streaming media.

Topologi Streaming

Jenis Streaming Live Streaming • Data yang dikirimkan langsung kepada klien dari broadcaster (sumber) walau melewati streaming server. On-Demand Streaming • Data dari broadcaster disimpan terlebih dahulu kedalam sereaming server, baru kemudian diakses oleh klien.

Generic Media Streaming System

Generic Media Streaming System

• Proses percakapan tersebut menggunakan istilah coding dan decoding. • Proses coding dilakukan oleh server sedangkan decoding dilakukan oleh klien. • Proses coding dilakukan untuk mengkompresi data sebelum dikirim ke klien melalui Internet, dan decoding dilakukan oleh klien untuk ditampilkan data tanpa kompresi, pada klien terjadi proses buffering. ● Proses tersebut sering disingkat menjadi codec.

Kendala Streaming • Kendala-kendala yang terjadi dalam melakukan streaming multimedia biasanya terletak pada Bandwith dan Sinkronisasi (delay). • Bandwith sangat berpengaruh terhadap kualitas presentasi suatu data stream, yang perlu diperhatikan adalah ukuran dari data stream harus sesuai dengan kapasitas bandwith jaringan. Untuk mengatasinya yaitu dengan menggunakan kompresi data dan penggunaan buffer.

• Agar media yang berbeda dipresentasikan sampai pada user sama seperti aslinya, maka media tersebut harus tersinkronisasi sesuai dengan timeline presentasi tersebut dan delay seminimal mungkin, delay yang buruk biasanya disebabkan oleh jaringan yang buruk sehingga timeline presentasi menjadi kacau.