Review on Basic Streaming Technologies

Introduction

The process of playing a file while it is being downloaded is known as streaming. Streaming technology allows a user to view and hear digitized content like video, sound and animation while it is being downloaded. It must be noted here that users are allowed to watch content without downloading the entire media file. This process is also known as streaming media. A world-wide web user plug-in can allow the playing/downloading of media at the users click. The Internet is home to various media file types which are used for the purpose of applications involving entertainment or video conferencing applications or video archiving applications or applications for remote learning or video on demand.

Functioning/Working

Links referencing a media hosting website are added to a website by a web designer. When one of these links is clicked upon the user, the media content is streamed directly to the watcher’s PC as though this content was coming from the original website. This is because a separate network hosts the media files and therefore streaming does not have any impact on the web servers. When a user logs in to a hosted streaming network he/she is automatically fed content from the closest available server on the INTERNET.

Streaming Technology: Protocols used for Streaming A protocol is a set of rules that governs the communications between computers on a network. In order for two computers to talk to each other, they must be speaking the same language that is following the same protocol for communication. Protocols define the packets thats are exchanged during communication. Streaming protocols that are studied in this paper are as follows:-

• Session Description Protocol(SDP) The session description protocol is essentially used to describe multimedia sessions in a format understood by the participants over a network.
• Depending on this description, a party decides whether to join a conference or when or how to join a conference.
• The owner of a conference advertises it over the network by sending multi cast messages which contain description of the session e.g. the name of the owner, the name of the session, the coding, the timing etc.
• Depending on these information, the recipients of the advertisement take a decision about participation in the session.
• The owner of a conference advertises it over the network by sending multicast messages which contain description of the session e.g. the name of the owner, the name of the session, the coding, the timing etc.
• Depending on these information, the recipients of the advertisement take a decision about participation in the session.
• SDP is generally contained in the body part of Session Initiation Protocol popularly called SIP. SDP is defined in RFC 2327.
• An SDP message is composed of a series of lines, called fields, whose names are abbreviated by a single lower-case letter, and are in a required order to simplify parsing.
• Motivation for SDP The motivation behind SDP is to define information about multimedia sessions for the purposes of session announcement, session invitation, and other forms of multimedia session initiation.

SDP is a short structured textual description. It conveys the name and purpose of the session, the media, protocols, codec formats, timing and transport information. A tentative participant checks these information and decides whether to join a session and how and when to join a session if it decides to do so. The format has entries in the form of = , where the defines a unique session parameter and the provides a specific value for that parameter. The general form of a SDP message is − x = parameter1 parameter2 ... parameterN The line begins with a single lower-case letter, for example, x. There are never any spaces between the letter and the =, and there is exactly one space between each parameter. Each field has a defined number of parameters.

Description Parameters for the Session v= protocol version o= owner/creator & session identifier s= session name i= *(session information) u= *(URI of the descriptor) e= *(email id) p= *(phone number) c= *(connection information – not required if included in all media) b= *(bandwidth information) z= *(time zone adjustments) a= *(zero/more session lines)