Streaming in a Nutshell

I had heard the word ‘streaming’ almost two years before (in 2005) when I was in Pulchowk Hostel. It was the first time that I was using internet in my own computer, Room No 317A-Block, New Boys Hostel, IOE,Pulchowk Campus. In this article, I am going to discuss about streaming.

May be you have already listen radios, news, movies using streaming but may not notice what it is. I usually play BBC Nepali news via Real Player. Yes, that is one example of streaming. Server computer sends the requested item to the client in server client model. For example, when you access the yahoo page using your browser, the browser shows the content to you which are provided by yahoo server. Let me describe a little more how you are getting that data on your browser. When you request any page through browser, it connects the server that you provide. The server sends the data to you packet-by-packet. A packet is nothing but a small piece of the content that you are requesting for.

Let’s enter into Streaming. Streaming takes files-whether they are sound, video, animation or other media types- breaks them up into smaller pieces and sends them to their destination. This is very similar to how computers send information access a network or the Internet in general. [1] In the following paragraphs, I refer some web pages to solve the basic questions about streaming.

So what is a stream?

Streaming provides a mechanism that allows you to watch the movie or to listen music without downloading the whole file. Above we explain what streaming does, but not exactly what it is. At least, not what it is for RealPlayer. Each stream carries specific types of information. When you watch a video the visual part, what you watch, comes to you in one stream while the sound comes in another.

What is life streaming?

Life streaming means continuous data delivery. To guarantee a smooth playback, each data packet must be delivered with a strict deadline. [2]

How can I prepare an audio streaming?

Figure: Creating an Audio Stream [1]

As shown in figure, there are four steps to create an audio stream. Each step is described below: [1]

Step 1: Capture Audio

This step records or creates an audio which is going to change into audio stream later.

Step 2: Edit the Capture Data

Content provider adds or removes some contents on the recorded audio from step1.

Step 3: Encoding

Encoding is the process of getting file ready to be streamed. It takes a file as input and breaks it up into readable packets so that it can be sent and read. Every clip or every stream in a clip is encoded for a specific bit rate. The higher the resolution (the more information) a stream has, the higher the bandwidth it needs to get the information through to you at a useable speed.

The edited file in step2 is encoded into a stream. It means that the file is prepared to be streamed.

Step 4: Deliver the clip

The encoded file is placed on a Server to serve so that the streaming client can play it for you.

How stream players play the streamed audio?

Well, the following figure clearly shows how the process works. In this example, I just copied the figure from [2].

Figure: How a Real Player plays the streamed audio

Steps:

Step1: Open webpage say http://www.bbc.co.uk/nepali

Step 2: Click Listen Online (Chose to Daily News)

Step 3: Browser knows that the media is streamed and handovers to

RealPlayer/Windows Media Player according to your setting.

Step 4: RealPlayer plays the streamed audio.

References:

[1]. http://service.real.com/help/player/plus_manual.8/htmfiles/whatisrpp.htm#20306

[2]. http://www.cs.iastate.edu/~tobyxu/research-PLP-ROA.htm

What is Wireless Mesh Network?

A wireless network that relies on all the nodes in the network to propagate signals. Although the wireless signal starts out at some base station (access point) attached to the wired network, a wireless mesh network extends the transmission distance by relaying the signal from one active device to another. Although this type of network has been used on the battlefield for path diversity for years, it is used today for sensor networks and can be used for personal computers. See mobile ad hoc network and wireless LAN.


Whereas the Internet is mostly a wire-based, co-operative electronic communication infrastructure similar to the international postal agreement, in that messages are mutually delivered and relayed within their separate domains free of charge (i.e. if you relay my messages within your domain I'll relay yours within mine), Mesh is a wireless co-operative communication infrastructure between a massive amount of individual wireless transceivers (i.e. a wireless mesh) that have Ethernet type capabilities.

Note: All above contents & figures are taken from [2]

Following figure clearly shows overall picture of mesh network, how it is connected to internet and how it connects to mesh clients.

Figure: Hybrid Mesh Network [1]

Wireless Mesh backbone: This is the upper large ellipse in the figure. It connects internet (on upperside in fig.) and client meshes on other sides. It consists of wireless mess routers and mesh routers with gateways/bridges.

Wireless Mesh Clients: Mobile ad hoc network (MANET) consisting of Wi-Fi, Wi-Max, Sensor Network, Cellular Network, as well as Conventional Clients as shown in figure.

Reference:

[1] Ian F. Akyildiz, “A survey on wireless Mesh Networks,” IEEE Radio Communication, Sept. 2005, pp. xxx-xxx.

[2] http://www.answers.com/main/ntquery?s=wireless+mesh+network&gwp=13

Difference between Wireless Mesh Network and Mobile Ad hoc Network

Wireless mesh networks (WMNs) have been proposed as an effective solution for ubiquitous last-mile broadband access. WMNs are characterized by static mesh routers connected by wireless links to each other, each providing connectivity to end hosts. The cost and deployability of WMNs make them particularly attractive for providing last-mile broadband access in rural and suburban areas. The main difference between WMNs and other multi-hop wireless networks such as mobile ad-hoc networks and sensor networks are that the routers in WMNs are static and typically not power-constrained. This shifts the focus of routing from dealing with mobility to finding high throughput routes. MAP currently consists of 32 nodes and is capable running in both 802.11a or 802.11b/g mode. MAP has been recently enhanced with multi-radio support for higher capacity.

Source: https://engineering.purdue.edu/MESH