Because the radio signal is relayed over the Internet, it is possible to access the stations from anywhere in the world—for example, to listen to an Australian radio station from Europe or America. This makes it a popular service for expatriates and for people who have interests that may not be adequately catered for by their local radio stations (such as progressive rock, anime themed music, 24/7 stand up comedy, and others). Some of the internet radio services offer news, sports, talkback, and various genres of music—everything that is on the radio station being simulcast over the internet with a netcast stream.
Internet radio technology
One of the most common ways to distribute internet radio is via streaming technology using a lossy audio codec. The MP3 codec is most popular, followed by Ogg Vorbis, Windows Media Audio, and RealAudio; use of HE-AAC (sometimes called aacPlus) is gaining in popularity. The bits are "streamed" over a TCP/IP connection, then reassembled and played within about 2 seconds. Therefore, streaming radio has about a two-second lag time.
There are three major components to an audio stream:
Audio stream source.
Audio stream repeater (server).
Audio stream playback.
Creating a stream
There are many methods for creating the audio stream source. Those more technologically savvy may opt for the SHOUTcast service, which utilizes Winamp and the SHOUTcast DSP plugin to deliver MP3 audio at higher bitrates. Other methods include open source technologies such as Streamcast, stream-db, IceS, and MuSE, and patent-free data formats such as Ogg Vorbis. Using open source stream source tools allows for interesting web interface possibilities like phpStreamcast.
Two of the most popular internet radio networks are Live365 and SHOUTcast. Open source alternatives include Icecast and Xiph.org, which include Ogg Vorbis streamings (that can be played by Winamp and Zinf). Collectively, these internet radio servers list thousands of Internet radio stations covering an ever-expanding variety of genres. The purpose of the server is to repeat the stream source to the audio playback software.
What you need to listen
Some sort of audio playback software or hardware, that is capable of reading HTTP data streams, is needed to listen to streaming MP3 audio. Some popular software players are Winamp for Windows, iTunes for Macintosh and Microsoft Windows, and Amarok or Rhythmbox on Unix/Linux. Listening to internet radio through stand-alone hardware devices has not been very popular in the past, due to the limited number of devices on the market, though the availability of such devices and their consumer popularity is expected to increase significantly during 2006. Here is a list of commercially available Internet radio devices. Many of these are limited in which audio codecs they can use and consequently the variety of internet radio stations they are compatible with although the number of codecs being used today is becoming somewhat limited due to the inevitable commercial process.
There is a tradeoff between audio quality and audience size. Stations that encode their streams at a lower bitrate have lower audio quality, but they are more accessible to listeners with a dialup connection, and they can serve more simultaneous users on a given upstream pipe. The compression algorithms of newer codecs such as AAC and AACplus attempt to address this issue by producing higher quality sound with a lower bit-rate.
There are also a small number of web radio programs that allow users to rate the songs they are listening to. This allows a user's music listening choices to be correlated against those of others, as with the programs iRATE radio, Last.fm, and Radio Paradise.
Audio and video programmes resembling those of radio and TV can also now be distributed by podcasting which can be published by various means including RSS feed and P2P clients.
The first Internet "radio station", Internet Talk Radio, was developed by Carl Malamud in 1993. Malamud's station used a technology called MBONE (IP Multicast Backbone on the Internet). Later that year, Austin Arts BBS began broadcasting pre-recorded information for members of the screenprinting community and artists from a Bulletin Board System in Austin, Texas. Austin Arts BBS, originally created in 1983 by Bill Hood was the first online screenprinting community. Hood created the first online radio presence for the screenprinting industry with Screenprinters Radio which featured interviews, stories, tips and tricks as well as music. In 1994, the Voice of America became the first broadcast news organization to offer continuously updated programming on the Internet.
In February, 1995, the first full-time, Internet-only radio station, Radio HK, began broadcasting the music of independent bands. Radio HK was created by Norman Hajjar and the Hajjar/Kaufman New Media Lab, an advertising agency in Marina del Rey, California. Hajjar's method was to use a CU-SeeMe web conferencing reflector connected to a custom created audio CD in endless loop. Later, Radio HK converted to one of the original RealAudio servers.
WXYC (89.3 FM Chapel Hill, NC USA) was the first radio station to announce broadcasting on the Internet on November 7 1994. WXYC used an FM radio connected to a system at SunSite, later known as Ibiblio, running CU-SeeMe. WXYC had begun test broadcasts and bandwidth testing as early as August, 1994. WREK (91.1FM, Atlanta, GA USA) also claims to have started streaming on November 7, using their own custom software called CyberRadio1, although the stream was not advertised until a later date.
KJHK 90.7FM in Lawrence, Kansas, began to stream its live broadcast using CU-SeeMe on December 3, 1994. KJHK was the first radio station to maintain a continuous, live signal over the Internet. This has been verified by the National Association of Broadcasters, Sports Illustrated, and CNN.
KPIG also began to transmit a live, 24/7 feed, in August 1995, first using Xing Streamworks and later switching to RealAudio. Bill Goldsmith, who was KPIG's Operations Manager & morning DJ at the time, and the one responsible for starting the webcast, now operates the popular Internet station Radio Paradise.
Netradio (Net.radio, NetRadio, NetRadio Network) founded by Scott Bourne and radio veteran Scot Combs in 1994. Netradio began the first all internet radio network using RealAudio 1.0 in November of 1995. Starting out with four formats and expanding to more than a dozen two years after. The radio network became so popular it was included as a preset in RealAudio (aka RealMedia) 2.0+ players. NetRadio was the first Internet Radio network to receive an experimental license from ASCAP which later became a standard license for all online radio stations. In July of 1996 NetRadio accomplished another first by offering the first weekly live internet only concert series hosted by NetRadio Webmaster Nathan Wright.
WUEV launched its live simulcast in January 1996, also using the Xing Streamworks technology at first, then adding RealAudio and moving from the Xing platform to Windows Media Technologies as equipment (and budget sizes) changed.
The first radio station to stream 24-hours a day in Europe was the UK's Virgin Radio, who started streaming a live simulcast using Real Networks in March 1996.
Tuning in to a broadcast like a traditional radio is not possible on internet, so finding different broadcasts has to be done with a search engine or a website that collects on-line radio broadcasts.
In 1996 GBS Radio Networks, founded by radio veteran Guy W. Giuliano, was one of the first to launch an internet radio programming service. The firm syndicated two commercial formats, hip-hop station BombRadio, and hard rock format LoudRadio. In 1998, GBS was purchased by Kent Kiefer's eMusic corporation in a highly publicized cash and stock deal. In 1999, LoudRadio.com became the first online radio station to be syndicated on a commercial broadcast station via KLOD-FM in Flagstaff, AZ.
In 1999, one of the first University/College stations to operate was in Antigonish, Nova Scotia at St. Francis Xavier University CFXU.
In 1999 a company called BMP released a tool, the MyCaster, that allowed people without much technical knowledge to operate their own internet radio stations. The MyCaster was a software MP3 player, similar to Winamp, which streamed the music that a person was listening to, utilizing the Mycaster website to list the stream. Like many early Internet radio endeavors, MyCaster succumbed to the dot com bust in 2001.
Peercasting uses P2P technology. Its requirement of communicating a URI before transmission and the lack of a centralized repository of such addresses reduced peercasting's widespread adoption.
Mercora IMRadio, a combination of social networking and Internet radio, streams music in the Ogg Vorbis format. Mercora allows users to webcast music and pays royalties to the copyright collectives such as ASCAP, BMI, SESAC, and SoundExchange.
RadioVague, in 2003, acquired a transportable satellite internet broadcast system and started broadcasting live shows from events and music festivals around Europe using only free and open source software, broadcasting in OGG/Vorbis format using Icecast and Icecast2 servers, their first event being the February 15, 2003 anti-war protest. Since then they have extended their distribution platform to allow both traditional FM radio stations and other internet radio stations to achieve a global audience.
In 2004, one of the more popular torrent websites, SuprNova, partnered with an amateur internet radio group and formed SuprNova Radio.The radio station was operated by an amateur DJ staff, which usually consisted of converted listeners, who worked on a voluntary basis. Much of the content played on the station was gathered from pirated material.
Most on-air stations broadcast the same commercial advertisements on their internet radio players. The costs of royalties and delivery are covered by the advertiser's payment to the station.
Others, which have no advertisements, like the BBC, simply send out their stream. The BBC is funded by the Television license which must be paid by all owners of a television in the United Kingdom. This fee funds the operation of the BBC's television radio and internet services. It should be noted however that the BBC is looking at methods of charging international users of its content through its commercial arm BBC Worldwide.
Other stations and shows charge a subscription monthly fee or a direct per-program fee for the internet radio broadcast.
More....( Courtesy: Wikkipedia )