Internet radio technology
Streaming
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.
Types
of radio that stream
Sites that aggregate links of
Internet radio broadcasts enable listeners to find internet
broadcasts by genre, language, or location. If looking for
traditional radio that streams online, you can use
RadioTime. It also aggregates radio station schedule
information, popular radio show topics, and access to radio
personalities that offer podcasts. The
Radeo Internet player includes a database with more than 500,000
broadcast, webcast, and podcast streams; search; and a player.
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
XMMS 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.
Audio
quality
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.
User
ratings
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.
You can also rate traditional
radio stations and radio programs that stream at a site like
RadioTime.
Portalcasting
Portalcasting
is a full featured
broadcasting service transmitted via the
Internet. Portalcasting stations broadcast more visual content
and sensory gratification for the listener than typical internet
radio stations. The music is high definition and the site supports
the station with active time displays of current song, requests,
dedication, games and other visual supporting content. Portalcasters
provide services via internet sites, cable tv systems and wireless
providers.
Podcasting
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. |
