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Llama Ahora 1
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This article describes a simple and comparatively
inexpensive way to build an Internet radio station that streams live
audio over the Internet. Internet radio generally is an audio stream
that sounds like an over-the-air radio station. It is difficult to
put a label on exactly what Internet radio is because, unlike
traditional over-the-air radio, you can create an Internet radio
experience in a number of ways, including:
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Live stream. You start with the
over-the-air model of a radio station, but instead of plugging the
program audio signal into a transmitter that sends the signal over
the airwaves, you plug it into an encoder and server that send the
signal over the Internet. In the following figures, the solid line
arrows indicate the path of the live signal or stream; the broken
line arrows indicate file transfers.
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Figure 1. Live stream type of Internet radio |
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The end-user experience is like listening to
a traditional over-the-air radio station.
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Automated program signal. Many
over-the-air radio stations use automation to create program
content. Production personnel and announcers produce individual
audio segments (such as music, announcer voice-overs, and
commercials), and then create a playlist that an automation system
uses to play the segments. These automated systems can also be
used for Internet radio. The output of the automated system is a
program audio signal.
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| Figure 2. Automated-program-signal type of
Internet radio |
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- Simulcast. Many over-the-air radio stations both stream
and broadcast their signals, in a process called simulcasting.
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| Figure 3. Simulcast type of Internet radio |
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Although a simulcast stream is technically not an
Internet radio station because it is intended primarily for
over-the-air delivery, the end-user experience is the same.
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Broadcast server-side playlist. This is
another form of automation. The difference is that with automated
radio, a live stream is encoded from the program signal produced
by an automation system. With a broadcast server-side playlist,
there is no live audio signal; individual program segments are
encoded into Windows Media Audio (WMA) files and the playlist is
run on a server running Microsoft® Windows Media® Services, so the
server is the automation system.
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| Figure 4. Broadcast-server-side playlist type of
Internet radio |
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On-demand playlist. This is a third form
of automation in which the automation system creating the Internet
radio experience is Microsoft Windows Media Player. Individual
audio segments are produced, and then encoded to Windows Media
Audio (WMA) files. The playlist is created in a Windows Media
metafile with an .asx extension; the Player downloads the file and
plays the items in the playlist.
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| Figure 5. On-demand playlist type of Internet
radio |
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| One advantage of an on-demand playlist is that the content can be
streamed from any server. |
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