Knowledgebase: Real Audio/Video
What
is Real Audio/Video?
RealAudio and RealVideo technology utilizes an interactive system between
the RealVideo Server and the RealPlayer to enable real-time audio and
video delivery over the Internet. When the user clicks on a link on a
Web page, the clip buffers and then begins to play, all within a few seconds.
This gives the deceiving impression that the file is linked directly to
the Web page. In reality, information is passing between the Web server
supporting the Web page, the RealVideo Server supporting the file, and
the RealPlayer.
What
is a Metafile and how does it work?
Metafiles are text files which contain the URL location of a RealAudio
or RealVideo file. Remember that RealAudio and RealVideo files cannot
be referenced directly by the Web page because this would cause them to
be downloaded in their entirety before playback. In order for the files
to be played in real-time, they must be played through a RealPlayer, and
served by a RealVideo Server. Therefore there must be a link between the
Web server and the RealVideo Server. The link is contained in the metafile.
How
does streaming audio/video work?
The file itself is not linked through the web page, contrary to general
belief. Information actually passes between the web server, the RealServer,
and the RealPlayer. RealAudio and Video can only be retreived by the RealPlayer.
If you have a link to the actual file on your server, the file will be
downloaded completely before it can be played by the RealPlayer. There
needs to be a go between between the web server and the Real Server. This
go between is a metafile. This metafile provides the URL of the file to
be played to the RealPlayer.
What
is the correct path for Real Audio on the Burningbulb servers?
Typically you'll create a realaudio file subdirectory under domain-www,
and put all your audiofiles there. Then your .ram file, a.k.a., metafile,
will contain an address with this format:
http://fulldomainname/subdirectory/filename.rm
The "subdirectory" is a subdirectory of your domain-www directory.
So for example: http://musicforyou.com/ra/music.rm
The above address goes in the .ram/metafile, not in your HTML code. Your
HTML code calls the .ram/metafile. Then the .ram/metafile is used to call
up the .rm/realmedia file. So for example, your HTML code would look something
like this:
<a href="http://musicforyou.com/ra/music.ram">Click here
to listen to music.</a>
Since
RealServer software is not on the Burningbulb servers can I still stream
Real files?
Yes, you will be able to stream RealMedia files. You will need to create
a .ram file that calls your real audio/video file. The .ram file is a
text file with an absolute URL. This URL will need to be:
http://full.domain.name/directory/filename.rm
Is
there a difference between streaming using PNM-protocol and HTTP-protocol?
If you visit http://www.real.com/, you might come across a term called
"pseudo-streaming". According to audiohost.com:
"Pseudo-streaming" is a discriminating name for HTTP-stream.
It was invented by the RealAudio promotion to suggest that you need to
use the RealAudio server if you want to get "real" streaming.
Here's a free translation: "Streaming RealAudio files without using
RealAudio server software". That's all there is to it! The RealAudio
server actually has some special features that cannot be achieved (in
RealAudio) without it. Regarding "streaming" we cannot find
a difference between the two protocols.
What
are some of the special features of the RealServer?
With the Real Server, you are able to take advantage of "bandwidth
negotiation". This feature takes into account the bandwidth of the
surfer's Internet connection when clicking on the hyperlink that requests
the RealMedia file. Depending on the connection, the RealServer will provide
a different version of the RealMedia file that best suits the visitor's
bandwidth connection. You also need the RealServer to broadcast live on
the Internet.
How
do I get around around not having "bandwidth negoations"?
While encoding, if you set the target audience to 28 K modem, you will
be able to reach the largest audience possible. If you want your higher
bandwidth connection visitors to receive better quality recordings, you
can always create a second link to a RealMedia file that is encoded with
a target audience of a higher bandwidth connection.
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