Pointer file - Push
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Pointer file:
A text file containing URL's
of media file locations, and proprietory information about the stream.
Sometimes called a meta
or reference
file, the most common ones have file extention .asx for Windows
Media .ram for Real
Media and .qtl for QuickTime.
Port:
A logical channel used for communicating information over a protocol
on a network interface.
Port Forwarding:
A way of negotiating a route through a firewall or router. e.g. A
broadcast from a computer on a internal network can have port forwarding
set up in order for the broadcast to appear to an external audience.
Progressive Download:
The playing of media whilst it is still being downloaded. Playback
commences only when enough data has been downloaded to sustain playback
of the full video without any loss of quality. This differs from true
streaming. It has the advantage of "almost" eliminating
buffering,
although disadvantage of delaying the start of playback.
Protocol:
Instruction set for the transfer of data. The common streaming protocols
are RTSP,
MMS
and HTTP.
Pull:
A connection made by a streaming
server or client computer to receive a broadcast
from an encoder
in order for re-distribution of a webcast.
Push:
A connection instigated by an encoder
to a streaming
server requiring a username and password. The streaming
server then re-distributes the
webcast.
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Pointer files
Pointer files are used to indicate to a web browser what they should
do with a particular file type. If these were not used and a direct
link to a streams URL is given, then errors may occur.
The contents of a pointer file is generally very basic with a couple
of instructions indicating where the stream is, and what protocol
to use, however they can contain all sorts of extra meta information
such as copyright notices, author and content descriptions, failovers
for different protocols and alternatives servers to use if capacity
limits are reached.
Pull vs Push
A "pull" stream is more economical in some instances because
the streaming server only connects when someone tunes in to the stream.
If nobody is watching, then no data is transfered.
A "push" does not require a static IP address, and is easier
to troubleshoot if a probelm arises.
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