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| Using PlayStream to deliver live audio/video
instills the edge you need to stand out above the
competition. We’ve built a high capacity, high quality,
distributed network that directs your end users to
the closest available datacenter;
and each data center has many different major
carriers from which to route your data. The end
result is that your end users experience a better
viewing performance. Broadcasting live with PlayStream
is simple and requires text industry tools that are
easily available and affordable. |
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| 1. Capturing Your Live Broadcast
To A Digital Format |
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The first of these steps is to capture
your media. In order to do this, you will need
an input device for your computer. For audio content,
the input device can be a text sound card. For
video content, you will need some type of video
capture device.
Examples of typical video capture devices are a
firewire port (firewire card) or a video capture
card. Common video capture cards that we know
work are the Osprey 220 from ViewCast
or capture cards from Winnov
or Pinnacle.
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| 2. Converting Your Live Broadcast
To A Streaming Format From An Encoding Station |
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An encoding station is simply a computer
that runs encoding software (the "encoder")
that converts your captured media to a streaming
format. Most encoders require a reasonably fast
computer to run. Normally a Pentium II with at
least 128 MB of RAM is good if you're a PC user
but, as always with computers, faster is better.
Typically, We recommend that you use the encoding
software that is provided by the manufacturer
of the streaming format you have chosen. That
is if you are a Windows user broadcasting a live
Windows Media stream, we suggest you use the Windows
Media Encoder. If you are broadcasting your
content in RealMedia
format, please use the newest encoder available
for your operating system. For QuickTime
Streaming we suggest the QuickTime Broadcaster
for Mac OSX.
During a live streaming media broadcast the encoding
software (the encoder) takes the data from your
input device and converts it to a streaming format.
Depending on the streaming platform (Windows Media,
RealMedia or Quicktime) the server either "pulls"
(contacts the encoder and requests the stream)
or the encoder "pushes" (sends the stream
to the server IP address) to rebroadcast the live
stream. When the encoder converts the stream,
it "buffers" (saves a certain amount
of the stream data on the encoding work station)
before the stream is distributed for rebroadcast
through the servers in our data centers. This
creates a certain amount of "latency"
(lag time between the actual event and when your
audience member sees it.) There are two other
sources of latency during a live streaming media broadcast.
The time it takes to get the stream across the
Internet to our servers and the time it takes
your audience member to receive the stream across
the Internet. These vary according to the position
of your encoding station on the Internet and the
position of the computer of each of your audience
members.
When you set up your stream for live broadcast,
you must specify the bit rate (quality of the
stream). This quality is constrained by the upstream
bandwidth of your Internet connection and cannot
exceed this limit or your stream will never reach
our servers. Along the same lines, your audience
member must have enough downstream bandwidth to
allow all of the data from the encoded stream
to play on their computer. If the encoded stream
you are sending for rebroadcast exceeds the downstream
bandwidth of your audience member, they will never
receive the stream. |
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| 3. Broadcasting Live Through Our
Content Delivery Network |
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Depending on how the servers are setup
they will deliver the media stream in one of two ways.
Either as a push configuration where servers are
continuously sent a stream from the encoder, or
in a pull configuration. A pull configuration
makes a connection and "pulls" the stream
when a player connects to it. Regardless of which
configuration is being used (the Windows Media
Server uses "pull" while the RealServer
and Darwin Server for QuickTime use "push".)
Once the feed is acquired on the inbound streaming
server it is re-distributed throughout our two
data centers via load-balancing.
When you set up your account, we send you a link
to access your broadcast through our globally
load balanced easy link system and you put this
link into the HTML of your Web page. when someone
visits your Web site and clicks a link for streaming
audio or video, that request is directed to the
data center closest to them and they stream your
live broadcast through our servers.
By directing your audience member to the closest
data center, we cut down on the time it takes
to deliver your stream to them. Once the closest
data center has been established, the streaming
request is sent down one of the many backbones
we are connected to via Internap's advanced "Synchronous-When-Optimal"
routing service. Our system delivers your media
by avoiding the often congested public and private
peering points of the Internet, thus greatly increasing
delivery performance and reducing problems such
as rebuffering. |
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| 4. Delivering Your Live Stream To
Your Audience |
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| When a streaming media Player makes a
connection to one of our streaming servers via our
easy link technology or a reference file (RAM for
RealMedia, ASX; WVX or WAX for Windows Media; or QTL
for QuickTime), the server sends the player data via
User Datagram Protocol (UDP) by default. If the streaming
media player cannot accept this data, the server tries
to resend it via the TCP protocol to several different
ports, with port 80 as it's final attempt if each
attempt fails. This process is called protocol rollover.
If this negotiation is successful, and the server
is either Windows Media or the RealServer, a check
is made for the connection speed configured in the
connection settings of the streaming media player.
Based on the connection speed returned to the server
from the player, the server will send the highest
play supported stream from a multiple-bit-rate streaming
file, the whole file in the case of a single-bit-rate
streaming file, or just the audio portion of an audio/video
streaming file if the player connection speed is not
fast enough to accept all video data. |