A Pre-Roll / gateway file is a stand alone audio/video file that plays first
when a user connects to your stream. There are several purposes for a
pre-roll/gateway file depending on your type of broadcast.

For example, let's say that you are a non profit organization and depend on
donations from the general public in order to fund your day to day
operations, including streaming. You could use a pre-roll / gateway file to
give to those tuning in a quick donation plug ("Funding for our stream
comes from generous donations from out listeners like you...").

Or let's say you are a main stream broadcaster. You could use a pre-roll /
gateway file to give a quick station ID ("You've just connected to the KRUD
99.5 FM live web stream...") or a even a station advert or program line up
("KRUD 99.5 Walla Walla's #1 Rock station!" or "...Don't forget to listen in
at every Wednesday at 10AM when you'll hear Cosmic Charley play the
album of the week").

No matter what type of broadcast you are doing, pre-roll /gateway files are
a useful tool in getting information about your stream to the user before
they are actually connected to it.

And adding a pre-roll / gateway file is not as difficult as it sounds. The
simplest way to do so is by using a play list file. All play list files are
designed to play what ever media is listed within them in a sequenced
manor. And the play list file doesn't care of it's a single independent file,
or a live stream, it will still play them in the order in which they are listed.
So, you just add your pre-roll / gateway file as the first item on the play
list.

And then add your stream as the second. It's that simple. The pre-roll /
gateway file will play first, then the play list will connect the user to your
live stream.

You can even add a file after your stream's link called a "post-roll". The
post roll file would contain a message stating something like "KRUD's
stream is currently experiencing technical difficulties and should be back up
shortly...Thank you". How this works is that should the play list not be
able to connect to your stream, it will skip past it and on the the next time
on it's list (the post roll file).

Keep in mind though that in general, the type of play list files used is
always going to be dependent on the type of stream you have. For more
information on creating play list files, click here.

When creating your pre-roll or post roll / gateway file(s), there is one
important thing you'll need to remember. Some players have trouble when
switching from a file that's encoded at particular bitrate and sample rate,
over to a live stream that is being encoded at a different bitrate and
sample rate. So, for best results, your pre-roll / gateway file(s) will always
need to be encoded at the exact same bitrate and sample rate that you are
stream is set for. Otherwise, once the pre-roll / gateway file plays, then
your stream may not play.