Chapter 7: Broadcasting Presentations

Concerts, presentations, speeches, can all be encoded and broadcast to clients almost instantaneously. Live presentations can be archived for later reference or later broadcast. For example, you can archive an event that happens in one time zone and then play it later for viewers in a later time zone with the G2SLTA tool.

Overview

Streaming live content is much the same as streaming static content. The only difference is the live file never actually exists. It is streamed as it's encoded, and a file is never actually created. Visitors who click a link to a live broadcast join the event as it happens, and everyone sees the same content at the same time.

RealServer can save a copy of all live broadcasts automatically, or it can save only broadcasts with specific virtual directory names.

Use the Simulated Live Transfer Agent (G2SLTA) to broadcast a stored file as if it were live. Events broadcast with G2SLTA appear to be live; everyone sees the same part of the broadcast at the same time.

Tip
RealBroadcast Network™ (RBN) provides full services for encoding and broadcasting events to a few or a few thousand viewers. See http://www.real.com/rbn for details.

	Tip
RealBroadcast Network™ (RBN) provides full services for encoding and broadcasting events to a few or a few thousand viewers. See http://www.real.com/rbn for details.

Live Broadcasting

Setting up RealServer to broadcast live files consists of four steps:

Configuring RealServer broadcasting mount points.
Configuring RealServer port settings.
Configuring the encoder.
Placing the correct link on the Web page or SMIL file.

Additional Information
Instructions on using RealSystem Administrator to modify RealServer is found in "Customizing RealServer".

	Additional Information
Instructions on using RealSystem Administrator to modify RealServer is found in "Customizing RealServer".

To configure G2 encoder mount points:

In RealSystem Administrator, click Broadcasting. Click G2 Encoders.
To change the mount point, modify the value in the Mount Point box. The G2 encoder typically uses the /encoder/ mount point.
Give the port number to which the encoder will send its live data by typing a number in the Port box. For RealSystem G2 encoders, a typical value is 4040. If you change this value, be sure to give the new port number to content creators.
If you have event files that you want to combine with your live stream, type their location in the Associated Media Path box. Any files in this directory with the same name as an incoming live stream will merge their events with the live stream.
Content creators using RealSystem G2 encoders can have individual user names and passwords. If you will be requiring user names and passwords from encoder connections, select the name of the appropriate realm from the Encoder Authentication Realm box. A typical realm for encoders is EncoderRealm. Select None if you do not want to require user names and passwords from encoders.

Additional Information
Realms and authentication are described in Chapter 10: Authenticating RealServer Visitors.
When you have finished making changes, click Apply.

	Additional Information
Realms and authentication are described in Chapter 10: Authenticating RealServer Visitors.

To configure pre-G2 encoder live settings:

In RealSystem Administrator, click Broadcasting. Click Pre-G2 Encoders.
To change the mount point, modify the value in the Mount Point box. The pre-G2 encoders use the /live/ mount point.
Give the port number to which the encoder will send its live data by typing a number in the Port box. For encoders created before version G2, a typical value is 5050. If you change this value, be sure to give the new port number to content creators.
If you have event files that you want to combine with your live stream, type their location in the Associated Media Path box. Any files in this directory with the same name as an incoming live stream will merge their events with the live stream.
Encoders developed before RealSystem G2 are able to supply passwords, but no user name. To require a password for older encoders, type the password in the Password box. The value was initially established during setup. All encoders connecting to the older encoder port will use this same password.
If you change the password, be sure to tell content creators what password to use.
When you have finished making changes, click Apply.

To configure the ports:

Ensure that the settings for HTTP Port, PNA Port and RTSP Port are correct. These indicate where requests will arrive at RealServer, and the links you create will need to match them.

Additional Information
See "Port Variables".

	Additional Information
See "Port Variables".

To connect the encoder to RealServer:

When a content creator sets up the encoder to broadcast a performance, he or she will indicate the RealServer port numbers to which it should send live streams.

If a G2 encoder is in use, and you have typed a value in the Authentication Realm box (described in the previous section), the person using the encoder will need to type a user name and password.

If a pre-G2 encoder (such as RealEncoder version 5.0) is in use, and you instructed RealServer to require a password by typing in the Password box, the person using the encoder will need to type a password.

Additional Information
Refer to your encoding software documentation for instructions on setting up the encoder.

	Additional Information
Refer to your encoding software documentation for instructions on setting up the encoder.

To link the Web page or SMIL file to the live stream:

Links to live events are similar to links for on-demand clips, with the addition of the mount point.

Follow the format of linking to an individual file, and use the live file mount point, usually /encoder/.

Additional Information
See "Links from Web Pages to Streamed Media Clips".

	Additional Information
See "Links from Web Pages to Streamed Media Clips".

Playing A "Please Stand By..." Message

Should a live stream be interrupted, you can still send information to clients, displaying a message that says "Currently experiencing technical difficulties" when a live broadcast is interrupted. This is possible by making a file that contains the message you want to display, and placing it in a subdirectory with the same name as the live mount point.

To create a "Please Stand By..." Message:

Create an actual subdirectory with the same name as the live mount point, and place it under the main base path.
In this subdirectory, place a file in the same format as your broadcast (RealAudio, RealVideo, or SMIL) that contains the error message you want to stream in place of the live file. You may want to include information about when the visitor should check back (keep in mind the different time zones in which visitors may live).

If a live stream fails to arrive at RealServer, RealServer will search for an actual directory that matches the URL. In this case, it will find the subdirectory with the error file in it.

Archiving Live Files

You can save (or "archive") a live broadcast for historical purposes or for later playback. For information on playing saved files as if they were live, see the next section, "Simulating a Live Broadcast".

When live archiving is enabled, RealServer examines all arriving live streams, and compares the names of the streams with the list names within the Live Archiving section of RealSystem Administrator or the configuration file. If it contains a list whose name matches the virtual directory name of the incoming live stream, RealServer will archive the file.

If no matching list name is found, RealServer does not archive the file.

Files are archived in locations specified by Target Directory.

RealNetworks' encoding products include an option to save a copy of a file while encoding. This setting is independent of the archiving feature in RealServer. Typically, there is more storage space on the RealServer system than there is on the content creator's computer.

Choosing the Size of the Archived Files

For each live broadcast that you want to save, you can choose to create one large file that contains everything in the original broadcast or several small files. These small files can be based on length of recording or file size. For example, RealServer can archive a continuous live feed into files each containing thirty-minutes of the broadcast, or can start a new archive file each time a certain size is met.

Live Archiving Options
Method of archiving	Suggested use
One large file	· Corporate presentations · Concerts
Small files, based on elapsed time	· Ongoing news broadcasts · Event coverage
Small files, based on file size	· Ongoing events · Where disk space is a concern

Large Files

Large files are appropriate when you want to save an entire event in one file. If RealServer archives a live broadcast with the same destination path and file name as an existing file, RealServer automatically renames the file by appending a unique number to the end. For example, if RealServer encountered a file named concert.rm in the archive directory, it would rename it as concert.rm.86400. The new file gets the concert.rm name. The number that RealServer chooses is related to a timestamp; larger numbers indicate newer files. In this way, one directory can be used to store the latest version of a broadcast and the previous versions as well. Reusing the same output file name can simplify Web page maintenance, because the links for a recurring event remain the same.

Small Files

Small files based on elapsed time are saved with the following method: as soon as the initial value indicated in the configuration file is reached, the archived file will be named filename01.rm. When the second archived file maximum size is reached, it is named filename02.rm where filename is the name of the live file stream.

File names for files based on size are named with the same method as for files archived according to elapsed time.

If RealServer tries to archive a stream for which an archived file already exists, it renames the existing file with the date and time that the live file was initiated where the date (filename) is in the format MMDDYY.

Setting Up Live Archiving

In its default configuration, RealServer puts all the files in the same directory, specified by the main mount point's Base Path.

To archive live streams:

In RealSystem Administrator, click Broadcasting. Click Live Archiving.
Click Add.
In the new browser window that appears, type a description for the live archiving setting in the Description box.
In the Virtual Path box, type the virtual path where the live data will arrive. This is the same text that the content creator will type in the encoder, including the live broadcasting mount point.
If you want to archive all live streams, name this list with an asterisk (*) rather than typing the virtual path.
In the Target Directory box, name the virtual directory where RealServer should store the files.
Target Directory can also be set to an absolute directory.

To limit the files by their size, select File Size and type the maximum desired size in megabytes.

To limit the size of the archived files by time, select File Time. Select the frequency with which a new archive file will be selected; use the table below.

Example FileTime Values
FileSize Value	Resulting File Contents
`30m`	Thirty-minutes
`1h`	One-hour
`1h30m`	One-and-a-half hours
`1d1m`	24 hours and one minute
`1d1h`	25 hours (one day plus one hour)
`23h59m`	23 hours and 59 minutes
`1d1h1m`	25 hours and one minute

If you give values to both File Time and File Size, RealServer will use the first, or lower, limit.

To save entire broadcasts without limiting the file size, omit values for both File Time and File Size.

If RealServer 5.0-style bandwidth is in use, select the Bandwidth Negotiation box. When this box is selected, and RealServer receives streams from encoders with the .rm extension, RealServer creates a directory named after the filename, including the extension. All the streamed files go in this subdirectory. For more information on 5.0-style bandwidth negotiation, see "Files Created with Previous Encoder Versions".

Note
If you are using bandwidth negotiation to create the files and the Bandwidth Negotiation box is clear, RealServer must make a choice as to which file it stores in the archive directory. It will store the first stream that arrives, as filename.rm (not as a directory), and the other bandwidth-encoded files will not be available. Be sure to specify the .rm extension when setting up the encoder to encode the live stream.

	Note
If you are using bandwidth negotiation to create the files and the Bandwidth Negotiation box is clear, RealServer must make a choice as to which file it stores in the archive directory. It will store the first stream that arrives, as `filename.rm` (not as a directory), and the other bandwidth-encoded files will not be available. Be sure to specify the `.rm` extension when setting up the encoder to encode the live stream.

Disabling Live Archiving

To turn off live file archiving, modify the NoArchive variable in the directory list which you do not want to archive. Set NoArchive to True.

Simulating a Live Broadcast

For replaying a pre-recorded stream as if it were live, RealServer includes the G2SLTA (Simulated Live Transfer Agent). Viewers who watch a presentation join the event in progress; no matter when visitors connect, they all see the same thing at the same time.

Tip
Use G2SLTA to test your system in anticipation of an actual live broadcast.

	Tip
Use G2SLTA to test your system in anticipation of an actual live broadcast.

There are three steps to using G2SLTA: setting up RealServer, creating a playlist of files to stream, and running G2SLTA. You will also need to link the Web page to the broadcast.

Setup for RealServer is minimal; G2SLTA uses the G2 Encoder information.

The playlist is a list of files that G2SLTA will play. If you want to simulate a live broadcast of only one file, the playlist will refer just to that file. If you have a series of files you want to play during your simulated live broadcast, list them in sequence in the playlist. G2SLTA includes an optional command to play files in a playlist in random order. The playlist itself is a text file.

When you start G2SLTA, you give a name to the stream, similar to a mount point. This is the name that will be included in the URL. The playlist is not included in the URL.

Tip
Because the URL is linked to the list of streamed files via the G2SLTA command line, you can use a different file name for each simulated live broadcast, yet the link on the Web page remains the same.

	Tip
Because the URL is linked to the list of streamed files via the G2SLTA command line, you can use a different file name for each simulated live broadcast, yet the link on the Web page remains the same.

Setting Up G2SLTA

Use the following instructions to set up G2SLTA.

To configure RealServer to work with G2SLTA:

This program uses the same configuration settings as the encoders. See "To configure G2 encoder mount points:".

To create a playlist:

In a text file, list each file that you want RealServer to play, one per line. Files are played in the order they are listed. File paths and names can be absolute, or they can be relative to the directory in which G2SLTA is located.

Even if you have only one presentation that you want to broadcast, you must still create a playlist file.

To include title, author, and copyright information for the entire playlist, type the following at the beginning of the file:


Title: your title
Author: your author
Copyright: your copyright information

The rest of the file lists the files to be played:


Title: your title
Author: your author
Copyright: your copyright information
first file
second file

To run G2SLTA:

From a command line, run G2SLTA:

G2SLTA Syntax


g2slta host port username password livefile playlist [-r] [-nN]

where:


`host`	Name of the RealServer system and domain name.
`port`	Port number specified in the `pn-encoder` list, usually `4040`.
`username`	Name of the encoder user as defined in the encoder realm.
`password`	The corresponding user's password. If you are not using authentication for encoders, you can omit both the user name and the password.
`livefile`	Name of the broadcast that you want to include in the URL that links to this event.
`playlist`	Name you gave to the playlist.
`-r`	Indicates that `RealServer` should randomly play the files in the playlist.
`-nN`	Gives the number of files in the playlist for RealServer to play. To indicate that RealServer should play seven files, include `-n7` in the command line. If a playlist contains three files, RealServer will play the file sequence twice, and will play the first item a third time, for a total of seven files played. To play a list of files indefinitely, omit the number from this switch. Use `-n` only.

An example of a G2SLTA command:


g2slta realserver.company.com 4040 swordfish annual.rm Annual_Report.txt

Tip
You can use both the -r and -nN switches to cycle randomly through the playlist N times.

	Tip
You can use both the `-r` and `-nN` switches to cycle randomly through the playlist `N` times.

To create the URL that links to the G2SLTA presentation:

In the Web page, create a link to the content using the format described in "Linking a Web Page to a SMIL File or Individual Clip". Use the encoder mount point.