Creating Your Own Auditorial
Learn how to create your own synchronized, multimedia presentation on the Web
By Bob Schmitt
June 29, 1997
In the past few weeks, we've been getting a tremendous response to our Auditorials. The most often asked question has been, how do you create an Auditorial?
In this tutorial, we'll show you how to create your own synchronized multimedia presentation, what we call Auditorials. You must be able to run a streaming media server in addition to your web server. We use the Netscape Media Server. The media server manages the delivery of a sound file to the user as a continuous stream of audio. It also causes pages to change in the user's browser. The user, of course, must have the media player plug-in to initiate a session with the streaming media server.
Some of the things we'll be covering in this tutorial include:
- How to compress your sound file into the Live Audio streaming format
- Creating a Live Audio metafile to control the Netscape Media Player; and
- Embedding your streaming audio into your Web page
Preparing the ingredients of an Auditorial
All Auditorials start from a script, much like a movie script. Auditorial scripts contain the words that the presenter will speak and descriptions of the images that will appear on the viewer's screen. An Auditorial consists of three main components:
- A set of Web pages, used to illustrate the key concepts in the script,
- A streaming audio file and
- A timeline for the sound file that will tell the user's browser when to go to the next Web page
When creating the sound file for your Auditorial be sure to start with the highest quality recording possible. For our Auditorials, we start with a 16-bit/44 Khz sound file. This may sound like overkill, but remember, you can't add quality back into your sound once it's been recorded. And, in our case, we want to capture the highest quality sound so we can repurpose our Auditorials later, for other media such as CD-ROMs or higher bandwidth Web presentations.
Once you've created your high-quality sound, you'll want to downsample it for use on the Internet. The Netscape Media Converter -- which we will use to compress and convert our sound into a streaming format -- comes with several built-in CODECs, the software that compresses and decompresses the sound. Use your sound editing software to downsample the file to the format that the CODEC requires. This will give you better results than if the Media Converter does the downsampling. For our Auditorials we use the bandwidth optimized speech CODEC from Elemedia, which requires a sample rate of 8Khz.
Converting the audio
After you've downsampled your file, it's time to go into the Netscape Media Converter.
The Netscape Media Converter interface.
Once you've started up the Media Converter, load the sound file you wish to compress. Do this by selecting Load from the File menu. Then, start the conversion process by selecting Convert from the File menu. This brings up the dialog box seen here.
The "Convert" dialog box.
The Media Converter comes with several templates that are available under the Express conversion option. These templates contain general settings to cover many common situations. We'll want to make our own template for our Auditorials using specific settings, so we'll select Custom conversion.
In the next screen, select the bandwidth range for optimization. You can select one of several preset ranges from the popup menu or select custom and enter in your own range. For example, if the speed of your average listener's Internet connection is 14.4 to 28.8, you'll want to select 14400 to 28800 bits per second from the popup menu. For our Auditorial, we're going to be using a low-bandwidth CODEC, so we'll select All rates with this setting, even the lowest bandwidth connections will get good results. If the sampling rate of your sound file does not match the sampling rate of the CODEC, check Allow Resampling and High Fidelity. This will allow the Media Converter to resample your file to the correct rate.
In the next screen, select a CODEC from the Format pop-up menu. For our Auditorials we use the SX8300P, bandwidth optimized speech CODEC from Elemedia. Many of the CODECs offer a choice of attributes selectable from the pop-up menu. The SX8300P CODEC has just one choice which is 8,000 Hz, Mono. This will provide the smallest file possible for delivery over the Web. If your sound file is not already downsampled to 8Khz, the Media Converter will do it for you.
Click OK and in the next screen select, Packetized Netscape Streaming Audio Format.
Next, name the Live Audio streaming file. The Media Converter will suggest a long, convoluted file name for you, but we recommend you rename the file something a little more friendly. Just be sure to leave the .la extension on the file name.
Click Next to start converting your sound. The amount of time it takes to complete the conversion depends on the size of your sound file, but one thing's for sure: it will take longer than our representation here!
Once the conversion is complete, you'll see the Statistics screen. At this point, you can listen to the compressed sound file by pressing the play button at the top left. The bit rate statistics show that, given optimal circumstances, someone with a 9600 baud modem could listen to this streaming audio file. Of course, once we add graphics and HTML files to our Auditorial, that won't be the case, but anyone with a 14.4 or faster connection should get reasonable results.
The next screen gives you three options: compress the file again at another bitrate, Finish compressing, or generate a LAM file. LAM stands for Live Audio Metafile. This is a text file that gives the Netscape Media Player the information it needs to control the playback of the streaming audio file. Now lets go through the automated process of creating a LAM file, to see how it works. After that, I'll show you how to create your own custom LAM file that includes a timeline that controls the changing of the Web pages.
In this first screen of the Generate LAM metafile dialog, you'll need to enter the IP address and port number of your Netscape Media Server. You will need to get these numbers from your system administrator. Next, name the file, being sure to keep the .LAM extension.
Enter your streaming server's IP address and name your LAM file.
This next screen shows the contents of the LAM file you just created. Not much to it, as you can see here. We'll be adding to this a little later in the tutorial.
Next, you are asked to select which controls the Netscape Media Player should show on the Web page. Again, we'll be creating our own custom HTML page and will go through these options later.
Lastly, the Media Converter allows you to create a template for this conversion. If you save the template, you can use the Express conversion option the next time you convert a file.
Now that you've converted your sound file to the Live Audio streaming format, you'll need to upload it to the media folder on your Netscape Media Server. Be sure to check with your system administrator for the correct path.
Now that the .la file is on the server, it's time to create the LAM file.
Creating the LAM file
A LAM file is simply a text file which you can create in any text editor. Your LAM file needs to contain three very important bits of information:
- The Netscape Media Server's IP address and Port number,
- The name of the Live Audio Source file, and
- A Timeline to control the changing of the slides.
| An example LAM file |
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You will need to get the IP address and port number of your Netscape Media Server from your system administrator. Enter these numbers under the [Server] heading. Next, under the [Source] heading, enter the name of the .la file you created earlier. With the Netscape Media Converter you can compress the same file several times for different bitrates. For example if you wanted to use a higher quality compression for users with connections faster than 56K, you could add a line after the Default line which says 56,000= and the name of the higher quality .la file. You can list as many options under source as you wish, the only required value is Default. Default is the source file that will be used for users connecting at any speed not listed.
The last thing you'll need to add to the LAM file is a timeline. The timeline controls the changing of the slides in the Auditorial. Each entry in the timeline consists of a time setting in minutes and seconds, the HTML document to be displayed at that time, and an optional frame target.
You can get the timings for the LAM file from your sound editing program, or by simply listening to the file in Netscape and make note of the times at which you'd like the pages to change. Because of the nature of the Web, you should allow for delays in delivery of the Web page slides. As the throughput of each user's connection will vary, it is not a good idea to have changes in your slides that depend on critical, to-the-second timing. We build 4-5 seconds of silence into our sound files between changing slides to give the page time to download before the audio moves on.
Now that you have created your LAM file, the last step is to add it to your Web page. This is done with the EMBED tag.
The EMBED tag works much like the IMG tag. Just put EMBED SRC= and the name of your LAM file, as shown here.
| HTML showing the EMBED tag |
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In addition to the SRC attribute, there are a variety of additional attributes that you may include in the EMBED tag to control various aspects of the Netscape Media Player.
| The EMBED tag's attributes | |
| width and height | Determines the width and height that the Player will appear on the page. |
| hidden | If TRUE, the Player will appear on the page, if FALSE, the player will not appear. |
| autostart | If TRUE, the audio file will begin to play automatically after the page has loaded. If FALSE, the audio will only begin after the user clicks the play button. |
| playbutton | If TRUE, the play button is visible, if FALSE, the play button is not visible |
| stopbutton | If TRUE, the stop button is visible, if FALSE, the stop button is not visible |
| options | If TRUE, the options menu button is visible, if FALSE, the options menu button is not visible |
| volume | If TRUE, the volume controls are visible, if FALSE, the volume controls are not visible |
| seek | If TRUE, the seek position slider is visible, if FALSE, the seek position slider is not visible |
| loop | If TRUE, the audio file will replay automatically, if FALSE, the audio file will not replay |
| latency | Specifies how many seconds of the streaming audio file to buffer before play begins |
Latency is one of the most important settings in the EMBED tag. This setting controls the amount of the audio file that is sent to the user, before the audio begins playing. The audio is then played from this buffer as more of the audio file is streamed to the user's computer. By playing the audio from the buffer, rather than directly from the stream, helps prevent skipping during times when the audio stream may be interrupted due to Net conditions.
Once you have completed your HTML documents, upload them -- and the LAM file -- to your Web server and you're done.
Follow these simple instructions and it should be a cinch to create your own Auditorial. When you do, be sure to send us the URL, we'd love to see what you've done.
Copyright © 2012 Robert Schmitt. All rights reserved.