Real Audio Primer
by Joshua Barlow

The Encoder | Before Encoding | The Encode | The Server | Linking

In this article, I hope to provide some simple and accessible solutions for those just getting started with audio on the Internet. For the sake of focus, I will be concentrating on encoding and uploading Real Audio. Articles on MP3, Quicktime, and Windows Media will follow at a later date.

What is Real Audio?

Real Audio is the trademark name for a streaming media format developed by Real Networks. The term streaming means that you don't have to download the entire file before you can listen to it - you listen to it as it is downloaded to your Real Audio player. The file can also adapt to multiple bandwidths, so you can distribute to a much wider audience. Another feature of Real Audio is that you can limit your users to listening to your audio only when they are online. Unlike MP3s, the actual Real Audio file only passes through the users player. It is not saved to their hard drive, where they can distribute and manipulate it any way they want. Real Audio is currently the most popular format for streaming audio content on the Web.

The Encoder

I recently had an interesting conversation with a producer who was about to invest about $3000 into a Real Audio encoding program. The main feature of this particular program was that it automatically encoded, named, and uploaded multiple files to a specified server. While this type of program would be useful to an organization that has to produce dozens of files daily, it seemed a bit much for someone who only wanted to do a handful of files each month and had a limited budget. When I suggested he might find a more cost efficient means, he asked "How much?" I replied "Free."

As it turns out, he already owned a digital editing program that was able to export to G2 SureStream (a Real Audio format capable of being streamed at multiple bandwidths). All he had to do was select "SAVE AS", write out his ramfiles, then upload to his server using a basic (and FREE) FTP program.

For those of you don't have an editing program that can export to Real Audio format, I suggest downloading one of the following:

Real Producer Basic (MAC/PC)
www.real.com
This is Real Networks entry level encoder. It can encode digital audio and video for either specified or multiple bandwidths (via G2 SureStream format). If you have access to a Real Audio G2 server, you can also produce live Webcasts. There is a encoding wizard as a part of the program that helps answer any questions you may have.

Limitations: Only encodes for Real Player 8 (i.e., not backward compatible for older players), and you can only encode one file at a time.

Pro Tools Free (MAC/PC)
www.digidesign.com
Besides being an incredible tool for digital multi-tracking and post proccessing, this program also exports to Real Audio.

Limitations: Only 8 tracks. Has issues with Pre-G3 Macs and Windows 98. Read the system requirements before downloading and installing.

FOR A FEW DOLLARS MORE

Real Producer Plus (MAC/PC/Linux/Solaris) - $149.95
www.real.com
This commercial version of the Real Producer includes much wider range of encoding schemes and filters for both audio and video, a bandwidth simulator to preview your end result, the ability handle larger files and also edit the Real Media after it has already been encoded. You can also make your files backwards compatible for older versions of the Real Player.

Sonic Foundry's Sound Forge (PC) - $349
www.sonicfoundry.com
If you are on a PC, and want an affordable, yet professional solution to editing your audio tracks and preparing them for radio, CD, or the Web - then Sound Forge is your solution. When exporting to Real Audio, you are given a good many choices on file information, and how it should be encoded, including whether or not it should be backward compatible for older players.

Before Encoding

Get Your Audio on the Computer
While you don't need a professional digital editing system to do this, you do need a sound card that enables you to record from your source to your hard drive. If your computer did not ship with one, you can pick up a decent sound card online or at your local computer store for under $80. If your sound is already in the digital domain, you can just import it via Zip disk, CD, network connection... or any other means you already have for transfering data files.

For more on digital recording, read Barrett Golding's article on "Recording Highs and Lows."

Audio Source
Obviously, you want to start with the best possible recording. Though the proccess of encoding will compress and eliminate certain frequencies in order to make it accessible for specified bandwidths, the clearer your original source - the clearer your Real Audio file will be for the Web.

While most encoders will open a wide variety of audio file formats, my experience has been that the best results come from encoding either .WAV or .AIFF files that are CD quality (44,100 khz). If you are just doing mostly speech, then you can get away with 22,050 Khz or even 10,025 Khz as the frequencies missing at these resolutions don't apply very noticeably to the natural range of the human voice.

The Encode

Encoding Options
If you will be streaming your files from a Real Audio G2 server (see below), then your best option for encoding is SureStream as it allows one file to adapt to the different bandwidth of different users. Instead of having one file for high speed users (DSL, Cable Modem, ISDN...) and another file for lower end users (56.6 - 28.8 kbps), the G2 SureStream file will adapt to these different modem connections. Though the lower the bandwidth, the lower the audio quality, having a wider range of connections will ensure a larger audience for your work. *NOTE - The wider range of bandwidths you encode for, the larger your Real Audio file will be.

If you don't have access to a G2 server, or wish to conserve space by encoding for a lower bandwidth, then don't bother with SureStream and target the bandwidth you feel will be most accessible without sacrificing too much in audio quality.

Bandwidth Considerations
Here is a list of bandwidth ranges and what you may gain or sacrifice by targeting them:

128 - 300 kbps - MP3 quality. Not quite CD, but very clear if you want to relay every nuance of your audio presentation. Best option for music, or pieces that have a lot of very subtle sounds. Huge file size, however, and if you want to share your work with those who don't have a consistent high speed connection (which are still the vast majority of users), you will have to do a different encode just for them. Ideal for users with T1, T3, Cable Modems, or High Speed DSL.

64-96 kbps - Near MP3 quality. Still sounds pretty darn good for music, and radio features. Speech is clear and you can still hear most of the aural nuances of the original recording. You are still limiting your audience to higher speed users, and if your piece is basically speech with a bit of background noise or music, you are sacrificing a larger potential audience for not a whole lot. Ideal for ISDN users or higher.

56.6 kbps - This is the most widely accessible bandwidth. Though you lose a noticeable amount of fidelity, dynamic, and frequency from the original recording, it is clear enough that the most important parts of the audio are there. Though there are few audio artifacts present after the encode, they are negligible and will probably not distract the listener. Ideal for users with a 56.6 modem or higher. If you have to pick just one bandwidth to encode for, I reccommend this one.

14.4 - 28.8 kbps - Let's just call this the AM radio of your options. If you are doing primarily speech and want to ensure your piece can reach absolutely everyone, then this is what you want. Music, however, will become noticeably garbled and you will probably hear more unwanted artifacts (especially at 14.4).

Mono vs. Stereo
Very simple. Twice the channels equals twice the file size. As you weigh your options and available file space on the Web, try to acccurately assess how important stereo imaging really is to your piece. If the piece stands on it's own without that impressive Doppler pan of a car passing by, then I would say go with mono.

The Server

Space on the Web is cheap and, a lot of time, FREE if you know where to look. Most ISPs actually give away 5-20 mb of space as a part of their regular service. As most Webpages weigh about 6k, and Web pictures are usually not much larger than 50k, a good deal of the free space they give away actually goes unused. There are also a great many sites that will give you free space in the hopes of creating an online community that will seem more attractive to their advertisers.

As you make the decision as to where you will be uploading your audio to, here are a few questions to ask both yourself and the companies that will host your space:

Is There a Real Audio G2 Server?
You don't have to use a Real Audio server to stream your Real Audio files. However, not using a Real Audio server will prevent you from taking advantage of G2 SureStreaming and the ability to Webcast live events. It will also limit how many people can stream your audio at any given time to about 6. If you are content encoding to one bandwidth, and are not worried about having your site being flooded with thousands of adoring fans when you post your latest garage band recording, then you should be fine. If you are serious about offering your audio in a wider variety of bandwidths, and would like to retain the option of becoming immensely popular all at once, then I suggest choosing a host who will give you space on their Real Audio G2 server.

How Much Space Do I Have for My Real Audio Files?
Knowing this will help you determine how many pieces you can upload and to what quality you should encode them. Recently, I encoded a mono radio story that was about 22 minutes long into a wide bandwidth G2 SureStream file. Once encoded, the file was about 12mb in size. If you've only got 20mb of space on your server, and you have a great many pieces you'd like to upload, you may want to consider encoding for lower bandwidths, or finding a host that can provide you with more space.

Getting Your Real Audio to the Server
Files for the Web are typically put on the server through a proccess known as FTP (File Transfer Protocol). Some hosts will feature a Web browser interface that will help you select your local files and arrrange them once they are on the server. More common, however, you will have to use a separate FTP program to move your files.

* NOTE: When uploading Real Audio, make sure that you have selected binary format for your transfer. Also, as most hosts do not keep their Real Audio and regular Web servers on the same machine, you will probably have to upload to separate addresses for your audio files and regular Web files.

Some Recommended & Free FTP Programs:

Fetch FTP (MAC)
Netfinder (MAC)
Leech FTP (PC)
Elite FTP (PC)

All are available through CNET.
www.download.com

Linking

Once you've moved your Real Audio files too their appropriate server, the next step is linking to them. While you could just link directly to the files themselves, doing this will not allow your users to stream your audio. Rather, they would have to wait for the entire file to download before listening to it. They will also be able to save that downloaded file to their hard disk, and if you want to encourage people to come back to your site, this is NOT the way to go. Instead, Real Networks has developed a standard linking system using what is know as a "RAMFILE."

What is a Ramfile?
A ramfile is essentially a one line text file that contains the Web address and transfer protocol for your Real Media file. These ramfiles can be placed on your regular Web server along with your other html documents. From your Web page, you can link to these ramfiles the same way you would to any other Web document.

Once the user has clicked on the link to the ramfile, the ramfile will direct their Real Player to the location of the actual Real Audio file, and they can begin streaming and enjoying your audio presentation.

How Do You Write a Ramfile?
Like I said, a ramfile is just one line of text that directs the users Real Player to the proper location. You can write a ramfile in any text editor such as Simple Text (MAC), or Notepad (PC). They must, however, be saved with the extension ".ram" or ".rmm". Otherwise, they will not work. Here is an example of what the inside of a ramfile actually looks like:

rtsp://ip.address.of.realaudioserver/mystuff.rm

"rtsp," in this case, stands for the streaming protocol for a Real Audio G2 server. "ip.address.of.realaudioserver" is exactly that. It is the unniversal Web address for the server that hosts your files. "mystuff.rm" is the name of the actual Real Audio file you are linking to.

HTTP Ramfiles
If you are not hosting your audio from a Real Audio Server, then you have to use HTTP inside of your ramfiles. Example:

http://ip.address.of.server/mystuff.rm

For more information on ramfiles, visit Real Networks:
service.real.com/learnnav/wb1.html#ram

Once you have linked to your ramfiles, all that's really left is to send out word that your work is now available via the "World Wide Web." Quite exciting, isn't it?

~Joshua Barlow
Web Director, Transom