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February-March 1997 Online Column
SQUEAK AND BLAT RAP ON MUSIC TECHNOLOGY
by Dave Williams and Peter Webster

Dear S and Q,

I'm really confused. I've been looking at music files on the Internet and most of them have .AU after the files. But then I've found .WAV and .AIF and .MID and most recently .RA. Can you guys help. This is confusing as heck and sometimes my browser doesn't even know what to do with them.

Manny Digits

Dave: Don't feel bad, Manny. Everyone gets confused over all these various types of audio files including your web browser. I'll let Blat tell you how to get your web browser to handle these things properly while I take a swing at explaining the differences. First, let's get MID files out of the way. These are completely different from AU, and WAV, and AIF, and RA files. MID files are MIDI files. A MIDI file contains performance directions for a music synthesizer to play your music, it doesn't contain the sounds themselves. You will need either a MIDI synthesizer attached to your computer (probably General MIDI compatible) or software that will help your computer create MIDI sounds like Quicktime on the Mac. MIDI files are very small because they only contain these instructions and not the sounds. There are MIDI helpers or plug-ins that you can add to your web browser so they will automatically play the MIDI files (Blat, quit playing with your spit value and help us here!). For more info on MIDI there are lots of web sites including The MIDI Farm (They also use NetForum on their site!). Now we can deal with AU and WAV and AIF and RA. These are all digital sound files. Someone has made a digital copy of a recording through their computer much like someone takes a picture and makes a digital scan of it from a graphic scanner. The entire sound experience is captured in the digital file. Now, where MIDI files are very small, digital files get big very, very quickly. So, people have figured out ways to save digital audio more efficiently by compressing the digital information. AIF and WAV are two digital file formats used on Macintosh and Wintel machines, respectively. This format gives you no compression and the quality depends on the sampling rate (11 kHz, 22 kHz, or 44 kHz), whether you save mono or stereo (stereo doubles the file size), and whether the sampling is 8-, 16-, or 24-bit. These are still pretty big files and very slow to download over the Internet. So folks started looking for a more compact way to transfer audio over the Internet and they started using AU files pretty universally (originally used on the NeXT computer). There is about an 2:1 compression ratio here. AU stands for mu-law (the mu is the Greek letter) and it is an internationally accepted standard for telephony encoding. Most web browsers will automatically play AU files for you without doing anything special. The newest format is RealAudio or RA. This is a commercial compression scheme first developed by Progressive Networks to broadcast radio over the Internet, but now vastly improved to provide incredible music transmission over the Internet with a 16:1 or better compression. A 20 megabyte digital recording of about 4 minutes of music can be reduced to 400 or 500K of file space. I broadcast my class over the Internet with RealAudio and a 1.5 hour lecture is only 6-7 megabytes. With a RealAudio server, the audio is "streamed" to your computer so you never have to download the complete 7 megabytes, just a few bytes at a time as you listen to the recording. This format has great potential for broadcasting live music performances over the Web. Check out more info on RealAudio from their web site. Here are four good sites to visit for more information. The "Serious Cybernetics" site has a great comparison chart of the most common digital audio formats.   Overview of creating audio on the web. Making sense of audio on the Internet Hope that helps. Blat, pick it up from here. Squeak.

Peter: OK Squeak! Here I go. Manny!! You are encountering those file format blues! Yes this is a difficult nasty on the net these days. I predict things will settle down, however, as browsers like Netscape and Microsoft's Internet Explorer include support for the standard sound files that we all use. Actually browsers are doing this in their most recent versions, so maybe the best thing to do might be to start by upgrading the version number of your browser. (For instance, new versions of browsers these days can play back simple .AU files and QuickTime movies without having you do anything!) You might need to add a little more memory to your computer, but doing so is a good idea anyway if you plan to do much work with sound over the internet. Of course, no browser out there can support everything. If it did, it would so big that it wouldn't fit on your hard drive! So some customizing is often necessary, especially for specialists like musicians who demand the highest sound quality possible. Realize that there are two sources of help that are used by your browser to render audio (or other multimedia) files. Helpers. "Helper" programs are applications (mostly free) that sit on your hard drive and wait to be called into action by the browser when it encounters a file format outside the browser that it does not understand. When this happens the browser looks in its database for a hint about where to find the application file. In Netscape, this can be found under the General Preferences item that is part of the Options menu. You will see a "Helpers" file tab that will lead to a listing of file types and a button that will let you "browse" for the location of the application that you want to use for that file type. You can even create your own category of file if it is not in the list. When your browser is asked to play a file type that is not referenced in this list, an error message occurs. For example, suppose that a web page you are visiting offers to play a digital sound file. You click on the link and your browser informs you that "file type .AIF is not supported" or some such message. Well, you are out of luck until you find an application that plays .AIF files and link it to your browser's database as described above. To fix this, find an application that supports the .AIF format, place it on your computer, and let the browser know where it is. It's a little bit of extra work, but the next time you encounter a page with this kind of file, the application should kick into action and play the file. Again, some of the more recent versions of the standard browsers may have this covered for you already by rendering these files natively OR by using "plug ins" which come with the browser automatically. Click here for a visit to the Netscape site that has a listing of many helpers that are available for Mac and Windows. Plug Ins. And that leads us the second source of help, "plug ins." These are also like separate applications, but really are more integrated into the browser itself. The user is not really sure if the rendering of the file is really being done by the browser itself or by the extended code that is offered by the plug in. For music, great plug ins are available for MIDI files, RealAudio files, and special QuickTime movie formats that might support sound. You simply include these plug-in files in a folder resident with your browser and they become an extension of the browser's code. This approach is actually being used more and more, with helpers being used less frequently. Click here for a great listing of such plug ins. These sites are based on the Netscape browser, but you can easily find your way to the respective site for Microsoft's Internet Explorer. Enjoy extending your browser with helpers and plug ins, Manny.