Sound file formats

A few years ago, the only way to post a sound file on the internet so that anybody could hear it was to use WAV files. Although readily accessible to everybody, WAV files have the disadvantage that they are big - I mean big. The solution is to use compressed audio formats. They have been around for a while now, most notably the MP3 and RealAudio formats, among others.

Recently, MP3 and RealAudio have become quasi standards for sound formats on the internet. They can cut down on download time (compared to WAV files) by a factor of 10 or more. So much, that a sound file can played over the net in real time (streaming mode) - there is virtually no download time at all.

There are different degrees of Audio compression, they are colloquially named by the bit rate (modem speed) over which they can stream. So we say there is, for instance, 20 kbit, 64 kbit, 96 kbit, or 128 kbit per second format. They differ in terms of file size and sound quality, but they're the same in that audio player software like Winamp, Windows media player, RA player, MusicMatch, and many others can play them all.

In the early days of compressed Audio, the brute force maximum compression format was popular. It allows, for instance, RealAudio streaming across a mere 14.4 modem connection. The sound quality is poor in that mode.

Today, higher bit rate formats have become common. The sound quality is quite acceptable, although the file may still less than 10% the size of the equivalent WAV file. And it gets REALLY good - virtually indistinguishable from CD Audio quality - if you use MP3 in 128 Mbit/s (or higher) bit rates.

Software Requirements

All you need to produce MP3 or RealAudio files is a sound recording program as well as an MP3 or RealAudio encoder program.

Many popular sound recording programs are available as shareware. I have tried CoolEdit, available from http://www.syntrillium.com/, with good results. The registration fee is about $50, if I remember correctly. CoolEdit can create WAV files, and it can also convert them to RealAudio format. For MP3, I use MusicMatch, available from http://www.musicmatch.com//

Once you have created a WAV file using any other sound recording program, you can convert it to RealAudio format using a RealAudio Encoder program, available from http://www.realnetworks.com/products/producer/basic.html. Conversion to MP3 can be done with many software tools, among them MusicMatch mentioned above.

Creating a RealAudio File

I will describe the process using the CoolEdit software.

Record a song from CD or tape with CoolEdit. Use the editing functions of Cool Edit to clip off unwanted parts of the recording (usually before the beginning of the actual song, and after the end). Use the "Normalize" function to amplify the recording to maximum volume without distortion. Use the "compressor" function to slightly clip the peak levels and amplify the silent parts. Use the "Amplify" function to fade out the end of the sound clip.

At this point of time, after putting a lot of effort into polishing the sound file, it is best to save it as a WAV file.

The next step is to convert the WAV file into an RA file. You can do this through CoolEdit, or through the RealAudio Encoder program. The process to create MP3 files is similar, except that you use an MP3 encoder program like MusicMatch..

When creating compressed Audio clips, you need to decide on the bit rate to be used. Low bit rates, like 20 kbit/s, can be played in streaming mode on most analog modems, but the sound quality is mediocre. High bit rates, like 128 kbit/s will sound very much like a CD, but you need a very fast internet connection to stream these files, or you may only be able to use them in non-streaming mode.

Putting a RealAudio File on your web page

RealAudio files can have a file extension of .ra or .rm. I usually rename .rm files to .ra before I upload them, which has worked better for me in some circumstances.

When posting the RA file on your page, you should offer both streaming mode and non-streaming mode. The former allows to listen to the music in real time if the modem is fast enough. The latter is to download the entire music file, then play it.

Here is how you put a RA file on your web page:

Upload the RA file to your web site. Let's assume the name of the file is mysong.ra, and your website's URL is http://www.mysite.com.

1) non-streaming mode

Create a link to the RA file like you would link to a web page, something like,

<a href=mysong.ra>click here to hear my song</a>

2) streaming mode

Create a link not to the RA file, but to a metafile, like this:

<a href=mysong.ram>click here to hear my song</a>

For this to work, you need to create the metafile on your web site that points to your RA file. The name of the metafile would be mysong.ram. This file just contains one line of plain text, namely, the full URL of your RA file. So, this one line in the file "mysong.ram" will read (without the quotes): "http://www.mysite.com/mysong.ra".

That's all, it's that simple. I am maintaining a few sites that use this technique, check them out:

http://www.fauzia.de
http://peepmatz.coolhaus.de
http://www.hvfg.org
http://www.neatone.com

The process for MP3 files is very similar. The file extension for the MP3 files is .mp3, and the file type for the metafile is .m3u. The rest of the concept is exactly the same.