Audio
Compression
EVERY DAY astounding scientific and technological advances are made that make our lives easier and more efficient. In recent history, no industry has made such rapid and dramatic changes in technology than the computer industry. Computers have completely changed the way we work and play today. It is thus very difficult to single out one important landmark in the history of multimedia. So why an article about MP3? Basically, although audio compression has been receiving major press lately, its foundations stretch back much farther.
MP3 can trace its roots to 1987, when the Fraunhofer Institute, the leading organization of applied research in Germany, joined with Dieter Seitzer, a computer scientist from the University of Erlangen, to begin work on a new audio codec. The idea was to develop a method of compressing audio data into a reasonably sized file without losing too much sound quality. The resulting technology was approved in 1992 by the Motion Picture Expert Group, or MPEG. And thus, MPEG-1 Audio Layer 3, or MP3 was created.
What exactly is an audio codec? Basically, a codec means coder/decoder, in the same way that modem means modulator/demodulator. In the case of MP3, the codec is an algorithm, or formula, that removes data that can't be detected by the human ear and data that it can assume from other data. This makes for a much smaller file size, meaning that the file can be broadcasted quickly. Digital audio signals record a lot of information that is basically not required for good quality sound. Compact disc audio typically eats ten megabytes of space per minute. MP3, on the other hand, will take up only one megabyte of space for that same minute.
Using MPEG audio coding can actually decrease a compact disc's original data by a factor of 12 without any loss of sound quality. The Fraunhofer Institute has even been able to develop audio coding that shrinks audio data by factors of 24 or more, while still maintaining reasonable sound quality.
An audio codec's usefulness is determined by three factors. How close to the original sound file does the compressed file sound? How much processing power is required to decode the codec? And at what rate can the encoded data be played back? As mentioned above, MP3 has a sound quality almost identical to the original compact disc.
Today's standard desktop computer can easily decode MP3, and compression/ decompression can be done in software instead of hardware without difficulty. MP3s can be recorded at varying bitrates. The most common is 128 kilobits per second, but it is not uncommon to see lower quality MP3s record at 96kbps, or higher quality ones at 168 or 256 kbps.
It's been seven years since the Motion Pictures Expert Group approved the MPEG-1 audio and video data compression specification. In computer years, that's a long time. So why didn't the codec developed by Seitzer and the Fraunhofer Institute catch on until recently? Simply because modems and processors weren't fast enough for users to download music quickly. Now that 56k modems and 300 MHz (or better) have become standard hardware, music fans can use MP3 to compress their favourite musical tracks and post them on the web. And the average computer user can download MP3 music files to their computer with relative ease.
Obviously, MP3 has huge implications for the recording industry. Anyone with the inclination can rip tracks from a compact disc, compress these files, and post them on the web. Instead of dealing with a recording company, bands can post their music on the web themselves. Hungry music fans can find thousands of free downloads at an ever-increasing number of MP3 sites. As a result, recording companies are terrified of losing control over distribution and are concerned about protecting artists against piracy. However, they have been unable to halt the growth of the downloadable music industry. Several attempts have been made to introduce new formats that had advantages - smaller file size for the same sound, but included copy protection. All of these formats have failed, and new ones have even less of a chance as the number of MP3s increases. In June of this year, EMI announced that they had hired Liquid Audio to digitize their music libraries for sale and distribution online. This has been touted as the first major step made by one of the five major labels (Sony, BMG, Universal and Warner being the other four) towards posting songs on the web for download.
Much of MP3 and the audio compression industry's history has yet to be written. What is certain is that MP3 has the potential to change the face of the well-established music business. While the recording industry argues about piracy and distribution issues, new MP3 sites are popping up everywhere and thousands of songs will continue to be posted on the web. And though "faster" codecs have been developed, it's not difficult to make a codec that results in smaller files and decodes at the same speed, but it is hard to do that and not have it take forever to compress. MP3s have a good tradeoff between compression and decompression. Downloadable music promises to be a huge industry. Audio compression is writing multimedia history as we speak, and this we can trace back to 1987, Dieter Seitzer and the Fraunhofer Institute.
Alison Hollingworth is a multimedia student at the Southern Alberta Institute of Technology. Her interests include (downloadable) music and design.
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