Compression

Compression, the Saviour of Audio?

MP3, FLAC, WMA, Vorbis, ATRAC are all forms of audio compression. You may have only heard of MP3 but many others are around in various other devices especially in computer audio formats. Audio compression is simply the process of squeezing the digital data that makes up the audio signal into a smaller size; this way the file it creates can easily be sent across the Internet and many songs can be fitted onto portable music players. There are now so many new devices such as portable music players, car audio systems, distributed audio for homes, PC entertainment systems and even music players that hang of your key ring, that it is hard to keep up!

Digital audio first came to prominence as the now humble CD player. The CD store about 74 minutes of music is a relatively high-resolution format that is still the most popular hifi format today. But think back to 1979 when Sony released the first Walkman style device, of course back then it was a cassette player but during the 80’s proved extremely popular. That device was copied by many other companies but they all still used the same format. Records were bought or borrowed and tapes made at home to be used on the run (with appropriate warble) and on public transport. They later morphed into portable CD players that had their own share of problems like skipping, short battery life and the all to common broken headphone socket.

These devices continued on for some time but sales were slow. Something changed and that was the development of MP3 and other audio compression. Simply put, a household computer was able to take the audio off a normal CD and compress the digital data into something much smaller, in fact even 100 times smaller. This was usually done by analysing the audio and removing sounds that could not usually be heard, by reducing the sampling rates and resolution of the audio and also by coding it in a different way. A single CD-ROM disc could hold many hundreds of songs instead of the usually 10-15 or so. At first playback was only on the computer, files could be stored on that PC or swapped between others via the Internet; the files were so small it was easy to do.

The “Walkman” style of portable audio device have now made a hugely successful comeback but in a digital form. Hand-held devices with in-built memory in the form of hard drives or solid-state memory chips held the compressed audio. Again due to the small size, you didn’t need much memory to hold a fair bit of music and it could easily be carried around. Music can easily be bought online, legally at that. But what about the quality? Sure, there are so-called lossless formats but these still take up a large percentage of the original space that the CD version did and would render the portability and fast downloads redundant. So most people end up with a large amount of compression and hence a much reduced quality level. Certain brands even force you to use their own propriety format of which there is little information about and also incompatibility between others. You are basically stuck with that one format.

For most of the people with these devices sound quality is the last thing on their minds, they are after the music first and foremost. So what to do if you have one of these devices or buy music online and want to achieve the best quality? First is to make sure you have the highest quality recoding possible. If making your own recordings (with attention paid to the legalities of course) use a lossless format; you can always get more storage as required, it is becoming cheaper all the time. Use quality connectors and try and find devices that at least pay attention to their playback quality. Many are designed just to sound okay through poor quality headphones, but many reputable hifi companies such as Marantz and JBL for example have released devices that can extract much better sound from a certain fruity brand of portable device. Also playback of MP3 is now possible through newer disc players, their output stages would be immensely better sounding than the portable ones. Another solution is the so-called home theatre PC; there is nothing to stop you using them for stereo playback as well, by using quality components within, very good sounding results can be achieved.

So where will all this end up? One would hope with the cost of memory in all its forms coming down and coupled with the miniaturisation as well, that music suppliers will reduce any detrimental compression to their audio files and allow an increase in quality. If they can be easily stored, why not make the quality better? Coupled with faster and faster Internet download speeds, it all makes sense. Well they probably wont as any extra cent they can save per song would be worth it for them considering millions that are being sold. However you can certainly contact them and ask for better quality to be provided, especially for particular music genres such as classical and jazz. Or simply track down that CD is it will very likely be better quality than any song you can download at this time!

Written by Leon Gross, originally published in Audio & Video Lifestyle magazine.