What is MP3 All About?

A brief non-technical explanation of what MP3 is and how to take advantage of this technology

If you were around in the 1970s, you might remember the launch of the audio cassette from Philips. No longer did people have to use bulky reel-to-reel tape recorders. Now the magnetic tape was hidden inside a robust plastic cassette, which could be easily slotted into a tape player/recorder. Compact audio cassettes (to give them their official name) quickly found their way into home hi-fi and car radios and ousted the cluncky 8-track cartridges people were trying out.

That was over 30 years ago and it is perhaps surprising that they lasted as long as they did, but for a long time, storing an hour or more of speech or music wasn't possible any other way, as the technology for storing a large amount of information in a small space just wasn't around. So in the meantime, the audio cassette reigned supreme, except in recording studios, which used large, high-quality, reel-to-reel, multi-track machines, often costing more than £100,000 each. Those on lesser bugets began to accept that, once in a while, their tape would be ejected with several feet of its contents still securely wrapped around the inner workings or, perhaps, the sound would momentarily drop out or the tape would snap. So what? It didn't happen too often and there was always the sellotape.

By the early 1980s, technology was progressing rapidly (and still is), driven largely by the new personal computer revolution. Almost every computer is digital in nature — that is, it handles information in the form of numbers, which it can store in special electronic circuits called memory chips. These numbers can represent anything you want — letters on a page, musical tones, the colours in a picture etc. The point is that they are stored in devices with no moving parts (although some early computers actually used casette recorders to load their software, but let's not get side-tracked for the moment).

So wouldn't it be great if we could store sound in one of these chips? Well, we can — the problem is that it takes a lot of space to store only a relatively short sample of sound, which made the task rather impractical, until two important developments. First, the computer market drove down the cost of the memory chips and also manufacturers were cramming more capacity to hold information into the same space. Second, engineers were looking at the possibility of processing the sound before it was stored, in such a way that some of the information could be thown away — but only those parts of the sound that don't make a big contribution to the intelligibility. This allows the sound to be squashed down, as it were (known as lossy compression), before being stored, so that more of the sound can be forced into the same amount of memory. The name given to the method of compressing the sound is derived from the name of a committee of experts who were given the task of defining how to achieve it. That name is MP3. Using this method of compression, it is possible to produce a range of quality of resulting sound. This is because the amount of compression can be specified — the more you throw away, the worse it sounds, but there is less of it at the end of the process to store away. If you want high quality, you can opt to apply less compression, but you end up with a larger amount of information (but still less than you started with, of course, or it wouldn't be very useful...)

If you're wondering if you need a computer to use this wonderful new technology, the good news is that you don't (although they are useful for storing large numbers of MP3 files). Nor do you need to spend a large amount of money on a player. The market is now awash with nifty little devices that play MP3-compressed sound, some of which cost under £10. This has effectively killed off the old-fashioned audio cassette for good — just try buying a C-90 or C-120 cassette in your high street and you'll see what I mean. Now you can listen to Bible studies and music anywhere using a device about the size of a match box. But if you don't have one (and I'm assuming that if you've read this far you either like my style or you really don't have an MP3 player), how do you go about getting set up to listen to Jonathon or Phil at your leisure? Here's all you need to do:

1. Buy an MP3 player. Don't be fooled into thinking you must have an i-pod and pay £100 or more. All you need is a cheap player and a memory card. If you have a PC or Mac, it will play MP3 files already through its speakers, so if you're content to spend quality time with your computer, then you can skip this step. Otherwise, check out www.7dayshop.co.uk. Here you can buy a player for £8.99 and a memory card to go with it for £18. So for a total outlay of just £27, plus postage, you've got yourself a player that will hold up to 10 hours of Bible teaching.

2. Before you can hear anything, you need a means to get the information onto your memory card. These cards are the same type that you might already have if you own a digital camera. They simply slot into the side of the player. If you don't have a PC, we can transfer whatever studies you want onto your card for you. Otherwise, you can plug your player into your PC and simply transfer any files between them. You can also have MP3 files put on a CD for you to transfer to your player or store on your PC. In fact, even cheap CD players costing under £50 will happily play a CD full of MP3-compressed audio.

The big advantage is that MP3 audio takes up so little space. For example, you could have Phil's entire series on Matthew, which spans 6 years of teaching, on just five CDs, as opposed to over 100 CDs. Also, their relatively small size means that, if you have broadband Internet, you can download MP3 files from other Calvary Chapel sites in just a few minutes. In addition, once transferred to your player, you can listen to it anywhere (although I haven't yet seen an underwater version!).

It's time to bin that old cassette player or, at least, consign it to the loft — digital audio has come of age. It's easy to use and very convenient — just talk to some of the people in the church who have been using it and, if you have any questions, please ask me over coffee on Sunday.

Dave Baxter