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Audio Compression:
Article by Nirudha
Perera aka "timeCrash"
March 08, 1999 |
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Introduction
How many music CDs do you own? Five? Twenty? More than a hundred? Except for the purist audiophiles who still use vinyl, the rest of the consumer world relies pretty much on CDs to store music on. But isn't it a pain to swap CDs all the time? You may have a changer but might want to have access to your tunes while you surf without leaving your computer. Would the idea of having a couple of CDs worth of music in your computer interest you? In that case you need to start using audio compression.
One compression format has risen to notoriety these days- namely, MP3 or MPEG 1 Layer 3 audio, which is all over the net now. Letting you shrink the size of a song up to eleven fold while maintaining sound quality which is not that far from a CD (at least it's better than tape and FM radio) MP3 technology has got the attention of the recording industry. While initially blaming the technology and all its uses -the valid as well as the illegal, such as pirating music on the net and on recorded CDs- the industry is now a bit more subtle in promoting its point of view. While this is really no change of heart and just a way of getting around the negative publicity they recieved initially, they do have a good point to make. See the box below to learn more about the legal issues.
Seeing the rise to fame -and the potential money making capability- of MP3 technology, several companies have launched competing audio compression technologies. The latest to enter the field is Microsoft. Claiming to give more sound quality at half the size of MP3 files (more on that later) they have released the rather creatively named Microsoft Audio 4.0 format. Real Networks has also tried to bring its streaming format G2 into the music archival scene. In this comparison we will also look at Japan's NTT corporation's TwinVQ technology. While neither NTT nor Yamaha (through whom they appear to be marketing the technology) promote this format, it has its own following on the web. Finally, we will also look at MP2 (MPEG 1 Layer 2), MP3's older sibling which has been in heavy use for professional studio work as well video CDs.
Note - This article looks at the various audio compression formats available for the home user or amateur artist who wishes to use his or her computer as a personal jukebox / music archive. It won't be dealing with such things as streaming audio nor non-musical content like voice. That said, you may still find the quality comparison useful if you wish to stream audio (albeit for high bandwidth connections).
For an index of this comparison click
here.
The legality of compressed audio |
| There has been a lot of controversy surrounding
audio compression especially of late. The CODEC (COmpressor/DECompressor)
known as MPEG 1 Layer 3 in particular has risen to notoriety. Take an average
4 minute long piece of music; if you record it at CD quality on your PC,
you get a file about 40 MB in size! By compressing that using MP3 technology,
for example, this file can be shrunk to a much more managable 4 MB, though
this can change depending on the level of compression used. Newer compression
technologies promise even smaller file sizes.
To really appreciate this, think of an audio CD which has a capacity of roughly 650 MB. This would let you store around 17 four minute songs. Now if you use that same CD to store MP3 files you could probably manage to squeez in 150+ songs! This, in fact, is what a lot of music pirates are doing. For less than $20 you can get 11 CDs worth of music of your favourite artistes or genre. Now this may seem excellent until you consider the fact that the artistes (and even more so, the record companies) don't get anything in return. In other words, this is like walking off with some CDs from a record store. Also remember that trading compressed audio files amongst friends is also illegal. |
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