Thursday, May 2, 2013
MP3 - Beginners Guide to MP3
Beginners Guide to MP3
MP3 is a compression algorithm that reduces the size of audio files by a factor of around ten. Audio data in the form of stereo CD recordings takes a large amount of hard drive space, around 10MB per one minute of stereo sound. Consequently, prior to the development of audio compression, trading audio files over the Internet was somewhat impractical due to file sizes. However, thanks to MP3, audio files could be compressed to about 1/10 of their original size while still retaining good audio quality. As MP3 file sizes were much smaller, people could now upload and download songs on the Internet. Once the established music industry latched on to this, legal action was taken against the likes of Napster to try and prevent music distribution via MP3 files.
Nowadays, the music industry has embraced MP3 to a certain extent, and Internet web sites such as Apple's iTunes allow people to download songs for a fee.
What Does MP3 Do
As stated above, MP3 is a compression algorithm. Typical audio CDs are recorded at 44,100 Hz and 16 bits. This means that 44,100 audio samples are recorded each second and each sample is 16 bits. This is a constant data stream which is equivalent to about 10 MB per minute of stereo audio.
MP3 works by throwing away some of this data, especially frequencies which are beyond human hearing. The trade off is reduced sound quality, but for most people the difference is scarcely perceivable. Sound quality can be improved by encoding the audio at higher bit rates, but this results in bigger files.
The big advantage of MP3, of course, is the compact file size. Audio files which are encoded at 128 kb per second are around 1/11 the size of the original audio file. As well as allowing Internet distribution of songs, the small size of MP3 files has also spawned the MP3 player market. MP3 players are compact devices, sometimes no bigger than a chocolate bar, that can hold hundreds of songs. MP3 players are currently one of the hottest consumer items in the world.
The process of applying an MP3 algorithm to an audio file is called encoding. For playback purposes the file must be decoded. For this reason, audio players need a CODEC - enCOder DECoder to play MP3 files. These codecs are included in virtually every portable audio player.
As with most things, MP3 is not the only form of audio compression algorithm. There are many other formats for compressing audio but support for these alternative formats is not universal. Therefore, when shopping for a portable audio player, one of the big considerations is the type of files it can handle.
Windows Media Audio - WMA
The second most popular format after MP3 is Windows Media Audio or WMA. This is a Microsoft format that claims to offer higher audio quality at lower bit rates. Lower bit rates translate into smaller file sizes, one of the reasons for the popularity of WMA.
Advance Audio Coding - AAC
Apple iPod portable music players support the Advance Audio Coding or AAC format. Advance Audio Coding allows up to 48 audio channels and handles higher frequencies better than MP3. The result is better sound with smaller file size.
OGG Vorbis
Ogg Vorbis is another format that is growing in popularity. Ogg Vorbis is an open source codec that is not subject to licensing fees and has a sound quality equal to or better than MP3.
For those concerned with audio purity, many players also support uncompressed audio files (WAV). However, at 10 MB per minute, very few WAV files can be stored on the typical portable audio player.
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