What is an audio compression?
On this site, we will use term audio compression in a sense of reducing the file size of digital audio data. Meaning - making your files smaller. You can fit more of those smaller files on your audio player, you can transfer them faster on fixed bandwidth. Advantages of smaller files are countless.
Like any other data compression, audio compression uses special algorithms to perform it's primary function. Most of you are already familiar with different data compression algorithms through usage of software like RAR/WinRAR, ZIP/WinZIP, WinACE etc...
While those algorithms work very well for general data compression, they are unsuitable for usage with audio files. Firstly, their levels of compression for audio files are unsatisfying leaving you with the files that are just too big, and secondly, they do not perform in a real-time, meaning you can't listen to a packed song, you have to unpack it and then listen. Obviously there was a need to develop special audio compression algorithms. You might know many of those algorithms implemented on your computer through audio codecs like MP3, FLAC, OGG, APE.
This is where we should point out the first difference in the way compression algorithms work. While you expect your document packed with WinRAR, WinZIP or some other to be EXACTLY the same after unpacking same usually does not apply to images or music compressed with codecs like jpg or mp3 respectively. You'll notice that your compressed images are not as sharp as original, that your music lost some of the higher frequency spectrum when compressed to MP3 and that radio streams at 128kbps sound just awful. This is because both of JPG and MP3 are LOSSY, while the RAR and ZIP are LOSSLESS.
