For example: if a louder part masks a softer part, lossy codecs decrease bit depth for the soft part to, say, 1 bit (see Fig. but have you ever thought about the description 'they remove parts of the music'? In fact, they don´t literally remove those parts what they do is dynamically decreasing bit depth for certain parts, frequencies or information they deem to be inaudible. I won´t go into detail describing how lossy codecs are able to shrink filesizes. Because of this ear/brain combination those codecs are called 'psychoacoustic' us humans never listen with our ears only, our brain is indeed the biggest part of our hearing. 'Perceive' is important as lossy codecs remove information our brain would ignore anyway. They remove parts of the music our ears AND our brain are unable to perceive. To make it short: they make music smaller while trying to keep sound quality on par with the original they were encoded from. But as I said above, MP3 still is the most used lossy codec even though it´s old and technically inferior to the other codecs (ATRAC is worse). The Xiph.Org foundation followed suit in 2000 with a completely open and free alternative called Vorbis, commonly referred to as OGG.

In the same year, the Fraunhofer Society standardized what was to be the successor to MP3: AAC or MP4 and just like WMA and MP3 the use of this codec costs money. In 1999, Microsoft released WMA in order to have its own MP3-alternative which then could be licensed to partners for loads of money (or so they wished). Around the same time (1992) Sony unleashed ATRAC necessary for the MiniDisc, by that catapulting lossy coding into mainstream consciousness. Since then, MP3 has become the most dominant codec to store music with. In fact, after his dissertation he further developed this codec in cooperation with other scientists at the Fraunhofer Society. Herr Brandenburg is called by many people the 'father' of MP3. The principles he wrote about are the foundations for any lossy codec and they have been in use ever since. He was part of a group of scientists at the University of Erlangen-Nuremberg and in 1989 he described in his dissertation several techniques necessary for lossy codecs. The guy above did it all: Karlheinz Brandenburg.

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