Digital music recording part 3
Time masking is based on the fact that if a silent one immediately follows a loud sound, then it can be ruled out, because the change in the hearing threshold of a human ear does not happen instantly.
All lossy audio encoding methods work according to the same scheme. First, the sound is divided into frames, from which the masked components are removed, after which the frames are encoded using the Hoffman method, whereby the most common code words are given the minimum duration, and the least frequent, on the contrary, the maximum. The difference between the methods lies in the way the sound is analyzed and the masked components are removed.
Lossless compression algorithms are relatively rare, although they have their own indisputable advantages. The point is, any loss spoils the sound. It is one thing if you, working at a computer, listen through plastic Chinese speakers – “Cheburashka” “And you kiss me everywhere …”, and another – when playing symphonic music on serious equipment. Furthermore, even a professional can hardly tell what exactly was missing from the sound during encoding. Vague terms such as “colorful”, “transparency”, “juiciness” … will be used.
There are many algorithms for compressing audio files and consequently the formats of these files. For example, the audio recording formats for PC games, audio players, and Internet downloads are different. The general rule of thumb is that high bit rate files have relatively high audio quality and large size, while low bit rate files are compact, but can only be called music as a courtesy.
Additionally, various audio file formats have been created for various computing platforms such as PC, Macintosh, Amiga, and others.
