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Štvrtok, 2. apríla 2020
MP3 or Size does Matter…
Dátum pridania: 25.03.2004 Oznámkuj: 12345
Autor referátu: sockagas
 
Jazyk: Angličtina Počet slov: 857
Referát vhodný pre: Stredná odborná škola Počet A4: 2.5
Priemerná známka: 2.97 Rýchle čítanie: 4m 10s
Pomalé čítanie: 6m 15s
 
If you have ever heard about MP3 file and wondered what it is or how it works then it will be my pleasure to introduce you „what is an MP3“. Making of MP3 file is based on compressing original music file into the file of smaller size but almost the same quality. Principle of this compression is based on imperfection of human ears, which can’t catch the whole scale of sounds. These are sound which are above or below the scale of tones which can be heared by human (above 20 000 Herz and below 20 Herz). The MP3 format is a compression system for music. The MP3 format helps reduce the number of bytes in a song without hurting the quality of the song's sound. The goal of the MP3 format is to compress a CD-quality song without noticably affecting the CD-quality sound. With MP3, a 32-megabyte song on a CD compresses down to about 3 MB. This lets you download a song in minutes rather than hours, and store hundreds of songs on your computer's hard disk without taking up that much space. However, the quality of this compression wasn’t always as good as now. Before MP3s we knew MP1 and MP2 files, although these weren’t used almost at all.
To make a good compression a technique called perceptual noise shaping is used. It is "perceptual" partly because the MP3 format uses characteristics of the human ear to design the compression algorithm. For example:
• There are certain sounds that the human ear cannot hear. • There are certain sounds that the human ear hears much better than others. • If there are two sounds playing simultaneously, we hear the louder one but cannot hear the softer one. Using facts like these, certain parts of a song can be eliminated without significantly hurting the quality of the song for the listener. Compressing the rest of the song with well-known compression techniques shrinks the song considerably. When you are done creating an MP3 file, what you have is a "near CD quality" song. The MP3 version of the song does not sound exactly the same as the original CD song because some of it has been removed, but it's very close. MP3 today (quality):
MP3 is so popular because of its small size, but mainly because of a high quality which can be found in few megabytes.
 
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