About MP3
Historical background of MP3-format
MP3-format appeared not so long ago: in early 90-ties. But at that time no one could believe that in 5-7 years it will become so popular all over the world.
It is a universally recognized fact that now MP3 is the most widely-used format for the music files storage (MPEG Audio Layer III). But few of us know that originally it was invented not for wide using, it was designed for the archiving of the digital audio materials in the field of moving pictures. The new coding method based on dataflow density (bitrate) enabled to compress the original material due to the required sound quality.
Briefly about the MP3 attributes
Varying bitrate amount in the dataflow gives the possibility to get different sound quality: from the minimum of 8 kbps 11025 Hz up to the maximum CD Audio-level of 320 kbps 44100 kHz. The optimal compression, giving the best correspondence between the size of the compressed file and its quality is of 128 bitreit. The absolute CD-like sounding is achieved by the bitrate from the 160 kbps and higher. So, being highly competitive with CD-format the new MP3 format won the instant popularity
File components
File in MP3 format it is a certain flow of multiple MP3 frames, which is called Elementary stream. Each frame comprises MP3 header and MP3 data. Frames are not autonomous structures, but the dependant ones, so they are not able to the accidental breaking the boundaries. The MP3 data is the audio content as it is. The MP3 header comprises a sync word, which aims to mark the new frame beginning. So, the full name of the MP3 format (MPEG-1 Audio Layer 3 or MP3) is combined by a bit which shows that this is the MPEG standard and two bits show that layer 3 is used. The values for each section of the header differ According to the MP3 file. It is achieved by ISO/IEC 11172-3 together with the specification of the header. Now the majority of MP3 files have ID3 metadata, which heads or tails the MP3 frame.
