Difference between revisions of "MP3"

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(Format properly)
(add that mp3 was invented by Fraunhofer, correct i hope :))
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* Company: Fraunhofer
 
* Microsoft Audio ID: 0x0055
 
* Microsoft Audio ID: 0x0055
 
* QuickTime FOURCCs: CBR: ('m', 's', 0x00, 0x55); VBR: '.mp3'
 
* QuickTime FOURCCs: CBR: ('m', 's', 0x00, 0x55); VBR: '.mp3'

Revision as of 18:39, 6 October 2007

  • Company: Fraunhofer
  • Microsoft Audio ID: 0x0055
  • QuickTime FOURCCs: CBR: ('m', 's', 0x00, 0x55); VBR: '.mp3'
  • Patents: US5214678, US5323396, US5777992

Lossy audio coding using a time-frequency transform consisting of a 32-subband polyphase quadrature filter followed by an 18-point MDCT on blocks of 576 samples. Each coded frame is padded to a byte boundary. In addition, coded frames may be padded by 1 byte as necessary to maintain a strict CBR. This rather odd design was meant to provide backwards compatibility with the blocksize and bit rates of the existing MP2 format. Although it is less efficient than using a pure MDCT (e.g. AAC and Vorbis) MP3 has become a de facto standard since it was the first widely available format.


Extensions

mp3PRO

mp3PRO is MP3 + SBR (Spectral Band Replication). (Standard MP3 decoders can decode mp3PRO encoded files/streams but without SBR you do not get the full quality. A SBR decoder could be share code with a aacPlus decoder as aacPlus also uses SBR).

XING and VBRI headers

GAIN (MP3Gain) header

There is two versions of this header: one for MP3 and one for AAC.