期考

nullnullMP3 :Moving Picture Experts Group Audio Layer III (动态影像专家压缩音频层面3 ) nullMP3 is a kind of Audio compression technology ,will sound with 1:10 or even 1:12 the compression ratio compression. Because of the compression of the way full name is MPEG Audio Layer3, so people see it referred to as "MP3. Introduction null1. Is a data compression format. 2.It abandon away pulse code modulation (PCM).( 脉冲编码调制) 3.MP3 audio can be in accordance with the different a speed compression .(压缩) 4.32 band multiphase integral filter. （多相积分滤波器 ） 5.36 or 12 tap improved discrete cosine filter (MDCT) .(改良离散余弦滤波器 ) 6.Have a wide range of client software support, have a lot of hardware support. For example Portable media player (指MP3播放器 )nullOrigin In 1991 ，Leon van DE Kerkhof (Layer I) and Gerhard Stoll (Layer II) completed. In 1992 in order to MPEG first standard MPEG-1 In 1994 set in the second MPEG groupMPEG-2 In 1994 Fraunhofer - Gesellschaft released the first called l3enc MP3 encoder. nullTo the public In 1995 selected extension. Mp3 MP2, MP3 and the Internet From the first half of 1995 until the whole ninety s, MP3 to start in the Internet vigorous development nullMP3 format Advantages 1.The same space can store more information 2.more suitable for sports appreciate music. 3. can follow one's inclinations edit their favorite songs. nullMP3 audio compression technology is a distortion compression. MP3 technology losing some sound , so sound quality is down .nullMP4 MP5 MP4 player is a set audio, video, picture browsing, ebook, the radio is a multifunctional player. Can‘t a MP5 popular understanding can be watching TV MP4 . null