Does AAC have a good analysis tool?

AAC format AAC audio format ADP audio coding details. A file compression format designed for audio data, similar to Mp3. Using AAC format, the sound file can be significantly reduced, and the sound quality will not be degraded. AAC format can be converted from MP3 to AAC through Qian Qian Listening (six components) or Apple iTunes. As early as 1987, Fraunhofer IIS started the research and development of "EUREKA project EU 147, Digital Audio Broadcasting (DAB)", which is the predecessor of MP3. Through the cooperation with Professor Dieter Seitzer, they developed the famous third-layer compression algorithm of ISO-MPEG audio. 1993, this algorithm was integrated into the MPEG- 1 standard, and MP3 was put into use. At the end of 1996, Flawn Hof IIS obtained a patent for MP3 in the United States, and announced on 1998 that it would collect royalties for MP3. Since 1999, MP3 format has become popular. In particular, there are many music websites that provide MP3 for free, and MP3 walkman has flooded into the market. Various factors make MP3 an extremely mainstream audio format. Although some challengers such as VQF and WMA appeared later, MP3' s solid foundation kept it firmly in the top position. But audio formats, like computer software and hardware, will eventually be updated. Isn't the tape eliminated by CD? CD will be replaced by DVD-Audio. As time goes by, MP3 can't meet our needs more and more. For example, the compression ratio lags behind Ogg, WMA, VQF and other formats, and the sound quality is not ideal (especially at low bit rate), with only two channels ... So Flawn Hof IIS cooperated with AT&T, Sony, Dolby, Nokia and other companies to jointly develop "2 1 century". Actually, the algorithm of AAC was completed in 1997, and it was called MPEG-2 AAC at that time, because it was also regarded as an extension of MPEG-2 (MP2) standard. However, with the formation of MPEG-4 (MP4) audio standard in 2000, MPEG-2 AAC has been regarded as the core of its coding technology, and some new coding features have been added, so we also call it MPEG-4 AAC (M4A). At present, there are few products supporting AAC, mainly because the patent royalties greatly limit the development of AAC! Fortunately, with the support of Nokia, Apple and Panasonic, the scene was not deserted. (1) Nokia promotes AAC formats in the field of mobile phones, including N-gage, 3G network 7600, media mobile phone 7700, fashion entertainment 3300, new look 6230 and mobile phone accessory music player HDR- 1, which can play AAC files stored on MMC cards. (2) Apple's heavyweight iPod and iPod mini can play 16-320 kbps AAC files, and the iTune music player that Apple has made great efforts to build paves a shortcut for making and playing AAC files. 3) Panasonic Panasonic's e-Wear SD audio player series walkman is a highlight of supporting AAC. At present, there are many products such as SV-SD05, SV-SD50, SV-SD75 and SV-SD85. 4) Other products In addition, some manufacturers' products support AAC, such as DIVA GEM of Daisy Multimedia, IPAQPA- 1 of Compaq supporting SM card expansion, MEA2 10 of Toshiba's SD card walkman, MM-EX300 of Aihua, IDP- 100 of iriver using DataPlay as storage medium, etc. Apple and Real also set up an online music store to compress the latest records into AAC format for download. Of course there is a charge, but the sales volume is very good. Apple's iTune online music store, in particular, can sell 3.3 million songs in a week. Not only promoted the development of the recording industry, but also safeguarded the copyright, which greatly promoted the popularization of AAC! AAC AAC's advanced functions are all developed on the basis of MP3, so their coding system has some points. But comparing the two coding flowcharts, you will find that the coding process of AAC is more complicated. The key differences between (1)AAC and MP3 are: ① filter bank): ② Time domain noise shaping (TNS): This magical technology can trim the distribution of quantization noise in time domain through frequency domain prediction. In the quantization of some special speech and rapidly changing signals, TNS