Kuyini AAC-format?

Nokho, Kuze kube manje, AAC-format namanje Siye azifinyelelanga ukusatshalaliswa kwenqwaba yemilayezo abathwali umsindo, eziningi nemingcele ungcono kakhulu zonke izinhlobo samanje kokucindezelwa alalelwayo, futhi ngenxa yalokho azinake yethu.

Kuyini lokhu?

Thina siqale incazelo: alalelwayo ifomethi AAC kuyinto nokuphathelene (lobunikazi) omunye kokucindezelwa lwefayela yomsindo. Ngesikhathi esifanayo it has a ukulahlekelwa encane izinga ngesikhathi esephepheni kuka MP3 ngesikhathi esifanayo izimo bit. Futhi, AAC-format kuyinto wideband umsindo esephepheni algorithm esebenzisa ezimbili eziyinhloko wekhodi simiso kakhulu ukunciphisa inani idatha adingekayo ukudluliselwa eliphezulu audio digital. Le isixazululo ubhekwa omunye eliphezulu kakhulu, lathengiswa, ukulahlekelwa kokucindezelwa ubuchwepheshe. Ifomethi isekela imishini yesimanje kunazo, ngisho ephathekayo. Kufanele kuqashelwe ukuthi amathoni indandatho AAC format angathengwa Store iTunes, futhi kule esitolo kukhona umculo, onomfutho kuphela esebenzisa isinqumo. Kufanele futhi kuthiwe AAC-format okudalwe njengoba owalandela MP3, okunganikeza ngcono izinga esephepheni. Isinqumo yanyatheliswa ngo-1997 njengoba entsha, 7th, ingxenye yomkhaya ka-MPEG-2.

Umgomo we operation

Lapho ikhodi ngalesi sakhiwo, izinqubo ezilandelayo: izingxenye imperceptible isignali ziyasuswa, bahlanza we anekhodi umsindo isignali komsebenzi. Ngemva kwalokho, ukwaziswa kusingathwa ngokuhambisana indlela ngokuvumelana MDCT umklamo wawo. Ngesikhathi sigaba esilandelayo amakhodi kunezelwa ukulungisa amaphutha ahlukahlukene yangaphakathi. Ekugcineni, isignali idluliselwa noma ukulondolozwa.

Yonke imininingwane

Ngokuthakazelisayo, AAC-format has a imvamisa zalokho phakathi 8-96 kHz futhi inani iziteshi isikhawu 1-48. MP3 Hybrid isebenzisa sihlungi. Libhekisela Ushintshe cosine leyehlukene uguqule, esikhundleni salokho AAC ngesilinganiso anda "amawindi", okusho sifinyelela 2048 amaphuzu.

Ngakho, AAC okuningi kuhambisana ngalokufanele encode yomsindo wokusakaza kokuba ishayela kanye sikwele-wave amasignali eziyinkimbinkimbi, uma kuqhathaniswa ne-MP3. Ifomethi yazuza ikhono ngamandla ukushintsha ubude MDCT block in the uhla 2048-256 amaphuzu. Uma kukhona short-term noma shift olulodwa, wasebenzisa "ifasitela" elincane 256 amaphuzu ukuze kuzuzwe isixazululo esingcono. Kulokhu, lo okuzenzakalelayo 2048-iphuzu "ifasitela" enkulu ukukhulisa kahle esephepheni. AAC has eziningi eziwusizo kuqhathaniswa ne-MP3 evamile. Phakathi kwabo kufanele sikusho: ukugcwaliseka inqwaba amashaneli omsindo (kufika ku-48), abalulekile kahle esephepheni ngaphansi kwezimo njalo futhi variable bit futhi izibonelo zalokho imvamisa in the uhla kusuka 8 Hz 96 kHz (I-MP3, lesi sibalo kusuka 8 Hz 48 kHz) futhi imodi ekhethekile enetjhuguluko ngokuthi stereo Joint. Njengoba amakhambi, "AAC +" - codec eligxile ukusebenza ongaphakeme bit. Ingabe inhlanganisela SBR kanye AAC LC, kanjalo ekufezeni umsindo ezinhle kakade uhla 32-48 kbit / s.