Yimuphi umsindo we-PCM nokuthi kungani kubalulekile
I-PCM imele i- P ulse C ode M ukuguqulwa.
I-PCM isetshenziselwa ukuguqula izibonakaliso zomsindo we-analog (ezimelelwe amafomu ombukiso) kumpawu zomsindo zedijithali (ezimelelwa yiminyaka engu-1 no-0-kufana nedatha yekhompyutha) ngaphandle kokucindezelwa . Lokhu kuvumela ukuqoshwa komculo womculo noma i-soundtrack ye-movie ukulingana esikhaleni esincane (qhathanisa ubukhulu beCD kumrekhodi we-vinyl).
Ama-PCM ayisisekelo
Ukuguqulwa komsindo we-PCM okungafani nedijithali kungaba yinkimbinkimbi, kuye ngokuthi yikuphi okuqukethwe okuguqulwayo, ikhwalithi edingekayo noma eyifunayo, nokuthi ulwazi lugcinwa kanjani, luhanjiswa noma luhanjiswa. Nokho, nansi okuyisisekelo.
Ifayili ye-PCM yinguqulo yedijithali yomsindo womsindo we-analog. Umgomo ukuphinda uphinde uphinde ulandele izakhiwo zesignali yomsindo we-analog ngangokunokwenzeka.
Indlela okuguqulwa ngayo i-analog-to-PCM yenziwa ngenqubo ebizwa nge-sampling. Njengoba kuphawuliwe ngenhla, umsindo we-analog uhamba emagagasi, kanti i-PCM yochungechunge lwe-1 ne-0. Ukuze uthathe umsindo we-analog usebenzisa i-PCM, amaphuzu athile omsakazo womsindo kufanele ashintshwe (imvamisa). Ukuthi kungakanani okushiwo yi-waveform esampuliwe endaweni ekhonjiwe (izingcezu) nakho kuyincenye yenqubo. Amaphuzu amaningi asetshenzisiwe kanye nezingxenye ezinkulu zegagasi elizwakalayo esampuliwe endaweni ngayinye lisho ukunemba okuthe xaxa ekupheleni kokulalela. Isibonelo, kumsindo weCD, i-analog waveform sampuliwe izikhathi ezingu-44.1 eziphindwe ngomzuzwana (noma 44.1kHz), ngamaphuzu angama-16bits ngobukhulu (ukujula). Ngamanye amazwi, izinga lokulalelwayo le-digital yomsindo weCD liyi-44.1kHz / 16bits.
I-PCM Audio Audio and Home Theatre
Uhlobo olulodwa lwe-PCM, i-linear plus code modulation (LPCM), lisetshenziswe ku-CD, i-DVD, i-Blu-ray Disc, nezinye izinhlelo zokusebenza zomsindo we-digital.
Ku-CD, i-DVD, noma i-Blu-ray Disc player, i-LPCM (ngokuvamile ebizwa ngokuthi isignali nje ye-PCM) ifundwa ku-disc futhi ingadluliselwa ngezindlela ezimbili:
- Enye indlela ukugcina ifomu layo ledijithali nokuthumela leyo mbonakaliso kumamukeli wendawo yaseshashalazini nge- digital optical, digital coaxial , noma uxhumano lwe-HDMI . I-receiver bese iguqula isignali ye-PCM ku-analog ukuze ithunyelwe ngokusebenzisa ama-amplifiers nakuzo kuzikhulumi. Isizathu sokuthi isignali ye-PCM kufanele iguqulwe ku-analog yukuthi indlebe yomuntu isebenza ngokuzwa izibonakaliso zomsindo we-analog.
- Indlela yesibili i-CD, i-DVD, noma isidlali se-Blu-ray Disc ukuguqula isignali ye-PCM emuva kwifomu le-analog ngaphakathi, bese udlulisela isignali ye-analog esakhiwe kabusha kumsakazo wasekhaya noma isamukeli se-stereo ngokusebenzisa uxhumano olujwayelekile lwama-analog audio. Kulokhu, isamukeli se-stereo noma yaseshashalazini akudingeki senze noma yikuphi ukuguqulwa okungeziwe ukuze ukwazi ukuzwa umsindo.Abanye abadlali beCD kuphela banikeza ukuxhumeka komsindo we-analog, ngakho-ke kuyadingeka ukuthi isignali ye-PCM ku-disc iguqulwe kuya ku-analog ngomdlali ngaphakathi. Kodwa-ke, abanye abadlali beCD (kanye nabo bonke abadlali beDVD ne-Blu-ray Disc) bangadlulisela isignali yomsindo we-PCM ngokuqondile ngokusebenzisa ukhetho lwe-digital optical noma i-digital coaxial option. Ngaphezu kwalokho, abaningi abadlali be-DVD ne-Blu-ray Disc bangaphinde badlulisele izimpawu ze-PCM nge-HDMI uxhumano.
I-PCM, i-Dolby, ne-DTS
Enye inkohlakalo abaningi abadlali beDVD nabakwa-Blu-ray Disc abangayenza ukufunda amasignali alalelwayo weDolby Digital noma we- DTS . I-Dolby ne-DTS yizakhiwo zomsindo wedijithali ezisebenzisa ukufaka ikhodi ephoqelela ulwazi ukuze uvumelane nolwazi oluzwakalayo lomsindo oluzungezile kwi-DVD noma i-Blu-ray Disc. Ngokuvamile, amafayela e-Dolby Digital ne-DTS angatholakali adluliselwa kumamukeli womdlalo wekhaya ukuze aphinde ahlaziywe ku-analog-kodwa kukhona enye inketho.
Uma usuqedile i-disc, ama-DVD amaningi noma abadlali be-Blu-ray Disc bangaphinda baguqule amasignali e-Dolby Digital kanye ne-DTS kwi-PCM engaxhunyiwe, bese usudlulisela isignali ekhonjiwe ngqo kumamukeli wendawo yaseshashalazini nge-HDMI uxhumano, noma ukuguqula isignali ye-PCM i-analog yokukhishwa ngamiphumela emibili ye-audio analog multichannel kumbekeli womdlalo womdlalo ophethe izinto ezihambelanayo ezihambisanayo.
Kodwa-ke, njengoba isignali ye-PCM ingagxiliwe, kuthatha isikhala sokudlulisa okuningi se-bandwidth. Ngakho-ke, uma usebenzisa uxhumano lwe-digital noma uxhumano lwe-coaxial, kunamathuba okwanele okudlulisela iziteshi ezimbili zomsindo we-PCM. Ukudlala kwe-CD okuhle kakhulu, kodwa kuma-signal we-Dolby Digital noma e-DTS azungezile aguqulelwe ku-PCM, udinga ukusebenzisa uxhumano lwe-HDMI, njengoba lungadlulisela iziteshi ezingu-8 zomsindo we-PCM.
Ukuze uthole ukuthi umsebenzi we-PCM osebenza kanjani phakathi komdlali we-Blu-ray Disc kanye nesamukeli semidlalo yaseshashalazini, bhekani kuzilungiselelo zomsindo we-Blu-ray Disc Audio: Bitstream vs PCM .