Kusho ukuthini ukulungiselelwa kwe-Chroma ku-Apple TV?

Uma ungomunye walabo basebenzisi abathanda ukusetha imikhiqizo yabo ngokuthanda kwabo ukuze ivumelane nabo ngangokunokwenzeka, cishe usuhlangabezane nesigaba sezilungiselelo ze-Apple TV. Ividiyo nomsindo ngento I-Chrome. Ngale nketho, ayatholakala ku-Apple TV izinketho ezimbili, ongakhetha kuzo. Kodwa-ke, iqiniso liwukuthi abasebenzisi abajwayelekile abangabhekani nolwazi futhi, ngokunokwenzeka, babonisa ubuchwepheshe, cishe abazi ukuthi inketho yeChroma isho ukuthini nokuthi yiziphi izilungiselelo okufanele bazikhethe. Kulesi sihloko, ake sibheke ndawonye ukuthi i-chroma isho ukuthini nokuthi ingasethwa kuphi ku-tvOS.

Yini i-chroma?

Isampula ye-Chroma Ngiwumfana ukucindezela, ngosizo lwalo ukunciphisa usayizi wolwazi lombala. Isiginali yevidiyo ihlukaniswe ngokwezigaba izici ezimbili eziyinhloko - ulwazi mayelana ukukhanya (luma) kanye nolwazi mayelana umbala (chroma). Ulwazi mayelana ukukhanya (i-luminance, i-luma efushanisiwe), ichaza izinga lokukhanya lesithombe esidlulisiwe, ngakho-ke i qhathanisa. Kuchaza uLuma ingxenye enkulu saso sonke isithombe, ngakho-ke isithombe esimnyama nokumhlophe asibukeki sinemininingwane emincane kunombala owodwa. Ulwazi mayelana umbala (i-chrominance, i-chroma efushanisiwe), nayo isetshenziselwa ukudlulisa isithombe kubalulekile, kodwa hhayi kakhulu njenge-luma - ukubeka kalula, i-chroma inomthelela omncane ekubukekeni okuphelele kwesithombe. Ngakho-ke, ngesikhathi sokudluliselwa kwesithombe, okuthiwa amasampula amancane, ngakho-ke ukunciphisa inani lolwazi lombala oludlulisiwe. Ngenxa yokuthi usayizi wedatha yombala odlulisiwe uncishisiwe, kungenzeka ukudlulisa ulwazi olwengeziwe mayelana nokukhanya, futhi isithombe esiphumela singakhanya ngokugqamile ngokwemibandela ikhwalithi engcono nenembe kakhudlwana. Ngesikhathi esifanayo, izogcinwa ukucaca kwesithombe futhi ngesikhathi esifanayo ungakwazi ukunciphisa usayizi wefayela lonke levidiyo lifike o 50%.

Icaciswa kanjani i-chroma?

Isilungiselelo siyatholakala ngaphakathi kwe-tvOS 4:2:2 noma 4:2:0, nokho, kufanele kuqashelwe ukuthi singahlangabezana nezilungiselelo 4:4:4. Inombolo yokuqala njalo ibonisa kulolu chungechunge lwezinombolo usayizi wesampula. Olandelayo izinombolo ezimbili bese behlobene lunyonga. Zombili lezi zinombolo zihlobana futhi zichaze inombolo yokuqala evundlile a amasampula aqondile. Lokhu kuchazwa kangcono ngesibonelo. Izilungiselelo 4:4:4 ayisebenzisi akukho compression, ngakho-ke akukho sampuli engaphansi - kulokhu kukhona i-carryover ulwazi oluphelele mayelana nokukhanya nombala. Izilungiselelo 4:2:2 bese idlulisela ingxenye ulwazi mayelana nombala - luza ku isampula evundlile. 4:2:0 iyadlulisela ingxenye yesine ulwazi mayelana nombala, ngakho-ke se umugqa owodwa ulwazi lombala ngokuphelele uyaphuthelwa. Ukuze usiqonde kangcono lesi sihloko, igalari ngezansi kwalesi sigaba uzothola izithombe ezihlobene nezilungiselelo zesampula ye-chroma.

Igalari yezithombe

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Imboni yefilimu kanye ne-chroma

Njengoba iningi lethu lisebenzisa i-Apple TV ikakhulukazi ukubuka izinhlelo, sizobheka ukuthi ukusampula kwe-chroma kuwathinta kanjani amamuvi, uchungechunge, namanye amavidiyo. Ukusetshenziswa kwesampula ye-chroma kuvame kakhulu embonini yamafilimu okwamanje 4: 2: 0. Isizathu esiyinhloko ukuthi iso lomuntu cishe alinalo ithuba lokuhlukanisa ekuqaleni umehluko phakathi kuka-4:2:0 no-4:4:4, ongasebenzisi noma yikuphi ukucindezela. Nini 4:2:0 nakuba kukhona okuthile ukulahlekelwa kolwazi lombala, kodwa ngokuqinisekile akuphathelene lutho olunzima. Ifomethi 4:2:0 ibuye isetshenziswe ngokujwayelekile Ama-Blu-ray discs futhi kwezinye izimo lapho ufuna ukuba nefilimu ngekhwalithi "engcono kakhulu" ngangokunokwenzeka. Umehluko phakathi kwezilungiselelo zesampula ye-chroma ubonakala kakhulu uma isesikrinini umbhalo omncane. Endabeni ye-subsampling, okuthiwa izinto zobuciko. Ungathola ngezansi igalari, lapho ungabuka khona lawo ma-artifact ngokuhlukene ngefomethi ngayinye.

Igalari yezithombe #2

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Ungayisetha kanjani iChroma ku-tvOS?

Ngaphakathi kwe-Apple TV, sinezilungiselelo ze-Chroma ezitholakala ngefomethi 4:2:0 noma 4:2:2, uma ikhethwa ngokuzenzakalelayo 4: 2: 0. Njengoba ungase ufunde emigqeni ebhalwe ngenhla, ifomethi engu-4:2:0 iyikhwalithi ephansi kakhulu kuleli cala, ngoba esimweni sayo "kuphela" ingxenye yesine yedatha yombala idluliselwa. Lesi silungiselelo sikhethwa ikakhulukazi ngenxa yokuthi abantu bavame ukusebenzisa izintambo ze-HDMI ezejwayelekile ngokuphelele, ezingakwazi ukuphatha ukudluliswa kwefomethi engu-4:2:2. Ngakho-ke ifomethi engu-4:2:2 kufanele ibekwe abantu abanjalo abanayo i-HDMI esheshayo nesezingeni eliphezulu ikhebula. Uma ufuna ukushintsha izilungiselelo ze-Chroma ku-tvOS, yiya ku Izilungiselelo -> Ividiyo Nomsindo -> I-Chroma. Uma uzama ukusetha ifomethi 4:2:2, ngakho-ke i-Apple TV izokwazisa bese yenza ukuhlolwa kwezintambo zakho. Uma izintambo zakho zidlula, kanjalo nefomethi 4:2:2 amasethi, kungenjalo kuyoba khona ukubuyisela izilungiselelo zangempela, kanjalo ukuze 4: 2: 0.

Igalari yezithombe #3

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