Cov xim ntawm lub tshuab network tuaj yeem muaj tseeb dua li lub koob yees duab analog. Lub teeb ci ci ntsa iab thiab chrominance teeb liab nyob rau hauv lub teeb liab analog video nyob ntawm tib lub zaus band. Thaum cov yeeb yaj kiab ntes nti siv rau kev lim dej comb (ci xim sib cais), nws nyuaj rau cais cov xim. Kev sib cais ua tiav ntawm kev siv zog thiab kev ci ntsa iab ua rau pom qhov txawv ntawm qhov sib txawv thiab xim nkag mus rau hauv daim duab. Cov koob yees duab digital siab tsis muaj qhov teeb meem no. Cov xim yog ntau lifelike, ntau txheej, thiab daim duab saturation yog zoo dua.
Cov duab scanning hom tau txais los ntawm high-txhais network tshuab yog nce qib scanning, thiab txhua thav duab ntawm cov duab yog tsis tu ncua scanned kab los ntawm kab ntawm lub electron beam. Lub hom scanning ntawm cov koob yees duab analog ib txwm siv interlaced scanning, thiab kab scanning zaus ntawm interlaced scanning yog ib nrab ntawm cov kev soj ntsuam zoo. Vim nws txoj kev ua hauj lwm, interlaced scanning muaj ntau yam shortcomings nyob rau hauv daim ntawv thov, xws li inter-line flicker, parallelism, los yog ntsug ntug jaggedness, thiab lwm yam undesirable teebmeem, thiab ua rau tag nrho cov lus tsa suab lub ntsiab lus yuav txo.
Kev daws teeb meem ntsug ntawm cov koob yees duab analog xim ib txwm tau txais yog 625 kab nyob rau hauv PAL system, 575 kab tom qab de-blanking, thiab qhov siab tshaj plaws yog txog 540 kab, uas yog qhov txwv tam sim no, thaum qhov tsawg kawg nkaus ntawm cov koob yees duab digital siab tuaj yeem ncav cuag ntau dua. 800 kab, thiab los ntawm qhov kev xav ntawm kev daws teeb meem, qhov kev daws teeb meem siab tshaj plaws ntawm cov koob yees duab analog tuaj yeem ncav cuag li D1 lossis 4CIF, uas yog kwv yees li (400,000 pixels), thaum lub koob yees duab digital tsis muaj qhov txwv, thiab tuaj yeem ncav cuag mega-pixels lossis txawm kaum. ntawm lab pixels. Qhov kev ua tau zoo ntawm qhov tseeb yog txawv kiag li.
Thawj qhov kev daws teeb meem ntawm lub koob yees duab simulation tsoos tsis siab. Tsis tas li ntawd, nws raug cuam tshuam los ntawm kev puas tsuaj video xws li rov ua A / D hloov dua siab tshiab, kev cuam tshuam ntawm electromagnetic kis, interlacing, D1 duab synthesis thiab deinterlacing, thiab nws yog qhov muag plooj heev thaum nws ncav cuag tib neeg lub qhov muag. Yog li ntawd, txawm nws yog D1 lossis 4CIF, thiab lwm yam, nws tsuas yog tus nqi theoretical xwb. Nyob rau hauv kev siv tswv yim, qhov clarity tsis yog mus txog theoretical tus nqi. Cov koob yees duab digital siv cov teeb liab kis tau tus mob, uas hloov cov teeb liab kho qhov muag rau hauv cov teeb liab digital, thiab tom qab ntawd cov duab compression thiab ua tiav los ntawm DSP. Thaum kawg, cov digital compressed video yog tso tawm los ntawm lub network. Lub koob yees duab digital tiv thaiv kev cuam tshuam ntawm electromagnetic cuam tshuam, nce qib scanning, thiab cov duab daws teeb meem. Hais txog tus nqi, lawv txhua tus muaj qhov zoo uas cov koob yees duab analog tsis tuaj yeem phim.
