Video thev naus laus zis tau dhau los ua qhov hloov pauv sai hauv ob peb lub xyoo dhau los.Yav dhau los, cov yeeb yaj kiab tau ua los ntawm cov ntawv sau loj ntawm cov duab tseem, thiab lawv siv cov ntaub ntawv loj heev los ua rau lawv digital.Tab sis tam sim no, video encoding tau coj kev hloov pauv thev naus laus zis - compressing cov ntaub ntawv no kom siv qhov chaw tsawg dua.Nws kuj tseem muaj peev xwm tshaj tawm cov yeeb yaj kiab hauv Is Taws Nem, ob qho tib si ntawm lub sijhawm thiab ntawm qhov xav tau.
Ib qho ntawm cov thev naus laus zis encoding nrov tshaj plaws yog H.264 (AVC - Advanced Video Coding) uas muaj peev xwm daws tau ntau yam teeb meem zoo txog kev tshaj tawm video.Nyob rau hnub no lub blog, cia peb kawm seb H.264 video encoding yog dab tsi, nws ua haujlwm li cas, thiab nws qhov zoo hauv kev nthuav dav.
H.264/AVC yog dab tsi?
H.264 tseem hu ua Advanced Video Coding (AVC) lossis MPEG-4 Part 10. Nws yog video compression technology sib koom ua ke tsim los ntawm International Telecommunications Union (raws li H.264) thiab Lub Koom Haum Thoob Ntiaj Teb rau Standardization/International Electrotechnical Commission Moving Picture Pawg kws tshaj lij (raws li MPEG-4 Part 10, Advanced Video Coding, lossis AVC).
Niaj hnub no, H.264 codec feem ntau yog siv nyob rau hauv video streaming.Qhov codec no yog tus qauv kev lag luam rau video compression uas pab tsim cov ntaub ntawv, compress, thiab faib lawv cov yeeb yaj kiab online.Nws muab cov yeeb yaj kiab zoo ntawm cov bitrates qis dua piv rau cov qauv dhau los.Li no, nws yog dav siv nyob rau hauv cable TV tshaj tawm thiab Blu-duab tshav disks.
Raws li ib tug yees duab codec, H.264 yog nquag tsim nyob rau hauv lub MPEG-4 thawv hom, uas siv lub .MP4 extension, raws li zoo raws li QuickTime (.MOV), Flash (.F4V), 3GP rau cov xov tooj ntawm tes (.3GP), thiab MPEG thauj kwj (.ts).Qee zaum, H.264 video yog encoded nrog suab compressed nrog Advanced Audio Coding (AAC) codec, tus qauv ISO/IEC (MPEG4 Part 3).
H.264/AVC ua haujlwm li cas?
Lub H.264 video encoder ua qhov twv ua ntej, hloov pauv, thiab cov txheej txheem encoding los tsim H.264 bitstream compressed.Nws siv cov txheej txheem thaiv-taw qhia nrog kev sib tw suab los ua cov txheej txheem ntawm cov ntsiab lus video.Cov zis yuav yog macroblocks uas muaj cov blocks loj li 16 × 16 pixels.
Tam sim no, H.264 video decoder ua cov txheej txheem ntxiv xws li kev txiav txim siab, hloov pauv hloov pauv, thiab rov tsim kho dua los tsim cov yeeb yaj kiab decoded.Nws tau txais cov compressed H. 264 bitstream, txiav txim siab txhua lub ntsiab lus syntax, thiab rho tawm cov ntaub ntawv xws li quantized transform coecients, kev kwv yees cov ntaub ntawv, thiab lwm yam. Tsis tas li ntawd, cov ntaub ntawv no yuav raug siv los thim rov qab cov txheej txheem coding thiab rov tsim ib ntu ntawm cov duab video.H.264 video coding thiab decoding txheej txheem yog qhia hauv qab no.
Qhov zoo ntawm H.264
1.Kev siv bandwidth qis dua thiab kev saib xyuas kev daws teeb meem siab dua - Nws muab cov kev sib kis tau zoo ntawm cov yeeb yaj kiab tag nrho nrog cov kev cai qis bandwidth thiab qis dua latency dua.tsoos video standardzoo li MPEG-2.H.264 siv cov codec ua tau zoo uas muab cov duab zoo thiab siv bandwidth tsawg.
2.Tsawg H.264 bitrate dua li lwm hom ntawv - Nws muaj 80% qis bitrate dua Motion JPEG video.Nws tau kwv yees tias qhov kev txuag nyiaj me me tuaj yeem yog 50% lossis ntau dua piv rau MPEG-2.Piv txwv li, H.264 tuaj yeem muab cov duab zoo dua ntawm tib qhov compressed bitrate.Ntawm tus nqi qis dua, nws muab cov duab zoo ib yam.
3.Txo qhov kev thov rau kev cia video - Nws txo qhov loj ntawm cov ntaub ntawv video digital los ntawm 50% thiab siv tsawg dua khaws cia video piv rau lwm cov qauv uas ua pov thawj qhov tseem ceeb kom tso cai rau kev sib kis tau yooj yim video los ntawm IP.
4.Zoo kawg video zoo – Nws muab cov ntsiab lus meej, zoo video ntawm cov ntaub ntawv tus nqi ntawm ¼, uas yog ib nrab ntawm qhov loj ntawm lwm hom video.
5.Ntau npaum - Nws yog ob npaug ntau npaum li cas, thiab cov ntaub ntawv loj yog 3X lub sij hawm me dua li MPEG-2 codecs - ua qhov compression hom ntau npaum li cas.Qhov no codec ua rau tsis tshua muaj kev sib kis bandwidth rau cov ntsiab lus video.
6.Haum rau cov ntsiab lus video qeeb-nws yog qhov ua tau zoo heev rau cov suab qis video codecs siv lub koob yees duab megapixel.
Post lub sij hawm: Nov-20-2022
