H.264 video encoding yog dab tsi? H.264 codec ua haujlwm li cas?

Cov thev naus laus zis video tau hloov pauv sai heev hauv ob peb xyoos dhau los. Ua ntej, cov yeeb yaj kiab tau ua los ntawm cov duab loj loj, thiab lawv siv cov ntaub ntawv loj heev los ua kom lawv digital. Tab sis tam sim no, kev encoding video tau coj kev hloov pauv thev naus laus zis - compressing cov ntaub ntawv no kom siv qhov chaw tsawg dua. Nws kuj tau ua tau los streaming video hla Is Taws Nem, ob qho tib si real-time thiab on-demand.

Ib qho ntawm cov thev naus laus zis encoding nrov tshaj plaws yog H.264 (AVC - Advanced Video Coding) uas tau daws tau ntau yam teeb meem zoo txog kev tshaj tawm video. Hauv blog hnub no, cia peb kawm txog H.264 video encoding yog dab tsi, nws ua haujlwm li cas, thiab nws cov txiaj ntsig kom ntxaws.

H.264/AVC yog dab tsi?

H.264 kuj hu ua Advanced Video Coding (AVC) lossis MPEG-4 Part 10. Nws yog ib qho thev naus laus zis video compression uas tau tsim los ntawm International Telecommunications Union (ua H.264) thiab International Organization for Standardization/International Electrotechnical Commission Moving Picture Experts Group (ua MPEG-4 Part 10, Advanced Video Coding, lossis AVC).

Niaj hnub nim no, H.264 codec feem ntau siv rau hauv kev tshaj tawm video. Cov codec no yog tus qauv kev lag luam rau kev nias video uas pab cov neeg tsim cov yeeb yaj kiab kaw, nias, thiab faib lawv cov yeeb yaj kiab online. Nws xa cov yeeb yaj kiab zoo ntawm cov bitrates qis dua piv rau cov qauv yav dhau los. Yog li ntawd, nws tau siv dav hauv kev tshaj tawm TV cable thiab Blu-ray disks.

Ua ib lub codec video, H.264 feem ntau yog tsim tawm hauv hom ntawv MPEG-4, uas siv qhov txuas ntxiv .MP4, nrog rau QuickTime (.MOV), Flash (.F4V), 3GP rau xov tooj ntawm tes (.3GP), thiab MPEG transport stream (.ts). Qee zaum, ib qho video H.264 raug encoded nrog lub 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 cov txheej txheem kwv yees, hloov pauv, thiab encoding los tsim cov H.264 bitstream compressed. Nws siv tus qauv block-oriented nrog kev sib tw txav mus los los ua cov thav duab ntawm cov ntsiab lus video. Cov zis yuav yog macroblocks uas muaj cov block loj li 16 × 16 pixels.

Tam sim no, lub tshuab txiav video H.264 ua cov txheej txheem sib txuas xws li kev txiav txim siab, kev hloov pauv rov qab, thiab kev tsim kho dua tshiab los tsim cov yeeb yaj kiab txiav txim siab. Nws tau txais cov bitstream H. 264 uas raug nias, txiav txim siab txhua qhov syntax, thiab rho tawm cov ntaub ntawv xws li cov lej hloov pauv ntau, cov ntaub ntawv kwv yees, thiab lwm yam. Ntxiv mus, cov ntaub ntawv no yuav raug siv los thim rov qab cov txheej txheem coding thiab rov tsim cov duab video. Cov txheej txheem coding thiab decoding video H.264 tau qhia hauv qab no.

Cov txiaj ntsig ntawm H.264

1.Kev siv bandwidth tsawg dua thiab kev saib xyuas qhov kev daws teeb meem siab dua - Nws muab kev xa cov yeeb yaj kiab zoo tshaj plaws nrog rau qhov yuav tsum tau bandwidth qis dua thiab latency qis dua licov qauv video ib txwm muajzoo li MPEG-2. H.264 siv cov codec zoo uas muab cov duab zoo thiab siv bandwidth tsawg kawg nkaus.

2.Qis dua H.264 bitrate dua li lwm hom ntawv - Nws muaj 80% bitrate qis dua Motion JPEG video. Kwv yees tias qhov txuag bitrate yuav yog 50% lossis ntau dua piv rau MPEG-2. Piv txwv li, H.264 tuaj yeem muab cov duab zoo dua ntawm tib lub bitrate compressed. Ntawm bitrate qis dua, nws muab cov duab zoo ib yam.

3.Txo qhov xav tau rau kev khaws cia video - Nws txo qhov loj ntawm cov ntsiab lus ntawm cov ntaub ntawv video digital los ntawm 50% thiab siv qhov chaw cia tsawg dua los khaws cov video piv rau lwm cov qauv uas ua pov thawj tseem ceeb kom tso cai rau kev xa cov yeeb yaj kiab yooj yim los ntawm IP.

4.Zoo kawg nkaus video - Nws xa cov ntsiab lus video meej, zoo ntawm tus nqi ntawm ¼, uas yog ib nrab ntawm lwm hom video.

5.Ua haujlwm tau zoo dua - Nws ua haujlwm tau zoo dua ob npaug, thiab qhov loj ntawm cov ntaub ntawv yog 3X npaug me dua li MPEG-2 codecs - ua rau hom ntawv compression no ua haujlwm tau zoo dua. Cov codec no ua rau muaj kev xa xov tsawg rau cov ntsiab lus video.

6.Haum rau cov ntsiab lus video qeeb qeeb - Nws ua haujlwm tau zoo heev rau cov codecs video qeeb qeeb siv cov koob yees duab megapixel.