Kodi kuyika ma codec a kanema wa H.264 n'chiyani? Kodi codec ya H.264 imagwira ntchito bwanji?

Ukadaulo wa makanema wasintha kwambiri m'zaka makumi awiri zapitazi. Kale, makanema ankapangidwa ndi zithunzi zambiri zosawoneka, ndipo ankagwiritsa ntchito mafayilo akuluakulu kuti akhale a digito. Koma tsopano, kugwiritsa ntchito njira yojambulira makanema kwabweretsa kusintha kwaukadaulo - kukanikiza mafayilowa kuti atenge malo ochepa. Zakhala zothekanso kuwonera makanema pa intaneti, nthawi yeniyeni komanso nthawi iliyonse yomwe mukufuna.

Chimodzi mwa ukadaulo wotchuka kwambiri wa encoding ndi H.264 (AVC - Advanced Video Coding) yomwe yatha kuthetsa mavuto ambiri abwino okhudzana ndi kufalitsa makanema. Mu blog ya lero, tiyeni tiphunzire tanthauzo la encoding ya makanema ya H.264, momwe imagwirira ntchito, ndi ubwino wake mwatsatanetsatane.

Kodi H.264/AVC ndi chiyani?

H.264 imatchedwanso Advanced Video Coding (AVC) kapena MPEG-4 Part 10. Ndi ukadaulo wochepetsera makanema womwe umapangidwa limodzi ndi International Telecommunications Union (monga H.264) ndi International Organization for Standardization/International Electrotechnical Commission Moving Picture Experts Group (monga MPEG-4 Part 10, Advanced Video Coding, kapena AVC).

Masiku ano, H.264 codec imagwiritsidwa ntchito kwambiri pakuwonera makanema. Codec iyi ndi muyezo wamakampani wochepetsera makanema womwe umathandiza opanga kujambula, kukanikiza, ndikugawa makanema awo pa intaneti. Imapereka makanema abwino kwambiri pamitengo yotsika poyerekeza ndi miyezo yakale. Chifukwa chake, imagwiritsidwa ntchito kwambiri mu ma TV a cable ndi ma Blu-ray disks.

Monga codec ya kanema, H.264 nthawi zambiri imapangidwa mu mtundu wa MPEG-4, womwe umagwiritsa ntchito .MP4 extension, komanso QuickTime (.MOV), Flash (.F4V), 3GP ya mafoni am'manja (.3GP), ndi MPEG transport stream (.ts). Nthawi zina, kanema wa H.264 amalembedwa ndi mawu ophatikizidwa ndi Advanced Audio Coding (AAC) codec, muyezo wa ISO/IEC (MPEG4 Part 3).

Kodi H.264/AVC imagwira ntchito bwanji?

Chojambulira makanema cha H.264 chimachita njira zolosera, kusintha, ndi kubisa kuti chipange bitstream ya H.264 yopanikizika. Chimagwiritsa ntchito muyezo wolunjika ku block ndi mpikisano woyenda kuti chikonze mafelemu a zomwe zili muvidiyo. Zotsatira zake zidzakhala ma macroblocks omwe ali ndi kukula kwa block mpaka ma pixel 16×16.

Tsopano, chojambulira makanema cha H.264 chimagwira ntchito zowonjezera monga kutanthauzira, kusintha kosintha, ndi kukonzanso kuti apange kanema wosinthidwa. Chimalandira bitstream yokakamizidwa ya H. 264, kutanthauzira gawo lililonse la syntax, ndikutulutsa chidziwitso monga ma quantized transform coefficients, zambiri zolosera, ndi zina zotero. Kuphatikiza apo, chidziwitsochi chidzagwiritsidwa ntchito kusintha njira yolembera ndikubwerezanso mndandanda wa zithunzi zamavidiyo. Njira yolembera ndi kutanthauzira makanema ya H.264 ikuwonetsedwa pansipa.

Ubwino wa H.264

1.Kugwiritsa ntchito bandwidth yotsika komanso kuwunika kwakukulu - Kumapereka kutumiza kwapamwamba kwa kanema woyenda bwino wokhala ndi zofunikira zochepa za bandwidth komanso latency yotsika kuposamiyezo yachikhalidwe ya makanemamonga MPEG-2. H.264 imagwiritsa ntchito codec yothandiza yomwe imapereka zithunzi zapamwamba komanso imagwiritsa ntchito bandwidth yochepa.

2.H.264 bitrate yotsika kuposa mitundu ina - Ili ndi bitrate yotsika ndi 80% kuposa kanema wa Motion JPEG. Akuti ndalama zomwe zimasungidwa mu bitrate zitha kukhala 50% kapena kuposerapo poyerekeza ndi MPEG-2. Mwachitsanzo, H.264 ikhoza kupereka chithunzi chabwino kwambiri pa bitrate yokakamizidwa yomweyo. Pa bitrate yotsika, imapereka chithunzi chofanana.

3.Kufunika kocheperako kwa malo osungira makanema - Kumachepetsa kukula kwa mafayilo a digito a kanema ndi 50% ndipo kumagwiritsa ntchito malo osungira ochepa posungira makanema poyerekeza ndi miyezo ina yomwe imatsimikizira kuti imalola kutumiza makanema mosavuta kudzera mu IP.

4.Ubwino wa kanema wabwino kwambiri– Umapereka makanema omveka bwino komanso apamwamba pa liwiro la data la ¼, lomwe ndi theka la kukula kwa mtundu wina wa kanema.

5.Yogwira ntchito bwino kwambiri - Ndi yogwira ntchito bwino kwambiri kawiri, ndipo kukula kwa fayilo ndi kocheperako katatu kuposa ma codec a MPEG-2 - zomwe zimapangitsa kuti mawonekedwe okakamiza awa akhale ogwira ntchito bwino kwambiri. Codec iyi imapangitsa kuti makanema azikhala otsika kwambiri.

6.Yoyenera makanema oyenda pang'onopang'ono - Ndi yothandiza kwambiri pama codec a makanema oyenda pang'onopang'ono pogwiritsa ntchito makamera a megapixel.