Kodi encoding ya kanema ya H.264 ndi chiyani? Kodi H.264 codec imagwira ntchito bwanji?

Ukadaulo wamakanema wasintha mwachangu zaka makumi angapo zapitazi. M'mbuyomu, makanema adapangidwa ndi zithunzi zazikuluzikulu zazithunzi, ndipo adagwiritsa ntchito mafayilo ochulukirapo kuti apange digito. Koma tsopano, kuyika makanema kwabweretsa kusintha kwaukadaulo - kukanikiza mafayilowa kuti adye malo ochepa. Zakhala zothekanso kutsitsa makanema pa intaneti, munthawi yeniyeni komanso pakufunidwa.

Chimodzi mwazinthu zodziwika bwino zamakasitomala ndi H.264 (AVC - Advanced Video Coding) yomwe yatha kuthetsa nkhani zambiri zamakhalidwe abwino pokhudzana ndi kuwulutsa kwamavidiyo. Masiku ano blog, tiyeni tiphunzire chimene H.264 kanema encoding ndi, mmene ntchito, ndi ubwino wake mwatsatanetsatane.

Kodi H.264/AVC ndi chiyani?

H.264 imatchedwanso Advanced Video Coding (AVC) kapena MPEG-4 Part 10. Ndiukadaulo waukadaulo wamakanema wopangidwa limodzi ndi International Telecommunications Union (monga H.264) ndi International Organisation for Standardization/International Electrotechnical Commission Moving Picture. Gulu la akatswiri (monga MPEG-4 Part 10, Advanced Video Coding, kapena AVC).

Masiku ano, H.264 codec imagwiritsidwa ntchito kwambiri potsatsa makanema. Codec iyi ndi muyeso wamakampani ophatikizira makanema omwe amathandiza opanga kujambula, kufinya, ndikugawa makanema awo pa intaneti. Imapereka makanema abwino pama bitrate otsika poyerekeza ndi miyezo yam'mbuyomu. Choncho, chimagwiritsidwa ntchito mu chingwe TV kuwulutsa ndi Blu-ray litayamba.

Monga kanema codec, H.264 kawirikawiri amapangidwa mu MPEG-4 chidebe mtundu, amene amagwiritsa .MP4 kutambasuka, komanso QuickTime (.MOV), Flash (.F4V), 3GP kwa mafoni (.3GP), ndi MPEG transport stream (.ts). Nthawi zina, kanema wa H.264 amasiyidwa ndi mawu opanikizidwa ndi Advanced Audio Coding (AAC) codec, muyezo wa ISO/IEC (MPEG4 Part 3).

Kodi H.264/AVC imagwira ntchito bwanji?

Kanema wa H.264 amalosera, kusintha, ndi ma encoding njira kuti apange woponderezedwa wa H.264 bitstream. Imagwiritsa ntchito mulingo wokhazikika wa block yokhala ndi mpikisano woyenda pokonza mafelemu a makanema. Kutulutsa kwake kudzakhala ma macroblocks omwe amakhala ndi kukula kwa chipika chachikulu ngati ma pixel 16 × 16.

Tsopano, chojambulira makanema cha H.264 chimagwira ntchito zina monga kumasulira, kusintha kosiyana, ndi kumanganso kuti zipangitse mavidiyo osinthidwa. Imalandila H. 264 bitstream yopanikizidwa, imazindikira kalembedwe kalikonse, ndikutulutsa zambiri monga ma quantized transform coeficients, zolosera, ndi zina zotero. Kuphatikiza apo, chidziwitsochi chidzagwiritsidwa ntchito kubweza khodi ndi kupanganso mndandanda wazithunzi zamakanema. Kanema wa H.264 kukod ndi kusindikiza kwamavidiyo akuwonetsedwa pansipa.

Ubwino wa H.264

1.Kugwiritsa ntchito ma bandwidth otsika komanso kuwunika kwapamwamba - Imapereka kufalitsa kwapamwamba kwambiri kwa kanema woyenda monse okhala ndi zofunikira zochepa za bandwidth komanso latency yotsika kuposamiyambo kanema wambangati MPEG-2. H.264 imagwiritsa ntchito codec yabwino yomwe imapereka zithunzi zapamwamba komanso imagwiritsa ntchito bandwidth yochepa.

2.Lower H.264 bitrate kuposa mawonekedwe ena - Ili ndi 80% yotsika bitrate kuposa kanema wa Motion JPEG. Akuti ndalama za bitrate zitha kukhala 50% kapena kupitilira apo poyerekeza ndi MPEG-2. Mwachitsanzo, H.264 akhoza kupereka bwino fano khalidwe pa wothinikizidwa bitrate yomweyo. Pa bitrate yotsika, imapereka chithunzi chofanana.

3.Kuchepetsa kufunikira kwa kusungirako mavidiyo - Kumachepetsa kukula kwa fayilo ya kanema ya digito ndi 50% ndipo imagwiritsa ntchito kusungirako pang'ono kusunga kanema poyerekeza ndi mfundo zina zomwe zimatsimikizira kuti ndizofunikira kuti mavidiyo azitha kutumiza mosavuta kudzera pa IP.

4.Makanema odabwitsa - Amapereka makanema omveka bwino, apamwamba kwambiri pamlingo wa ¼, womwe ndi theka la mavidiyo ena.

5.Kuchita bwino kwambiri - Ndikokwanira kuwirikiza kawiri, ndipo kukula kwa fayilo ndi kocheperako ka 3X kuposa ma codec a MPEG-2 - kupangitsa kuti mawonekedwe ophatikizika awa akhale opambana. Kodeki iyi imabweretsa bandwidth yotsika yotumizira makanema.

6.Yoyenera mavidiyo oyenda pang'onopang'ono- Ndiwothandiza kwambiri kwa ma codec otsika omwe amagwiritsa ntchito makamera a megapixel.