Me’a fakafuofua ‘o e Bitrate ‘o e mitia

Ki he 1080p (1920 × 1080) vitio ‘i he 30fps, ‘Oku angamaheni ‘aki ‘a e bitrate lelei taha mei he 8-12 Mbps ki he tu’unga ‘o e kakano ‘o faka’aonga’i ‘a e H.264 faka’ilonga. Ki ha ngaahi me’a ‘oku lahi ange ‘a e malohi hange ko e sipoti pe ngaahi scenes ngaue, mahalo te ke fie ma’u ‘a e 12-15 Mbps. ‘I hono faka’aonga’i ‘o e 60fps, fakalahi ‘a e ngaahi mahu’inga ko ‘eni ‘aki ‘a e fakafuofua ki he 50%. ‘E lava ke a’usia ‘e he codecs ‘oku toe lelei ange hange ko e H.265/HEVC pe AV1 ‘a e tu’unga tatau ‘i he 30-50% bitrates ma’ulalo ange. ‘E lava ke kehekehe ho’o ngaahi fie ma’u pau ‘o makatu’unga ‘i he faingata’a ‘o e kakano mo e tu’unga taumu’a.

‘Oku fakapapau’i fakahangatonu ‘e he Bitrate ‘a e lahi ‘o e faile ‘o faka’aonga’i ha fomula faingofua: Lahi ‘o e faile (MB) = Bitrate (Mbps) × Loloa (sekoni) ÷ 8. Hange ko ‘eni, ko ha vitio miniti ‘e 10 ‘oku fakakouti ‘i he 10 Mbps ‘e iku ia ki ha faile ‘oku fakafuofua ki he 750 MB ‘i he lahi (10 Mb0 × 8 s). ‘Oku taki ‘e he bitrates ma’olunga ange ki he ngaahi faile lalahi ange ka ‘oku toe fakalelei’i fakalukufua ‘a e tu’unga lelei. Ko hono kumi ‘o e palanisi lelei taha ‘oku makatu’unga ia ‘i ho’o ngaahi fie ma’u ‘o e tu’unga lelei mo e ngaahi fakangatangata ‘o e tanaki’anga/bandwidth.

‘Oku kehekehe ‘a e ngaahi fie ma’u bitrate ‘a e streaming mo e downloadable ‘a e ngaahi me’a ‘oku tefito koe’uhi ko e ngaahi fakangatangata ‘o e bandwidth. ‘Oku fie ma’u ‘e he streaming ‘a e tu’uaki taimi mo’oni, ko ia kuo pau ke tu’uloa ‘a e bitrate mo e fehokotaki’anga ‘initaneti ‘a e tokotaha mamata ke faka’ehi’ehi mei he buffering. Ko e lahi taha ‘o e ngaahi tu’unga streaming ‘oku nau fokotu’u atu ‘a e bitrates ma’ulalo ange ke fakapapau’i ‘oku lava ke ma’u ki ha kau fanongo lahi ange. Downloaded ‘a e kakano, Ka neongo ia, ‘Oku ‘ikai ke fakangatangata ‘e he tu’uaki taimi mo’oni, ‘o faka’ata ‘a e bitrates ma’olunga ange mo e tu’unga lelei. ‘Ikai ngata ai, ‘Oku fa’a fakahoko ‘e he ngaahi tu’unga ‘o e streaming ‘enau transcoding ke fa’u ha ngaahi tu’unga lelei lahi, ko ia ‘oku mahu’inga hono ‘omi ‘o ha faile ma’u’anga fakamatala ma’olunga-lelei na’a mo e taimi ‘e lava ke tafe ai ‘a e end-user ‘i ha bitrate ma’ulalo ange.

Ko e ngaahi founga kehekehe ‘eni ‘o e pule’i ‘o e tu’unga ‘oku ne fakapapau’i ‘a e founga ‘oku vahevahe ai ‘a e bitrate:

• CBR (Tu’unga ‘o e Bit tu’uma’u): Tauhi ‘a e bitrate tatau ‘i he kotoa ‘o e vitio, tatau ai pe pe ko e faingata’a. ‘Oku lelei ‘aupito ‘eni ki he streaming ‘a ia ‘oku mahu’inga ai ‘a e tu’uma’u ‘o e bandwidth ka ‘e lava ke ta’e’aonga ki he ngaahi me’a kehekehe.
• VBR (Tu’unga ‘o e Bit kehekehe): Vahe’i ‘a e bitrates ma’olunga ange ki he ngaahi scenes faingata’a mo e bitrates ma’ulalo ange ki he ngaahi scenes faingofua ange. ‘Oku fakatupu ‘e he me’a ni ‘a e tu’unga lelei ange ‘i he ‘avalisi tatau ‘o e bitrate ‘i hono fakafehoanaki ki he CBR, ‘o ‘ai ai ia ke lelei ‘aupito ki he kakano kuo download.
• CRF (Meʻa ʻo e Tuʻunga Tuʻumaʻu): Tauhi ‘a e tu’unga lelei tu’uma’u kae ‘ikai ko e bitrate, ‘o faka’ata ‘a e encoder ke ne faka’aonga’i ha fa’ahinga bitrate ‘oku fie ma’u ke tauhi ‘a e tu’unga ‘o e tu’unga lelei kuo fakapapau’i. ‘Oku lelei ‘aupito ‘eni ki he archival mo e ngaahi tu’unga ‘oku fakamu’omu’a ai ‘a e tu’unga lelei ‘i he predictability ‘o e lahi ‘o e faile.

Ki he streaming, ‘Oku fokotu’u atu ‘a e CBR pe capped VBR ‘i he angamaheni. Ki he ngaahi vitio kuo download, ‘Oku fa’a ‘omi ‘e he VBR pe CRF ‘a e tu’unga lelei ange ‘o e ‘aonga.

‘Oku ‘omi ‘e he codecs fo’ou ange ‘a e ngaahi fakalakalaka lahi ‘o e ‘aonga ‘i he H.264 ‘oku lahi hono faka’aonga’i:

• H.265/HEVK: A’usia ‘a e tu’unga tatau mo e H.264 ‘i he fakafuofua ki he 40-50% bitrates ma’ulalo ange, ka ‘oku fie ma’u ‘a e malohi lahi ange ‘o e ngaue ke encode mo e decode. ‘Oku poupou’i lahi ia ‘i he ngaahi device fo’ou ange pea ‘oku lelei ‘aupito ki he 4K ‘a e kakano.
• AV1: Na’a mo e lelei ange ‘i he HEVC, ‘o ‘omi ‘a e tu’unga tatau ‘i he 20-30% bitrates ma’ulalo ange ‘i he HEVC (pe 50-60% ma’ulalo ange ‘i he H.264). Ka neongo ia, ‘Oku lolotonga fu’u processor-lahi ‘a e encoding ‘o e AV1, neongo ‘oku tupulaki vave ‘a e poupou decoder.
• VP9: Google ‘a e fe’auhi ki he HEVC, ‘oatu ‘a e ngaahi fakalelei’i ‘o e ‘aonga tatau ‘i he H.264 mo e poupou browser lelei ange ‘i he HEVC ka ‘oku si’isi’i ange ‘a e vave ‘o e hardware.

‘I he taimi ‘oku fili ai ha codec, fakakaukau ki he fe’unga mo ho’o ngaahi device taumu’a/ngaahi tu’unga, encoding taimi fakangatangata, mo e ngaahi fie ma’u ‘o e tu’unga lelei/lahi. ‘Oku kei hoko pe ‘a e H.264 ko e fili ‘oku fe’unga lahi taha, lolotonga ia ‘oku ‘oatu ‘e he codecs fo’ou ange ‘a e ola lelei ange ‘i he totongi ‘o e fe’unga pe vave ‘o e encoding.

Fakatou’osi ‘a e resolution mo e bitrate ‘oku ne uesia lahi ‘a e tu’unga lelei ‘o e vitio, ka ‘oku kehekehe ‘enau mahu’inga ‘o fakatatau ki he tu’unga:

Solova’anga ‘oku ne fakapapau’i ‘a e lahi ‘o e pixels ‘i he fakava’e takitaha, ‘o uesia ‘a e malava fakaikiiki mo e sharpness. Ka neongo ia, kapau ‘oku fu’u ma’ulalo ‘a e bitrate ki he fakalelei’i, te ke sio ki he ngaahi me’a faka’ofo’ofa ‘o e compression ‘oku ne faka’ikai’i ‘a e ngaahi lelei ‘o e fakalelei’i ma’olunga ange.

Bitrate ‘oku ne fakapapau’i ‘a e lahi ‘o e fakamatala ‘oku faka’aonga’i ke encode ‘a e sekoni takitaha ‘o e vitio, ‘o uesia fakahangatonu ‘a e lelei ‘o e ngaahi fakaikiiki mo e ngaue ‘e lava ke tauhi. Ko ha bitrate ma’olunga ange ‘i ha resolution ma’ulalo ange ‘oku fa’a ‘asi lelei ange ia ‘i ha resolution ma’olunga ange ‘oku ‘ikai fe’unga ‘a e bitrate.

Ko e founga lelei taha ko hono fakapalanisi fakatou’osi ‘o fakatatau ki ho’o kakano. Ki he fakaikiiki, ngaahi scenes faingata’a, fakamu’omu’a ‘a e bitrate fe’unga ki ho’o resolution kuo ke fili. Ki he ngaahi me’a faingofua ange hange ko e ngaahi faka’ali’ali pe ngaahi faka’ali’ali, ‘e ala mahu’inga ange ‘a e resolution ‘i he bitrates ma’olunga ‘aupito. ‘Oku fokotu’u atu ‘e he’etau me’a fakafuofua ‘a e ngaahi tu’unga palanisi ‘oku ne fakalelei’i ‘a e ongo me’a ki ho’o fa’ahinga kakano pau.