MPG → PNG

Chifukwa cha zomwe zimachokera. MPG zomwe zili ndi zofalitsa ndi DVD zimasunga madera awiri apakati pamphepete mwa mbale, zomwe zimatha kuwonetsedwa ndi theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka la theka

Ngati MPG siyimagwiritsa ntchito, chifukwa MPG siyimagwiritsa ntchito mawu osakira omwe angasankhidwe kuti azimitsa. Chomwecho MPG chikuwonetsa pazenera ndi chithunzicho, choncho ndicho chilichonse PNG chotulutsa chimapanga ndipo palibe chosankha chomwe chimachotsa pambuyo pake. Mukapeza fayilo yosiyana ya mawu osakira pamodzi ndi kanema, chotsani kuchokera kuzinthu zomwe zidatenga ma frame awiri osiyana. MPG amalandira zonse MPEG-2 kuletsa - heavy bitrate, interlacing, palibe soft subtitle - kuphatikizapo kusokonezeka kwa awiri zowonjezera kwa mtundu wina.

Format imagwira ntchito, koma chiyambicho sichimakhala ndi alpha kuti ipereke - ma frame a video ndi masamba opangidwa ndi mawonekedwe owoneka bwino, kotero kuti ma pixel onse amafika molimba. Chingwe cha alpha chimakhala chothandiza pambuyo pake: kumatanthauza kuti mutha kuchotsa chinthu kuchokera ku PNG pambuyo pake popanda kusintha mtundu. PNG ndi kusankha koyenera kwa zithunzi, malogo, line art ndi chilichonse ndi zosalimba mapiko kapena kuwala - palibe kuyimba, palibe kuwala band.

Kukula kwakukulu kuposa momwe mungayembekezere, chifukwa PNG imasunga ma pixel onse moyenera kuposa kuyerekezera. 1080p imakhalabe pafupi ndi 2-5 MB ndipo 4K imakhalabe pafupi ndi 6-15 MB, kotero kutulutsa kwanthawi yayitali kumawonjezera mwachangu. Izi ndi malonda abwino pamene zithunzi zimatha kutulutsa kuwongolera, ndipo zoyipa pamene zikuyenda mozungulira patsamba la webusaiti. PNG amagwiritsa ntchito DEFLATE kusamvana pa scanlines zofiltered, choncho aliyense pixel amapulumuka moyenera, kuphatikizapo 8-bit alpha channel.

Kuwala kofanana ndi MPG kanema - 1080p MPG imapanga 1920 × 1080 PNG ma frame; 4K MPG imapanga 3840 × 2160 PNG ma frame. Pezani ntchito yosintha kukula pambuyo pochotsa ngati mukufuna zithunzi zochepa kapena zokongoletsera zazing'ono.

Ndikofunika, koma onetsetsani kuti muwerenge fayilo - 30fps 1-mphindi MPG imapanga 1,800 PNG ma frame. Timawapaka m'ma ZIP mosasintha. Kwa ma clip ochepa, kusankha "1 pa mphindi" (ma frame 60) kapena ma timestamps okhudzana ndi nthawi imapatsa zotsatira zoyenera.

Ndikoyenera - mtundu umasinthidwa ndi mamatrix omwe chiyambi MPG chimagwiritsa ntchito (BT.709 kwa HD, BT.2020 kwa 4K HDR). Mafuta a HDR amasinthidwa ku SDR pochotsa ku PNG chifukwa ambiri a PNG amtundu (PNG, JPG) sangathe kusungira ma pixel a HDR mwanjira yosadziwika.

Kutengera pa resolution ndi PNG codec. 1080p PNG frame ndi 2 mpaka 5 MB; 1080p JPG pa quality-85 ndi 200 mpaka 500 KB; 4K PNG ndi 6 mpaka 15 MB. Pamapeto pake, kuchotsa PNG panthawi iliyonse ya 10-mphindi 1080p MPG kumabweretsa ~ 50 GB pamodzi.

MPG yokhala ndi MPG siyimasunga EXIF pa frame momwe kamera ikugwirira ntchito, choncho mafayilo a PNG amatuluka ndi EXIF yopanda pake. Timayika `creation_time` yokhala ndi nthawi yoyambira ya frame kuti muthe kubwezeretsa bundle ndi kujambula.

Kutulutsa kwa frame ndi kosavuta - nthawi zambiri 20 mpaka 30% ya nthawi yoyambira pa standard pipeline. 5-mphindi MPG → PNG bundle imatha m'miphindi pafupifupi popanda malire a frame count, chifukwa bowa ndi PNG encoder, osati MPG demuxer.

Ndiyo — njira yophunzirira imavomereza mndandanda wa ma timestamps ogawidwa ndi koma (mwachitsanzo `00:01:23,00:05:00,00:10:42`) ndipo imapanga fayilo imodzi ya PNG pa timestamp. Ndikothandiza kwa mathumbnails a bokosi, ma shots a scene reference, kapena mathumbnails a maphunziro ochepa.