Cinematography | Compression

“A codec is a method for making video files smaller, usually by carefully throwing away data that we probably don’t need.”

Setelah shooting, maka perlu dilakukan transfer & backup terhadap data RAW files dan kemudian dilakukan transcoding. Alasan perlunya dilakukan transcoding adalah karena RAW files memiliki kompresi yang besar, sehingga harus dilakukan compressing ke tipe lain (proxy file). Berbeda dengan MOV yang merupakan container dari suatu file, codec yang digunakan umumnya adalah H264, H265, DNXHD, atau HFVC untuk windows dan ProRes untuk apple. Codec sendiri merupakan suatu perangkat atau program komputer yang mendekode aliran data digital atau sinyal agar bisa digunakan di tempat lain dengan cara membuang sebagian informasi yang tidak diperlukan.

(Sumber: learnmediatech.com)

  • Chroma subsampling: Throws away some color data (4:4:4 is no chroma sampling. 4:2:2 is some chroma subsampling. 4:2:0 is lots of chroma subsampling). Bad if you’re doing color-correction. Really bad if you’re doing green screen or VFX work.
(Sumber: blog.ampedsoftware.com)
  • Macro-Blocking: Finds blocks (varying size) of similar colors and makes them all the same color. Bad for VFX and color-correction. Almost all codecs use this to some degree, and the amount tends to vary with the bitrate.
(Sumber: semanticscholar.org)
  • Temporal compression: Uses previous frames (and sometimes following frames) to calculate the current frame. Bad for editing.
(Sumber: reacinverter.com)
  • Bit depth: The number of possible colors. Deeper bit-depth (larger numbers) is good for color-correction and VFX.[1]

[1] https://blog.frame.io/2017/02/15/choose-the-right-codec/

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