What are Codecs?



Codecs, short for coder-decoder, are simply a process to interpret video data in different ways. Codecs are loosely used to describe how video is compressed and decompressed.

Why are codecs important in video cameras?

As filmmakers we are mostly concerned with codecs that cameras use, and most are limited to only one or two types of codecs. When choosing a camera, it’s important to know how that camera handles the image it’s taking in. Codecs are necessary to enable the recording of such high resolution video because of our technological limitations of bandwidth on most cameras. They essentially take very large streams of data and compress them into much more manageable sizes for storage and processing within the camera. Thus knowing what codec your camera uses has a direct correlation to the quality of the image you will receive in production. Typically as cameras get more expensive, better codecs become available with less compression.

Everything you could possibly want to know about codecs is talked about in this video by David Kong.

  • What a codec is – And how it differs from a container.
  • Different types of codecs – And why I frequently use 4 different codecs on a single project.
  • Bit Depth – What it means and why it matters.
  • Chroma Subsampling – 4:4:4, 4:2:2, and 4:2:0, and when it becomes an issue.
  • Spatial Compression and Blocking – One of the most common artefacts you see with normal work.
  • Temporal Compression – Long-GOP codecs, inter-frame compression, and ALL-I codecs.
  • Lossless vs. Lossy compression – How image compression differs from data compression.
  • Bit Rate – How to calculate bit rates and the differences between kbps/kBps/Mbps/MBps.
  • Raw – Briefly, the difference between Raw, compressed, and uncompressed (this could have been a 40-minute tutorial on its own!)