Everything You Need to Know About Codecs

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“It shoots AVCHD MPEG-4 AVC/H.264 1080P 24Mbps at 8-bit 4:2:0.”

Say what??

David Kong here with another video tutorial for you, this time on codecs. I’ve found a lot of confusion and mis-information around the internet about how codecs work, how the differ, and why those differences matter.

Hopefully, this video/post will clear those up. I know it’s long, but I really wanted to break it down and explain things thoroughly, rather than just skimming the surface like a lot of tutorials do. Codecs can sound impossibly complex when all you get is a bunch of numbers and acronyms, but the main concepts at work really aren’t that complicated.

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I explain the concepts behind different types of codecs, but I also give some real-world examples which should help you understand how these algorithms work on a practical level, pulling frames into Photoshop to break them down and examine how our codecs have changed the image.

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The reality is that there are dozens of different techniques that codecs use, but I focused on the ones that are most important for you to understand because they can impact your shooting and editing decisions on a day-to-day basis.

Here’s an outline of what I cover in this tutorial:

  • 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!)

As always, comment and let me know if anything here isn’t clear.

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How Codecs Work – Tutorial from David Kong on Vimeo.

Coming Soon…

I’m also going to do a more “practical” post on how to choose export settings when you’re rending out of Premiere / Final Cut. This video was more theoretical, explaining the techniques that codecs use. The next video will be all about how you make those decisions about how to tweak the settings. Let me know if there’s a particular setting that has always confused you, and I’ll make sure that I cover it!

– David

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