Video Codecs Can be Problematic: About Video Compression & Decompression

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Codec (Compression & Decompression)

There are some facts of digital video life that make most who write about it shy away from talking about… or if they do touch on it, it’s with a simple comment such as explaining that ‘codec’ means compression (co) and decompression (dec). It’s kind of cool to know the derivation of the word, but not much practical help if you need a codec you don’t have, or are wrestling with a bunch of clashing codecs. One such experience is enough to turn you away from any thoughts about doing movie projects. Codecs can be an extremely difficult and confusing subject. The more you learn about them, the easier your video editing career will be. 

Digital video files are compressed as they are created, using any of hundreds of codecs. One compressor or codec takes care of the visual and a different one does the audio or sound track. Those codecs are not the ones you need to open or play the video file.

The video files themselves don’t include the decompression codecs. The assumption by the publisher is your computer already has the codecs needed to play the videos, or you can get them as needed.

When the software on the computer of the viewer opens the file, and appropriate codecs are there to decompress it, the video looks and sounds great. If software is well written by a company that is concerned about your viewing experience, and the needed codec isn’t there, it would provide a note telling you what codec is needed, and where to get it. Most don’t go that far to help, letting you walk unaided through codec hell.

Sometimes there are dozens or hundreds of codecs on your system, and the one that tries to open the file can’t handle it… or more than one of them is tagged as being appropriate to play the file… but they clash. Your player can hang or crash. In extreme cases your whole system can crash. There’s not even a “Welcome to codec hell” note, but you’ve arrived.

Some players note which codecs they are using. Most don’t. Codecs that can open a file are not necessarily able to edit it… even if things are not crashing, freezing or hanging, there’s much to learn about codecs to easily do video work, even if you don’t care to understand them.
There will be lots more about codecs in later articles…