The Video Codec Moment

  • Steve Puffenberger
  • Video Production
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The Video Codec Moment

An overview of the various digital video formats and codecs.

What's a video codec? Quick answer: it's a mashup of the words "COmpressor" and "DECompressor." But like everything else, that's just the tip of the iceberg. Think of a codec as a digital "secret decoder ring." The video is encoded when it is made, and without the corresponding decoder, it's just 1s and 0s that don't do anything. You can't have digital video without a codec.

Why is Video Compressed?

The amount of data to display video is immense. Imagine 30 full-frame 2 Megapixel pictures (approximately 2 megabytes each) every second. That’s 60 megabytes every second. You would quickly fill your hard drive, flash drive, your cloud account, and even a few of your neighbors' cloud accounts with just a few minutes of video.

To make video workable, it has to be COMPRESSED. Using really fancy math (beyond my pay grade), the COMPRESSOR (used at the time the release video is made) actually throws away data and encodes the video stream with clues for the computer in the playback device to try to reconstruct the original picture as closely as possible upon playback, depending on the data rate specified.

A DECOMPRESSOR within your computer, mobile device or set-top box player reads those clues and reconstructs the picture on the fly. How accurately that happens depends on the data rate (bit rate) of the video file, coupled with the efficiency of the codec and the processing power of the playback machine. The bigger the file, the better the look. Imperfections are known as digital "artifacts."

Put "COmpressor" and "DECompressor" together as a software package and you have a "CODEC." There are many codecs, hundreds, in fact, and none are compatible with each other, so your computer must have the correct codec installed before you can play a corresponding video file.

Common Codecs

Common codecs include h.264 – the most common codec today, also known as MPEG4. It’s become the defacto standard thanks to the ubiquity of YouTube. But it’s relatively new and some older systems won’t have the codec installed.

A company called “Sorenson” makes a codec that is common in older Macs.

Another common codec is MPEG2. This is the codec used in DVDs and some BluRay disks. It's also the codec of digital TV (DTV) broadcasts. In comparison to h.264, it's quite inefficient, requiring bigger files to achieve the same quality. The Motion Picture Experts Group (MPEG) charges computer manufacturers a license fee to have the codec installed on devices, and the OS manufactures have stopped paying that fee. Therefore DVDs, Blu-rays, or other MPEG2 files cannot play on a computer unless 3rd party player software (that supports those codecs) is installed.

Uncommon Codecs

When we step into the professional video world, you find all sorts of "uncommon" codecs, though they're quite common within pro circles. Apple ProRes is one, which is a QuickTime variant. So is the Avid DNxHD, Sony XAVC variants, and various formats from Panasonic, Canon and other pro camera makers. Some of these codecs record in RAW format, where every pixel in every frame is compressed without loss. Others compress very mildly to provide superior pictures. Also uncommon are obsolete codecs, such as MPEG-1, RealVideo, WindowsMedia and others. Regardless, your computer must have the appropriate decoding codec installed to read the files.

The Various Video Formats (aka Wrappers)

Making things more confusing are the various video formats, mp4, mov, avi, etc. These are sometimes known as “wrappers.” The wrapper is a snippet of code that “wraps” the video file and tells the computer how to decode the video, often in a player that is specific to the wrapper. The wrapper format (and its file extension) is sometimes mistaken for the codec. Some wrappers are “pluggable,” meaning they can hold video with one of many flavors of codec – but unless that particular codec is installed on the machine you won't see anything - even if you have a player that supports the wrapper format.

In the Mac world, the most common wrapper format is QuickTime, which always has the .MOV extension. QuickTime files can hold h.264, Sorenson, or a host of other consumer and professional codecs. The QuickTime app has to be installed on your PC to open any MOV file - but even with QuickTime installed, a video with an uncommon codec may not play. QuickTime (and the QuickTime player) is standard on Macs but QuickTime for Windows is no longer supported by Apple and due to known security flaws with the application, it is highly recommended to remove QuickTime from your PC.

The legacy "pluggable" wrapper format for the PC is the AVI file, which again can contain a variety of different codecs. Also, Microsoft invented their own pluggable Windows Media Video (.WMV) format. While they started backing away from it in 2013, if you have an older version of PowerPoint on Windows, WMV usually works best.

The MPEG-4 wrapper (.mp4) has become a defacto standard release format these days because it only holds the h.264 codec and it works on all (modern) operating systems, making it truly cross-platform. PowerPoint 2013 and newer has standardized on this format.

Codecs to Come

Finally, be forewarned, all this is going to change. To manage up to 8K resolution and HDR (high dynamic range) video within reasonable data rates, the High Efficiency Video Codec (HEVC), also known as h.265, and a couple of other competing formats have been introduced to bring richer content to your screens. These new codecs look amazing, but the more they compress, the more computing power it takes to decode them. Expect to have to upgrade your hardware. Don't get too comfortable with your codec!

The takeaways:

  • The most common codec is h.264, though there are others such as Sorenson.
  • MPEG2 is the codec of DVD and can only play on a computer with 3rd party software
  • The file name extension of a video file defines the wrapper, not necessarily the codec. Common wrappers are .MOV (QuickTime), .AVI (legacy Windows) .WMV (Windows Media Video), and .MP4 (cross platform – contains h.264 or h.265).
  • QuickTime Player no longer works in Windows.

To learn how this interfaces with PowerPoint for Mac or PC, read our article "Video in PowerPoint: What Works and What Won't."

At Advent Media, Inc., we regularly keep up with the changes in video formats and are able to deliver your next video production project so you can play it virtually anywhere.

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