If you work with video files, you've likely come across files with the AVI extension. And while you know your way around a computer, you may only have a vague notion of what an AVI file is and what it stands for.

However, you do know that you have a bunch of AVI files sitting on your laptop taking up space, and at some point, you're going to have to do something about that.

But before you start deleting files en masse, check out this quick refresher on AVI files, which may save you from making a costly mistake.

What are AVI files?

AVI, which stands for Audio Video Interleave, is a fairly common file format for data that contains both audio and video. Developed by Microsoft in 1992, AVI is a proprietary file format known as a container. Other containers you may have seen include OGG, MKV, MPG, and MOV, among others.

Containers are not only comprised of the actual data but also multiple codecs. A codec is a portmanteau word made up of "coder" and "decoder." Essentially, codecs are computer programs that convert data into a coded form (encode) suitable for storage or transmission purposes, including compressing or encrypting the data. Codecs also decode encoded data, which is necessary to playback or edit files. So in an AVI file, you'd have the audio and video data in a container, as well as codecs like DivX and XviD that will help you encode and decode your data.

AVI codecs don't typically compress audio and video data as much as some other video formats. And some videographers prefer to capture and store footage without compressing the data at all. Doing so allows video editors to play the footage without quality loss and make more complex edits.

To complete complex editing projects, such as a film or television editing, usually requires a team. And even if all the team members are working in the same building, they need to share files. An uncompressed AVI file can take up as much as 3 GB per minute of footage, making sharing AVI files via email or through a File Transfer Protocol (FTP) server a challenge. To do so, you'll need to compress the files first using a file compression tool.

Why you need to compress AVI files

Sharing video footage for editing purposes is far from the only reason you may need to compress AVI files. AVI files can be huge and require massive amounts of storage space. However, compressing them reduces the amount of storage space you'll ultimately need for your file (and back-up copies) on your computer, server, or cloud-based storage solution. Compressed data can also be sent more quickly over the Internet. If you've got a deadline to hit, you don't want your team member across the country or the world to be stuck waiting to receive your files. Compressed data can also load quicker on your computer.

How to Compress AVI files

When you compress AVI files, you're typically either using a lossy or lossless compression method. Lossy compression permanently eliminates some data to reduce file sizes — data that the average person would not miss. If, for example, you shot a video of a stream in a park, lossy compression might eliminate some sounds inaudible to humans that your mic picked up, among other data. However, over time, repeated encoding and decoding of these files will lead to visible and audible degradation in their quality.

How to Compress AVI Files in WinZip

From File Explorer:

  1. From your File Explorer select all of the files you want to compress.
  2. Right-click on the selected files. WinZip > Add/Move to Zip File… This will open WinZip with options about how you want your file zipped.
  3. Select your file options, like name, location, encryption, and any other features you want to include.
  4. Select Add. This will create a zip file in the location you selected containing all your files.

From within WinZip:

  1. From within WinZip, locate the files you want to zip using the panel on the left.
  2. Select all of the files you want to compress.
  3. Select the Add to Zip button at the bottom of the left panel.
  4. After you add all of the files you want to the Zip file, select the "Save as" button in the right bottom corner. Name your file and select save.

Note: Certain file types do not compress as much as others. You must have WinZip installed on your computer to use these methods.


Lossless compression techniques, by contrast, keep all data intact during the compression process. And while lossy compression may be good enough for one-off video needs, anyone who needs their AVI files to retain the same quality over time requires software that uses lossless compression techniques. You'll need easy-to-use and time-tested software like WinZip that helps you easily compress your AVI and other large file formats so that you can get them where they need to go.

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