Before converting Video include MKV, WMV, MP4, and so forth to AVI, we must go over AVI definition first.
The so-called "Audio Video Interleaved" which means to be possible to play video and audio in sync. The audio is interleaved as "packets" into the video frames in AVI format. Being an advanced technology, AVI can be compared to Apple's QuickTime in functions. If want to know how to convert video to AVI format, you need a software which has the function, such as AVS Video Converter - a powerful video converter.
The guide below will take converting video to AVI as an example to help you to learn how to convert video to AVI with video to AVI Converter fastly.
Free download the trial version software to convert video to AVI format.
Tips: If you are running the Mac OS, please download Mac Video Converter!
Step 1: Import video files
Start the program and then click "Browse..." button to select a video format you want.

Step 2: Settings
Click "To AVI " button to choose the output format for video to AVI Converter, and choose the advanced from "Advanced>>" button, and then click the "Browse..." button after Output File Name textbox to specify a destination folder.

Step 3: Start to convert video to AVI format
When everything is done, Just click "Convert Now!" button on the right corner at the bottom to start the conversion.
Download the professional software and learn how to convert video to AVI format, if you want to learn more about AVS Video Converter, please visit the bottom links.More about video to AVI format:
How to Convert VOB to AVI, How to Convert FLV to AVI, How to Convert 3GP to AVI