Q: I can't play .avi file in my imac

I can't play .avi file in my imac

The referenced article is quite explicit. Nothing has changed since its 2010 posting. Either codecs are supported or they arenot supported. If not supported, then the proper codec(s) must be installed IF AVAILABLE to support the data in the AVI file container. In some cases, depending on which QT player app you are trying to use, the data may not be supported in the AVI file container but may be supported in an MOV, TS, MPG, or MPEG file container. Thay is why you need to follow the instructions and determine which specific compression formats were used to create the file. AVI is a "legacy" file container that has not been officially supported by Microsoft for more than a decade. If you do not want to determine the specific problem preventing your viewing of the file and fix it, then download a third-party player like VLC that employs its own internal FFmpeg codec support and does not rely on your Apple's system configuration for palyback or use a converter app like Handbrake that has presets that will convert the AVI file to QT compatible compression formats in QT compatible file containers and suffer some possible loss in video quality.

AVI can be better supported by Windows PC. And for iMac, MOV files would be perfect accepted. So now the most directly way for you to watch AVI on iMac is to use some video converter to make a simple transition/conversion, converting AVI to QuickTime MOV. In this case, if you find that your devices cannot play some format vidoes, for the most of time due to different codec, you can try using converter to convert your videos to the proper output format first, and it solves problems for most of the time. Good luck to you~