AVI is old enough to vote. And yet. Every so often someone needs one, usually for legacy hardware, old presentation systems, or software last updated in 2012.
- Be honest first: you almost certainly should not use AVI by choice. Enormous files, inefficient, every modern alternative beats it. - Reality check: when the church projector only plays AVI off a USB stick, should does not help. - HandBrake, VLC, Shutter Encoder, FFmpeg: all do MP4 to AVI without drama. Pick a sensible codec, keep bitrate reasonable. - Test the file on the actual target device before the event. The step people skip and the one that matters most.
If you do this more than once a year, keep a converter installed. Format emergencies do not schedule themselves. And for the opposite problem, turning hours of video into short clips, ReelCut does it for $4.99 a video.