(FFmpeg) How to Convert AVI to MP4?

The AVI format is a multimedia container format developed and maintained by Microsoft. AVI has support for multiple video codecs including MPEG-4. This makes the conversion to MP4 simple:

 $ ffmpeg -i input.avi output.mp4 

If the input.avi codec is not MPEG-4, setting the libx264 codec might be required:

 $ ffmpeg -i input.avi -c:v libx264 output.mp4 

Tip: Instagram and Twitter do not support AVI video uploads.