Needing to convert some avi files to a format that After Effects could read. Settled on converting the avi file to a x264 format in a mov container using the following syntax:

ffmpeg -i input-file.avi -c:v libx264 -crf 0 -preset ultrafast output-file.mov

This creates large x264 files with a minimum compression setting. As close to lossless as it can get with x264 format. It’s also a very quick conversion.