What is MP4?

The container video actually travels in: what phones record, what messaging apps accept, what every player since the iPod era opens. It usually carries H.264 video and AAC audio. Its one structural quirk matters to converters - the index of every frame lives in a table that has to be exactly right, or nothing plays.

What is AIFF?

Apple's uncompressed format, the Mac counterpart to WAV, and still what Logic and older Pro Tools sessions expect. Its one genuine oddity is storing the sample rate as an 80-bit extended float, a data type almost nothing else in computing still uses.