OGV and M4A explained
OGV is the Ogg container carrying Theora video, an early royalty-free codec that has been comprehensively superseded by VP9 and AV1.
M4A is an MP4 container holding only audio — usually AAC, sometimes Apple Lossless. The extension exists mainly so players know not to look for a video track.
- Where OGV files come from
- Open-source projects and Wikipedia media from the early 2010s.
- Where M4A is used
- iTunes purchases, Apple Music downloads, voice memos and audiobooks.