Music and sound effects
How do I add my own music?
Upload it on the Upload page, tagging it as Music, and it lands in your Library. From there you can put it on a music lane in the Main Editor — either by picking it from the Library, or by using Replace on an existing music clip.
One thing that trips people up: an empty music lane only offers Generate and Library, with no direct upload button. So upload first, then pick your track from the Library.
Your own music behaves exactly like generated music once it is on the timeline — it ducks under the voice automatically, and you can set its level and ducking depth.
Supported formats are MP3, WAV, M4A, AAC, OGG and FLAC (on Free, WAV and FLAC are held for paid plans). Note that Cast will not license music you brought yourself: the commercial license covers music generated in Cast, not third-party tracks, and clearing those is on you.