The "Original audio" slider, 0–100.
The "Song" slider, 0–100.
Where the clip starts in the song, in milliseconds (audio_asset_start_time_in_ms).
The music search item's track, as the library's music search returned it (it carries the search's sessions).
The catalog song of a Reel, as the person picked it in the app's music search. The song is downloaded as the app's player does and mixed into the file that is uploaded (two sound tracks: the song with the original sound, and the original sound alone).