Afterglow lets you open recordings together and switch between them while listening. Each track keeps its own playback position, notes, and labels. You can return to a passage in one file, then hear the corresponding passage in another.
Afterglow is available for iPhone. Its comparison screen is for listening to the files yourself. It doesn't calculate a similarity score, find duplicate files, or produce an audio file containing only the differences.
Opening recordings together
Import the files into the same project. Open the recording selector beside the bottom player dock, then choose Compare tracks. The tracks appear together, with a waveform and playback position for each one. One track plays at a time.
Switching the audible track lets you move between recordings without closing one player and finding the other file. Their positions remain independent, so moving through one waveform doesn't move the others.
A passage at two different times
The same passage doesn't always start at the same timestamp. One version may have a longer introduction, or an edit may have shifted everything after it.
Labels give you a way to mark that passage in each recording. In the fictional project below, the Chorus label is at 0:34 in Mix 2 and 0:36 in Demo 1.
Choosing that shared label brings each track to its own placement. You can then listen from those points. The label is a reference you place yourself; Afterglow doesn't detect or match the sections automatically.
A track without a placement for that label keeps its current position.
You can hear the beginning of the chorus in Mix 2, switch to Demo 1, and hear its beginning there. If you want to return to the two starting points after listening further, select Chorus again. The shared name points to the placements you chose; the files themselves keep their original timing.
When the timestamps already match
Sync moves the other tracks to the selected track's current timestamp. This can be useful when both files have the same timing and you want to start from the same point.
The move happens once. Playback positions remain independent afterward, and Sync doesn't change the files, stretch their timing, or match their tempos. If a track is shorter than the selected timestamp, its position stops at its end.
Keeping observations with the right file
Each track keeps its own notes. A comment on one take stays with that take when you import another, so you can see which recording prompted it.
For example, a note on Mix 2 could say, "Love this vocal. Could we keep the guitar from Demo 1 underneath it?" The note belongs to Mix 2 even though its text mentions another recording. Afterglow doesn't copy it to Demo 1 or apply it to a later version.
You can mark a note resolved and keep it with the track. Exporting notes as text includes the project and track names, so the recipient can identify which version you mean. The audio is sent separately.
You might want to return to one passage rather than choose a single preferred file. Labels keep those places available, and timestamped notes hold the thoughts or questions attached to them.
What comparison leaves to you
Afterglow doesn't automatically match loudness or tempo, and it doesn't provide a blind listening test or decide which file sounds better. Differences in level remain in the playback.
The comparison screen gives you access to the recordings, their positions, and your notes. The recordings themselves remain unchanged.
