I've recently begun trying to create a mobile app (iOS/Android) that will automatically beat match (http://en.wikipedia.org/wiki/Beatmatching) two songs.
I know that this exists out there, and there have been others who have had some success, but I'm running into issues related to the accuracy of the players.
Specifically, I run into "sync" issues where the "beats" don't line up. The various methods used to date are:
Calculate the BPM in advance, identify a "beat" (using something like sonicapi.com), and trying to line up appropriately, and begin a mix in with its playback rate adjusted (tempo adjustment)
Utilizing a bunch of meta data to trigger specific starts and stops
What does NOT work:
- Leveraging echonest's API (it beat matches on the server, we want to do it on the client)
- Something like pydub (does not do it in realtime)
Who uses this algorithm today:
iwebdj
Traktor
Does anyone have any suggestions on how to solve this problem? I've seen lots of people do it, but doing it in real time on a mobile device seems to be an issue.