Improve phase-adjustment algorithm

[Owen Williams]

Pushing the sync button also adjusts the phase of the track, often in ways that are tough to predict and that shift the track sync by a whole beat. Phase adjustment should take into account whether the playhead is nearer to the previous beat or the next beat to better anticipate where the DJ intends to place sync.

Here's a patch that does that.

[RJ Skerry-Ryan (rryan)]

Maybe this could slip into 1.10. I didn't put too much thought into how the actual sync worked and now that I think about it, you're right it's kind of odd.

[Owen Williams (ywwg)]

The only possible bug I can think of is that I call findNthBeat(dThisPosition, -2); -- what happens if there is no beat there? Is there some sort of error value returned? I tried sync-playing at the start of a track, thinking there wouldn't be a -2 bug, but it still seemed to work.

[Owen Williams (ywwg)]

edit: "I tried sync-playing at the start of a track, thinking there wouldn't be a -2 *beat*, but it still seemed to work."

[RJ Skerry-Ryan (rryan)]

I played with it a bit and I agree it feels more natural. Added to the 1.10 branch.

[Swiftb0y (swiftb0y)]

Mixxx now uses GitHub for bug tracking. This bug has been migrated to:
https://github.com/mixxxdj/mixxx/issues/6146