Mixxx

beats_adjust_faster pivoting around some point midway through the track

Bug #1930930 reported by Owen Williams on 2021-06-04

This bug affects 2 people

Affects		Status	Importance	Assigned to	Milestone
	Mixxx	Fix Released	High	Owen Williams	Mixxx 2.3.0

Bug Description

beats_adjust_faster and _slower used to pivot around the first beat: the first beat would remain in place, and the rest of the track would move relative to that. Now when I use these commands, the beat markers seem to pivot around some point later in the track, like around 2/3 of the way. The function should use the CUE point as the anchor of the adjustment. This affects main, I haven't tested 2.3 yet.

Revision history for this message

ronso0 (ronso0) wrote on 2021-06-06:

Confirmed with 2.3

Assigned to the 2.3 milestone -- feel free to reassign if it's not feasible to fix this for the release.

Changed in mixxx:
status:	New → Confirmed
importance:	Undecided → Medium
milestone:	none → 2.3.0

Revision history for this message

Owen Williams (ywwg) wrote on 2021-06-08:

I suspect this is a basic regression, looking at it now. Would def like to fix for 2.3

Changed in mixxx:
assignee:	nobody → Owen Williams (ywwg)

Revision history for this message

Owen Williams (ywwg) wrote on 2021-06-08:

This is a regression in the beat detection. The "first beat" is being set wrong in the constant beat grid detector. It looks like a problem in BeatUtils::makeConstBpm where startRegionIndex is never getting updated for some reason. I don't really understand the code involved, but it seems like the requirements for that loop are so strict, nothing passes it :).

This means that for tracks whose beats were already detected, the beat grid adjustment works. For new tracks, the first beat is wrong.

Changed in mixxx:
assignee:	Owen Williams (ywwg) → Daniel Schürmann (daschuer)
importance:	Medium → High

Revision history for this message

Owen Williams (ywwg) wrote on 2021-06-08 (last edit on 2021-06-08):

In my opinion this is a release blocker, because it would cause all newly-analyzed const grid tracks to have bad data. After the fix, users will need to redetect beatgrids

Owen Williams (ywwg) on 2021-06-08