beats_adjust_faster pivoting around some point midway through the track

[mixxxbot]

Reported by: ywwg
Date: 2021-06-04T20:42:48Z
Status: Fix Released
Importance: High
Launchpad Issue: lp1930930

---

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.

[mixxxbot]

Commented by: ronso0
Date: 2021-06-06T20:44:46Z

---

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.

[mixxxbot]

Commented by: ywwg
Date: 2021-06-08T00:16:02Z

---

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

[mixxxbot]

Commented by: ywwg
Date: 2021-06-08T01:01:14Z

---

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.

[mixxxbot]

Commented by: ywwg
Date: 2021-06-08T01:02:25Z

---

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

[mixxxbot]

Commented by: ronso0
Date: 2021-06-10T15:00:20Z

---

#3965

[mixxxbot]

Issue closed with status Fix Released.