Loop size goes to 1/32 when activating a saved loop

[cokeramirez]

Bug Description

See video:

2026-08-12_21-48-12.mp4

Whenever I activate the saved loop (that's 16 beat long) the beat value goes to 1/32

I think is related to: https://mixxx.zulipchat.com/#narrow/channel/267968-testing/topic/Rolls.20strange.20behaviour/with/615129379

Version

2.6-beta-368-g00fae74dbf

OS

Windows 11

[ronso0]

This happens because the size of the saved loop deosn't matach any of the pre-defined sizes (1/32, 1/16, .. 1, 2, 4, etc.) which can happen when set a loop with one of these sizes and either shift the loop in or out, or when you stretch or expand the beat grid (increase or decrease BPM).
At least I can only reproduce with these steps.

Though the fallback to 1/32 is confusing.

Fixing this is part of a bigger endavour though with a few breaking changes. I made some attempts in #12509 and #12522

[cokeramirez]

Could we have a quick fix to default fallback to 4 beats? it is the standard and looping a 1/32 piece by mistake is catastrophic compared to a 4 loop by mistake

[ronso0]

Sure. I'm working on it right now.
There is another case here where we don't alter the loopsize if it's not one of the presets, and I'll simply adopt that for LoopingControl::setLoop()

mixxx/src/engine/controls/loopingcontrol.cpp

Line 1231 in 9e670c1

void LoopingControl::trackBeatsUpdated(mixxx::BeatsPointer pBeats) {

[ronso0]

Fix is #16881