Multiple beat grid on a single track

[acolombier]

Feature Description

It would be great to be able to set multiple grid offsets on a single track. This would allow keeping the grid align with the beat when there is a tempo change. or a missing beat

Currently, using variable BPM, it often happens that the grid ends up off by half a bit on one of tempo.

It would be great to be able to add grid marker to help adjusting the generated beat grid, which is usually only off by a certain offset.

Relates to #10811 and partially #10164

[Swiftb0y]

https://mixxx.zulipchat.com/#narrow/stream/109171-development/topic/beatgrid.20editing.20UI

[acolombier]

The GSoC/PR related to this stream is a beast... Anything simpler we could consider instead?

[Swiftb0y]

Not sure, I mean there is #12343 which is much more reduced in scope, but it only addresses the downbeat feature request, not your variable BPM grid request. IIUC the underlying infrastructure is there (src/track/beats.h), it "just" needs to be hooked up and tested. Not sure how much is salvageable from #2961. Then there is also #2930. I was linking that thread mostly not to suggest to adopt that work but instead to provide context to the previous discussion around this so we don't start yet another design process.