Play multiple tempos in a masterbar

[hd-i]

Is there an existing issue for this?

• I have searched the existing issues

Current Behavior

current behavior is read last tempo of a masterbar and set in tempoAutomation.value

Expected Behavior

Each tempo must be applied in a masterbar.
GuitarPro Musicsheet for test : Moonlight Sonata ( Piano ver ) , Masterbar 22

Steps To Reproduce

---

Link to jsFiddle, CodePen, Project

https://github.com/hd-i/GPFiles

Found in Version

1.2

Platform

Web

Environment

- **OS**: Windows 10
- **Browser**: Firefox,Chrome

Anything else?

No response

[Danielku15]

I don't really understand this bug report. Can you try to rephrase what is effectively not working in alphaTab or handled wrong? Not talking on code level what alphaTab might do but rather from an application level what is happening.

[hd-i]

I uploaded a musicsheet on github to show this to you.
Please see my uploaded musicsheet and open that with guitarpro and see masterbar 22. on this masterbar , there are 4 tempos ( 48, 45, 42, 40) that guitarpro can handle correctly and it can controls playing speed but alphatab cannot handle all tempos in masterbar 22 and just playing last tempo of this masterbar.
please see my uploaded guitarpro file in this repository :
https://github.com/hd-i/GPFiles

[Danielku15]

Thanks. I think I understand now. It is indeed not supported to have multiple tempo changes in one masterbar.

[Danielku15]

Merged from #1207

alphaTab currently assumes a single tempo change per master bar but this is not correct. Guitar Pro and many other formats can have multiple tempo changes (and other automations) within a single bar.

We currently already read the automations correctly into the beats. but for tempo automations which are having an impact on master bar level we only treat one change.

Related code places:
https://github.com/CoderLine/alphaTab/blob/develop/src/importer/Gp3To5Importer.ts#L867 (GP3-5 importer)
https://github.com/CoderLine/alphaTab/blob/develop/src/importer/GpifParser.ts#L2328 (Gp6-8 importer)
https://github.com/CoderLine/alphaTab/blob/develop/src/importer/AlphaTexImporter.ts#L1889 (alphaTex importer)
https://github.com/CoderLine/alphaTab/blob/develop/src/model/MasterBar.ts#L111 (data model)
https://github.com/CoderLine/alphaTab/blob/develop/src/midi/MidiFileGenerator.ts#L187 (midi generation)
https://github.com/CoderLine/alphaTab/blob/develop/src/rendering/effects/TempoEffectInfo.ts (rendering)
https://github.com/CoderLine/alphaTab/blob/develop/src/midi/MidiTickLookup.ts#L201 (midi tick)

This change will have significant impact on certain duration calculations.