Vibed - Issues exporting at 192 kHz

[zonkmachine]

System Information

Ubuntu 22.04

LMMS Version(s)

1.2.2, master at bda042e

Bug Summary

Vibed has issues exporting at 192 kHz.

Expected Behaviour

It exports at 192 kHz all the time?

Steps To Reproduce

Export VibedExport.mmp.txt at 192 kHz! (remove .txt)
Observe the curve (see image).
Export the project again but adjust the knob Length (string length) to 2.
The exported soundfile now looks like expected.

The steps above was done with fpe debugging flags set so no floating point errors detected.

Screenshots / Minimum Reproducible Project

[Rossmaxx]

If you are talking about oversampling, that is indeed bugged and i remember @LostRobotMusic campaigning for it to be removed.

[zonkmachine]

If you are talking about oversampling,

I'm not. I'm talking about export frequency sampling rate. Please test the steps above.

[zonkmachine]

...Sampling rate.

[Rossmaxx]

Please test the steps above.

That's my main limitation rn. I don't have my pc with me so can't test anything.+ College sucking up my time and energy.

[michaelgregorius]

This is caused in the constructor of VibratingString.cpp. Line 46 seems to be the relevant line:

lmms/plugins/Vibed/VibratingString.cpp

Line 46 in 71dd300

int stringLength = static_cast<int>(m_oversample * sampleRate / pitch) + 1;

m_oversample is 0 here which means that stringLength becomes 1.

Why is m_oversample though? That's because of this line in the constructor:

lmms/plugins/Vibed/VibratingString.cpp

Line 39 in 71dd300

m_oversample{2 * oversample / static_cast<int>(sampleRate / Engine::audioEngine()->baseSampleRate())},

oversample is set to 1, sampleRate is set to 192000 and Engine::audioEngine()->baseSampleRate() is 44100.

This gives 2 * 1 / (192000 / 44100) ~ 2 / 4.35 ~ 0.46. This rounds down to 0 for the int.

[softrabbit]

I wonder... should the plugins really know about any other sample rates than the one they're supposed to spit out samples at? I mean, is there (and should there be) a difference between e.g. 88200 Hz and 44100 Hz with 2x oversampling?

[michaelgregorius]

IMO the plugins should only know about the sample rate that the DAW tells it to process data at. This is the sample rate at which audio is coming in and expected to come out of the plugin. This is how it's implemented in all the plugin standards, e.g. VST, CLAP, etc., as well.

The plugin should not access any other data from the DAW. In fact "regular" plugins cannot even do that because DAWs are different and all they know is the interface of the plugin standard they are implemented in.