LMMS / LMMS/lmms

TripleOscillator with hi-pass produces different output depending on the export settings

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bug
Dominant language
C++
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Description

Either TripleOscillator's noise generator or the Hi-pass filter has a bug, causing the exported file to sound differently with different export settings, which even includes whether you use the graphical interface or the command line.
I made a project file on which the problem comes out very clearly, and exported it with a few different settings, using both gui and cli. The interpolation was "sincmedium" on every file.
[Here is the project and the exported wav files.](https://github.com/LMMS/lmms/files/5460024/noise-filter-export.tar.gz)
Affected versions: current master and most probably 1.2.2 too.

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First steps

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  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Download the linked noise-filter-export.tar.gz project and WAV files, then reproduce the differing results with the same sincmedium interpolation through both the graphical interface and command line. Compare the TripleOscillator noise generator and Hi-pass filter behavior to isolate the source; done means equivalent export settings produce consistent audio output.

Written by the indexing model from the issue text.

Assessment

Tech stack
cpp
Domain
audio-video-rtc
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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