Search Issue Tracker
By Design
Votes
0
Found in
2018.4
2020.1.0f1
2020.2
Issue ID
1266474
Regression
No
There's a pop sound when changing the High Pass Audio Filter's Cutoff Frequency from a lower to a higher value
How to reproduce:
1. Open user's attached "HPFTest" project
2. Open the "SampleScene" Scene
3. Enter the Play Mode
4. In the Hierarchy select the "Cube" GameObject
5. In the Inspector set the Audio High Pass Filter's Cutoff Frequency to 10
6. In the Inspector change the Audio High Pass Filter's Cutoff Frequency to 100
Expected result: No pop sound when changing the Cutoff Frequency
Actual result: There's a pop sound when changing the Cutoff Frequency
Reproducible with: 2018.4.26f1, 2019.4.8f1, 2020.1.2f1, 2020.2.0a20
Notes:
- This is only happening on the Audio High Pass Filter Component, it does not happen on the Audio Low Pass Filter Component
- Only happens when changing the Cutoff Frequency from a lower to a higher value
Add comment
All about bugs
View bugs we have successfully reproduced, and vote for the bugs you want to see fixed most urgently.
Latest issues
- Object Picker takes the debounce time to load objects when Object Selector is set to Advanced search
- Packman: The same asset data is displayed differently in "Import" and "Remove" popups
- Reference to a deleted GameObject becomes "None" instead of "Missing" when the GameObject is restored with undo after entering and exiting Play Mode
- Size value in Particle System Curve's tab is highlighted with selection across all tab header
- Particle System Curve's Presets window has no visual indication of what preset is selected
Resolution Note:
It is an expected pop you get from a drastic change of a filter's cutoff frequency. FMOD does not perform any interpolation of its parameters, so if you need a smoother change, you need to write a script that gradually interpolates the cutoff to the target value over a couple of frames. You will likely need some kind of logarithmic mapping on the interpolation, since you're interpolating frequency where changes in the lower end are perceived more than in the higher end, and also depending on frame rate the interpolation may need to be carried out over several frames.
The only thing in FMOD that is being interpolated is in fact volume changes, but even those have a fixed interpolation range that may be too jumpy for quick changes. This is why in the audio mixer we could not use this but had to do per-sample interpolation to eliminate artefacts from sudden changes, which adds significant cost to the mixing. The same would apply if we were to add this to all parameters in FMOD, and for filters this is even more expensive, because recalculating internal filter coefficients is way more expensive, so it also needs a check then to only react on changed parameters and only recalculate the coefficients every Nth sample.