[MU4 Issue] MuseSounds reverb has flipped polarity in one of its channels

[teetow]

Describe the bug In the MuseSounds Strings pack (and possibly others) the reverb tail has one of its channels flipped

To Reproduce Steps to reproduce the behavior:

1. Make pretty music with MuseSounds
2. Stop playback
3. Listen to the reverb tail
4. Notice one of its channels has its polarity flipped

Expected behavior An actual stereo reverb that doesn't make my ears uncomfortable

Screenshots Waveform while instruments are playing (no issue)

Reverb tail immediately after stopping playback (one channel is flipped)

Platform information

• OS: Windows 10

Additional context Using October 24 nightly

[davidwhearn]

I can't seem to reproduce this - please do reopen the issue if it's still occurring for you. It would be super helpful to have a score attached so that we can reference

[teetow]

Yes, it still happens. I literally just opened up a new project and added some MuseStrings. I also tried with MS Basic, the issue is even more pronounced there since those samples are a lot drier. The reason you might have a harder time reproducing it now is that stopping playback will also kill the verb tail, at least in MuseSounds. Not sure if / when that changed.

However, the issue is clearly still present. Here's a screenshot from Audition again, with the Phase analysis window showing. As you can see, it's firmly in the red, meaning the current signal is 180° out of phase. The issue is also clearly audible, exactly the kind of hollowed-out disembodied sound you'd expect.

[iamtesch]

@teetow -- just to double check, you are experiencing this with MS Basic as well, correct?

[teetow]

Yup.

[teetow]

In the meantime, is there any chance we can just get a toggle for disabling the realtime reverb entirely? I'd have that as a feature request anyway.

[RomanPudashkin]

@teetow hello! Is this still an issue in 4.1.1? Thanks!

[LWinterberg]

Update: Disregard, I wasn't looking at the reverb but the content

[teetow]

As far as I can tell, it's still there. Here are some in-depth steps to reproduce:

1. Create a Musescore project with a series of short notes
2. Render the project twice: once with reverb, once without
3. Add both tracks in parallel to a DAW (e.g. Reaper)
4. Invert polarity of one of the tracks, so that the dry signal is cancelled out
5. Render the result to onlyverb.wav -- you now have a file with only the verb tail
6. Analyze the rendered file (onlyverb.wav). It's got significant material to the sides (meaning, it's out of phase).
7. Split the file into L and R channels, invert polarity of one of the channels
8. Analyze the result. It's significantly more in-phase now, and sounds much more pleasing.

So at some stage in your reverb DSP chain (either inside the plugin or outside) a channel gets its polarity flipped. If you can't figure out where, I suggest just adding an extra step in the Reverb plugin that flips one of them again =)

[sampleeditor]

@teetow You are 100% correct. The reverb is out of phase. This is likely a signal processing issue within Muse Score and/or the Reverb itself.