export artefact with echo in zasfx

[musikBear]

LMMS 1.2.0 64B WIN10
listen to this export. The hiss is an artefact
artefacts.zip
Also same hiss a in 24b and 32b
Export settings: default
I think its resonance?

[SecondFlight]

This can't be diagnosed unless we have steps to reproduce and/or a project file. Please provide at least one of those.

[musikBear]

file yes of-cause (added
I have digged in, and the export-artefact emerges, when Echo-effects are added :
Edit-instrument| Effect| Echo

artefacts.zip

[PhysSong]

Confirmed. Here's the comparison of exported(top) and normally played(bottom) audio samples.

[PhysSong]

The issue is from the fact that the delay time of the Zyn echo uses forward writing(instead of backward reading) and interpolates the value of the time.
Suppose there's a note at the beginning of the project. When exporting it, Zyn starts to interpolate the delay time. At the same time, Zyn plays the note and applies the echo effect. It results in the mentioned artifact.
The upstream worked around by disabling the interpolation(zynaddsubfx/zynaddsubfx@b4f6091), but I'm not sure if it's the best way. It's almost impossible to avoid artifacts when automating the delay time, so I think there're no perfect ways to handle it.

[musikBear]

Excellent dissect 👍

[onpon4]

Hi, so this little bug is one that's caused me inconvenience before. I don't really fully understand the technicalities of it, but I know that I only get this noticeably when a Zyn note is played right at the start of the track, so I work around this by shifting everything over, exporting, and then trimming off the silence at the beginning (it's tedious, but it works). Would it be possible to automate a sort of hack like this to solve the problem? (Not necessarily that exact procedure, but some trickery so that the thing Zyn does to cause the artifact behaves as if there's silence at the beginning of the track.)

🦇

[musikBear]

I work around this by shifting everything over, exporting, and then trimming off the silence at the beginning (it's tedious, but it works).

Try to simply set loopmarkers covering exactly the whole project, and then use Export-between-loopmarkers, in the export-dialog. Let us know if that also works

[onpon4]

Try to simply set loopmarkers covering exactly the whole project, and then use Export-between-loopmarkers, in the export-dialog. Let us know if that also works

Nope, that doesn't lead to any improvement. In fact, if I do my solution of shifting everything over by one but export by loop markers starting at the real start position (after the bit of silence I insert at the start), that creates the same artifact as if I exported normally with everything in its original position. The only way I have no artifact is if the start of the audio being exported isn't playing a Zyn note (and presently the easiest way to do that is to make it have a bit of silence at the start and then trim off that bit of silence with Audacity or whatever).

🦇

[musikBear]

Nope, that doesn't lead to any improvement.

Can you make a dummy project with the artefact.
You can upload .MMP files right here.

[onpon4]

Well there shouldn't be a need to, you already posted such a project file with the same artifact (#5135 (comment)). Is there any particular reason that one is inadequate?

🦇

[musikBear]

No its just me that is inadequate
Over & out 🤦‍♂️