Stereo effects plugin summing to mono in FL studio

[d.healey]

A user has reported to me that my FX plugin is turning a stereo signal into a mono one. It only happens in FL studio as far as I'm aware, he tested in another DAW and I've tested in several with no problem.

I am using HI_SUPPORT_MONO_TO_STEREO=1 and have Support Mono FX checked. Is this a known issue and is there a solution?

[Dan Korneff]

I think this happened to me in the past. I gotta search the forum to see what happened.

[orange]

@d-healey which version of the plugin? Vst or Au?
Which OS?

[d.healey]

@orange I'll check. Can FL load AU?

[orange]

@d-healey said in Stereo effects plugin summing to mono in FL studio:

@orange I'll check. Can FL load AU?

Yes, FL support AU plugins too.

[d.healey]

@orange Windows 10, VST3

[orange]

@d-healey said in Stereo effects plugin summing to mono in FL studio:

@orange Windows 10, VST3

Are you using HI_SUPPORT_MONO_TO_STEREO=1 for the VST3 version too? Normally you shouldn't do it. because VST3 plugins process mono channels to stereo without any flag. This flag is only for AAX for Windows. And AAX & AU for the macOS.

You need to build a different plugin for the mono-to-stereo processing with a Different Plugin Name and Plugin code. So DAWs won't be confused.

This is what I do. For example, if the plugin's name is: MyPlugin;

---

STEREO & MONO VERSIONS ---> No HI_SUPPORT_MONO_TO_STEREO=1 flag. But Support Mono FX is enabled.

• MyPlugin.vst3
• MyPlugin.aax
• MyPlugin.au (for macOS)

---

MONO TO STEREO VERSIONS ---> With different Plugin Code and Plugin name. I add - m to s afterfix to the name. Both HI_SUPPORT_MONO_TO_STEREO=1 flag and Support Mono FX is enabled.

• MyPlugin - m to s.aax
• MyPlugin - m to s.au (for macOS)

---

[d.healey]

@orange said in Stereo effects plugin summing to mono in FL studio:

You need to build a different plugin for the mono-to-stereo processing with a Different Plugin Name and Plugin code. So DAWs won't be confused.

I don't believe that's the case any more - https://forum.hise.audio/topic/793/mono-versions-of-fx-plugins/48?_=1703789300279

Both the AU and VST3 works fine, on stereo or mono tracks, in all DAWs tested except for this issue in FL studio.

[orange]

@d-healey

I see, but HI_SUPPORT_MONO_TO_STEREO=1 flag shouldn't be enabled on VST3 versions.

[Christoph Hart]

I vaguely remember spending a few hours last year on this problem. Here's are the relevant parts of the project_info.xml of the FX project I was working on at the time:

<ProjectSettings>
  <ExtraDefinitions value="HI_SUPPORT_MONO_CHANNEL_LAYOUT=1&#10;HI_SUPPORT_MONO_TO_STEREO=1"/>
  <SupportMonoFX value="0"/>
  <EnableMidiInputFX value="No"/>
  <EnableSoundGeneratorsFX value="0"/>
  <VST3Support value="1"/>
  <ForceStereoOutput value="1"/>
  <EnableMidiOut value="No"/>
</ProjectSettings>

Not sure if the preprocessors in the extra definitions are required but I think the solution was to disable SupportMonoFX and enable ForceStereoOutput, then you get a stereo->stereo and a mono->stereo plugin with the same binary.

[d.healey]

@Christoph-Hart said in Stereo effects plugin summing to mono in FL studio:

Not sure if the preprocessors in the extra definitions are required but I think the solution was to disable SupportMonoFX and enable ForceStereoOutput, then you get a stereo->stereo and a mono->stereo plugin with the same binary.

Does it work on a mono track?

Edit: Doesn't look like force stereo is useful in my case because my project only has two channels on the master container.

int numChannels = chain->getMatrix().getNumSourceChannels();
    
if(IS_SETTING_TRUE(HiseSettings::Project::ForceStereoOutput))
      numChannels = 2;
    
return "HISE_NUM_PLUGIN_CHANNELS=" + String(numChannels);

@Christoph-Hart said in Stereo effects plugin summing to mono in FL studio:

disable SupportMonoFX

So what is SupportMonoFX for?

Edit: Looks like it does the same thing

String monoSupport = GET_SETTING(HiseSettings::Project::SupportMonoFX) == "1" ? "enabled" : "disabled";

REPLACE_WILDCARD_WITH_STRING("%SUPPORT_MONO%", monoSupport);

HI_SUPPORT_MONO_CHANNEL_LAYOUT=\"%SUPPORT_MONO%\"

As it looks like I have everything setup correctly, and this issue appears to only be in FL Studio. I think it is another FL edge case - or user error.

@orange Does FL Studio have separate mono and stereo track types? (I'm not familiar with it).

[Christoph Hart]

@d-healey said in Stereo effects plugin summing to mono in FL studio:

Does it work on a mono track?

Yes, but it converts it to stereo (it's a convolution reverb with stereo IRs and I assumed that your plugin wants that too).

So what is SupportMonoFX for?

Allows processing of a single channel. But I think you can either have mono->mono or mono->stereo, you can't have both, hence my suggestion of disabling this and enabling ForceStereoOutput

[d.healey]

@Christoph-Hart Right but in your example you have HI_SUPPORT_MONO_TO_STEREO=1 which is the same as enabling the SupportMonoFX check box.

[Christoph Hart]

in your example you have HI_SUPPORT_MONO_TO_STEREO=1 which is the same as enabling the SupportMonoFX check box.

Oops you're right, but I think the project settings override the extra definitions. Could be an interesting thing to investigate on a rainy day though :)

[d.healey]

@Christoph-Hart Well in that case I think I have everything setup correctly, but still there seems to be an issue in FL studio.

I think I'm going to have to try it myself though because it could just be some setup issue on the user side - although he seems to know what he's doing.

[d.healey]

I can confirm the issue on my system. I'll now try out various combinations of things to see if I can find a solution.

[d.healey]

@Christoph-Hart I tried your configuration suggestion and the problem is still there in FL studio. So I'm pretty sure this is an FL Studio only bug

[d.healey]

@orange Do your stereo effects work in FL?

[orange]

@d-healey said in Stereo effects plugin summing to mono in FL studio:

@orange Do your stereo effects work in FL?

Yes it works.

You can try it yourself from here: https://noiseash.com/downloads/

Just install the Prestige Racks plugin, and pm to me if you need the license.

[d.healey]

@orange said in Stereo effects plugin summing to mono in FL studio:

@d-healey

I see, but HI_SUPPORT_MONO_TO_STEREO=1 flag shouldn't be enabled on VST3 versions.

@Christoph-Hart If this is the case, can you make it so this flag if ignored for VST3 builds? Otherwise we have to go in and change it between building VST3 and AU or AAX

@orange said in Stereo effects plugin summing to mono in FL studio:

Yes it works.

Thanks, just confirmed it works here, and removing the flag allows my plugin to work in FL too.