Enable a plugin to upmix in Logic Pro

Development
1

When using Apple’s Delay Designer on a stereo track which has a surround output, we get the option to select the option to upmix from stereo to surround:

Screenshot 2024-07-11 at 13.16.39

I would like to achieve the same with my plugin, but I can’t get this to work. My plugin overrides isBusesLayoutSupported() and returns true on the supported combinations.

When running through auval the correct channel capabilities are reported:

Reported Channel Capabilities (explicit):
      [1, 1]  [1, 2]  [1, 6]  [1, 10]  [1, 12]  [2, 2]  [2, 6]  [2, 10]  [2, 12]

Input/Output Channel Handling:
1-1   1-2   1-4   1-5   1-6   1-7   1-8   2-2   2-4   2-5   2-6   2-7   2-8   4-4   4-5   5-5   6-6   7-7   8-8
X     X                 X                 X                 X

# # AudioChannelLayouts (5), Input Scope:
ChannelLayout is Writable: T
The Unit publishes the following Channel Layouts:
  0x640001, 0x650002, 0x660002, 0x670002, 0x6A0002,

Is Audio Channel Layout Available:
Mono    Stereo  Binau.  AU_4    Ambi.   AU_5    AU_5_0  AU_6    AU_6_0  AU_7_0  AU_7_0F AU_8    AU_5_1  AU_6_1  AU_7_1  AU_7_1F
X       X       X

# # AudioChannelLayouts (11), Output Scope:
ChannelLayout is Writable: T
The Unit publishes the following Channel Layouts:
  0x640001, 0x650002, 0x660002, 0x670002, 0x6A0002, 0x790006, 0x7A0006, 0x7B0006, 0x7C0006, 0xC0000C, 0xC4000A,

Is Audio Channel Layout Available:
Mono    Stereo  Binau.  AU_4    Ambi.   AU_5    AU_5_0  AU_6    AU_6_0  AU_7_0  AU_7_0F AU_8    AU_5_1  AU_6_1  AU_7_1  AU_7_1F
X       X       X                                                                               X

Based on this auval report I would expect Logic to be able to instantiate the plugin as stereo → 5.1, but it doesn’t.

What am I missing?

2

Quite possible that Logic’s aggressive caching of plugin channel capablities is biting you. Recently a colleague had a similar issue that was only possible to fix by changing the PLUGIN_CODE so that Logic would actually respect the new channel capabilities being reported to auval.

3

Thanks! That solved part of the problem!

The other part is that this plugin also supports 1:1 surround channel layouts, enabling passthrough of surround tracks.

When I disable this 1:1 surround pass through the plugin allows to be instantiated as stereo => surround, but when the 1:1 surround pass through is enabled is doesn’t allow to be instantiated as stereo => surround.

Any more suggestions?

4

I was able to fix this by testing for the amount of channels of the ChannelSets instead of comparing the supported ChannelSets themselves.

So instead of doing:

if (in == juce::AudioChannelSet::mono() || in == juce::AudioChannelSet::stereo())
{
    if (out == juce::AudioChannelSet::mono() || out == juce::AudioChannelSet::stereo() ||
        out == juce::AudioChannelSet::create5point1() || out == juce::AudioChannelSet::create7point1point2() ||
        out == juce::AudioChannelSet::create7point1point4())
    {
        return true;
    }
}

I’m now doing:

if (in.size() == 1 || in.size() == 2)
{
    if (out.size() == 1 || out.size() == 2 || out.size() == 6 || out.size() == 10 || out.size() == 12)
        return true;
}
3 Likes
5

Unfortunately this broke the AAX versions which was now reporting invalid (unsupported) channel configurations.

Then I tried to wrap the channel count based logic into a special case for logic like this:

if (pluginHostType.isLogic())
{
    // A hack for Logic Pro which seems to probe the plugin without specific channel sets.
    if (in.size() == 1 || in.size() == 2)
    {
        if (out.size() == 1 || out.size() == 2 || out.size() == 6 || out.size() == 10 || out.size() == 12)
        {
            return true;
        }
    }
}

But now Logic doesn’t consider the plugin capabel of doing upmixing (mono to stereo, or mono/stereo to surround).

The behaviour of Logic seems to be very inconsistent, changing the plugin id helped a t bit, but also not consistently. I haven’t found a pattern in it’s behaviour yet.

Is there anyone with insight into what might be going on? Or have any tips?

6

I found that when running in auval the channel configurations were reported incorrectly:

FORMAT TESTS:

Reported Channel Capabilities (explicit):
      [-1, -1]

Input/Output Channel Handling:
1-1   1-2   1-4   1-5   1-6   1-7   1-8   2-2   2-4   2-5   2-6   2-7   2-8   4-4   4-5   5-5   6-6   7-7   8-8
X                                         X                                   X           X     X     X     X

After changing the custom Logic logic (pun intended) to this:

const auto pluginHostType = juce::PluginHostType();
if (pluginHostType.isLogic() || pluginHostType.isAUVal() || pluginHostType.getHostPath().containsIgnoreCase ("auval"))
{
    // A special case for Logic Pro which seems to probe the plugin without specific channel sets.
    if (in.size() == 1 || in.size() == 2)
    {
        if (out.size() == 1 || out.size() == 2 || out.size() == 6 || out.size() == 10 || out.size() == 12)
        {
            LOGINFO (
                "Using workaround of channelcounts for Logic Pro (ins={}, outs={})",
                in.size(),
                out.size());
            return true;
        }
    }
}

auval now reports the correct channel configs:

FORMAT TESTS:

Reported Channel Capabilities (explicit):
      [1, 1]  [1, 2]  [1, 6]  [1, 10]  [1, 12]  [2, 2]  [2, 6]  [2, 10]  [2, 12]  [3, 3]  [4, 4]  [5, 5]
      [6, 6]  [7, 7]  [8, 8]  [9, 9]  [10, 10]  [11, 11]  [12, 12]  [13, 13]  [14, 14]  [15, 15]  [16, 16]

Input/Output Channel Handling:
1-1   1-2   1-4   1-5   1-6   1-7   1-8   2-2   2-4   2-5   2-6   2-7   2-8   4-4   4-5   5-5   6-6   7-7   8-8
X     X                 X                 X                 X                 X           X     X     X     X

This tels me that juce::PluginHostType().isAUVal() is not working correctly, because it matches on auvaltool whereas the tool is called auval and is located inside /usr/bin/.

Nevertheless, after verifying the channel configurations with auval, Logic Pro is still not picking up the correct channel configurations.

7

I found that the Apple Info helper also instantiates the plugin. I’m not sure on exactly when.

After updating the special case for Logic like this:

    const auto pluginHostType = juce::PluginHostType();
if (pluginHostType.isLogic() || pluginHostType.isAppleInfoHelper() || pluginHostType.isAUVal() ||
    pluginHostType.getHostPath().containsIgnoreCase ("auval"))
{
    // A special case for Logic Pro which seems to probe the plugin without specific channel sets.
    if (in.size() == 1 || in.size() == 2)
    {
        if (out.size() == 1 || out.size() == 2 || out.size() == 6 || out.size() == 10 || out.size() == 12)
        {
            return true;
        }
    }
}

The plugin is correctly loaded on a fresh installation of macOS and Logic. However, on my development machine I can’t get it to work. I think this is because of the aggressive caching as mentioned above, but I want to try prevent to change the plugin code because that’s break existing projects when updating the plugin.