Make DAL virtual camera plugin to show up in QuickTime

Hi,

I have written a DAL virtual webcam plugin which works fine with all apps (Zoom, OBS, ...) except Apple QuickTime.

Other 3rd party virtual webcams show up in QuickTime, for instance the OBS virtual cam plugin: https://github.com/obsproject/obs-studio/tree/dde4d57d726ed6d9e244ffbac093d8ef54e29f44/plugins/mac-virtualcam/src/dal-plugin

My first intention was that it has something to do with code signing, so I removed the signature from OBS virtual cam plugin but it kept working in QuickTime.

This is the source code of my plugin's entry function:

#include <CoreFoundation/CoreFoundation.h>

#include "plugininterface.h"

extern "C" void *TestToolCIOPluginMain(CFAllocatorRef allocator, CFUUIDRef requestedTypeUUID)
{
	// This writes to a log file in /tmp/logfile.txt but is NEVER called from QuickTime:
	Logger::write("Called TestToolCIOPluginMain");

    if (!CFEqual(requestedTypeUUID, kCMIOHardwarePlugInTypeID))
        return nullptr;

    return VCam::PluginInterface::create();
}

And the plugin's Info.plist (almost the same as OBS virtual cam's one):

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
        <key>CFBundleDevelopmentRegion</key>
        <string>English</string>
        <key>CFBundleExecutable</key>
        <string>TestDriverCIO</string>
        <key>CFBundleIdentifier</key>
        <string>com.test.cmio.DAL.VirtualCamera</string>
        <key>LSMinimumSystemVersion</key>
        <string>10.13</string>
        <key>CFBundleInfoDictionaryVersion</key>
        <string>6.0</string>
        <key>CFBundleName</key>
        <string>TestDriverCIO</string>
        <key>CFBundlePackageType</key>
        <string>BNDL</string>
        <key>CFBundleShortVersionString</key>
        <string>3.0.0</string>
        <key>CFBundleSignature</key>
        <string>????</string>
        <key>CFBundleVersion</key>
        <string>3.0.0</string>
        <key>CFBundleSupportedPlatforms</key>
        <array>
                <string>MacOSX</string>
        </array>
        <key>CFPlugInFactories</key>
        <dict>
                <key>AAAAAAAA-7320-5643-616D-363462697402</key>
                <string>TestToolCIOPluginMain</string>
        </dict>
        <key>CMIOHardwareAssistantServiceNames</key>
        <array>
                <string>com.test.cmio.VCam.Assistant</string>
        </array>
        <key>CFPlugInTypes</key>
        <dict>
                <key>30010C1C-93BF-11D8-8B5B-000A95AF9C6A</key>
                <array>
                        <string>AAAAAAAA-7320-5643-616D-363462697402</string>
                </array>
        </dict>
</dict>
</plist>

Interestingly "TestToolCIOPluginMain" is never called (the logger never writes an output) when starting QuickTime and the camera is not shown in QuickTime.

Is there something special required to get the DAL plugin to show up in QuickTime? What am I missing here?

Regards,