QAudioDevice and (un)supported QAudioFormat formats

[csab6597]

The following simple code

int main(int argc, char** argv) {
	QApplication app(argc, argv);

	QAudioFormat fmt;
	fmt.setSampleRate(44100);
	fmt.setChannelCount(2);
	fmt.setSampleFormat(QAudioFormat::Float);

	const auto devices = QMediaDevices::audioOutputs();
	for (const QAudioDevice& dev : devices) {
		qDebug() << "device" << dev.description();
		qDebug() << "sampleRate min" << dev.minimumSampleRate() << "max" << dev.maximumSampleRate();
		qDebug() << "channelCount min" << dev.minimumChannelCount() << "max" << dev.maximumChannelCount();
		qDebug() << "preferredFormat" << dev.preferredFormat();
		qDebug() << "format" << fmt << "isFormatSupported" << dev.isFormatSupported(fmt);
		qDebug();
	}

	return app.exec();
}

will give me the following output

device "DENON-AVRHD (NVIDIA High Definition Audio)"
sampleRate min 48000 max 48000
channelCount min 5 max 6
preferredFormat QAudioFormat( 48000 Hz,  6 Channels,  Float Format )
format QAudioFormat( 44100 Hz,  2 Channels,  Float Format ) isFormatSupported false

device "DELL U2715H (NVIDIA High Definition Audio)"
sampleRate min 48000 max 48000
channelCount min 2 max 2
preferredFormat QAudioFormat( 48000 Hz,  2 Channels,  Float Format )
format QAudioFormat( 44100 Hz,  2 Channels,  Float Format ) isFormatSupported false

device "Realtek Digital Output (Realtek High Definition Audio)"
sampleRate min 48000 max 48000
channelCount min 2 max 2
preferredFormat QAudioFormat( 48000 Hz,  2 Channels,  Float Format )
format QAudioFormat( 44100 Hz,  2 Channels,  Float Format ) isFormatSupported false

which I try to make sense of. As stated I indeed use a Nvidia Graphics Card for audio output. That device very much supports different sample rate and channel counts, but the code tells me that ALL devices can handle a sample rate of 48000 ONLY, as this is the min and max value. Similarly no device would handle mono output according to this text. So with that knowledge the example QAudioFormat of 44100 Stereo is rejected via the isFormatSupported() function. But really?

My System is Windows 11, Qt 6.8.2, MSVC 2022, Nvidia Geforce RTX 3060