QAudioOutput buffer underrun

[BartBlackMagic]

Hi, I was planning to write a small VOIP program using QUdpSockets, but this always ended in buffer underrun problems. I looked with Wireshark whether the receiving end was getting packets and it was.
To better understand the problem, I made the following ridiculous code that gets data from the QAudioInput component via the QIODevice "device" and gives this device to QAudioOutput that I expected to play the audio from the microphone. But it doesn't, the QAudioOutput still gives "buffer underrun" messages.

Anyone has an idea what i'm doing wrong?

AudioController::AudioController()
{
    // Set up the format, eg.
    format.setFrequency(10100);
    format.setChannels(1);
    format.setSampleSize(8);
    format.setCodec("audio/pcm");
    format.setByteOrder(QAudioFormat::LittleEndian);
    format.setSampleType(QAudioFormat::UnSignedInt);
 
    QAudioDeviceInfo info(QAudioDeviceInfo::defaultOutputDevice());
    if (!info.isFormatSupported(format)) {
        qDebug("raw audio format not supported by backend, cannot play audio.");
        return;
    }
 
    input = new QAudioInput(format, this);
    output = new QAudioOutput(format, this);
 
    connect(input,SIGNAL(stateChanged(QAudio::State)),SLOT(inputPlaying(QAudio::State)));
    device = input->start();
 
    connect(output,SIGNAL(stateChanged(QAudio::State)),SLOT(outputPlaying(QAudio::State)));
    output->start(device);
 
}

AudioController::AudioController()
{
    // Set up the format, eg.
    format.setFrequency(10100);
    format.setChannels(1);
    format.setSampleSize(8);
    format.setCodec("audio/pcm");
    format.setByteOrder(QAudioFormat::LittleEndian);
    format.setSampleType(QAudioFormat::UnSignedInt);

    QAudioDeviceInfo info(QAudioDeviceInfo::defaultOutputDevice());
    if (!info.isFormatSupported(format)) {
        qDebug("raw audio format not supported by backend, cannot play audio.");
        return;
    }

    input = new QAudioInput(format, this);
    output = new QAudioOutput(format, this);

    connect(input,SIGNAL(stateChanged(QAudio::State)),SLOT(inputPlaying(QAudio::State)));
    device = input->start();

    connect(output,SIGNAL(stateChanged(QAudio::State)),SLOT(outputPlaying(QAudio::State)));
    output->start(device);

}

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[BartBlackMagic]

I still haven't figured out what to do to solve this buffer underrun problem. Is there nobody who has experience in this field?
Thx