How do I make a QAudioOutput object play from a buffer?

Question

int main(int argc, char *argv[])
{
    QCoreApplication b(argc, argv);

    QBuffer *buffer;
    QAudioOutput *a;

    QAudioFormat format;
    format.setSampleRate(8000);
    format.setChannelCount(1);
    format.setSampleSize(8);
    format.setCodec("audio/pcm");
    format.setByteOrder(QAudioFormat::LittleEndian);
    format.setSampleType(QAudioFormat::UnSignedInt);

    QAudioDeviceInfo info(QAudioDeviceInfo::defaultOutputDevice());
    if (info.isFormatSupported(format))
    {
        cout << "Format supported" << endl;
    }
    else
    {
        cout << "Format not supported" << endl;
    }

    char *data = (char*)malloc(32768 * sizeof(char));

    //generating a sound
    for (int i = 0; i<256; ++i)
    {
        for (int j = 0; j<128; ++j)
        {
            data[i * 128 + j] = (char)j;
        }
    }

    cout << "Created samples" << endl;

    //copying into the buffer
    buffer = new QBuffer;
    buffer->open(QIODevice::ReadWrite);
    buffer->seek(0);
    buffer->write(data, 32768);
    cout << "Filled buffer" << endl;

    //playing
    QThread thr;
    a = new QAudioOutput(format);
    //a->moveToThread(&thr);

    //thr.start();
    //QMetaObject::invokeMethod(a, "start", Q_ARG(QIODevice*, buffer));

    a->start(buffer);

    system("pause");

    return b.exec();
}

I am trying to make my console application output sound and I can't figure out why my QAudioOutput object doesn't do that. I placed the code above. Can you tell me what did I do wrong? PS If i write that vector to a file and play it as raw sound I can hear a low frequency buzz.

Answer 1

First, you definitely shouldn't have system("pause") before your main loop as @Hayt mentioned.

Second, you should seek to the beginning after you've written the data.

buffer->write(data, 32768);
buffer->seek(0);