Program crashes trying to play audio using QAudioOutput

ERSUCC

I am trying to use QAudioOutput to play an endless sine wave from a byte array. When I run it, the program crashes just after the audio device's state changes to ActiveState. When I use debugging mode, it says the crash occurs in QBuffer::readData(). Here is the creation of the buffer I am trying to use:

QByteArray buffer;

for (int i = 0; i < SAMPLE_RATE; i++)
{
    buffer.append(QString("%1").arg(sin(2 * M_PI * (double)i / SAMPLE_RATE)));
}

audioPlayer->play(&buffer);

Here is the play function in AudioPlayer:

void AudioPlayer::play(QByteArray *data)
{
    QMetaObject::invokeMethod(&audioThread, "play", Qt::QueuedConnection, Q_ARG(QByteArray, *data));
}

Here is the play function in AudioThread (buffer is a QBuffer member variable):

void AudioThread::play(QByteArray data)
{
    buffer.setBuffer(&data);
    buffer.open(QIODevice::ReadOnly);

    audioOutput->setBufferSize(buffer.size());
    audioOutput->start(&buffer);
}

The last line of play in AudioThread is the last line that I can trace in my code before the error occurs, and I'm guessing it is the line with the problem, because I never hear any audio. Thanks in advance for your help, and let me know if I should include any other sections of my code.

Bonnie

@ERSUCC said in Program crashes trying to play audio using QAudioOutput:

buffer.setBuffer(&data);

I think this line is the cause of the crash.
data here is a local variable, it will be destroyed at the end of this function.
You set buffer to use it as internal buffer, but it is not accessible after that.

void QBuffer::setBuffer(QByteArray *byteArray)
...
The caller is responsible for ensuring that byteArray remains valid until the QBuffer is destroyed, or until setBuffer() is called to change the buffer.

Try use buffer.setData(data) instead.

ERSUCC

That worked! Thank you so much!