QAudioDecoder memory leak

void readSoundRecord(const QString &_fileName, QAudioFormat &_format, QByteArray &_bytearray)
{ 
    QAudioDecoder audiodecoder;

    connect(&audiodecoder, SIGNAL(error(QAudioDecoder::Error)), this, SLOT(audioDecoderError(QAudioDecoder::Error)));
    audiodecoder.setSourceFilename(_fileName);

    QEventLoop _el;
    connect(&audiodecoder, SIGNAL(finished()), &_el, SLOT(quit()));
    connect(&audiodecoder, SIGNAL(error(QAudioDecoder::Error)), &_el, SLOT(quit()));
    connect(&audiodecoder, &QAudioDecoder::bufferReady, [&audiodecoder, &_bytearray, &_format] () {
        QAudioBuffer _ab = audiodecoder.read();
        _format = _ab.format();
        _bytearray.append(QByteArray(_ab.constData<char>(),_ab.byteCount()));
    });
    audiodecoder.start();
    _el.exec();
}