How to play sound continuously using QTConcurrent

harish__rajora

The scenario is that I have to process some bytes of data continuously to the QBuffer and play it. I have the following code with QtConcurrent:

    {

        file_name = QFileDialog::getOpenFileName(this, "Open a file");
        if (!file_name.isEmpty()){
            QLabel *fileName = findChild<QLabel*>("fileName");
            fileName->setText(file_name);
            cout<<file_name.toStdString();

            QFile audio_file(file_name);

            if(audio_file.open(QIODevice::ReadOnly)) {
               readheader();
                audio_data = audio_file.readAll();
                audio_file.close();
            
                QDataStream audio_ds(audio_data);
                int val = 0;
                audio_ds>>val;
                audio_buffer = new QBuffer(&temporary_audio_array);


            
                int initial_byte = 0;



                     temporary_audio_array.clear();
                     audio_buffer->reset();
                     for(int i = initial_byte; i < initial_byte + 80000; i++)
                           temporary_audio_array.append(audio_data[i]);

             

                qDebug()<<"The size of audio_buffer is"<<audio_data.size();
                audio_buffer->seek(0);
                QAudioFormat format = QAudioFormat();
             

                cout << "Filled buffer" << endl;
                QAudioOutput *outputstream;
                outputstream = new QAudioOutput(this);
                format.setSampleFormat(QAudioFormat::Int16);
              
                myplayer->setAudioOutput(outputstream);
                if(!audio_buffer->open(QIODevice::ReadWrite)) qDebug() << "Buffer not opened";
                    else
                    {
                        qDebug() << "Buffer size:" << audio_buffer->size();
                        audio_buffer->seek(0);
            
                        myplayer->setSourceDevice(audio_buffer, QUrl(file_name));

                    }
              }
          }
      }

The following is the play function

    {
            QFuture <void> res = QtConcurrent::run(&MainWindow::printCounter, this);

        if(current_playState == false){

           
            myplayer->play();
            current_playState = true;
        } else {
            myplayer->pause();
            current_playState = false;
        }

      }

This is the thread code

void MainWindow::printCounter(){
        qInfo()<<QThread::currentThread();
        for(int i = 0; i < 80000; i++)
            temporary_audio_array.append(audio_data[i]);
    }

The audio plays only till the first 80k bytes. I am new to this. Any help appreciated.

SGaist

Hi,

What exactly are you trying to achieve with QtConcurrent ?

harish__rajora

I have a library that can decode a fixed number of bytes at a time. I need to parallel process bytes through the library and keep playing the audio. I am using QConcurrent to process the bytes in a thread while the batch that has already been processed plays.

Can you help me in any way? How to achieve this?

SGaist

I would rather write a dedicated class that works with that processing library and once a batch is done emit a signal with a QByteArray containing these data that you can then directly write into the sink.