Hello. Please tell me how to remove the delay when sending voice from the microphone to the speakers.
(OS Linux Mint 18.1, pulseaudio)
Qt Code: 
  1. #include <iostream>
  2. #include <cassert>
  3. #include <QCoreApplication>
  4. #include <QAudioInput>
  5. #include <QAudioOutput>
  6. #include <QBuffer>
  7. #include <QDebug>
  8.  
  9. int main(int argc, char *argv[])
  10. {
  11.     QCoreApplication app(argc, argv);
  12.  
  13.     QBuffer rdBuff;
  14.     QBuffer wrBuff;
  15.     wrBuff.open(QBuffer::WriteOnly);
  16.     rdBuff.open(QBuffer::ReadOnly);
  17.  
  18.     QObject::connect(&wrBuff, &QIODevice::bytesWritten, [&wrBuff, &rdBuff](qint64)
  19.     {
  20.         // remove all data that was already read
  21.         rdBuff.buffer().remove(0, rdBuff.pos());
  22.  
  23.         // set pointer to the beginning of the unread data
  24.         const auto res = rdBuff.seek(0);
  25.         assert(res);
  26.  
  27.         // write new data
  28.         rdBuff.buffer().append(wrBuff.buffer());
  29.  
  30.         // remove all data that was already written
  31.         wrBuff.buffer().clear();
  32.         wrBuff.seek(0);
  33.     });
  34.  
  35.     const auto decideAudioFormat = [](const QAudioDeviceInfo& devInfo)
  36.     {
  37.         QAudioFormat format;
  38.         format.setSampleRate(8000);
  39.         format.setChannelCount(1);
  40.         format.setSampleSize(16);
  41.         format.setCodec("audio/pcm");
  42.         format.setByteOrder(QAudioFormat::LittleEndian);
  43.         format.setSampleType(QAudioFormat::SignedInt);
  44.  
  45.  
  46.         if (devInfo.isFormatSupported(format))
  47.         {
  48.             return format;
  49.         }
  50.     };
  51.  
  52.     QAudioInput audioInput(decideAudioFormat(QAudioDeviceInfo::defaultInputDevice()));
  53.     QAudioOutput audioOutput(decideAudioFormat(QAudioDeviceInfo::defaultOutputDevice()));
  54.  
  55.     audioInput.start(&wrBuff);
  56.     audioOutput.start(&rdBuff);
  57.     return app.exec();
  58. }
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