Crash on terminate when switching sources and calling play

[yunag]

Hi, valbok. I experienced some crashes when switching network sources and calling play. This crash might happen after multiple attempts.

Here is small demo:

#include <QApplication>
#include <QtAVPlayer/qavaudiooutput.h>
#include <QtAVPlayer/qavplayer.h>

#include <QComboBox>
#include <QLoggingCategory>
#include <QPushButton>
#include <QVBoxLayout>
#include <QWidget>

using namespace std::chrono_literals;

int main(int argc, char *argv[]) {
  QLoggingCategory::setFilterRules("qt.QtAVPlayer.debug=true");

  QApplication app(argc, argv);

  QAVPlayer p;

  QComboBox *combo = new QComboBox;
  combo->setMaximumWidth(300);

  combo->addItem("https://s7-webradio.rockantenne.de/alternative/stream/mp3");
  combo->addItem("http://79.120.77.11:8000/punkru");
  combo->addItem("https://live.hunter.fm/rock_high");

  QWidget window;

  QPushButton *playButton = new QPushButton("Play");
  QPushButton *stopButton = new QPushButton("Stop");

  QVBoxLayout layout(&window);
  layout.addWidget(combo);
  layout.addWidget(playButton);
  layout.addWidget(stopButton);

  QAVAudioOutput *audioOutput = nullptr;

  QObject::connect(combo, &QComboBox::currentIndexChanged, &p, [&]() {
    p.stop();

    if (audioOutput) {
      audioOutput->stop();
      audioOutput->deleteLater();
    }

    audioOutput = new QAVAudioOutput(&p);
    audioOutput->setVolume(0.5);

    p.setSource(combo->currentText());
    p.play();

    // audioOutput.setBufferSize(128 * 1024);
    QObject::connect(
        &p, &QAVPlayer::audioFrame, audioOutput,
        [audioOutput](const QAVAudioFrame &frame) { audioOutput->play(frame); },
        Qt::DirectConnection);
  });

  QObject::connect(playButton, &QPushButton::clicked, &p, [&]() { p.play(); });
  QObject::connect(stopButton, &QPushButton::clicked, &p, [&]() { p.stop(); });

  window.show();

  return app.exec();
}

Reproduce:

1. Switch source and call play()
2. Repeat first step multiple times

Possible reason:
Functions executing in wrong order. We waiting for futures when we already deallocated some resources that futures might depend on.

If I'm wrong please correct me.

[valbok]

as I remember, first we clear queues and after we wait that threads finished to consume all frames.

[valbok]

thanks, got this BT:

QAVPacket::duration (this=0x7fffddbfeef0) at ../../src/QtAVPlayer/qavpacket.cpp:76
76	    auto tb = d->stream.stream()->time_base;
(gdb) bt
#0  QAVPacket::duration() const (this=0x7fffddbfeef0) at ../../src/QtAVPlayer/qavpacket.cpp:76
#1  0x0000555555570dc5 in QAVPacketQueue<QAVFrame>::dequeue() (this=0x5555558b7648) at ../../src/QtAVPlayer/qavpacketqueue_p.h:241
#2  0x000055555556e100 in QAVPacketQueue<QAVFrame>::frontFrame(QAVFrame&) (this=0x5555558b7648, frame=...) at ../../src/QtAVPlayer/qavpacketqueue_p.h:161
#3  0x00005555555636ee in QAVPlayerPrivate::doPlayStep(bool&, double, QAVQueueClock&, QAVPacketQueue<QAVFrame>&, bool&, std::function<void (QAVFrame const&)> const&)
    (this=0x5555558b74d0, master=@0x7fffddbff02d: false, refPts=-1, clock=..., queue=..., sync=@0x7fffddbff02e: true, cb=...) at ../../src/QtAVPlayer/qavplayer.cpp:707
#4  0x0000555555563f42 in QAVPlayerPrivate::doPlayAudio() (this=0x5555558b74d0) at ../../src/QtAVPlayer/qavplayer.cpp:793
#5  0x00005555555766a8 in QtConcurrent::VoidStoredMemberFunctionPointerCall0<void, QAVPlayerPrivate>::runFunctor() (this=0x7fffb825a8c0) at /usr/include/x86_64-linux-gnu/qt5/QtConcurrent/qtconcurrentstoredfunctioncall.h:205
#6  0x000055555556b835 in QtConcurrent::RunFunctionTask<void>::run() (this=0x7fffb825a8c0) at /usr/include/x86_64-linux-gnu/qt5/QtConcurrent/qtconcurrentrunbase.h:136
#7  0x00007ffff46cff92 in  () at /lib/x86_64-linux-gnu/libQt5Core.so.5
#8  0x00007ffff46ccca1 in  () at /lib/x86_64-linux-gnu/libQt5Core.so.5
#9  0x00007ffff3e94ac3 in start_thread (arg=<optimized out>) at ./nptl/pthread_create.c:442
#10 0x00007ffff3f26850 in clone3 () at ../sysdeps/unix/sysv/linux/x86_64/clone3.S:81

[yunag]

Oh I also got this backtrace and then tried to add some null checks after each crash and it not helped me a lot. Then other type of issues occurred. I thought it was easy peasy but now i realize it's not

[valbok]

could you check #503 ?

[yunag]

I confirm. Everything is working now!

[valbok]

I confirm. Everything is working now!

thanks, just need to understand why tests failed, maybe would require another fix