QMediaPlayer not starting playback on Windows when started outside QtCreator

1
votes

I wanted to accommodate myself with Qt5 and so I started a very small mp3 player. It compiles on Linux and Windows 7, both 64 bit.

When running on Windows however the selected mp3 file will only start playing when I start the program within QtCreator. When I start the standalone (shared compiled) EXE the program opens but instead starting the playback nothing happens (when debugging inside the IDE everything seems to work, sort of a Heisenbug I guess).

When looking at the file access in Processmonitor I see the directory scan, however when the MP3 should be opened nothing happens.

Maybe I missed to copy a DLL, however I have no hint which one is missing, so it may be another issue. Dependency Walker output (though it does not tell me which files/funcionts cause the errors, maybe I missed it):

Error: At least one module has an unresolved import due to a missing export function in an implicitly dependent module.
Error: Modules with different CPU types were found.
Warning: At least one module has an unresolved import due to a missing export function in a delay-load dependent module.

This is my directory content from where I try to start the EXE

  • folder "platforms" including: qminimal.dll, qwindows.dll
  • icudt49.dll, icuin49.dll, icuuc.49.dll
  • IEShims.dll (works without it, however Dependency Walker told its missing)
  • libEGL.dll
  • libgcc_s_sjlj-1.dll
  • libGLESv2.dll
  • libstdc++-6.dll
  • libwinpthread-1.dll
  • Qt5Core.dll, Qt5Gui.dll, Qt5Multimedia.dll, Qt5Network.dll, Qt5Widgets.dll
  • purr.exe

You can look at the complete source @ https://github.com/VashSan/purr - part of the source code where i start the playback:

void PurrWindow::playMedia()
{
    // [...]
    // QMediaPlayer is a member of PurrWindow:

    QUrl media = QUrl::fromLocalFile(selectedFile);
    player.setMedia(media);
    player.play();
}

I compiled the program once with MSVC2010 and once with Mingw with no difference.

I tried to google QMediaPlayer errors but most of them concern mobile platforms. However it did not leave a good impression of the QMediaPlayer to me, maybe I should look at a more reliable playback library. However if it would just start playback I'd be happy.

1
c++windowsqtmp3dll
Does Qt show selectedFile show as accessible (i.e., exists and readable)? – Kaleb Pederson
It's working both cases on my computer with Qt5 msvc2010 – Min Lin
@Vash Please review the answers carefully, and up vote the ones that helped you. You can also click on the checkbox near an answer to select it as the official answer to your question. – karlphillip

1 Answers

1
votes

Use DLL Export Viewer to find out if your .exe is referring to the right .dlls.

Sometimes people have more than one Qt/Phonon version installed and the PATH environment variable doesn't point to the directories where those DLLs are located.

Also, make sure selectedFile has the full path to the file. It's a good idea to check if the path is valid after:

selectedFile = fileDialog.getSelectedPath();

with:

QFile file( selectedFile );
if( !file.exists() )
{
  qDebug() << "!!! Invalid file: " << selectedFile;
  return;
}