Deploying Qt application using QtMultimedia in release mode

问题

I am developing a Qt 5.0 dekstop application using mingw47. I use QtMultimedia in this application to record and play audio. I have tested it for debug and it works. When I try to build it for release and run the executable file, I can't play the audio file that can normally be played in debug mode. I've added the following dlls before running the executable file:

D3D_Compiler_43.dll,
icudt49.dll,
icuin49.dll,
icuuc49.dll,
libEGL.dll,
libgcc_s_sjlj-1.dll,
libGLESv2.dll,
liblibmpeg2_plugin.dll,
libstdc++-6.dll,
libwinpthread-1.dll,
Qt5Core.dll,
Qt5Gui.dll,
Qt5Multimedia.dll,
Qt5Network.dll,
Qt5Widgets.dll,
Qt5Xml.dll,
plugins/platforms/(all dlls),
plugins/mediaservice/(all dlls),
plugins/playlistformats(all dlls)

What is probably wrong? Or what other dlls am I missing?

回答1:

UPDATE: Use windeployqt.exe! It works really well.

http://doc.qt.io/qt-5/windows-deployment.html#the-windows-deployment-tool

The simplest way to use windeployqt is to add the bin directory of your Qt installation (e.g. ) to the PATH variable and then run:
windeployqt <path-to-app-binary>

While you are running your application in release mode (when it is working, ran from inside Qt Creator), execute depends.exe and point it at the application.

Make note of all the dlls that are referenced from your Qt folder.

Alternate way if you want to take more time with it:

You can figure it out by hand by trying to delete files because Windows won't let you delete a folder or a dll while it is in use. So you could go and make a back up of your Qt installation, and then run you application, make sure it has connected to all the dll's it is going to use, and then try to delete folders and files in your Qt installation. Windows won't let you delete files that are in use by your release.

Also here is how Windows resolves dll's if you wanted to know:

http://msdn.microsoft.com/en-us/library/7d83bc18(v=vs.80).aspx

EDIT: Also, you don't need to make the folder called plugins in your exe directory. It should be something like this:

Qt 4.x:

./myexe.exe
./QtCore.dll
./imageformats/qjpegd4.dll  // Note: there isn't a "plugins" folder here

Qt 5.x: (take from here)

The executable                   ./plugandpaint.exe
The Basic Tools plugin           ./plugins/pnp_basictools.dll
The ExtraFilters plugin          ./plugins/pnp_extrafilters.dll
The Qt Windows platform plugin   ./platforms/qwindows.dll
The Qt Core module               ./Qt5Core.dll
The Qt GUI module                ./Qt5Gui.dll
The Qt Widgets module            ./Qt5Widgets.dll

Also run qDebug() << QApplication::libraryPaths(), and make note of paths that are searched for dlls on your computer.

Hope that helps.

回答2:

All of the DLL's in your list that have their import libraries linked to the application will be automatically loaded by the OS. If any of them are missing you will get a dialog telling you which DLL it failed to load. The only ones that look like they might be loaded manually by the application are the plugins. Make sure you are telling the QT multimedia system to load the them. Also make sure you check the error codes returned by the multiamedia manager.

Given your recent comment that the audio plays in debug mode but not in release mode is a good indication you have put the plugin DLL's in the wrong place. When you launch your application from Explorer or the command line the plugins directory needs to be in the same directory as the application. Your directory structure should look something like below

c:\stackoverflow\myprogram.exe
c:\stackoverflow\plugins\platforms\(all dlls)
c:\stackoverflow\plugins\mediaservice\(all dlls)
c:\stackoverflow\plugins\playlistformats\(all dlls)
c:\stackoverflow\D3D_Compiler_43.dll
c:\stackoverflow\icudt49.dll

... other dll's here...

c:\stackoverflow\Qt5Network.dll
c:\stackoverflow\Qt5Widgets.dll
c:\stackoverflow\Qt5Xml.dll