Phonon problem in Windows 7 with code compiled in XP

I have some code compiled using Visual Studio 2010 (C++), with Qt for the GUI and Phonon to show some videos.

I compile and run the code in a Windows XP machine and everything works fine. The videos and controls are shown correctly, and the same in other Windows XP machines. But at the moment that I try to use a Windows 7 machine, the video i开发者_开发百科s not shown. Phonon controls are loaded, I can adjust the size of the Phonon VideoWidget but nothing is shown. I am using the SetFile method to indicate the file location and I have also tried (of course, with no luck) with setCurrentSource in the MediaObject (it works, though, in Windows XP).

I have tried different locations of files (absolute/relative) but nothing seems to work. Also, in XP when a video is not found an alert message is shown while in Windows 7 there is no error message, but also no video is shown. If I try to open the videos with other players, they work fine (I tried also with videos with different formats).

Any idea on what can be wrong? Is there something that I am missing with Phonon and Windows 7? Thanks!

When deploying your application to a different computer, make sure you don't forget to copy the Phonon backend. Not just the DLL contained in it (the ds backend for me), but also the directory itself.

That is

 -Application Directory
 ¦-myexe.exe
 ¦-phonon_backend
  ¦-phonon_ds94.dll

Furthermore the Phonon backend on Windows (and Mac I think) makes use of the QtOpenGL module. So don't forget to copy this either. It can go inside the application directory.

In any case you could help yourself out a bit by adding a small bit of code that shows (perhaps writes to a file) which mimetypes are available. If it doesn't spit out anything, there is a problem with your backend. (Well, that of your application...)

This is what I had to do when I used Phonon to play video inside my application. Since I only quickly added this some time ago to my application, I'm not 100% sure that this is the only (or even the proper) way to do this, so anyone who has different insights feel free to comment on this.