I doubt ubuntu's 2-year-old bug is relevant here, even if the symptoms seem the same.

(In reply to comment #1)
> I doubt ubuntu's 2-year-old bug is relevant here, even if the symptoms seem the
> same.

Ok, but my program gives the same error:

WARNING: bool Phonon::FactoryPrivate::createBackend() phonon backend plugin could not be loaded
WARNING: bool Phonon::FactoryPrivate::createBackend() phonon backend plugin could not be loaded
WARNING: bool Phonon::FactoryPrivate::createBackend() phonon backend plugin could not be loaded
WARNING: bool Phonon::FactoryPrivate::createBackend() phonon backend plugin could not be loaded
Phonon::createPath: Cannot connect Phonon::MediaObject(no objectName) to Phonon::AudioOutput(no objectName).
WARNING: bool Phonon::FactoryPrivate::createBackend() phonon backend plugin could not be loaded

I write a simples test, using this command:

Phonon::MediaObject *mediaObject = Phonon::createPlayer(Phonon::NoCategory, Phonon::MediaSource("./file.ogg"));

mediaObject->play();

It worked in previous versions of qt on fedora, and still working on windows 7 with qt 4.7.4

The installation location of the Phonon stuff is the same in current Fedora 15 updates (Phonon 4.5.1) and current Fedora 16 updates (Phonon 4.5.57).

I think your problem is related to, but not the same as the Ubuntu issue. What's going on is that Phonon installs to /usr/lib(64)/kde4/plugins/phonon_backend/, which is only added to the Qt plugin path for KDE Plasma sessions. I see 2 possible fixes:
* unconditionally add this to the Qt plugin path (in /etc/profile.d, as we have been doing in the past, though only if KDE stuff was installed – we'd need to move this to kde-filesystem or something equally low-level instead to enforce this even for only Phonon) or
* install the Phonon stuff to the default Qt plugin directory instead.

One way to find out for sure, set

QT_PLUGIN_PATH=/usr/lib64/kde4/plugins

does it work now?

From a irc chat with phonon dev:

[12/05/11 07:19] <tdfischer> hmm
[12/05/11 07:19] <tdfischer>         QCoreApplication::addLibraryPath(QLatin1String(PHONON_LIBRARY_PATH));
[12/05/11 07:19] <tdfischer> if no platform plugin is loaded, that should cause QLibrary to look inside kde4/plugins

So, in general, PHONON_LIBRARY_PATH should get searched regardless of whether one is in a plasma session or not.

and my simple test using xfce + clementine (a qt-only phonon-using application) worked ok for me.

So, it's hard to say yet.

According to the backend loading code in libphonon, it first checks if there is a platform plugin and if it provides a backend. If not, it then searches QCoreApplication::libraryPaths() + "/phonon_backend/" for the first loadable plugin.

Prior to getting to this point, it adds PHONON_LIBRARY_PATH to that list, which is defined at buildtime to ${PLUGIN_INSTALL_DIR}/plugins.

This feels to me like a buggy system, and not a libphonon bug. This code was added in 2008 according to git, and you seem to be the only person with this bug.

Could you find out what QT_PLUGIN_PATH is and the value of libraryPath in any Trolltech.conf you find on your system?

echo $QT_PLUGIN_PATH returns an empty line. And none of the Trolltech.conf files has an line with libraryPath.

Created attachment 541013 [details]
Trolltech.conf on /etc/ diretory

Created attachment 541014 [details]
Trolltech.conf on $HOME/.config/ diretory

doing QT_PLUGIN_PATH=/usr/lib64/kde4/plugins doesnt solve the problem

You've some other problem then, resetting summary.

Mind reproducing the test I tried?

yum install clementine
and, run it, (ideally with some audio files in ~/Music)


what DE are you using?


mind posting your code that doesn't work?

Or another simple test case,

yum install qt-examples

and run,
/usr/lib64/qt4/examples/phonon/qmusicplayer

er, make that:
/usr/lib64/qt4/examples/phonon/qmusicplayer/qmusicplayer

An strace log might also be helpful, to see where it's looking for the plugin.

Oh, and are you sure your app is 64-bit? 32-bit apps need the 32-bit phonon-backend-gstreamer multilib.

I installed phonon-backend-gstreamer 32-bits and dont work anyway.

Some error message using qmusicplayer

Created attachment 542091 [details]
strace log of qmusicplayer

Well, I'll be a monkey's uncle,

QT_PLUGIN_PATH= \
/usr/lib64/qt4/examples/phonon/qmusicplayer/qmusicplayer
WARNING: bool Phonon::FactoryPrivate::createBackend() phonon backend plugin could not be loaded 

and, indeed, looking through my own strace, see no references to /usr/lib64/kde4/plugins

but,
QT_PLUGIN_PATH=/usr/lib64/kde4/plugins \ /usr/lib64/qt4/examples/phonon/qmusicplayer/qmusicplayer

go figure.

Now, here's the oops, methinks, PHONON_LIBRARY_PATH looks like a relative path according to cmake's generated files:

phonon/CMakeFiles/phonon.dir/flags.make:... -DPHONON_LIBRARY_PATH=\"lib64/kde4/plugins\"

I'd have expected this to be /usr/lib64/kde4/plugins instead.

Yup, according to FindKDE4Internal.cmake
#  PLUGIN_INSTALL_DIR       - the subdirectory relative to the install prefix where plugins will be installed (default is ${KDE4_LIB_INSTALL_DIR}/kde4)

So, Ill try prepending PREFIX in there somewhere

diff -up phonon-4.5.57/phonon/CMakeLists.txt.plugindir phonon-4.5.57/phonon/CMakeLists.txt
--- phonon-4.5.57/phonon/CMakeLists.txt.plugindir       2011-10-21 08:54:42.000000000 -0500
+++ phonon-4.5.57/phonon/CMakeLists.txt 2011-12-07 12:18:01.148682382 -0600
@@ -78,7 +78,7 @@ if (PHONON_NO_PLATFORMPLUGIN)
     add_definitions(-DQT_NO_PHONON_PLATFORMPLUGIN)
 endif (PHONON_NO_PLATFORMPLUGIN)
 
-add_definitions(-DPHONON_LIBRARY_PATH="${PLUGIN_INSTALL_DIR}/plugins")
+add_definitions(-DPHONON_LIBRARY_PATH="${CMAKE_INSTALL_PREFIX}/${PLUGIN_INSTALL_DIR}/plugins")
 
 automoc4_add_library(phonon SHARED ${phonon_LIB_SRCS})
 target_link_libraries(phonon ${QT_QTCORE_LIBRARY} ${QT_QTGUI_LIBRARY})


this seems to do the trick, makes the case of unsetting QT_PLUGIN_PATH work for me without error.

phonon-4.5.57-4.20111031.fc16 has been submitted as an update for Fedora 16.
https://admin.fedoraproject.org/updates/phonon-4.5.57-4.20111031.fc16

phonon-4.5.1-2.fc15 has been submitted as an update for Fedora 15.
https://admin.fedoraproject.org/updates/phonon-4.5.1-2.fc15

Package phonon-4.5.1-2.fc15:
* should fix your issue,
* was pushed to the Fedora 15 testing repository,
* should be available at your local mirror within two days.
Update it with:
# su -c 'yum update --enablerepo=updates-testing phonon-4.5.1-2.fc15'
as soon as you are able to.
Please go to the following url:
https://admin.fedoraproject.org/updates/FEDORA-2011-16858/phonon-4.5.1-2.fc15
then log in and leave karma (feedback).

phonon-4.5.57-4.20111031.fc16 has been pushed to the Fedora 16 stable repository.  If problems still persist, please make note of it in this bug report.

phonon-4.5.1-2.fc15 has been pushed to the Fedora 15 stable repository.  If problems still persist, please make note of it in this bug report.

Problem on Fedora15 64bit :

Using phonon-4.5.1-2.fc15 on X86_64 still not working.
But downgrade to phonon-4.5.0-2.fc15 make things back in place (sudo yum downgrade phonon phonon-devel)

This problem can be seen using 
/usr/lib64/qt4/examples/phonon/qmusicplayer/qmusicplayer

sounds like you're experiencing a separate problem then.  The patch provided here was to fix something that has been broken in phonon since forever, 4.5.0 included.

Just to restore some sanity here,

Does,

QT_PLUGIN_PATH=/usr/lib64/kde4/plugins \
/usr/lib64/qt4/examples/phonon/qmusicplayer/qmusicplayer

make phonon-4.5.1 work for you?

Yes, 

QT_PLUGIN_PATH=/usr/lib64/kde4/plugins \
/usr/lib64/qt4/examples/phonon/qmusicplayer/qmusicplayer

Works. But if this is a workaround, I'm not sure this is the best method (patch QT_PLUGIN_PATH prior launching our tools)

Our tools use default Fedora provided Qt and Phonon packages, maybe those packages shall be configured to integrate together without any user configuration ?

OK, no that just confirms my backporting the patch for phonon-4.5 didn't work right.  I'll have to look into it more.  thanks for the confirmation.

phonon-4.5.1-3.fc15 has been submitted as an update for Fedora 15.
https://admin.fedoraproject.org/updates/phonon-4.5.1-3.fc15

Package phonon-4.5.1-3.fc15:
* should fix your issue,
* was pushed to the Fedora 15 testing repository,
* should be available at your local mirror within two days.
Update it with:
# su -c 'yum update --enablerepo=updates-testing phonon-4.5.1-3.fc15'
as soon as you are able to.
Please go to the following url:
https://admin.fedoraproject.org/updates/FEDORA-2012-4052/phonon-4.5.1-3.fc15
then log in and leave karma (feedback).

Would you mind testing the update:

# su -c 'yum update --enablerepo=updates-testing phonon

and give some feedback if it works for you?

phonon-4.5.1-3.fc15 has been pushed to the Fedora 15 stable repository.  If problems still persist, please make note of it in this bug report.