There's nothing strange with my system. Bong.Da.City (I hope he'll post again because I need support here haha) has the same problem. Two same situations with the same problem in the same thread? I don't believe into such coincidences...Our systems haven't got any problem.
@wysota I installed them. MP3 still can't be played.
@Talei, I got errors when trying to install both phnon-vlc and phonon-mplayer when doing cmake..The output is:
VLC:
Qt Code: 
  1. alex@MaD-pc:~/phonon/phonon-vlc$ cmake vlc
  2. -- The C compiler identification is GNU
  3. -- The CXX compiler identification is GNU
  4. -- Check for working C compiler: /usr/bin/gcc
  5. -- Check for working C compiler: /usr/bin/gcc -- works
  6. -- Detecting C compiler ABI info
  7. -- Detecting C compiler ABI info - done
  8. -- Check for working CXX compiler: /usr/bin/c++
  9. -- Check for working CXX compiler: /usr/bin/c++ -- works
  10. -- Detecting CXX compiler ABI info
  11. -- Detecting CXX compiler ABI info - done
  12. CMake Error at CMakeLists.txt:45 (automoc4):
  13.   Unknown CMake command "automoc4".
  14.  
  15.  
  16. CMake Warning (dev) in CMakeLists.txt:
  17.   No cmake_minimum_required command is present.  A line of code such as
  18.  
  19.     cmake_minimum_required(VERSION 2.8)
  20.  
  21.   should be added at the top of the file.  The version specified may be lower
  22.   if you wish to support older CMake versions for this project.  For more
  23.   information run "cmake --help-policy CMP0000".
  24. This warning is for project developers.  Use -Wno-dev to suppress it.
  25.  
  26. -- Configuring incomplete, errors occurred!
  27. alex@MaD-pc:~/phonon/phonon-vlc$
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MPlayer:
Qt Code: 
  1. -- The C compiler identification is GNU
  2. -- The CXX compiler identification is GNU
  3. -- Check for working C compiler: /usr/bin/gcc
  4. -- Check for working C compiler: /usr/bin/gcc -- works
  5. -- Detecting C compiler ABI info
  6. -- Detecting C compiler ABI info - done
  7. -- Check for working CXX compiler: /usr/bin/c++
  8. -- Check for working CXX compiler: /usr/bin/c++ -- works
  9. -- Detecting CXX compiler ABI info
  10. -- Detecting CXX compiler ABI info - done
  11. CMake Error at libmplayer/CMakeLists.txt:15 (qt4_wrap_cpp):
  12.   Unknown CMake command "qt4_wrap_cpp".
  13.  
  14.  
  15. CMake Warning (dev) in CMakeLists.txt:
  16.   No cmake_minimum_required command is present.  A line of code such as
  17.  
  18.     cmake_minimum_required(VERSION 2.8)
  19.  
  20.   should be added at the top of the file.  The version specified may be lower
  21.   if you wish to support older CMake versions for this project.  For more
  22.   information run "cmake --help-policy CMP0000".
  23. This warning is for project developers.  Use -Wno-dev to suppress it.
  24.  
  25. -- Configuring incomplete, errors occurred!
  26. alex@MaD-pc:~/phonon/phonon-mplayer$
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Thx again.