Phonon/Environment Variables

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Load a specific backend. The backend name must be the backend plugin name without file extension. For example "phonon_vlc" for the VLC backend. Mind that the backend must be in the Phonon or Qt plugin path.


Set to a value between 0 and 5 to define verbosity of debug output.

PHONON_PAINT (QML Branch only)

Set to change painting method of VideoGraphicsObject and QML VideoOutput. Can be:

  • qpainter to force QPainter (will create an RGB32 QImage)
  • Only working when a QGLContext is present (i.e. the output/object is in a QGraphicsView with QGLWidget viewport)
    • glsl for GLSL shader painting
    • glarb for GLARB shader painting
    • qglcontext to force painting via context builtin functions (will create an RGB32 QImage)


Set to the full path of a platform plugin to make it preferred choice over autodetected plugins.


Set to a value between 0 and 5 to define verbosity of PulseAudio debug output.


Set to any number to deactivate PulseAudio integration completely. This can also be implicitly achieved by setting QT_NO_GLIB to 1.


Set to value between 0 and 5 to define the verbosity of debug output from the backend itself.


This value is passed to the backend's underlying library or framework's debugging system, such as via gst_init() or libvlc_new(). The value's interpretation depends on that particular library.

Phonon GStreamer


Set to C integer boolean to allow listing of all effect plugins known to GStreamer.


Set to a valid GStreamer audiosink name to force a specific sink (ignored when PulseAudio support is active)


Set to anything to activate display of frames per second. This only works with videomode software.


Forces a painting method on the GStreamer VideoWidget. Can be:

  • opengl only if built with OpenGL support
  • software paint using QPainter and intermediate creation of a QImage
  • xwindow only available on X11, uses X11 overlay painting


Activates OpenMAX support on Tegra graphics setups. This only works with xwindow videomode.

Phonon VLC