Audio Backends

Quod Libet currently supports GStreamer and Xine as an audio backend. The default backend can be changed in ~/.quodlibet/config by setting the backend option (gstbe = GStreamer, xinebe = Xine, nullbe = no backend). Make sure Quod Libet isn’t running while you edit the file.

There is also an experimental Mac OS X NSSound backend (macbe) available in the issue tracker.

GStreamer Backend

Custom Pipelines

It’s possible to attach a custom GStreamer pipeline to the player backend under MusicPreferencesPlaybackOutput Pipeline. The pipeline syntax is equivalent to what is used in the gst-launch utility. See man gst-launch for further information and examples.

In case the custom pipline doesn’t contain an audio sink, Quod Libet will add a default one for you.

Debugging Pipelines

In case you are interested in which GStreamer elements and audio formats are used in the current pipeline, start Quod Libet in debug mode (quodlibet --debug), go to MusicPreferencesPlayback and press the Print Pipeline button. It will print the whole pipeline used for the current active song to stdout.

For debugging GStreamer related issues see the official GStreamer docs: Running and debugging GStreamer Applications

Gapless Playback

Gstreamer supports gapless playback for all common formats except MP3. See the following bug report for more information: https://bugzilla.gnome.org/show_bug.cgi?id=620323

Selecting an Output Device

If you want QL to output to a different device you have to pass the device option to the sink by setting a custom pipeline. In case of alsa you can get a list of available devices by executing:

python -c 'import gst; sink = gst.element_factory_make("alsasink");sink.probe_property_name("device"); print "\n".join(sink.probe_get_values_name("device"))'

which should give you something like:

hw:0,0
hw:0,1
hw:2,0

and a pipeline using hw:2,0 looks like:

alsasink device=hw:2,0

And similar for pulseaudio:

python -c 'import gst; sink = gst.element_factory_make("pulsesink");sink.probe_property_name("device"); print "\n".join(sink.probe_get_values_name("device"))'

which outputs something like:

alsa_output.pci-0000_00_1b.0.analog-stereo

and the pipeline should look like:

pulsesink device=alsa_output.pci-0000_00_1b.0.analog-stereo

Xine Backend

The Xine backend needs either xine-lib 1.1.x or xine-lib 1.2.x. Since most distributions make QL only depend on GStreamer, you might have to install xine-lib manually (libxine1, lixine2 in Debian/Ubuntu).

To enable the backend, set the backend option in the config file to "xinebe" while QL isn’t running.