gstreamer-properties incorrectly claims that esdsink doesn't work when a
user tries to test it after setting the default output sink to esdsink. 
Despite this claim, if esd is active the sink may be working anyway.

This is because esdsink can't play sinesrc directly, unlike other output
sinks.  I.e., gst-launch sinesrc ! esdsink fails.  Audioconversion is
necessary first.

The correct test pipeline to use would involve using the spider plugin to
hook together the sources and sinks, to automatically take care of such
problems.  sinesrc ! spider ! esdsink works, as does any other sink.

Line 34 of gstreamer-properties/pipeline-constants.c should be changed to read:
static gchar audiosink_test_pipe[] = "sinesrc freq=512 ! spider";