Thanks for the reply Jiri. The short story is that with your suggestions from above I was able to solve the problem - I was missing the gstreamer "ugly" plugin.

So thanks for the help! (The long version is below if you're interested...)



I can't find a way to confirm 100% that I have libwebkitgtk3 installed but all libwebkit*.so files on my machine are libwebkit*-3.0.so files. So, I assume I do. Here's the output from the first command:

----------------------

typefindfunctions: application/x-id3v2: mp3, mp2, mp1, mpga, ogg, flac, tta
typefindfunctions: application/x-id3v1: mp3, mp2, mp1, mpga, ogg, flac, tta
typefindfunctions: application/x-apetag: mp3, ape, mpc, wv
typefindfunctions: audio/mpeg: mp3, mp2, mp1, mpga

----------------------

And here's the output from the other command:


----------------------
0:00:00.005392923  7991      0x1fc7430 INFO      GST_PLUGIN_LOADING gstplugin.c:317:_priv_gst_plugin_initialize: registering 0 static plugins
0:00:00.005671288  7991      0x1fc7430 INFO      GST_PLUGIN_LOADING gstplugin.c:225:gst_plugin_register_static: registered static plugin "staticelements"
0:00:00.005697133  7991      0x1fc7430 INFO      GST_PLUGIN_LOADING gstplugin.c:227:gst_plugin_register_static: added static plugin "staticelements", result: 1
0:00:00.014712123  7991      0x1fc7430 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstplayback.so" loaded
0:00:00.014773359  7991      0x1fc7430 INFO     GST_ELEMENT_FACTORY gstelementfactory.c:365:gst_element_factory_create: creating element "playbin"
Setting pipeline to PAUSED ...
0:00:00.015977969  7991      0x1fc7430 INFO     GST_ELEMENT_FACTORY gstelementfactory.c:365:gst_element_factory_create: creating element "uridecodebin"
0:00:00.016969931  7991      0x1fc7430 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstcoreelements.so" loaded
0:00:00.017016176  7991      0x1fc7430 INFO     GST_ELEMENT_FACTORY gstelementfactory.c:363:gst_element_factory_create: creating element "filesrc" named "source"
0:00:00.017332710  7991      0x1fc7430 INFO     GST_ELEMENT_FACTORY gstelementfactory.c:365:gst_element_factory_create: creating element "decodebin"
0:00:00.017583077  7991      0x1fc7430 INFO     GST_ELEMENT_FACTORY gstelementfactory.c:363:gst_element_factory_create: creating element "typefind" named "typefind"
Pipeline is PREROLLING ...
0:00:00.022362387  7991      0x205c540 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgsttypefindfunctions.so" loaded
0:00:00.023240634  7991      0x205c540 WARN            uridecodebin gsturidecodebin.c:880:unknown_type_cb:<uridecodebin0> warning: No decoder available for type 'application/x-id3'.
Missing element: ID3 tag demuxer
0:00:00.023373606  7991      0x205c540 WARN               decodebin gstdecodebin2.c:3703:gst_decode_bin_expose:<decodebin0> No suitable plugins found
WARNING: from element /GstPlayBin:playbin0/GstURIDecodeBin:uridecodebin0: No decoder available for type 'application/x-id3'.
0:00:00.023443394  7991      0x205c540 WARN               decodebin gstdecodebin2.c:3705:gst_decode_bin_expose:<decodebin0> error: no suitable plugins found
Additional debug info:
gsturidecodebin.c(880): unknown_type_cb (): /GstPlayBin:playbin0/GstURIDecodeBin:uridecodebin0
ERROR: from element /GstPlayBin:playbin0/GstURIDecodeBin:uridecodebin0/GstDecodeBin:decodebin0: Your GStreamer installation is missing a plug-in.
Additional debug info:
gstdecodebin2.c(3705): gst_decode_bin_expose (): /GstPlayBin:playbin0/GstURIDecodeBin:uridecodebin0/GstDecodeBin:decodebin0:
no suitable plugins found
ERROR: pipeline doesn't want to preroll.
Setting pipeline to NULL ...
0:00:00.023606521  7991      0x205c540 WARN               decodebin gstdecodebin2.c:1731:analyze_new_pad:<decodebin0> error: A ID3 tag demuxer plugin is required to play this stream, but not installed.
0:00:00.023760285  7991      0x205c540 WARN               decodebin gstdecodebin2.c:1731:analyze_new_pad:<decodebin0> error: No decoder to handle media type 'application/x-id3'
Freeing pipeline ...
--------------------


So...


I installed the gst-plugins-base and gst-plugins-good packages for Arch and this enabled me to get further:



--------------------
0:00:00.001919494 12666       0xa51430 INFO      GST_PLUGIN_LOADING gstplugin.c:317:_priv_gst_plugin_initialize: registering 0 static plugins
0:00:00.002027585 12666       0xa51430 INFO      GST_PLUGIN_LOADING gstplugin.c:225:gst_plugin_register_static: registered static plugin "staticelements"
0:00:00.002042434 12666       0xa51430 INFO      GST_PLUGIN_LOADING gstplugin.c:227:gst_plugin_register_static: added static plugin "staticelements", result: 1
0:00:00.001883157 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:317:_priv_gst_plugin_initialize: registering 0 static plugins
0:00:00.002010445 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:225:gst_plugin_register_static: registered static plugin "staticelements"
0:00:00.002028125 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:227:gst_plugin_register_static: added static plugin "staticelements", result: 1
0:00:00.004184700 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstisomp4.so" loaded
0:00:00.004669301 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstspeex.so" loaded
0:00:00.004924947 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstgoom2k1.so" loaded
0:00:00.005149196 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgsticydemux.so" loaded
0:00:00.006972885 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstsouphttpsrc.so" loaded
0:00:00.007171572 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgsty4menc.so" loaded
0:00:00.008922774 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstpulse.so" loaded
0:00:00.009866728 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgsteffectv.so" loaded
0:00:00.011163480 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgst1394.so" loaded
0:00:00.011771747 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstrtsp.so" loaded
0:00:00.012940000 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstavi.so" loaded
0:00:00.013396898 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstwavpack.so" loaded
0:00:00.013805930 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstjack.so" loaded
0:00:00.014054385 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstmultipart.so" loaded
0:00:00.014382920 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstinterleave.so" loaded
0:00:00.014648174 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstossaudio.so" loaded
0:00:00.017975355 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstrtp.so" loaded
0:00:00.019195430 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstximagesrc.so" loaded
0:00:00.019428225 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstimagefreeze.so" loaded
0:00:00.021116138 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstshout2.so" loaded
0:00:00.021387144 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstmulaw.so" loaded
0:00:00.021818532 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstsmpte.so" loaded
0:00:00.022132587 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstequalizer.so" loaded
0:00:00.022852134 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstgdkpixbuf.so" loaded
0:00:00.023095651 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstlevel.so" loaded
0:00:00.023513402 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstflac.so" loaded
0:00:00.023783226 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstshapewipe.so" loaded
0:00:00.024017672 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstwavenc.so" loaded
0:00:00.024320441 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstpng.so" loaded
0:00:00.024763532 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstflv.so" loaded
0:00:00.025364509 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstcacasink.so" loaded
0:00:00.025695640 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstmultifile.so" loaded
0:00:00.026172661 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstvpx.so" loaded
0:00:00.026596742 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstreplaygain.so" loaded
0:00:00.027062726 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstoss4audio.so" loaded
0:00:00.027527352 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstdebug.so" loaded
0:00:00.027824064 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstvideobox.so" loaded
0:00:00.030452714 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgsttaglib.so" loaded
0:00:00.030714041 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstalphacolor.so" loaded
0:00:00.031170593 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstudp.so" loaded
0:00:00.033195151 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstvideo4linux2.so" loaded
0:00:00.033802668 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstwavparse.so" loaded
0:00:00.035018408 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstmatroska.so" loaded
0:00:00.035460137 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstspectrum.so" loaded
0:00:00.035764518 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstapetag.so" loaded
0:00:00.036237197 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstjpeg.so" loaded
0:00:00.036507720 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstnavigationtest.so" loaded
0:00:00.036839640 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstalaw.so" loaded
0:00:00.038059999 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstdeinterlace.so" loaded
0:00:00.039102389 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstrtpmanager.so" loaded
0:00:00.039433181 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstflxdec.so" loaded
0:00:00.039869994 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstvideocrop.so" loaded
0:00:00.040145107 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstmonoscope.so" loaded
0:00:00.040438464 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstcutter.so" loaded
0:00:00.040754483 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstalpha.so" loaded
0:00:00.041834056 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstaudiofx.so" loaded
0:00:00.042160199 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstautodetect.so" loaded
0:00:00.042632389 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstvideofilter.so" loaded
0:00:00.042914139 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstgoom.so" loaded
0:00:00.044665440 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstdv.so" loaded
0:00:00.045166780 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstaasink.so" loaded
0:00:00.045669028 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstaudioparsers.so" loaded
0:00:00.045888869 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstid3demux.so" loaded
0:00:00.046167053 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstvideomixer.so" loaded
0:00:00.078250536 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstcairo.so" loaded
0:00:00.081080272 12667      0x1e94e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstauparse.so" loaded
0:00:00.001873188 12668      0x1d86e30 INFO      GST_PLUGIN_LOADING gstplugin.c:317:_priv_gst_plugin_initialize: registering 0 static plugins
0:00:00.002001561 12668      0x1d86e30 INFO      GST_PLUGIN_LOADING gstplugin.c:225:gst_plugin_register_static: registered static plugin "staticelements"
0:00:00.002019280 12668      0x1d86e30 INFO      GST_PLUGIN_LOADING gstplugin.c:227:gst_plugin_register_static: added static plugin "staticelements", result: 1
0:00:00.002914388 12668      0x1d86e30 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstauparse.so" loaded
0:00:00.001829258 12669       0xed2e30 INFO      GST_PLUGIN_LOADING gstplugin.c:317:_priv_gst_plugin_initialize: registering 0 static plugins
0:00:00.001957241 12669       0xed2e30 INFO      GST_PLUGIN_LOADING gstplugin.c:225:gst_plugin_register_static: registered static plugin "staticelements"
0:00:00.001976341 12669       0xed2e30 INFO      GST_PLUGIN_LOADING gstplugin.c:227:gst_plugin_register_static: added static plugin "staticelements", result: 1
0:00:00.001831346 12670      0x1293e30 INFO      GST_PLUGIN_LOADING gstplugin.c:317:_priv_gst_plugin_initialize: registering 0 static plugins
0:00:00.001945028 12670      0x1293e30 INFO      GST_PLUGIN_LOADING gstplugin.c:225:gst_plugin_register_static: registered static plugin "staticelements"
0:00:00.001962772 12670      0x1293e30 INFO      GST_PLUGIN_LOADING gstplugin.c:227:gst_plugin_register_static: added static plugin "staticelements", result: 1
0:00:00.133313838 12666       0xa51430 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstplayback.so" loaded
0:00:00.133355207 12666       0xa51430 INFO     GST_ELEMENT_FACTORY gstelementfactory.c:365:gst_element_factory_create: creating element "playbin"
Setting pipeline to PAUSED ...
0:00:00.133855244 12666       0xa51430 INFO     GST_ELEMENT_FACTORY gstelementfactory.c:365:gst_element_factory_create: creating element "uridecodebin"
0:00:00.134259656 12666       0xa51430 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstcoreelements.so" loaded
0:00:00.134284601 12666       0xa51430 INFO     GST_ELEMENT_FACTORY gstelementfactory.c:363:gst_element_factory_create: creating element "filesrc" named "source"
0:00:00.134403652 12666       0xa51430 INFO     GST_ELEMENT_FACTORY gstelementfactory.c:365:gst_element_factory_create: creating element "decodebin"
0:00:00.134501553 12666       0xa51430 INFO     GST_ELEMENT_FACTORY gstelementfactory.c:363:gst_element_factory_create: creating element "typefind" named "typefind"
Pipeline is PREROLLING ...
0:00:00.137410821 12666       0xbba540 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgsttypefindfunctions.so" loaded
0:00:00.139049376 12666       0xbba540 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstid3demux.so" loaded
0:00:00.139065309 12666       0xbba540 INFO     GST_ELEMENT_FACTORY gstelementfactory.c:365:gst_element_factory_create: creating element "id3demux"
0:00:00.140105373 12666 0x7fd78802c0a0 WARN                   id3v2 id3v2frames.c:724:id3v2_tag_to_taglist: Ignoring invalid value for total 0 in tag track-number
0:00:00.140127424 12666 0x7fd78802c0a0 WARN                   id3v2 id3v2frames.c:724:id3v2_tag_to_taglist: Ignoring invalid value for total 0 in tag album-disc-number
0:00:00.140134671 12666 0x7fd78802c0a0 WARN                   id3v2 id3v2frames.c:742:id3v2_tag_to_taglist: Ignoring invalid value 0 in tag album-disc-number
0:00:00.141270516 12666 0x7fd78802c0a0 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstaudioparsers.so" loaded
0:00:00.141287935 12666 0x7fd78802c0a0 INFO     GST_ELEMENT_FACTORY gstelementfactory.c:365:gst_element_factory_create: creating element "mpegaudioparse"
0:00:00.143585979 12666       0xaab850 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstpulse.so" loaded
0:00:00.143615178 12666       0xaab850 INFO     GST_ELEMENT_FACTORY gstelementfactory.c:365:gst_element_factory_create: creating element "pulsesink"
0:00:00.145471951 12666       0xaab850 WARN                   pulse pulsesink.c:560:gst_pulseringbuffer_open_device:<pulsesink0> error: Failed to connect: Connection refused
0:00:00.146270410 12666       0xaab850 INFO      GST_PLUGIN_LOADING gstplugin.c:830:gst_plugin_load_file: plugin "/usr/lib/gstreamer-1.0/libgstalsa.so" loaded
0:00:00.146291362 12666       0xaab850 INFO     GST_ELEMENT_FACTORY gstelementfactory.c:365:gst_element_factory_create: creating element "alsasink"
0:00:00.151018441 12666       0xaab850 WARN                    alsa conf.c:4551:parse_args: alsalib error: Unknown parameter AES0
0:00:00.151049029 12666       0xaab850 WARN                    alsa conf.c:4711:snd_config_expand: alsalib error: Parse arguments error: No such file or directory
0:00:00.151062055 12666       0xaab850 WARN                    alsa pcm.c:2239:snd_pcm_open_noupdate: alsalib error: Unknown PCM default:{AES0 0x02 AES1 0x82 AES2 0x00 AES3 0x02}
0:00:00.151760516 12666       0xaab850 WARN            uridecodebin gsturidecodebin.c:880:unknown_type_cb:<uridecodebin0> warning: No decoder available for type 'audio/mpeg, mpegversion=(int)1, mpegaudioversion=(int)1, layer=(int)3, rate=(int)44100, channels=(int)2, parsed=(boolean)true'.
Missing element: MPEG-1 Layer 3 (MP3) decoder
0:00:00.151814915 12666       0xaab850 WARN               decodebin gstdecodebin2.c:3703:gst_decode_bin_expose:<decodebin0> No suitable plugins found
WARNING: from element /GstPlayBin:playbin0/GstURIDecodeBin:uridecodebin0: No decoder available for type 'audio/mpeg, mpegversion=(int)1, mpegaudioversion=(int)1, layer=(int)3, rate=(int)44100, channels=(int)2, parsed=(boolean)true'.
0:00:00.151835773 12666       0xaab850 WARN               decodebin gstdecodebin2.c:3705:gst_decode_bin_expose:<decodebin0> error: no suitable plugins found
Additional debug info:
gsturidecodebin.c(880): unknown_type_cb (): /GstPlayBin:playbin0/GstURIDecodeBin:uridecodebin0
0:00:00.151885950 12666       0xaab850 WARN               decodebin gstdecodebin2.c:3703:gst_decode_bin_expose:<decodebin0> No suitable plugins found
0:00:00.151904992 12666       0xaab850 WARN               decodebin gstdecodebin2.c:3705:gst_decode_bin_expose:<decodebin0> error: no suitable plugins found
ERROR: from element /GstPlayBin:playbin0/GstURIDecodeBin:uridecodebin0/GstDecodeBin:decodebin0: Your GStreamer installation is missing a plug-in.
Additional debug info:
gstdecodebin2.c(3705): gst_decode_bin_expose (): /GstPlayBin:playbin0/GstURIDecodeBin:uridecodebin0/GstDecodeBin:decodebin0:
no suitable plugins found
0:00:00.151942632 12666       0xaab850 WARN               decodebin gstdecodebin2.c:2462:pad_added_cb:<decodebin0> Couldn't expose group
ERROR: pipeline doesn't want to preroll.
Setting pipeline to NULL ...
0:00:00.152068521 12666       0xaab850 WARN               baseparse gstbaseparse.c:3038:gst_base_parse_loop:<mpegaudioparse0> error: streaming stopped, reason not-linked
Freeing pipeline ...
----------------------


And then I installed the gst-plugins-ugly package... And the mp3 played.

What's more, nuvola now works!

So all is good. Thanks for the help Jiri.