GStreamer DLL loader plugin

When playing files such as the one at
<http://bugzilla.gnome.org/attachment.cgi?id=122237&action=view>, there is
an error:

GstAudioConvert: not negotiated

Hopefully the verbose output of gst-launch can help:

$ gst-launch -v playbin uri=file://$PWD/PianoDemo1.wma
Setting pipeline to PAUSED ...
/GstPlayBin:playbin0/GstDecodeBin:decodebin0/GstTypeFindElement:typefind.Gs
tPad:src: caps = video/x-ms-asf
Pipeline is PREROLLING ...
/GstPlayBin:playbin0/GstStreamSelector:selector_audio_src0: active-pad =
NULL
/GstPlayBin:playbin0/GstDecodeBin:decodebin0/GstQueue:queue0.GstPad:sink:
caps = audio/x-wma, wmaversion=(int)3, bitrate=(int)192016, depth=(int)16,
rate=(int)44100, channels=(int)2, block_align=(int)8917,
codec_data=(buffer)1000030000000000000000000000e0000000
/GstPlayBin:playbin0/GstDecodeBin:decodebin0/GstQueue:queue0.GstPad:src:
caps = audio/x-wma, wmaversion=(int)3, bitrate=(int)192016, depth=(int)16,
rate=(int)44100, channels=(int)2, block_align=(int)8917,
codec_data=(buffer)1000030000000000000000000000e0000000
/GstPlayBin:playbin0/GstDecodeBin:decodebin0/dmodec_wmadmodv3:dmodec_wmadmo
dv30.GstPad:src: caps = audio/x-raw-int, width=(int)16, depth=(int)16,
signed=(boolean)true, endianness=(int)1234, rate=(int)44100,
channels=(int)2
/GstPlayBin:playbin0/GstDecodeBin:decodebin0/dmodec_wmadmodv3:dmodec_wmadmo
dv30.GstPad:sink: caps = audio/x-wma, wmaversion=(int)3,
bitrate=(int)192016, depth=(int)16, rate=(int)44100, channels=(int)2,
block_align=(int)8917,
codec_data=(buffer)1000030000000000000000000000e0000000
/GstPlayBin:playbin0/GstStreamSelector:selector_audio_src0.GstSelectorPad:s
ink0: caps = audio/x-raw-int, width=(int)16, depth=(int)16,
signed=(boolean)true, endianness=(int)1234, rate=(int)44100,
channels=(int)2
/GstPlayBin:playbin0/GstDecodeBin:decodebin0.GstGhostPad:src0: caps =
audio/x-raw-int, width=(int)16, depth=(int)16, signed=(boolean)true,
endianness=(int)1234, rate=(int)44100, channels=(int)2
/GstPlayBin:playbin0/GstDecodeBin:decodebin0.GstGhostPad:src0.GstProxyPad:p
roxypad1: caps = audio/x-raw-int, width=(int)16, depth=(int)16,
signed=(boolean)true, endianness=(int)1234, rate=(int)44100,
channels=(int)2

(gst-launch-0.10:15417): GStreamer-WARNING **: pad dmodec_wmadmodv30:src
returned caps which are not a real subset of its template caps
ERROR: from element /GstPlayBin:playbin0/GstBin:abin/GstAudioConvert:aconv:
not negotiated
Additional debug info:
gstbasetransform.c(1826): gst_base_transform_handle_buffer ():
/GstPlayBin:playbin0/GstBin:abin/GstAudioConvert:aconv:
not negotiated
ERROR: pipeline doesn't want to preroll.
Setting pipeline to NULL ...
/GstPlayBin:playbin0/GstStreamSelector:selector_audio_src0.GstSelectorPad:s
ink0: caps = NULL
/GstPlayBin:playbin0/GstDecodeBin:decodebin0.GstGhostPad:src0: caps = NULL
/GstPlayBin:playbin0/GstDecodeBin:decodebin0/dmodec_wmadmodv3:dmodec_wmadmo
dv30.GstPad:src: caps = NULL
/GstPlayBin:playbin0/GstDecodeBin:decodebin0/dmodec_wmadmodv3:dmodec_wmadmo
dv30.GstPad:sink: caps = NULL
Total Unfree 0 bytes cnt 0 [(nil),0]
/GstPlayBin:playbin0/GstDecodeBin:decodebin0/GstQueue:queue0.GstPad:src:
caps = NULL
/GstPlayBin:playbin0/GstDecodeBin:decodebin0/GstQueue:queue0.GstPad:sink:
caps = NULL
/GstPlayBin:playbin0/GstDecodeBin:decodebin0/GstASFDemux:asfdemux0.GstPad:a
udio_00: caps = NULL
/GstPlayBin:playbin0/GstDecodeBin:decodebin0/GstTypeFindElement:typefind.Gs
tPad:src: caps = NULL
FREEING pipeline ...