hyades@hyades-Inspiron-N5010:~/gst/master/gstreamer/tools/.libs$ gdb gst-switch-ui
GNU gdb (GDB) 7.5-ubuntu
Copyright (C) 2012 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from /home/hyades/gst/master/gstreamer/tools/.libs/gst-switch-ui...(no debugging symbols found)...done.
(gdb) r
Starting program: /home/hyades/gst/master/gstreamer/tools/.libs/gst-switch-ui
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Gtk-Message: Failed to load module "overlay-scrollbar"
[New Thread 0x7fffed423700 (LWP 11234)]
./tools/gstvideodisp.c:144:info: display video 3001
[New Thread 0x7fffe6932700 (LWP 11236)]
./tools/gstswitchui.c:446:info: Encoded output port: 3002
[New Thread 0x7fffe6131700 (LWP 11237)]
[New Thread 0x7fffe5723700 (LWP 11238)]

(gst-switch-ui:11231): GStreamer-WARNING **: gstpad.c:4503:store_sticky_event:<gdpdepay0:src> Sticky event misordering, got 'segment' before 'caps'

(gst-switch-ui:11231): GStreamer-WARNING **: gstpad.c:4503:store_sticky_event:<videoconvert0:src> Sticky event misordering, got 'segment' before 'caps'

(gst-switch-ui:11231): GStreamer-WARNING **: gstpad.c:4503:store_sticky_event:<overlay:src> Sticky event misordering, got 'segment' before 'caps'

(gst-switch-ui:11231): GStreamer-WARNING **: gstpad.c:4503:store_sticky_event:<videoconvert1:src> Sticky event misordering, got 'segment' before 'caps'

(gst-switch-ui:11231): GStreamer-WARNING **: gstpad.c:4503:store_sticky_event:<sink:sink> Sticky event misordering, got 'segment' before 'caps'

(gst-switch-ui:11231): GStreamer-WARNING **: gstpad.c:4503:store_sticky_event:<videoconvert1:sink> Sticky event misordering, got 'segment' before 'caps'

(gst-switch-ui:11231): GStreamer-WARNING **: gstpad.c:4503:store_sticky_event:<overlay:sink> Sticky event misordering, got 'segment' before 'caps'

(gst-switch-ui:11231): GStreamer-WARNING **: gstpad.c:4503:store_sticky_event:<videoconvert0:sink> Sticky event misordering, got 'segment' before 'caps'

(gst-switch-ui:11231): GStreamer-WARNING **: gstpad.c:3908:gst_pad_push_data:<gdpdepay0:src> Got data flow before stream-start event

(gst-switch-ui:11231): GStreamer-WARNING **: gstpad.c:3677:gst_pad_chain_data_unchecked:<videoconvert0:sink> Got data flow before stream-start event

(gst-switch-ui:11231): GStreamer-WARNING **: gstpad.c:3908:gst_pad_push_data:<videoconvert0:src> Got data flow before stream-start event

(gst-switch-ui:11231): GStreamer-WARNING **: gstpad.c:3677:gst_pad_chain_data_unchecked:<overlay:sink> Got data flow before stream-start event

(gst-switch-ui:11231): GStreamer-WARNING **: gstpad.c:3908:gst_pad_push_data:<overlay:src> Got data flow before stream-start event

(gst-switch-ui:11231): GStreamer-WARNING **: gstpad.c:3677:gst_pad_chain_data_unchecked:<videoconvert1:sink> Got data flow before stream-start event

(gst-switch-ui:11231): GStreamer-WARNING **: gstpad.c:3908:gst_pad_push_data:<videoconvert1:src> Got data flow before stream-start event

(gst-switch-ui:11231): GStreamer-WARNING **: gstpad.c:3677:gst_pad_chain_data_unchecked:<sink:sink> Got data flow before stream-start event
./tools/gstaudiovisual.c:76:info: init 0x7890a0
./tools/gstaudiovisual.c:237:info: display audio 3003
0:00:10.006664508 11231       0x6b3470 ERROR           GST_PIPELINE ./grammar.y:670:priv_gst_parse_yyparse: no element "monoscope"
./tools/gstaudiovisual.c:221:error: missing element: monoscope
./tools/gstaudiovisual.c:221:error: missing element: (null)

Program received signal SIGSEGV, Segmentation fault.
0x00007ffff5ae03b1 in vfprintf () from /lib/x86_64-linux-gnu/libc.so.6
(gdb) bt
#0  0x00007ffff5ae03b1 in vfprintf () from /lib/x86_64-linux-gnu/libc.so.6
#1  0x00007ffff5b9f1e1 in __vasprintf_chk ()
   from /lib/x86_64-linux-gnu/libc.so.6
#2  0x00007ffff60f8deb in vasprintf (__ap=<optimized out>,
    __fmt=<optimized out>, __ptr=0x7fffffffdab8)
    at /usr/include/x86_64-linux-gnu/bits/stdio2.h:199
#3  g_vasprintf (string=string@entry=0x7fffffffdab8, format=<optimized out>,
    args=args@entry=0x7fffffffdad8)
    at /build/buildd/glib2.0-2.36.0/./glib/gprintf.c:314
#4  0x00007ffff60d692d in g_strdup_vprintf (format=<optimized out>,
    args=args@entry=0x7fffffffdad8)
    at /build/buildd/glib2.0-2.36.0/./glib/gstrfuncs.c:517
#5  0x00007ffff60c1b74 in g_print (format=<optimized out>)
    at /build/buildd/glib2.0-2.36.0/./glib/gmessages.c:1434
#6  0x000000000040f68d in gst_audio_visual_missing ()
#7  0x0000000000405adb in gst_worker_create_pipeline ()
#8  0x0000000000407b65 in gst_worker_prepare_unsafe ()
#9  0x0000000000407fb4 in gst_worker_prepare ()
#10 0x0000000000405f84 in gst_worker_start ()
#11 0x000000000040ad7b in gst_switch_ui_new_audio_visual_unsafe ()
#12 0x000000000040ae44 in gst_switch_ui_new_audio_visual ()
#13 0x000000000040c973 in gst_switch_ui_add_preview_port ()
#14 0x00000000004128d2 in gst_switch_client_add_preview_port ()