(gdb) bt
#0  0x00007ffff13193af in mlt_consumer_stop () from /usr/lib/libmlt.so.6
#1  0x00007ffff742a62e in synfig::SoundProcessor::set_playing(bool) () from /usr/lib/libsynfig.so.0
#2  0x00000000007b972e in studio::CanvasView::stop_async() ()
#3  0x00007ffff5bd48c8 in Glib::SignalProxyNormal::slot0_void_callback(_GObject*, void*) () from /usr/lib/libglibmm-2.4.so.1
#4  0x00007ffff45eb015 in g_closure_invoke () from /usr/lib/libgobject-2.0.so.0
#5  0x00007ffff45fd304 in ?? () from /usr/lib/libgobject-2.0.so.0
#6  0x00007ffff4605dfc in g_signal_emit_valist () from /usr/lib/libgobject-2.0.so.0
#7  0x00007ffff460612f in g_signal_emit () from /usr/lib/libgobject-2.0.so.0
#8  0x00007ffff53765bd in ?? () from /usr/lib/libgtk-3.so.0
#9  0x00007ffff5376625 in ?? () from /usr/lib/libgtk-3.so.0
#10 0x00007ffff45eb015 in g_closure_invoke () from /usr/lib/libgobject-2.0.so.0
#11 0x00007ffff45fcb9c in ?? () from /usr/lib/libgobject-2.0.so.0
#12 0x00007ffff4605dfc in g_signal_emit_valist () from /usr/lib/libgobject-2.0.so.0
#13 0x00007ffff460612f in g_signal_emit () from /usr/lib/libgobject-2.0.so.0
#14 0x00007ffff53746b0 in ?? () from /usr/lib/libgtk-3.so.0
#15 0x00007fffecb761f0 in ffi_call_unix64 () from /usr/lib/libffi.so.6
#16 0x00007fffecb75c58 in ffi_call () from /usr/lib/libffi.so.6
#17 0x00007ffff45ebd65 in g_cclosure_marshal_generic_va () from /usr/lib/libgobject-2.0.so.0
#18 0x00007ffff45eb244 in ?? () from /usr/lib/libgobject-2.0.so.0
#19 0x00007ffff4605a46 in g_signal_emit_valist () from /usr/lib/libgobject-2.0.so.0
#20 0x00007ffff460612f in g_signal_emit () from /usr/lib/libgobject-2.0.so.0
#21 0x00007ffff5422961 in ?? () from /usr/lib/libgtk-3.so.0
#22 0x00007ffff45ede2e in g_cclosure_marshal_VOID__BOXEDv () from /usr/lib/libgobject-2.0.so.0
#23 0x00007ffff45eb244 in ?? () from /usr/lib/libgobject-2.0.so.0
#24 0x00007ffff4605a46 in g_signal_emit_valist () from /usr/lib/libgobject-2.0.so.0
#25 0x00007ffff460612f in g_signal_emit () from /usr/lib/libgobject-2.0.so.0
#26 0x00007ffff541fcbe in ?? () from /usr/lib/libgtk-3.so.0
#27 0x00007ffff54212e3 in ?? () from /usr/lib/libgtk-3.so.0
#28 0x00007ffff5423eb5 in ?? () from /usr/lib/libgtk-3.so.0
#29 0x00007ffff53f3b8b in gtk_event_controller_handle_event () from /usr/lib/libgtk-3.so.0
#30 0x00007ffff55a44ab in ?? () from /usr/lib/libgtk-3.so.0
#31 0x00007ffff5468f5a in ?? () from /usr/lib/libgtk-3.so.0
#32 0x00007ffff45eb244 in ?? () from /usr/lib/libgobject-2.0.so.0
#33 0x00007ffff4605558 in g_signal_emit_valist () from /usr/lib/libgobject-2.0.so.0
#34 0x00007ffff460612f in g_signal_emit () from /usr/lib/libgobject-2.0.so.0
#35 0x00007ffff55a64ec in ?? () from /usr/lib/libgtk-3.so.0
#36 0x00007ffff54662ce in ?? () from /usr/lib/libgtk-3.so.0
#37 0x00007ffff546807c in gtk_main_do_event () from /usr/lib/libgtk-3.so.0
#38 0x00007ffff4fe1a72 in ?? () from /usr/lib/libgdk-3.so.0
#39 0x00007ffff4316dc7 in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#40 0x00007ffff4317020 in ?? () from /usr/lib/libglib-2.0.so.0
#41 0x00007ffff4317342 in g_main_loop_run () from /usr/lib/libglib-2.0.so.0
#42 0x00007ffff54672a5 in gtk_main () from /usr/lib/libgtk-3.so.0
#43 0x00000000004e5d50 in main ()