Signal Callbacks never being called on webrtcbin

Ashwin Dharne ashwindharne at dm.ai
Thu Aug 2 05:08:30 UTC 2018


I backtraced in gdb and got this:

Thread 3 "gst-pc-ops" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7fffe65e2700 (LWP 23189)]
_find_pad_template (element=0x0, direction=direction at entry=GST_PAD_SINK,
presence=presence at entry=GST_PAD_REQUEST, name=name at entry=0x7ffff0954e4b
"rtp_sink_%d")
    at ../subprojects/gst-plugins-bad/ext/webrtc/utils.c:32
32   const GList *l = gst_element_class_get_pad_template_list
(element_class);
(gdb) bt
#0  0x00007ffff095017e in _find_pad_template (element=0x0,
direction=direction at entry=GST_PAD_SINK,
presence=presence at entry=GST_PAD_REQUEST,
name=name at entry=0x7ffff0954e4b "rtp_sink_%d")
    at ../subprojects/gst-plugins-bad/ext/webrtc/utils.c:32
#1  0x00007ffff094f3ec in transport_send_bin_constructed
(object=0x7fffe001a0c0) at
../subprojects/gst-plugins-bad/ext/webrtc/transportsendbin.c:412
#2  0x00007ffff37ff760 in  () at
/usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#3  0x00007ffff3801420 in g_object_new_valist () at
/usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#4  0x00007ffff3801799 in g_object_new () at
/usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#5  0x00007ffff0950087 in transport_stream_constructed
(object=0x7fffe0005800) at
../subprojects/gst-plugins-bad/ext/webrtc/transportstream.c:177
#6  0x00007ffff37ff760 in  () at
/usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#7  0x00007ffff3801420 in g_object_new_valist () at
/usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#8  0x00007ffff3801799 in g_object_new () at
/usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#9  0x00007ffff0950167 in transport_stream_new (webrtc=<optimized out>,
session_id=<optimized out>) at
../subprojects/gst-plugins-bad/ext/webrtc/transportstream.c:248
#10 0x00007ffff09455d5 in _create_transport_channel
(webrtc=webrtc at entry=0xfa40f0,
session_id=session_id at entry=0) at
../subprojects/gst-plugins-bad/ext/webrtc/gstwebrtcbin.c:1367
#11 0x00007ffff094973c in sdp_media_from_transceiver
(type=GST_WEBRTC_SDP_TYPE_OFFER, media_idx=0, trans=<optimized out>,
media=0x7fffe65e1d00, webrtc=0xfa40f0)
    at ../subprojects/gst-plugins-bad/ext/webrtc/gstwebrtcbin.c:1742
#12 0x00007ffff094973c in _create_offer_task (options=<optimized out>,
webrtc=0xfa40f0) at
../subprojects/gst-plugins-bad/ext/webrtc/gstwebrtcbin.c:1811
#13 0x00007ffff094973c in _create_sdp_task (webrtc=0xfa40f0,
data=0x7fffe00072f0) at
../subprojects/gst-plugins-bad/ext/webrtc/gstwebrtcbin.c:2205
#14 0x00007ffff09444df in _execute_op (op=0x7fffe0007310) at
../subprojects/gst-plugins-bad/ext/webrtc/gstwebrtcbin.c:634
#15 0x00007ffff35200f5 in g_main_context_dispatch () at
/usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#16 0x00007ffff35204c0 in  () at /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#17 0x00007ffff35207d2 in g_main_loop_run () at
/usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#18 0x00007ffff09445fa in _gst_pc_thread (webrtc=0xfa40f0) at
../subprojects/gst-plugins-bad/ext/webrtc/gstwebrtcbin.c:585
#19 0x00007ffff3547e05 in  () at /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#20 0x00007ffff7bbd6db in start_thread (arg=0x7fffe65e2700) at
pthread_create.c:463
#21 0x00007ffff6cf288f in clone () at
../sysdeps/unix/sysv/linux/x86_64/clone.S:95

I'm not sure how to interpret this, is 'element' in _find_pad_template the
culprit? I'm not ver y familiar with gstreamer's internals so I'm unsure
what that entails or how to fix it.

On Wed, Aug 1, 2018 at 2:21 PM Nicolas Dufresne <nicolas at ndufresne.ca>
wrote:

> Le mercredi 01 août 2018 à 12:31 -0700, Ashwin Dharne a écrit :
> > I figured out that error and managed to install everything correctly,
> > but for some reason when running I run into the errors:
> >
> > sys:1: Warning: g_object_set: assertion 'G_IS_OBJECT (object)' failed
> > sys:1: Warning: invalid (NULL) pointer instance
> > sys:1: Warning: g_signal_connect_data: assertion
> > 'G_TYPE_CHECK_INSTANCE (instance)' failed
> >
> > (python3:8091): GStreamer-CRITICAL **: 12:28:52.849: gst_bin_add:
> > assertion 'GST_IS_ELEMENT (element)' failed
> >
> > (python3:8091): GStreamer-CRITICAL **: 12:28:52.849:
> > gst_element_link_pads_full: assertion 'GST_IS_ELEMENT (src)' failed
> >
> > ** (python3:8091): WARNING **: 12:28:52.849:
> > (transportsendbin.c:387):tsb_setup_ctx: code should not be reached
> > Segmentation fault (core dumped)
> >
> > I'm not sure what's wrong anymore, I've only gotten a similar error
> > on my own client before that wasn't working and I assumed it was a
> > dependency error.
>
> You have a NULL pointer somewhere. Try and set G_DEBUG=fatal_criticals
> and then run this inside gdb to locate where this null pointer is from.
>
> >
> >
> > On Tue, Jul 31, 2018 at 9:00 PM Ashwin Dharne <ashwindharne at dm.ai>
> > wrote:
> > > I see. On a different note, I am now attempting to run the cerbero
> > > build tool to automate the dependency building, but am getting the
> > > error GstWebRTC Namespace not available, could you possibly shed
> > > any light on what the issue might be? I understand that it relates
> > > to the .typelib file not being in the girepository-1.0 directory,
> > > but for some reason it doesn't get built there. Thanks!
> > >
> > > On Tue, Jul 31, 2018 at 11:05 AM Mathieu Duponchelle <
> > > mathieu at centricular.com> wrote:
> > > > On 07/31/2018 07:54 PM, Ashwin Dharne wrote:
> > > > > Also, I'm trying to follow the python demo given, but I'm not
> > > > seeing a statement that runs the mainloop anywhere, am I missing
> > > > something?
> > > > >
> > > >
> > > > It does not use a GMainLoop, but the asyncio event loop.
> > > > _______________________________________________
> > > > gstreamer-devel mailing list
> > > > gstreamer-devel at lists.freedesktop.org
> > > > https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel
> > >
> > >
> > > --
> > > Ashwin Dharne
> > > Software Engineer, DMAI Inc.
> > > (949)878-7682
> >
> >
> > _______________________________________________
> > gstreamer-devel mailing list
> > gstreamer-devel at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel
>
> _______________________________________________
> gstreamer-devel mailing list
> gstreamer-devel at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/gstreamer-devel
>


-- 
*Ashwin Dharne*
Software Engineer, DMAI Inc.
(949)878-7682
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