Bad error message?

[Russel Winder]

In an application using gtkglsink I just got the error message:


ERROR:gtkgstglwidget.c:432:_get_gl_context: code should not be reached

which is fairly frightening

On using GST_DEBUG=3 the real message arrives:


gtkgstglwidget.c:430:_get_gl_context:<GtkGstGlwidget@0xf7a2eo> Error creating GdkGLContext : Unable to create a GL context

So my point is that the original message is a problem, the message
above is what should have been issued in the first place. Is this bug
report type stuff?


The question arises of course why no GL context could be created, this
is a ThinkPad T500 running integrated (Intel) graphics with the Intel
driver. It runs other GL stuff just fine.

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[Sebastian Dröge-3]

On Sa, 2016-03-19 at 09:07 +0000, Russel Winder wrote:

> In an application using gtkglsink I just got the error message:
>
>
> ERROR:gtkgstglwidget.c:432:_get_gl_context: code should not be
> reached
>
> which is fairly frightening
>
> On using GST_DEBUG=3 the real message arrives:
>
> gtkgstglwidget.c:430:_get_gl_context:<GtkGstGlwidget@0xf7a2eo> Error
> creating GdkGLContext : Unable to create a GL context

The first one is an assertion. Basically the problem here is that your
GTK seems broken: gtk_gl_area_get_context() returns NULL.

If you enable debug logs, you should also see another error right
before that. Something like "Error creating GdkGLContext".


Instead of an assertion it would of course be better to gracefully
error out, but it seems like running into this code didn't even seem
possible during implementation. If you have a GtkGLArea widget, it
should be able to give you its OpenGL context.

> So my point is that the original message is a problem, the message
> above is what should have been issued in the first place. Is this bug
> report type stuff?

Yes, please report this together with at least a debug log with
GST_DEBUG=6 and ideally also a small application that causes the
problem for you. Does it work for you with the example gtkglsink
applications?

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Sebastian Dröge, Centricular Ltd · http://www.centricular.com


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[Russel Winder]

On Sat, 2016-03-19 at 11:32 +0200, Sebastian Dröge wrote:
> […]
> The first one is an assertion. Basically the problem here is that
> your
> GTK seems broken: gtk_gl_area_get_context() returns NULL.

Turns out I was running on Wayland when I thought I was running on
XOrg. It is still a bug though.

> If you enable debug logs, you should also see another error right
> before that. Something like "Error creating GdkGLContext".

Exactly what I got with GST_DEBUG=3.

> Instead of an assertion it would of course be better to gracefully
> error out, but it seems like running into this code didn't even seem
> possible during implementation. If you have a GtkGLArea widget, it
> should be able to give you its OpenGL context.

I guess my position is that any system in production that generates an
assertion fail to the user is "broken": production installations should
always fail gracefully. Hence my confidence this is a big of some sort
in GStreamer even if the causation is a bug outside GStreamer.

> Yes, please report this together with at least a debug log with
> GST_DEBUG=6 and ideally also a small application that causes the
> problem for you. Does it work for you with the example gtkglsink
> applications?

Wilco.

I will make sure I try stuff before reporting in so as to give as full
a report as possible.

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[Sebastian Dröge-3]

On Sa, 2016-03-19 at 10:08 +0000, Russel Winder wrote:
> 
> > If you enable debug logs, you should also see another error right
> > before that. Something like "Error creating GdkGLContext".
> Exactly what I got with GST_DEBUG=3.

What did it say after that in the same line? There should be the error
message from GDK. Why it actually failed.

> > Instead of an assertion it would of course be better to gracefully
> > error out, but it seems like running into this code didn't even seem
> > possible during implementation. If you have a GtkGLArea widget, it
> > should be able to give you its OpenGL context.
> I guess my position is that any system in production that generates an
> assertion fail to the user is "broken": production installations should
> always fail gracefully. Hence my confidence this is a big of some sort
> in GStreamer even if the causation is a bug outside GStreamer.

Yes, it should be handled more gracefully in GStreamer... and GTK/GDK
should already fail much earlier too instead of providing a useless
GtkGLArea. Do other GtkGLArea based applications work btw?

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Sebastian Dröge, Centricular Ltd · http://www.centricular.com


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