[Bug 796640] Fix for a synchronization bug in 1.14.1 ext/qt/gstqsgtexture.cc

[GStreamer (GNOME Bugzilla)]

https://bugzilla.gnome.org/show_bug.cgi?id=796640

--- Comment #7 from jimmy <jipe4153 at gmail.com> ---
(In reply to Jan Schmidt from comment #6)
> I've uploaded the patches as 2 separate plain files so they can be more
> easily reviewed.
> 
> 2 comments:
> * The git commit summary should be a single line less than 76 characters,
> then leave 1 blank line and write any commit log description that needs more
> than 76 chars.
> * 0001 contains some extra unnecessary white-space changes

Do you need me to submit a new patch with modified git commit summaries?

> 
> Does the mutex actually have any effect, or is the
> gst_gl_sync_meta_wait_cpu() call sufficient?

In my testing the gst_gl_sync_meta_wait_cpu call was sufficient (appears to be
the same as glFinish()) BUT

>From reading the comments it seemed as if the gstreamer thread calls
GstQSGTexture::setBuffer while Qt:s render thread calls on GstQSGTexture::bind,
this prompted me to add this lock.

> 
> I gather the bug you're seeing is flashing and out-of-order frames, but how
> are you reproducing it? I haven't seen such behaviour with qmlglsink myself.

Yes flashing and out-of-order frames.

The issue is clearly visible on the Tegra X2 platform (most of the time) when
running the modified qmlglsink example (moving ball pattern), it is even more
obvious when live streaming from a camera. 

Since this is timing related, it might not be visible or rarely visible on
other platforms.

I could snap a video of the issue with my cell-phone and send to you if you
really want to see it.

-- 
You are receiving this mail because:
You are the QA Contact for the bug.
You are the assignee for the bug.