Created attachment 244653 [details] [review]
videomixer2: Protect flush_stop_pending with the collectpad stream lock

And make sure to expect a flush-stop after a flush-start

Created attachment 244654 [details] [review]
videomixer: Do not send flush_stop when receiving a seek

There is no reason to send a flush-stop when receiving a seek event.
In the case of a flushing seek, we could eventually want to, but in
the code path were we check if the seek is "flushing", we have the
following comment that makes sense:

"we can't send FLUSH_STOP here since upstream could start pushing data
after we unlock mix->collect.
We set flush_stop_pending to TRUE instead and send FLUSH_STOP after
forwarding the seek upstream or from gst_videomixer_collected,
whichever happens first."

Created attachment 244656 [details] [review]
videomixer: Send caps event from the streaming thread

This way we avoid races in caps negotiation and we make sure
that the caps are sent after stream-start.

Created attachment 244657 [details] [review]
videomixer: Send a reconfigure event upstream if sinkpad caps are not usable

Created attachment 244658 [details] [review]
tests: Re-enable videomixer test

This is a dup of https://bugzilla.gnome.org/show_bug.cgi?id=684237

After some testing, it seems better, though I still get the following pipeline to fail from time to time:

gst-launch-1.0 videotestsrc num-buffers=1 ! mix. videotestsrc num-buffers=1 ! alpha alpha=0.5 ! mix. videotestsrc num-buffers=1 ! mix. videomixer name=mix ! videoconvert ! xvimagesink

So I'm wondering if the re-enabled test won't fail also from time to time.

I have been running (In reply to comment #6)
> This is a dup of https://bugzilla.gnome.org/show_bug.cgi?id=684237

Sorry for the duplication, I didn't search properly before posting. I properly state that bug as a duplicate of the otherone, do I need to copy the patches there?
 
> After some testing, it seems better, though I still get the following pipeline
> to fail from time to time:
> 
> gst-launch-1.0 videotestsrc num-buffers=1 ! mix. videotestsrc num-buffers=1 !
> alpha alpha=0.5 ! mix. videotestsrc num-buffers=1 ! mix. videomixer name=mix !
> videoconvert ! xvimagesink

running

    while gst-launch-1.0 videotestsrc num-buffers=1 ! mix. videotestsrc \
    num-buffers=1 ! alpha alpha=0.5 ! mix. videotestsrc num-buffers=1 ! mix.\
    videomixer name=mix ! videoconvert ! xvimagesink; do echo "hey"; done

never fails here, could you please send a full debug log to see where it fails

> So I'm wondering if the re-enabled test won't fail also from time to time.

I have been running the test with .forever for +30mins without any failure.

*** This bug has been marked as a duplicate of bug 684237 ***