[gstreamer-bugs] [Bug 574289] New: [decodebin2] race in state change to PAUSED

[GStreamer (bugzilla.gnome.org)]

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  GStreamer | gst-plugins-base | Ver: git
           Summary: [decodebin2] race in state change to PAUSED
           Product: GStreamer
           Version: git
          Platform: Other
        OS/Version: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: Normal
         Component: gst-plugins-base
        AssignedTo: gstreamer-bugs at lists.sourceforge.net
        ReportedBy: manauw at skynet.be
         QAContact: gstreamer-bugs at lists.sourceforge.net
     GNOME version: Unspecified
   GNOME milestone: Unspecified


Consider a decodebin2 (in e.g. playbin2) that is set to PAUSED and builds e.g.
a id3demux ! oggdemux ! multiqueue ! vorbisdec pipeline, then a race occurs
between mainloop and streaming thread(s).

Consider order of events:
* streaming thread(s) cause the above elements to be added, and a.o. a
decodegroup to be created
* just before a decodepad is added to it, the mainloop fires the id3demux
no-more-pads signal, which marks the group complete.  Since there is no
decodepad yet, the group is also considered blocked, and is therefore exposed
* [streaming thread again:]
a decodepad is added, and corresponding ghostpad is set to blocked
* streaming continues, and blocks in the pad block.  Since the group is already
considered exposed, no action is taken (the pad is not unblocked).

So, streaming is blocked with no hope for subsequent unblocking and no pads
have been exposed.


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