[gstreamer-bugs] [Bug 539858] New: not enough NEWSEGMENT events from matroskademux

[GStreamer (bugzilla.gnome.org)]

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  GStreamer | gst-plugins-good | Ver: HEAD CVS
           Summary: not enough NEWSEGMENT events from matroskademux
           Product: GStreamer
           Version: HEAD CVS
          Platform: Other
        OS/Version: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: Normal
         Component: gst-plugins-good
        AssignedTo: gstreamer-bugs at lists.sourceforge.net
        ReportedBy: eugeni.stepanov at gmail.com
         QAContact: gstreamer-bugs at lists.sourceforge.net
     GNOME version: Unspecified
   GNOME milestone: Unspecified


In case when a subtitle stream is lagging behind, matroskademux sends
NEWSEGMENT events to its peers. It is done when the current position is at
least 0.5 seconds after the end of the last packet is the stream (aka stream
position). Well, this is not good enough: subtitles can overlap. This happens
very often with SSA/ASS, most likely USF and probably plaintext subtitles as
well. This means that even if there is a subtitle that ends far in the future,
there still could be one starting in the past that we (an overlay element) have
not seen yet.

The solution is very simple: let's count the lag from the start of the last
packet, not from the end of it. I'm attaching a patch implementing this.


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