[Bug 707340] New: qtmux: should NOT use PTS if DTS is missing

[GStreamer (bugzilla.gnome.org)]

https://bugzilla.gnome.org/show_bug.cgi?id=707340
  GStreamer | gst-plugins-good | git

           Summary: qtmux: should NOT use PTS if DTS is missing
    Classification: Platform
           Product: GStreamer
           Version: git
        OS/Version: All
            Status: UNCONFIRMED
          Severity: normal
          Priority: Normal
         Component: gst-plugins-good
        AssignedTo: gstreamer-bugs at lists.freedesktop.org
        ReportedBy: matej.knopp at gmail.com
         QAContact: gstreamer-bugs at lists.freedesktop.org
     GNOME version: ---


This commit
http://cgit.freedesktop.org/gstreamer/gst-plugins-good/commit/?id=4f4f6432ccf99779a46be70bb3864ff0b673f7d2 

if DTS is missing on a buffer for some reason, PTS is taken instead. But that
is not good. Because if there is DTS on next buffer, it may be lower than PTS
on previous buffer. Thus you end up with negative delta.

Timestamp handling in qtmux is a mess, but this makes it even worse.

I think what should happen on missing DTS is this:
If DTS are missing at the beginning (probably because it was clipped to segment
start) make DTS = 0
This way there might be few buffers at the beginning with 0 duration, but
there's not much we can do about it until gstreamer can handle negative DTS.

If DTS are missing mid-stream, take the previous sample DTS (or previous sample
DTS + previous sample duration).

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