[Bug 743407] New: qtdemux: doesn't ignore data after last sample in mdat.

[GStreamer (bugzilla.gnome.org)]

https://bugzilla.gnome.org/show_bug.cgi?id=743407
  GStreamer | gst-plugins-good | git master

           Summary: qtdemux: doesn't ignore data after last sample in
                    mdat.
    Classification: Platform
           Product: GStreamer
           Version: git master
        OS/Version: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: Normal
         Component: gst-plugins-good
        AssignedTo: gstreamer-bugs at lists.freedesktop.org
        ReportedBy: floobleflam at gmail.com
         QAContact: gstreamer-bugs at lists.freedesktop.org
     GNOME version: ---


If qtdemux is demuxing a fragmented stream (e.g., a DASH stream), and it
receives a fragment that contains data in its mdat after the end of the last
sample, playback fails.

The reason is that qtdemux will start trying to parse the next fragment
starting from the byte following the end of the last sample (i.e., while still
inside the current fragment's mdat) rather than discarding the remaining bytes
in the mdat and starting parsing from the beginning of the next fragment. At
that point playback fails, since the bytes after the last sample won't be valid
ISOBMFF boxes.

This can be demonstrated by playing this DASH stream:

gst-launch-1.0 playbin
uri=http://rdmedia.bbc.co.uk/dash/ondemand/testcard/1/client_manifest-nosurround-ctv.mpd

Some of the audio fragments in this stream have "watermarks" in them; the
watermark consists of some data inserted in their mdat after the end of the
last sample. When the client reaches one of these segments (which on my system
happens when playback reaches roughly 1m 29s), it throws an error and exits:

ERROR: from element
/GstPlayBin:playbin0/GstURIDecodeBin:uridecodebin0/GstDecodeBin:decodebin0/GstQTDemux:qtdemux1:
This file is invalid and cannot be played.
Additional debug info:
qtdemux.c(5045): gst_qtdemux_process_adapter ():
/GstPlayBin:playbin0/GstURIDecodeBin:uridecodebin0/GstDecodeBin:decodebin0/GstQTDemux:qtdemux1:
atom RD
Execution ended after 0:01:29.561894521

The ISOBMFF spec allows data other than sample data to be carried in an mdat;
the demuxer should extract only the sample data that is referenced by metadata
in the fragment's moof box.

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