[gstreamer-bugs] [Bug 568555] New: Interlaced MJPEG files not handled correctly by jpegdec

[GStreamer (bugzilla.gnome.org)]

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  GStreamer | gst-plugins-good | Ver: git
           Summary: Interlaced MJPEG files not handled correctly by jpegdec
           Product: GStreamer
           Version: git
          Platform: Other
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: Normal
         Component: gst-plugins-good
        AssignedTo: gstreamer-bugs at lists.sourceforge.net
        ReportedBy: thaytan at mad.scientist.com
         QAContact: gstreamer-bugs at lists.sourceforge.net
     GNOME version: Unspecified
   GNOME milestone: Unspecified


For example: http://gstreamer.freedesktop.org/media/incoming/douche.MJPEG-A.mov

With this kind of file, each packet from qtdemux contains 2 sequential jpeg
images, one per field.

jpegdec detects that it is running in 'packetised' mode, and only decodes the
first jpeg image in each packet, resulting in half-height output of online the
first field. It needs to allocate a buffer twice the height and then decode
each field into that buffer.

I'm not sure what happens with the sub-sampled chroma planes in this case. I
guess each field contains a subsampled version of that field only.

ffdec_mjpeg correctly decodes both jpeg images in the packet, and outputs a
Y42B frame.


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