MNG with jpeg compression?

  • Derek Pomery

    Derek Pomery - 2003-11-18

    Everyone seems so busy here, which is really awesome given the amount of time I've personally had lately to focus on extra-occupational activities - unfortunately not even the time to do something fairly simple like merging in patches.

    But, was just wondering.  I saved an MNG in GIMP, just a simple experiment at a 3D image using the flip-book method.
    Until now, this only has been workable using GIF 256 colour pallette.  MNG allows a full-colour scene, only the default zlib compression is inefficient with most photographs.
    convert -compress jpeg -quality 30 zlib.mng jpeg.mng

    Did the trick, creating something that was viewable in xnview.
    However, mozilla reports that image, and other MNG with jpeg compression images created, contain "errors"

    I was wondering if this had ever been supported in Mozilla, since it is quite simply something impossible to do in GIF - a photographic quality animation.
    If it isn't is it something we need to work on, and do you guys think it would take much effort with libmng?

    • Glenn Randers-Pehrson

      Which mozilla, specifically, reports errors?  See bugzilla's bug #196770 which I believe is fixed in the latest mngzilla downloads but not in official mozilla or firebird distributions.

    • Derek Pomery

      Derek Pomery - 2003-11-24

      Hm.  I don't think that was the bug you meant - maybe 196670?
      Thing is, I was using a 1.4.1 linux build capable of displaying JNG images.  MNG animation with jpeg compression seems beyond it though.

      • Glenn Randers-Pehrson

        Right, 196670.  Mozilla-1.4.1 (and MozillaFirebird 0.7) crashes when trying to read JNG images, if it was built on Windows 2000 or later with the Microsoft compiler.  You can try the MozillaFirebird binaries available here (in the mngzilla project) which have worked around the Microsoft bug, or build your own with the latest patch from bug #196670 applied.

    • Glenn Randers-Pehrson

      Hmm, you say you use Linux.  Perhaps you are using a buggy version of ImageMagick--there were some errors in version 5.5.6 and earlier when writing JNG files; try the current version which is 5.5.7-13.

    • Derek Pomery

      Derek Pomery - 2003-11-26

      Well, here's an experiment with it.  2 frame "flipbook" MNG

      • Glenn Randers-Pehrson

        Your longwood3d example works for me with the
        official Mozilla-1.4 build on Win95.

        As a JPEG-encoded MNG (converted with ImageMagick 5.5.8), it's at


        • Glenn Randers-Pehrson

          The example also is displayed properly on Win95 with Mngzilla-Firebird 0.7 and the Mngzilla-Firebird 20031109 nightly binaries from the mngzilla download area.

    • Derek Pomery

      Derek Pomery - 2003-12-01

      Yep was ImageMagick's fault.
      Your reencoding displayed fine, as did mine when I updated ImageMagick.

      Thanks for looking into it.


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