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m4a mising tags

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James
2007-11-23
2013-05-30
  • James

    James - 2007-11-23

    Hi,

    I've tried a few upnp server and mediatomb certainly works best for me, streaming to the PS3 and everything so great job, keep up the good work. 

    The only problem I seem to have is that some of my music tracks are aac encoded (file extension m4a) and mediatomb does not seem able to get the tags.  Mime type is reported as audio/mp4 as expected and I can read all the tags using amarok on the same machine as mediatomb is running on.  Any ideas, i tried compiling the lastest svn and same results.  I'm currently running 0.10.0 on Ubuntu gutsy using the feisty packages.

    I've googled till I'm blue in the face.

    Any help much appreciated.

    Cheers

    James

     
    • Jin

      Jin - 2007-11-23

      The reason is quite simple: it's not supported :)
      We use id3lib or taglib (the 0.10.0 binaries are compiled vs. id3lib) to get the tags, this library only handles ID3 tags, while taglib additionally handles ogg and flac.

      I do not know which library is capable of reading m4a tags, it is possible that ffmpeg can do that (we have a ffmpeg based metadata handler in the latest SVN code), if you are saying that amarok can read those then I could probably take a look to see what they use.

      Alternatively you could try compiling the latest SVN code to see if the ffmpeg metadata handler does the job.

      Kind regards,
      Jin

       
    • Brian S. Julin

      Brian S. Julin - 2007-11-23

      On linux m4a tag reading/writing is accomplished with libmp4v2

      There is also an "easytag" X application that supports a
      huge number of formats, might be good reference code.

       
    • Jin

      Jin - 2007-11-24

      Cool, thanks for the hint, I will take a look.

       
      • Brian S. Julin

        Brian S. Julin - 2007-11-27

        I also looked into libtag, and they don't have m4a support
        and probably won't until the maintainer gets something
        he is happy with -- he doesn't want to pull in external
        dls.  Understandable the way these things can mushroom,
        hell on package maintainers.

        However the amarok project has in-house extensions
        to libtag (a.k.a. taglib) -- one with libmp4v2 which
        was later replaced with one that uses a "libitunes"
        which I cannot find and which may be more limited.

        http://osdir.com/ml/kde.devel.taglib/2005-11/msg00011.html

        One thing to watch out for is that it might be the
        mp4 tagging code (not AAC) that has the worst patent
        baggage.  I don't know the specifics but IIRC you
        can only ship source of some of this stuff.

        Which makes me wonder... hrmmm -- maybe interpreted
        languages can be shipped with just a user-thrown "safety
        switch" because they are both source and code.  Ever used
        embedded perl? (I have in C but I am crap in C++) :-)

        http://search.cpan.org/~jhar/MP4-Info-1.12/Info.pm

        Anyway I have no clue what the actual restrictions
        are and just thought you might want to research that
        before picking a solution.

         
    • scrotimusprime

      scrotimusprime - 2007-11-24

      Hey, if you want testers/debuggers for that, I'd be happy to help out.  It would be a really useful feature.

       
    • Jin

      Jin - 2007-11-24

      Could you create a fully tagged m4a file for me (also check if m4a supports album art) and send it to jin at mediatomb dot cc ?

       
    • Jin

      Jin - 2007-11-27

      Well, libmp4v2 is available in Fedora, so it's probably OK.. as far as I know they do not even ship XMMS compiled with MP3 playback support (because of patent issues), so I believe that if it made its way into Fedora then it should not be a problem.

      Anyway, I do not want to pull in sources of even another library (we are actually trying to get rid of libupnp now), so we will jus tuse whatever is there (like taglib, id3lib, libmp4v2, etc.) to read metadata; and since all of them are optional and can be compiled out it should give everyone the possibility to pick the desired configuration.

       
    • James

      James - 2007-11-29

      Hi, as a quick update, I tried compiling from source with ffmpeg support.  All went well but still no m4a tags. I turned on debugging and added a few extra comments to the ffmpeg handler code and can see that although it is calling the ffmeg handler correctly and trying to get the metadata, it thinks all the metadata has 0 length and so does not retreive the data.  I guess the problem there is that the AVFormatContext structure pFormatCtx has not been filled in.

      I'm no programmer so this is about the limit of my abilities, jsut thought I'd let you know where I had got to

      thanks, keep up the great work

       
    • Jin

      Jin - 2007-11-29

      Well, I guess that means that ffmpeg is not capable of reading out those tags.

      libmp4v2 looks good though, I can't promise that I will have something for the upcoming release, but surely for the one afterwards.

       
    • edriss

      edriss - 2007-11-29

      Hi Jin,
      Would this also work for mp4 video files (ie as tagged by iTunes amongst other programs with Album Art, descriptions, etc)

      Thanks,

       
      • Jin

        Jin - 2007-11-29

        Hi,

        I think it would. You can test this rather easily, install the libmp4v2 library (if you are on fedora then a simple yum install libmp4v2 will do the job), along with this package an mp4info program is provided. Run it, giving one of your mp4 files as argument, it will print out all the metadata that it can find. That will be the data that we can make use of.

        Kind regards,
        Jin

         

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