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  1. Member
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    Oct 2014
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    So I have an MKV that I'm converting to MP4 for compatibility purposes, but I'd like to keep the multiple audio and subtitle streams in place. However, post conversion, the metadata title seems to get lost in translation.

    So then I tried forcing the metadata via command line.

    As an example, I find that when running FFMPEG, if I add the following flags:
    Code:
    -metadata:s:a:1 language=jpn
    It works fine and forces the audio track specified to come up as Japanese (even though it was English in the original file; again, I purely did this to test to make sure the command line parameter is working correctly, which it did).

    However, if I specify:
    Code:
    -metadata:s:a:1 title="Commentary Track"
    The resulting output file lacks the metadata title for the audio stream.

    This gets really weird in that FFMPEG seems to think it's working just fine, as it including the following in its output:

    Code:
    Stream #0:2(jpn): Audio: ac3 ([165][0][0][0] / 0x00A5), 48000 Hz, 5.1, fltp, 640 kb/s (default)
    Metadata:
      title           : Commentary Track

    So my question is whether this is an issue with FFMPEG, or whether the MP4 container is simply incapable of supporting this level of metadata, and FFMPEG is failing silently?

    Thanks in advance
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  2. Member
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    MP4 isn't really much of a standard, it was based on the apple mov container and has components from that plus a bunch of other stuff made just for mp4. Take chapters for instance, MP4 has two kinds of chapters - Apple Text, which is basically a mutant subtitle stream which originated from the mov container and Nero Chapters, which is actual metadata in the file.

    This is how FFProbe displays my mp4 audio tracks:
    Code:
        Stream #0:1(eng): Audio: aac (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 15
    9 kb/s (default)
        Metadata:
          creation_time   : 2014-04-23 00:56:33
          handler_name    : English AAC(2.0)
    The 'title' comes under the heading "Handler Name" ("English AAC(2.0)" in this case). Maybe you've set the wrong field, or maybe there are two places to set the title so players just don't bother.

    -Edit- and wouldn't you know it VLC doesn't display the track title. Have you checked the file in MediaInfo?
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  3. Member
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    I played around with it a bit more and found some weird behavior with the handler_name, as you described, but after some digging, I found out that it appears that it was an issue with FFMPEG. I was using the version from 02/2014, and after updating my FFMPEG version to the latest build from yesterday, the file is converted just fine now.

    Thanks for your help, and I hope anyone else having this issue doesn't make my mistake in forgetting to make sure all the tools in question are properly up -to-date :P
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  4. Member Cornucopia's Avatar
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    Just played around with QTPro to see how it fared:

    Container change to MP4 strips all overall, container-related annotations EXCEPT copyright.
    Vid Track-related annotations seem to all be intact.

    Surprisingly, MediaInfo is VERY DEFICIENT in displaying annotations from either my source file (MOV) or my converted file (MP4).

    Scott
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  5. Probably because most folks only use iTunes compatible tagging for mp4 files nowadays.
    (+ nobody requested additional support, or the author doesn't deem it important enough to make a free update with it)
    users currently on my ignore list: deadrats, Stears555
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  6. Member
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    http://www.differencebetween.net/technology/difference-between-mov-and-mp4/

    The changes that were introduced were very minor and mostly involved data tagging information.
    I'm guessing that's why Apple Text chapters are subtitles (text streams). I'm no expert on MP4, I just know that I found it almost impossible to do anything with MP4Box because Apple tends to go their own way without any regard for standards and there's no easy way to duplicate those features with the program (I guess technically Nero did the same thing).
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  7. Member
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    From the Latest MediaInfo Changelog:

    + MOV/MPEG-4: basic support of iTunMOVI tag
    + MOV/MPEG-4: support of track title and few other track related tags
    + MOV/MPEG-4: detection of Dolby E in a stereo track
    Jerome doesn't seem to even bother listing them as separate containers.

    https://bitbucket.org/wez/atomicparsley/issue/1/itunes-atom-itunmovi
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  8. Member Cornucopia's Avatar
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    Some things with this were improved, some got worse. I will have to send him some sample clips w/explanations...

    Scott
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