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Thread: Mapping of metadata between file formats

  1. #1
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    Mapping of metadata between file formats

    Just as a serious experiment, I tried converting a modestly tagged MP3 file to FLAC. I just wanted to learn how dMC handled the tags. Much to my surprise, many but not all of the MP3 tags showed up as Vorbis comments. Some were recreated verbatim with the same field names, others mapped to a new field name and others ignored or combined in some way.

    While we are creating a large radio station music library on a server in the FLAC file format, we need to consider what tags are preserved, ignored or mapped to a different field name if we choose to create ALAC versions of the same album.

    Is there a widely-accepted FLAC mapping table, or a table that is used by dbpoweramp to map tags between formats? We're really only interested in lossless formats, but of course we need to consider implementing equivalent FLAC tags that are often used in MP3 files.

    Now, having said that, we also wish to extend the basic Vorbis comments into a larger set that includes such tags as ALBUMARTIST, STYLE, UPC (UPC or EAN barcode), PRODUCER and so on. We also wish to tweak a couple of the definitions of the standard set of tags, wherein ARTIST is really the track's lead artist(s) and PERFORMER is a list of all of the performers on the track. What can anyone, especially Spoon, do to help us learn what others are doing in this area and if an extended set of tags for FLAC files is already in use elsewhere?

    Thanks in advance...

    d2b

  2. #2
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    Re: Mapping of metadata between file formats

    You need to try R14.3 (beta) which has a new mp3 tag reader, and new flac tagging routines.

  3. #3
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    Re: Mapping of metadata between file formats

    I'll try this again: Is there a widely-accepted FLAC mapping table, or a table that is used by dbpoweramp to map tags between formats?

    Some tags are mapped verbatim, other get a field name change (organization --> publisher) and others are ignored or combined. What are your rules for converting between, say, MP3, FLAC and ALAC?

    You mention that new FLAC tags for TRACKTOTAL and DISCTOTAL were added to 14.3 (beta). Where did those field names come from? Did you make them up? I do know that others, including ourselves, use TOTALTRACKS and TOTALDISCS for these field names.

    d2b

  4. #4
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    Re: Mapping of metadata between file formats

    >Did you make them up?

    http://wiki.xiph.org/Field_names

    All other mappings which are done can be seen in the configuration program >> dBpoweramp Configuration >> Codecs >> Advanced

  5. #5
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    Re: Mapping of metadata between file formats

    It seems odd (but not disingenuous) to adopt proposed changes to VorbisComments (TRACKTOTAL and DISCTOTAL) while at the same time dropping ORGANIZATION and DESCRIPTION which are defined in the official minimum set. <G>! Are there applications that do support these new tags?

    Having said that, I do prefer TRACKTOTAL and DISCTOTAL to our respective counterparts (TOTALTRACKS and TOTALDISCS) and will soon retag our library to change over to this usage. If the tags are presented in alphabetical order when displayed (e.g., when performing ALT-T using mp3tag) at least they show up together in the list of included tags.

    A question that remains unresolved relates to R14.3 (beta). I do not see any means for CD Ripper to write these two new tags, and it doesn't do that to the best of my knowledge. Is there something I'm missing, or is the feature not really there?

    d2b

  6. #6
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    Re: Mapping of metadata between file formats

    All other mappings which are done can be seen in the configuration program >> dBpoweramp Configuration >> Codecs >> Advanced
    Those mappings do not explain how dbpaMC converts FLAC tags to ALAC tags. Many are copied verbatim, including some or all of our custom FLAC tags, a few are renamed (ORGANIZATION --> Publisher. for example) and a few others did not show up at all.

    The basic question is still unanswered: "Is there a table or published criteria for how to map tags between FLAC, MP3 and ALAC formats in either direction?"

    TIA

    d2b

  7. #7
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    Re: Mapping of metadata between file formats

    There is no table, only that we try to standardize tags from one format to the other.

    >dropping ORGANIZATION and DESCRIPTION

    Not dropped, rather defaulted these to not mapped, as each year we field about 100 questions why they are mapped when people do not expect them, we cannot be the only program to follow the standard...

    There are a handful such as org >> publisher, that are always mapped.

    ALAC is based on iTunes tagging, they have set fields we have to write to. By doing a conversion of a fully tagged file between the formats then looking at the tags you will be able to see what goes where.

  8. #8
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    Re: Mapping of metadata between file formats

    >> ALAC is based on iTunes tagging, they have set fields we have to write to. <<

    I've tried to find the 'standard' for iTunes tags. Can you point me in the right direction, please? That would be very helpful.

    Thanks...

    d2b

  9. #9
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    Re: Mapping of metadata between file formats

    Apple only release the document to registered developers with Apple.

  10. #10
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    Re: Mapping of metadata between file formats

    Hmmm. I was afraid of that. Such restrictions only make the "open source" version of ALAC far less attractive, making our decision to rely on FLAC all the more sensible.

    d2b

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    Re: Mapping of metadata between file formats

    I had the same question as the thread title.

    I am trying to handle the LABEL and ORGANIZATION fields consistently in Vorbis comments of FLAC/OGG files, considering the different behaviours of dbpoweramp, tag&rename and mediamonkey.

    For d2b this page gives the mapping of several tagging formats: http://age.hobba.nl/audio/tag_frame_reference.html.

    I could (and would prefer) to stick to ORGANIZATION as defined by the Vorbis 1 specification if I didn't discover that most of my collection was tagged with Tag & Rename that uses "LABEL".

    Concerning dbpoweramp 14.2, the pop-up window and Edit ID-Tag functionalities display a "Label" field name and is able to read the value of the LABEL field and the ORGANIZATION fields. However a display rule prioritizes the LABEL value over the ORGANIZATION value. So if both values are present only the LABEL value is displayed and can be edited.

    I didn't check if removing the mapping "Label to Organization" in the CODEC advanced options changes anything to that. But it's actually there and doesn't help in my situation, so maybe this option is only used during file conversion.

    Thanks.

  12. #12

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    Re: Mapping of metadata between file formats

    Quote Originally Posted by Zam View Post
    I didn't check if removing the mapping "Label to Organization" in the CODEC advanced options changes anything to that. But it's actually there and doesn't help in my situation, so maybe this option is only used during file conversion.
    That option probably will work for your next conversions.

    Have you experimented MP3Tag? And even Foobar2000 audio player can help you on fixing tags in case you want to use another metadata editor for repairing existing files.

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