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#+title : File metadata
#+date : "2020-04-13 17:32:27 +08:00"
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#+date_modified : "2021-05-02 02:11:01 +08:00"
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#+language : en
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File metadata is one of the most subtle requirements in [[file:2020-04-23-23-21-47.org ][Personal information management ]].
It embeds data without relying too much on filesystem such as the file name, creation date, and modification date.
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Each type of files have different ways of embedding metadata:
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- Image files such as JPEG or PNG, metadata are embedded in Exchangeable image file format (EXIF).
- MP3 files have the ID3 as the de-facto standard for embedding contextual information such as the artist, album, genre, comments, and others.
- Vorbis comments is a universal format commonly found on OGG.
- HTML documents contain the ~<head>~ element to store the metadata.
- Org mode documents allow file-level properties that are functionally equivalent to embedded metadata.
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There are also universal formats such as Extensible metadata platform (XMP) or Meta Information Encapsulation (MIE) available either as embedded or a separate file.
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Beware about caring too much on metadata to the point of our metadata takes more space than the data themsevles.
Cautionary tales such as [[https://en.wikipedia.org/wiki/MS_Fnd_in_a_Lbry ][MS Fnd in a Lbry ]] have been written about it.
They are, after all, merely data on data;
if the referred data does not exist in the first place, might as well as the metadata.
