:PROPERTIES: :ID: ccb3bc14-a801-4ed0-b066-50b1bcd853aa :END: #+title: File metadata #+date: "2020-04-13 17:32:27 +08:00" #+date_modified: "2021-05-04 20:52:15 +08:00" #+language: en File metadata is one of the most subtle requirements in [[id:88f2256a-3359-4d10-92a3-9273cabce414][Personal information management]]. It embeds data without relying too much on filesystem such as the file name, creation date, and modification date. Each type of files have different ways of embedding metadata: - 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 ~~ element to store the metadata. - Org mode documents allow file-level properties that are functionally equivalent to embedded metadata. There are also universal formats such as Extensible metadata platform (XMP) or Meta Information Encapsulation (MIE) available either as embedded or a separate file. 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.