:PROPERTIES:
:ID:       ccb3bc14-a801-4ed0-b066-50b1bcd853aa
:END:
#+title: File metadata
#+date: "2020-04-13 17:32:27 +08:00"
#+date_modified: "2021-05-09 18:22:14 +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 format.
- Vorbis comments is a universal format commonly found on OGG.
- HTML documents contain the ~<head>~ element to store the metadata.
- [[id:c422175a-5b65-4311-8cc6-11efd55364e8][Org mode]] and Asciidoctor 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.

Tools exist for writing and reading data such as [[https://exiftool.org/][Exiftool]].
While file metadata are good and dandy, don't worry too much on them.
Just start with the more important data such as the title, authors, and the date.
It is preferred if you can edit the metadata manually so you can mark more relevant information.
Having too much however might as well have no metadata due to information overload.
