File metadata is one of the most subtle requirements in [[file:personal-information-management.org][Personal information management]] (or at least, that's what I think).
With the right tools such as desktop search engines (see [[file:desktop-search-engines.org][Add a desktop search engine for your digital library]]), you can quickly retrieve information as well as preserve some of its related information.
[[https://en.wikipedia.org/wiki/Metadata][Each type of files have different ways of embedding metadata.]]
- Image files such as JPEG or PNG, metadata are embedded in [[https://wikipedia.org/wiki/Exchangeable_image_file_format][Exchangeable image file format]] (EXIF) and you can modify it with various tools such as [[http://owl.phy.queensu.ca/~phil/exiftool/][ExifTool]].
- MP3 files have the [[https://en.wikipedia.org/wiki/ID3][ID3]] as the de-facto standard for embedding contextual information such as the artist, album, genre, comments, and others. [fn:: Though the standard is designed with MP3 in mind, it can be freely included in other formats such as MP4 or WAV files.]
- HTML documents contain the [[https://developer.mozilla.org/en-US/docs/Learn/HTML/Introduction_to_HTML/The_head_metadata_in_HTML][~<head>~]] element to store the metadata.
However, modern standards such as [[https://fr.wikipedia.org/wiki/Extensible_Metadata_Platform][Extensible metadata platform]] (XMP) targets unison of creating metadata among media files: images (e.g., MP3, OGG), videos (e.g., MP4, MKV), documents (e.g., PDF).
Certain search engines such as Recoll and Tracker currently support searching metadata with XMP.
To modify the metadata of a file, certain tools such as [[https://exiftool.org/][Exiftool]] and [[https://www.alfresco.com/][Alfresco]] exists.
The process of manually adding metadata to non-textual files can be tedious but it may be worth the price if we're trying to retrieve some things especially for note-taking or [[file:maintaining-a-digital-library.org][Maintain your own digital library]].
