# Metadata 1.0 **URL:** \ **Category:** Ruby\ **Created:** [September 22, 2007, 1:13pm UTC](https://www.ruby-forum.com/t/metadata-1-0/115251 "2007-09-22T13:13:57Z")\ **Posts on this page:** 1\ **Page:** 1
**Author:** ![Ilmari\_H](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/i/a587f6/32.png) [@Ilmari\_H](https://www.ruby-forum.com/u/Ilmari_H)\ **Post date:** [September 22, 2007, 1:13pm UTC](https://www.ruby-forum.com/t/metadata-1-0/115251/1 "2007-09-22T13:13:57Z")
tarball: [http://dark.fhtr.org/repos/metadata/metadata-1.0.tar.gz](http://dark.fhtr.org/repos/metadata/metadata-1.0.tar.gz) gem: [http://dark.fhtr.org/repos/metadata/metadata-1.0.gem](http://dark.fhtr.org/repos/metadata/metadata-1.0.gem) git: [http://dark.fhtr.org/repos/metadata](http://dark.fhtr.org/repos/metadata) ## Thanks Konrad M. for his patient testing and bug reports. Darren Kirby for the heads-up on wmainfo’s ASF-parsing capabilities (along with being the author of wmainfo-rb and flacinfo-rb.) ## Description This package `Metadata' comes with a library called `metadata’ and a small program called `mdh’. The library probes files for their metadata (e.g. jpeg dimensions and camera make, mp3 artist, pdf text and word count) and returns the metadata as a Hash. All strings in the metadata are converted to UTF-8. The `mdh’-program can print out file metadata as YAML and package the metadata with the file. The metadata hash follows the shared file metadata spec naming, with some additional fields, see list at the end of this file (Appendix A.) For details on the MDH file format, see the end of this file (Appendix B.) ## Example output ## $ mdh break\_\_enter.flac Audio.Performer: The Prodigy Audio.Album: Music For The Jilted Generation Audio.Samplerate: 44100 Audio.TrackNo: 2 Audio.Bitrate: 800.0 Audio.Title: Break & Enter Audio.Genre: (18) Audio.Duration: 608.0 Audio.ReleaseDate: 1994-01-01T00:00:00Z File.Size: 60889216 Audio.Codec: fLaC Audio.Channels: 2 File.Modified: !timestamp 2007-09-21T10:59:38+0300 File.Format: audio/x-flac Audio.Artist: The Prodigy ## $ mdh random\_plastic.mpeg Video.Duration: 236.0 Audio.Samplerate: 44100 Audio.Bitrate: 64.0 Video.Framerate: 10.0 Image.DimensionUnit: px Video.Codec: FMP4 File.Size: 4854088 Image.Width: 422 Image.Height: 364 Video.Bitrate: 90.624 Audio.Codec: “80” Audio.Channels: 2 File.Modified: !timestamp 2007-09-21T10:57:16+0300 Video.Demuxer: avi File.Format: video/x-msvideo ## Usage # print out metadata for myfile.jpg mdh myfile.jpg # create myfile.jpg.mdh, which consists of an MDH metadata header + myfile.jpg mdh -c myfile.jpg # print out the metadata header from an MDH file mdh -e -p myfile.jpg.mdh # strip out the metadata header from an MDH file and save it to myfile.jpg mdh -e myfile.jpg.mdh # print out the list of options mdh -h irb\> require ‘metadata’ irb\> Metadata.extract(‘myfile.jpg’) irb\> Metadata.extract\_text(‘myfile.pdf’) irb\> Pathname.new(“myfile.jpg”).metadata ## List of supported formats Audio: Whatever you manage to make mplayer play. Plus special handlers for FLAC, m4a, ape, musepack, wavepack and wma. Successfully tested with: mp3, flac, ogg, wav, ra, m4a, wma Should also work: wv, mpc, ape Video: Whatever you manage to make mplayer play. Successfully tested with: wmv, mov, divx, xvid, flv, ogm, mpg, mkv Images: Should handle pretty much anything (apart from ORF.) Successfully tested with: jpeg, png, gif, nef, dng, crw, pef, psd, tga, tif, xcf, xpm, ppm, bmp Documents: Successfully tested with: pdf, ppt, odp, sxi, ps, ps.gz, html, txt Should work: - OpenOffice docs work to some degree (personally, I’m using unoconv to convert OO docs to temp PDFs for the text & dimensions extraction, so those bits of data are missing.) - MS Office docs to some degree (ppt at least, doc and xls should work too, dimensions missing due to the above temp PDF -thing.) Others: - BitTorrent .torrent files - Archive contents - Whatever `extract’ outputs and I am handling ## Requirements - Ruby 1.8 - Tons of metadata extraction programs and libs. This package has many dependencies since there is no single universal metadata header format that all files use. Blame resource forks, filename extensions, bags of bytes and mimetypes. - You do want to install the latest versions of dcraw and shared-mime-info to be able to handle camera raw images. [http://cybercom.net/~dcoffin/dcraw/](http://cybercom.net/~dcoffin/dcraw/) [shared-mime-info](http://freedesktop.org/wiki/Software/shared-mime-info) - Python + chardet library [http://chardet.feedparser.org/](http://chardet.feedparser.org/) ## Install De-compress archive and enter its top directory. Then type: ($ su) # ruby setup.rb These simple step installs this program under the default location of Ruby libraries. You can also install files into your favorite directory by supplying setup.rb some options. Try “ruby setup.rb --help”. ## Appendix A: Additional metadata fields This list contains the metadata fields added to the shared file metadata spec. [shared-filemetadata-spec](http://wiki.freedesktop.org/wiki/Specifications/shared-filemetadata-spec) ## field name | field type Archive.Contents array of pathnames Audio.Band string Audio.Composer string Audio.Conductor string Audio.Copyright string (copyright message) Audio.Grouping string Audio.Image binary string (embedded image data) Audio.InterpretedBy string Audio.Lyricist string Audio.Publisher string Audio.RemixedBy string Audio.Subtitle string Audio.Tempo integer Audio.VariableBitrate boolean Audio.Writer string Audio.Publicationright string Audio.File string Audio.EAN/UPC string Audio.ISBN string Audio.Catalog string Audio.LC string Audio.Media string Audio.Index string Audio.Related string Audio.ISRC string Audio.Abstract string Audio.Language string Audio.Bibliography string Audio.Introplay string Audio.Dummy string Audio.DebutAlbum string Audio.RecordDate string Audio.RecordLocation string Doc.Album string Doc.Artist string Doc.Charset string Doc.Description string Doc.Genre string Doc.Language string Doc.ModifyDate date Doc.PageSizeName string (A4, A5, letter, …) File.Software string (software used to create the file) Image.DateCreated date Image.DateTimeCreated date Image.DateTimeOriginal date Image.DimensionUnit string (px, mm, pt, …) Image.EXIF string (exiftool output) Image.Frames integer Image.Modified date Image.OriginatingProgram string Location.Latitude float Location.Longitude float Video.Album string Video.Artist string Video.Bitrate integer Video.Codec string Video.Comment string Video.Duration float Video.Framerate float (frames per second) Video.Genre string Video.ReleaseDate date Video.Title string Video.TrackNo integer Video.Demuxer string BitTorrent.Name string BitTorrent.Files array of { ‘path’ =\> string, ‘length’ =\> integer, ‘md5sum’ =\> string } BitTorrent.Length integer (size of single-file torrents) BitTorrent.MD5Sum string (md5sum for single-file torrents) BitTorrent.PieceCount integer BitTorrent.PieceLength integer (length of a single piece BitTorrent.Comment string BitTorrent.Announce string (announce url) BitTorrent.AnnounceList array of arrays of strings BitTorrent.Nodes array of [hostname, port] -arrays ## Appendix B: The MDH file format MDH files are built as follows: ## bytes | content ``` 3 | "MDH" - MDH file format identifier 1 | "\x01" - MDH file format version number 4 | Long, network byte order - the size of the metadata struct in ``` bytes var | YAML - The MDH metadata struct var | The actual file contents All string fields in the metadata are UTF-8. ## License Ruby’s