# Metadata extractor

**URL:** <https://www.ruby-forum.com/t/metadata-extractor/114300>\
**Category:** Ruby\
**Created:** [September 11, 2007, 1:18am UTC](https://www.ruby-forum.com/t/metadata-extractor/114300 "2007-09-11T01:18:59Z")\
**Posts on this page:** 2\
**Page:** 1

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**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 11, 2007, 1:18am UTC](https://www.ruby-forum.com/t/metadata-extractor/114300/1 "2007-09-11T01:18:59Z")

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url: [http://dark.fhtr.org/repos/metadata](http://dark.fhtr.org/repos/metadata)  
tarball: [http://dark.fhtr.org/repos/metadata/metadata-0.1.tar.gz](http://dark.fhtr.org/repos/metadata/metadata-0.1.tar.gz)

## 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 word count) and returns the metadata  
as a Hash.

Mdh can print out file metadata as YAML and package the metadata  
with the file.

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.

The metadata hash mostly follows the shared-metadata-spec naming.  
[shared-filemetadata-spec](http://wiki.freedesktop.org/wiki/Specifications/shared-filemetadata-spec)

## Usage

# print out metadata header

mdh -p myfile.jpg

# create myfile.jpg.mdh, which consists of metadata header +

myfile.jpg  
mdh myfile.jpg

# print out metadata header from mdh file

mdh -e -p myfile.jpg.mdh

# strip out metadata header from mdh file and save it to myfile.jpg

mdh -e myfile.jpg.mdh

irb\> Metadata.extract(‘myfile.jpg’)  
irb\> Metadata.extract\_text(‘myfile.pdf’)  
irb\> Pathname.new(“myfile.jpg”).metadata

## Requirements

- Ruby 1.8

- Tons of metadata extraction programs,  
list of debian packages follows:  
dcraw  
libimlib2-ruby  
extract  
libimage-exiftool-perl  
poppler-utils  
mplayer  
html2text  
imagemagick  
unhtml  
pstotext  
antiword  
catdoc  
shared-mime-info

- 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/)

## License

Ruby’s

Ilmari H. \<ilmari.heikkinen gmail com\>

---

<div class="post-metadata">

**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 13, 2007, 10:16am UTC](https://www.ruby-forum.com/t/metadata-extractor/114300/2 "2007-09-13T10:16:23Z")

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Quoth Ilmari H. on Monday 10 September 2007 04:18:25 pm:

> and camera make, mp3 artist, pdf word count) and returns the metadata  
> [shared-filemetadata-spec](http://wiki.freedesktop.org/wiki/Specifications/shared-filemetadata-spec)
> 
> # print out metadata header from mdh file
> 
> Requirements  
> poppler-utils  
> shared-mime-info to be able to handle camera raw images.
> 
> Ilmari H. \<ilmari.heikkinen gmail com\>

Any chance this could be expanded to add FLAC and OGG support?

Thanks!