mp3hash 0.1

Music file hasher

mp3hash

Hashes music files ignoring meta-data.

Useful to detect the same song in different tagged files.

The following metadata standards are supported:

id3v1, id3v1 extended, id3v2.2, id3v2.3 and id3v.24

Javier Santacruz (2012-2013)

Command line usage

Similarly to sha1sum or md5sum, it takes one or more files and returns the hashes, in this way:

$ ./mp3hash  *.mp3
6611bc5b01a2fc6a6386a871e8c51f86e1f12b33 13_Hotel-California-(Gipsy-Kings).mp3
6611bc5b01a2fc6a6386a871e8c51f86e1f12b33 14_Hotel-California-(Gipsy-Kings).mp3

It returns the same hash number, even though the tags are different, and so their regular hashes:

$ sha1sum *.mp3
6a1d5f8317add10e205ae30174630b47645fb5b4  13_Hotel-California-(Gipsy-Kings).mp3
c28d6976114d31df3366d9935eb0bedd36cf1f0b  14_Hotel-California-(Gipsy-Kings).mp3

The hash it’s made strictly using the music data in the file, by calculating the tags sizes and omitting them.

The default hashing algorithm is sha-1, but any algorithm can be used as long it’s supported by the Python’s hashlib module. A complete list of all available hashing algorithms can be obtained by calling the program with the --list-algorithms.

$ ./mp3hash --list-algorithms
md5
sha1
sha224
sha256
sha384
sha512

./mp3hash --algorithm md5
ac0fdd89454528d3fbdb19942a2e6653 13_Hotel-California-(Gipsy-Kings).mp3
ac0fdd89454528d3fbdb19942a2e6653 14_Hotel-California-(Gipsy-Kings).mp3

Installation

It doesn’t have any dependences besides python2.7+. In order to access to the mp3hash script, the package should be installed.

python setup.py install

And the mp3hash command should be available in path.

API

The main components are the mp3hash function and the TaggedFile class.

• mp3hash will compute the hash on the music (and only the music) of the file in the given path.

  from mp3hash import mp3hash mp3hash(‘/path/to/song.mp3’) Out: 6611bc5b01a2fc6a6386a871e8c51f86e1f12b33

• TaggedFile class takes a file-like object supporting seek and negative values for seek and will parse all the sizes for the metadata stored within it.

  from mp3hash import TaggedFile with open(‘/path/to/song.mp3’) as file: TaggedFile(file).has_id3v2 Out: True

Developers, developers, developers!

Testing environment

You’re adviced to use a virtualenv

$ virtualenv --python python2 --distribute env
$ . env/bin/activate

Once into the virtualenv, install the package and the testing dependences.

$(env) python setup.py develop
$(env) pip install -r dev-reqs.txt

In order to perform the testing, run ‘nosetests’ from the root of the project (same dir of setup.py).

$ nosetests

About id3v1

• id3v1 is 128 bytes at the end of the file starting with ‘TAG’

• id3v1 extended is 227 bytes before regular id3v1 tag starting with ‘TAG+’

total size: 128 + (227 if extended)

id3v1 is 128 bytes at the end of the file starting with ‘TAG’ id3v1 extended is 227 bytes before regular id3v1 tag starting with ‘TAG+’

total size: 128 + (227 if extended)

About id3v2

id3v2 has a 10 bytes header at the begining of the file. byte 5 holds flags. 4th bit indicates presence of footer in v2.4 bytes 6-10 are the tag size (not counting header)

total size: header + tagsize + footer (if any)

Based on id3v1 wikipedia docs: http://en.wikipedia.org/wiki/ID3 Based on id3v2 docs:

• http://id3.org/id3v2-00

• http://www.id3.org/id3v2.3.0

• http://id3.org/id3v2.4.0-structure