freezetag

About

freezetag is a tool that saves, strips, and restores file paths and music metadata. This metadata is written to a freezetag file (usually just a few kB) that can transform downloaded music files between different filename/tag states.

Use cases:

1. Freezetags can be generated after a torrent finishes downloading to freeze the directory state. Later, even after moving, retagging, and renaming those files, the original downloaded state can be restored (thawed).

2. Additionally, these freezetags can be mounted, allowing retagged music to coexist with the original downloaded music files without taking up extra disk space. This means you can retag your music and continue to seed in your torrent client from the same set of files. Have your cake and eat it too!

3. In the same vein, users can seed torrents between different trackers with just one copy of the music files, even if the music has been retagged and renamed between trackers.

4. Freezetags can also be generated for an entire music library after the music has been retagged to back up your personal tags. These quick incremental backups will archive your tags and filenames, which can later be restored from the original torrents.

Requirements

freezetag requires Python 3.5.2 or greater (older versions may technically work, but are untested).

A FUSE implementation must also be installed to use freezetag mount:

• Windows users can install WinFsp.
• Mac users can install FUSE for macOS via brew cask install osxfuse or manually.
• Linux users can install fuse2 from their package managers or manually.

Installation

$> pip install git+https://github.com/x1ppy/freezetag

Usage

usage: freezetag [-h] command ...

Saves, strips, and restores file paths and music metadata.

positional arguments:
  command
    freeze    Save paths and music metadata to a freezetag file.
    thaw      Restore paths and music metadata from a freezetag file.
    mount     Recursively mount a directory and its freezetags.
    shave     Strip metadata from all music files.
    show      Display the contents of a freezetag file.

optional arguments:
  -h, --help  show this help message and exit

Use "freezetag [command] --help" for more information about a command.

Supported Formats

Currently, FLAC and MP3 formats are supported. Vorbis comments are supported for FLAC files, and ID3 tags are supported for MP3 files.

Note that metadata will be frozen/thawed/shaved for supported music and metadata formats only.

Examples

freeze

Create a freezetag that stores paths and metadata for all files in this directory, saving the freezetag to a file named Fa-b-c.ftag (as described in Freezetag ID) to this directory:

$> freezetag freeze

Same as above, except downloads/Pink Floyd - Dark Side of the Moon (1973 MSFL UDCD 517) - FLAC is used instead of the current directory:

$> freezetag freeze "downloads/Pink Floyd - Dark Side of the Moon (1973 MSFL UDCD 517) - FLAC"

If --ftag is passed, the freezetag will be written to that directory instead of the directory being frozen:

$> freezetag freeze --ftag ~/ftags

Or, if the --ftag argument is a file, the freezetag will be explicitly named (redacted-pink-floyd-the-wall.ftag in this case):

$> freezetag freeze --ftag ~/ftags/redacted-pink-floyd-the-wall.ftag

These examples all freeze a single album's state. With the default usage, it's recommended that each album has its own freezetag, as shown here. This way, other directories under downloads can be added/changed/removed without affecting the freezetag corresponding to each individual download.

Freezetags are unique for a given group of files with the same metadata, so album-level freezetags can be shared among users to recreate the exact torrent download state. In fact, if two users independently create freezetags for the same downloaded directory, the freezetags (and their IDs) will be identical. In theory, trackers could even provide freezetags alongside download links that match the given releases, and freezetag IDs could be an API-queryable alternative to torrent info hashes.

--backup

freezetag freeze also includes an incremental backup mode, enabled with the --backup flag:

$> freezetag freeze ~/music --backup

This mode is intended to be used on your top-level music directory, and allows you to export all of your personal tags. freezetag thaw can later be used on the original torrent downloads in your ~/downloads directory to fully recreate your personal tagged library.

Unlike the default mode, backup mode writes last modified dates and file sizes to the freezetag. This enables incremental backups, meaning that the original freezetag freeze --backup of your library can take awhile (minutes to hours depending on the size of your library), but subsequent freezetag freeze --backups can complete in mere seconds. Only the most recent freezetag will be read for an incremental backup, and if the library is unchanged since the last backup, a new freezetag will not be created.

Backup freezetags follow a different naming scheme, and will be named Fyyyy-MM-dd_hh-mm-ss.ftag using the date of creation.

thaw

Restore files in-place in the current directory to the freezetag state, using whatever freezetag is in the current directory (prompting the user if multiple .ftags exist):

$> freezetag thaw

Same as above, except downloads/Pink Floyd - Dark Side of the Moon (1973 MSFL UDCD 517) - FLAC is used instead of the current directory:

$> freezetag thaw "downloads/Pink Floyd - Dark Side of the Moon (1973 MSFL UDCD 517) - FLAC"

For parity with freeze, thaw supports an --ftag flag that searches the given directory for a freezetag instead:

$> freezetag thaw --ftag ~/ftags

Or, if a freezetag is explicitly passed with --ftag, that freezetag will be used to thaw. The following thaws files in-place in the current directory using the given freezetag:

$> freezetag thaw --ftag ~/ftags/redacted-pink-floyd-the-wall.ftag

By default, thaw will thaw files in-place, meaning files and directories will be moved/modified/created to match the freezetag state. If the --to flag is passed, no files will be modified, but will instead be copied and thawed to the given directory:

$> freezetag thaw --to ~/out

The thawed files will be written to a subdirectory named according to the root directory from the freezetag. The root is the name of the top directory when the files were frozen. So if we freeze a directory and thaw it with --to:

$> cd "downloads/Pink Floyd - Dark Side of the Moon (1973 MSFL UDCD 517) - FLAC"
$> freezetag freeze
$> freezetag thaw --to ~/out

This will restore the freezetag state to ~/out/Pink Floyd - Dark Side of the Moon (1973 MSFL UDCD 517) - FLAC.

As another example, say we regularly make backups of our music library state:

$> freezetag freeze ~/music --backup --ftag ~/ftags

We could then recover this backed-up state from a directory of downloaded music:

$> freezetag thaw ~/downloads --to ~ --ftag ~/ftags

This will restore our library from ~/downloads to ~/music, keeping ~/downloads intact.

mount

Recursively mount music files and freezetags in ~/music to ~/freezefs:

$> freezetag mount ~/music ~/freezefs

Music files in ~/music will appear under ~/freezefs in their original frozen states (paths and tags) from corresponding freezetag files found under ~/music. A file in ~/music will not be mapped to~/freezefs if there is no freezetag matching that file. On the other hand, a file in ~/music can be mapped to ~/freezefs multiple times under different paths (and possibly with different tags) if there are multiple freezetags referring to that same file.

freezetag mount enables renamed/retagged music to be seeded without requiring copies on disk. For example, let's say we download a torrent to ~/downloads/Pink Floyd - Dark Side of the Moon (1973 MSFL UDCD 517) - FLAC. Assuming our personal tagged library is stored under ~/music and mounted as shown above, we can then:

1. Run freezetag freeze ~/downloads/Pink Floyd - Dark Side of the Moon (1973 MSFL UDCD 517) - FLAC` after the torrent finishes.
2. Retag/rename/move the files (e.g., to ~/music/Pink Floyd/Dark Side of the Moon). Assuming we also move the freezetag from step 1 along with it, this will automatically make a new Pink Floyd - Dark Side of the Moon (1973 MSFL UDCD 517) - FLAC directory appear under our mount point (~/freezefs).
3. Point our torrent client to seed the files from ~/freezefs/Pink Floyd - Dark Side of the Moon (1973 MSFL UDCD 517) - FLAC.

Ideally, the above steps would be automated by your torrent client/music importer.

Mounts are read-only. Mounts are "live", meaning new files added to the source directory will automatically appear under the mount point (assuming there's a matching freezetag), and deleted files will automatically disappear. Similarly, changes in tags or freezetag files will be reflected automatically.

Note: The initial mount may take awhile depending on how large your library is. Mount metadata is cached on disk, so subsequent mounts should activate in just a few seconds.

shave

Strips all metadata from music files in the current directory:

$> freezetag shave

Same as above, except downloads/Pink Floyd - Dark Side of the Moon (1973 MSFL UDCD 517) - FLAC is used instead of the current directory:

$> freezetag shave  "downloads/Pink Floyd - Dark Side of the Moon (1973 MSFL UDCD 517) - FLAC"

freezetag shave can be useful if you want to share the "bare" music files. This has the advantage of smaller overall distribution size (especially if the music contains images), and it allows tags to be shared separately. That is, users can create and distribute different freezetag files using the same bare music files, and the bare music files will remain unchanged.

show

Shows the contents of a freezetag file.

$> freezetag show
version: 1
mode:    default
id:      Fc58e43e83c0487f5-56ddb165-e8a1171b
root:    Pink Floyd - Dark Side of the Moon (1973 MSFL UDCD 517) - FLAC
96f5c1b465b263d5090deae5d177df47f0f36efa 01 - Speak To Me.flac
dbd1dc0c8ad514d9641919bc52c99010f5cf3ad2 02 - Breathe.flac
65cbc81d99b7ed68125b1652819e5fbec7e7a845 03 - On The Run.flac
40af1c90071abc0d66dbbfad5be39fac25967b5e 04 - Time.flac
a9fe89c25630794252aa3fe6b1e8078a4eb2308d 05 - The Great Gig In The Sky.flac
1a3dfb4396cd1c0ccf7804fc66c0e512b65df65d 06 - Money.flac
caeaf72fcee0df11c167bea2edffe4f7acbcec72 07 - Us And Them.flac
3ed0c16c900d8430f470011ba877fbaa15a5f7ef 08 - Any Colour You Like.flac
fee17fdb47c04037d57094ad14260f20cf8e7a83 09 - Brain Damage.flac
f3539291afa214e7af868ff9b0f044a372cf9e9b 10 - Eclipse.flac
25041f6026518a0e0a0aa4df3c5fdfd62f8001ea Pink Floyd - The Dark Side Of The Moon.log
76e4c8325809583bca447ba2d0e9fdaa4b39fa1e Pink Floyd - The Dark Side Of The Moon.m3u
15fdc9bc1bbe2646ba3cd076789c805f811f9b10 The Dark Side Of The Moon.cue

You can also use the --json flag to get parse-friendly output:

$> freezetag show --json
{
  "version": 1,
  "mode": "default",
  "id": "Fc58e43e83c0487f5-56ddb165-e8a1171b",
  "root": "Pink Floyd - Dark Side of the Moon (1973 MSFL UDCD 517) - FLAC",
  "files": [
    {
      "path": "01 - Speak To Me.flac",
      "checksum": "96f5c1b465b263d5090deae5d177df47f0f36efa"
    },
    {
      "path": "02 - Breathe.flac",
      "checksum": "dbd1dc0c8ad514d9641919bc52c99010f5cf3ad2"
    },
    {
      "path": "03 - On The Run.flac",
      "checksum": "65cbc81d99b7ed68125b1652819e5fbec7e7a845"
    },
    ...
  ]
}

Freezetag ID

By default, the freezetag file will be saved to the processed directory as Fa-b-c.ftag, where:

• a is a 16-character hex string that uniquely identifies the music
• b is an 8-character hex string that uniquely identifies the metadata
• c is an 8-character hex string that uniquely identifies the freezetag

While this naming scheme might seem unusual, the uniqueness property lets you quickly see whether two freezetags are identical simply by comparing their file names:

• The a and b segments do not change between freezes if any paths change or if any non-music files are modified. Additionally, the a segment doesn't change if the music files are retagged.

• This means if two different .ftag files have the same a segment, they represent the same set of raw music. If they have both the same a and b segments, they represent the same set of raw music and their metadata.

• If all three segments are the same, the two freezetag files are identical. Therefore, running freezetag freeze twice will only result in a single freezetag file being created: since the ID will stay the same, the existing freezetag file will be replaced on the second invocation.

If you use a custom naming scheme for your freezetags (by passing --ftag to freeze), the ID can still be found using freezetag show.

Changelog

1.2.1 - 2021-04-21

• Fixed --json flag for show
• Fixed file monitoring for failed stat

1.2.0 - 2020-04-26

• Added mount command
• Refactored modules and API

1.1.1 - 2020-04-16

• Fixed thaw where multiple copies of the same file are frozen

1.1.0 - 2020-04-16

• Added freeze --backup for incremental backups
• Added freeze --ftag for custom output path
• Fixed show --json to properly dump JSON
• In-place thaw now deletes processed files immediately to reduce temporary disk usage
• Created safety checks and prompts for thaw
• Added thaw --skip-checks to allow skipping checks

1.0.4 - 2020-04-10

• Don't delete files on thaw if they aren't listed in ftag

1.0.3 - 2020-04-09

• Allow show to accept .ftag directly

1.0.2 - 2020-04-09

• Fixed directory argument parsing

1.0.1 - 2020-04-06

• Added selection prompt for multiple freezetags

1.0.0 - 2020-04-06

• Initial release