This is a script that allows you to recompress FLAC files while preserving their tags, intended for whole directories and for safety regardless of file name characters and encoding.
When storing FLACs on your big storage (desktop computer, NAS, etc),
there may be a desire to compress them to the maximum extent possible,
saving disk space and potentially many gigabytes for large
collections. For this, you might use reflac --best on them.
However, slow and old systems might not have the capability to decode
a maximally-compressed (or even the standard compression ratio) quick
enough for real-time playback, and recompressing in a lower setting
might be beneficial as well. This script started life, in a very
rudimentary form for this purpose. The author used Rockbox on an old
black/white display iPod, and found that flac -3 was the maximum he
could compress FLACs while maintaining uninterrupted playback on the
device.
flac needs to be in your $PATH. This program is normally packaged
as “flac” by distributions.
The script both depends on Bash and GNU features of other core
utilities. Versions of mv, getopt, sync, etc from other sources
(such as the *BSD operating systems) might work, but require
compatibility with the same switches found in the GNU versions.
reflac has only been developed on tested on GNU+Linux, but should work on any other operating system with the appropriate tools.
By default, reflac performs a sync on files after two points of its process: after moving the recompressed file from the temporary directory to the original location, and after renaming the file from “*.new” to the original name. This should provide safety in the case of system crashes or processes being killed.
Assuming file system syncs have not been disabled, one of two scenarios should arise in the worst case:
-
No new files appear in the directory. A complete FLAC file may or may not still be available in a temporary staging directory under /tmp.
-
There exists an additional “*.new” file in the directory being processed, which may or may not be a complete FLAC file, the status of which can be tested with
flac -t.
Usage: reflac [OPTION]... [--] DIRECTORY...
-h --help Displays this help text
-0 --fast Use the fastest, but worst, compression possible.
-1..-7 Adjust FLAC compression between these standard ranges.
The default is -5, the same as for flac itself.
-8 --best Use the slowest, but best, compression possible.
-n --no-action Do not recompress. With --verbose, displays a list of
files that would be processed.
-r --recursive Recurse into directories.
-s --no-sync Do not synchronize file data. Will return faster, with
the potential danger to lose your files in a system crash.
-v --verbose Increases the verbosity. Use once to display the FLACs
currently being processed, use twice for the full ‘flac’
output.
-V --version Displays the version of this program
DIRECTORY should point ‘reflac’ to somewhere that contains *.flac
files. Optionally terminate the argument list with -- so that any
possible directory names don’t get misinterpreted as arguments.
What, bugs? This program is flawless! Joking aside, although the author tries to resolve in reflac itself, it is at the mercy of bugs and limitations from flac and metaflac.
Tag preservation in the light of malformed tags simply does not exist. Certain release groups use buggy software with the creation of their files and will trigger some grievances.
You might see something like this:
$ reflac FLAC
/tmp/reflac.p8OjPn32z8/1-01 The Strange Green Pipe (Medley) [Mikeaudio].tag: ERROR: malformed vorbis comment field "Super Mario 64: Portrait of a Plumber",
field contains no '=' character
reflac will not continue after the error, resulting in the untagged-but-recompressed file remaining in the temporary directory, the path of which should be part of the error message as in the example. The original file will not have been overwritten, maintaining the existing compression as well as the existing tags.
The choice is left to the user for repairing the file manually, such
as by using metaflac, or removing the temporary directory
altogether. The author uses, and recommends,
MusicBrainz Picard to retag files
before using reflac.