abstracting the conversion between id3 tags, m4a tags, flac tags
Question:
I’m looking for a resource in python or bash that will make it easy to take, for example, mp3 file X and m4a file Y and say “copy X’s tags to Y”.
Python’s “mutagen” module is great for manupulating tags in general, but there’s no abstract concept of “artist field” that spans different types of tag; I want a library that handles all the fiddly bits and knows fieldname equivalences. For things not all tag systems can express, I’m okay with information being lost or best-guessed.
(Use case: I encode lossless files to mp3, then go use the mp3s for listening. Every month or so, I want to be able to update the ‘master’ lossless files with whatever tag changes I’ve made to the mp3s. I’m tired of stubbing my toes on implementation differences among formats.)
Answers:
You can just write a simple app with a mapping of each tag name in each format to an “abstract tag” type, and then its easy to convert from one to the other. You don’t even have to know all available types – just those that you are interested in.
Seems to me like a weekend-project type of time investment, possibly less. Have fun, and I won’t mind taking a peek at your implementation and even using it – if you won’t mind releasing it of course 🙂 .
I needed this exact thing, and I, too, realized quickly that mutagen is not a distant enough abstraction to do this kind of thing. Fortunately, the authors of mutagen needed it for their media player QuodLibet.
I had to dig through the QuodLibet source to find out how to use it, but once I understood it, I wrote a utility called sequitur which is intended to be a command line equivalent to ExFalso (QuodLibet’s tagging component). It uses this abstraction mechanism and provides some added abstraction and functionality.
If you want to check out the source, here’s a link to the latest tarball. The package is actually a set of three command line scripts and a module for interfacing with QL. If you want to install the whole thing, you can use:
easy_install QLCLI
One thing to keep in mind about exfalso/quodlibet (and consequently sequitur) is that they actually implement audio metadata properly, which means that all tags support multiple values (unless the file type prohibits it, which there aren’t many that do). So, doing something like:
print qllib.AudioFile('foo.mp3')['artist']
Will not output a single string, but will output a list of strings like:
[u'The First Artist', u'The Second Artist']
The way you might use it to copy tags would be something like:
import os.path
import qllib # this is the module that comes with QLCLI
def update_tags(mp3_fn, flac_fn):
mp3 = qllib.AudioFile(mp3_fn)
flac = qllib.AudioFile(flac_fn)
# you can iterate over the tag names
# they will be the same for all file types
for tag_name in mp3:
flac[tag_name] = mp3[tag_name]
flac.write()
mp3_filenames = ['foo.mp3', 'bar.mp3', 'baz.mp3']
for mp3_fn in mp3_filenames:
flac_fn = os.path.splitext(mp3_fn)[0] + '.flac'
if os.path.getmtime(mp3_fn) != os.path.getmtime(flac_fn):
update_tags(mp3_fn, flac_fn)
There’s also tagpy, which seems to work well.
Here’s some example code, a script that I wrote to copy tags between
files using Quod Libet’s music format classes (not mutagen’s!). To run
it, just do copytags.py src1 dest1 src2 dest2 src3 dest3, and it
will copy the tags in sec1 to dest1 (after deleting any existing tags
on dest1!), and so on. Note the blacklist, which you should tweak to
your own preference. The blacklist will not only prevent certain tags
from being copied, it will also prevent them from being clobbered in
the destination file.
To be clear, Quod Libet’s format-agnostic tagging is not a feature of mutagen; it is implemented on top of mutagen. So if you want format-agnostic tagging, you need to use quodlibet.formats.MusicFile to open your files instead of mutagen.File.
Code can now be found here: https://github.com/DarwinAwardWinner/copytags
If you also want to do transcoding at the same time, use this: https://github.com/DarwinAwardWinner/transfercoder
One critical detail for me was that Quod Libet’s music format classes
expect QL’s configuration to be loaded, hence the config.init line in my
script. Without that, I get all sorts of errors when loading or saving
files.
I have tested this script for copying between flac, ogg, and mp3, with “standard” tags, as well as arbitrary tags. It has worked perfectly so far.
As for the reason that I didn’t use QLLib, it didn’t work for me. I suspect it was getting the same config-related errors as I was, but was silently ignoring them and simply failing to write tags.
I have a bash script that does exactly that, atwat-tagger. It supports flac, mp3, ogg and mp4 files.
usage: `atwat-tagger.sh inputfile.mp3 outputfile.ogg`
I know your project is already finished, but somebody who finds this page through a search engine might find it useful.
Since the other solutions have mostly fallen off the net, here is what I came up, based on the python mediafile library (python3-mediafile in Debian GNU/Linux).
#!/usr/bin/python3
import sys
from mediafile import MediaFile
src = MediaFile (sys.argv [1])
dst = MediaFile (sys.argv [2])
for field in src.fields ():
try:
setattr (dst, field, getattr (src, field))
except:
pass
dst.save ()
Usage: mediafile-mergetags srcfile dstfile
It copies (merges) all tags from srcfile into dstfile, and seems to work properly with flac, opus, mp3 and so on, including copying album art.
I’m looking for a resource in python or bash that will make it easy to take, for example, mp3 file X and m4a file Y and say “copy X’s tags to Y”.
Python’s “mutagen” module is great for manupulating tags in general, but there’s no abstract concept of “artist field” that spans different types of tag; I want a library that handles all the fiddly bits and knows fieldname equivalences. For things not all tag systems can express, I’m okay with information being lost or best-guessed.
(Use case: I encode lossless files to mp3, then go use the mp3s for listening. Every month or so, I want to be able to update the ‘master’ lossless files with whatever tag changes I’ve made to the mp3s. I’m tired of stubbing my toes on implementation differences among formats.)
You can just write a simple app with a mapping of each tag name in each format to an “abstract tag” type, and then its easy to convert from one to the other. You don’t even have to know all available types – just those that you are interested in.
Seems to me like a weekend-project type of time investment, possibly less. Have fun, and I won’t mind taking a peek at your implementation and even using it – if you won’t mind releasing it of course 🙂 .
I needed this exact thing, and I, too, realized quickly that mutagen is not a distant enough abstraction to do this kind of thing. Fortunately, the authors of mutagen needed it for their media player QuodLibet.
I had to dig through the QuodLibet source to find out how to use it, but once I understood it, I wrote a utility called sequitur which is intended to be a command line equivalent to ExFalso (QuodLibet’s tagging component). It uses this abstraction mechanism and provides some added abstraction and functionality.
If you want to check out the source, here’s a link to the latest tarball. The package is actually a set of three command line scripts and a module for interfacing with QL. If you want to install the whole thing, you can use:
easy_install QLCLI
One thing to keep in mind about exfalso/quodlibet (and consequently sequitur) is that they actually implement audio metadata properly, which means that all tags support multiple values (unless the file type prohibits it, which there aren’t many that do). So, doing something like:
print qllib.AudioFile('foo.mp3')['artist']
Will not output a single string, but will output a list of strings like:
[u'The First Artist', u'The Second Artist']
The way you might use it to copy tags would be something like:
import os.path
import qllib # this is the module that comes with QLCLI
def update_tags(mp3_fn, flac_fn):
mp3 = qllib.AudioFile(mp3_fn)
flac = qllib.AudioFile(flac_fn)
# you can iterate over the tag names
# they will be the same for all file types
for tag_name in mp3:
flac[tag_name] = mp3[tag_name]
flac.write()
mp3_filenames = ['foo.mp3', 'bar.mp3', 'baz.mp3']
for mp3_fn in mp3_filenames:
flac_fn = os.path.splitext(mp3_fn)[0] + '.flac'
if os.path.getmtime(mp3_fn) != os.path.getmtime(flac_fn):
update_tags(mp3_fn, flac_fn)
There’s also tagpy, which seems to work well.
Here’s some example code, a script that I wrote to copy tags between
files using Quod Libet’s music format classes (not mutagen’s!). To run
it, just do copytags.py src1 dest1 src2 dest2 src3 dest3, and it
will copy the tags in sec1 to dest1 (after deleting any existing tags
on dest1!), and so on. Note the blacklist, which you should tweak to
your own preference. The blacklist will not only prevent certain tags
from being copied, it will also prevent them from being clobbered in
the destination file.
To be clear, Quod Libet’s format-agnostic tagging is not a feature of mutagen; it is implemented on top of mutagen. So if you want format-agnostic tagging, you need to use quodlibet.formats.MusicFile to open your files instead of mutagen.File.
Code can now be found here: https://github.com/DarwinAwardWinner/copytags
If you also want to do transcoding at the same time, use this: https://github.com/DarwinAwardWinner/transfercoder
One critical detail for me was that Quod Libet’s music format classes
expect QL’s configuration to be loaded, hence the config.init line in my
script. Without that, I get all sorts of errors when loading or saving
files.
I have tested this script for copying between flac, ogg, and mp3, with “standard” tags, as well as arbitrary tags. It has worked perfectly so far.
As for the reason that I didn’t use QLLib, it didn’t work for me. I suspect it was getting the same config-related errors as I was, but was silently ignoring them and simply failing to write tags.
I have a bash script that does exactly that, atwat-tagger. It supports flac, mp3, ogg and mp4 files.
usage: `atwat-tagger.sh inputfile.mp3 outputfile.ogg`
I know your project is already finished, but somebody who finds this page through a search engine might find it useful.
Since the other solutions have mostly fallen off the net, here is what I came up, based on the python mediafile library (python3-mediafile in Debian GNU/Linux).
#!/usr/bin/python3
import sys
from mediafile import MediaFile
src = MediaFile (sys.argv [1])
dst = MediaFile (sys.argv [2])
for field in src.fields ():
try:
setattr (dst, field, getattr (src, field))
except:
pass
dst.save ()
Usage: mediafile-mergetags srcfile dstfile
It copies (merges) all tags from srcfile into dstfile, and seems to work properly with flac, opus, mp3 and so on, including copying album art.