Saturday, August 12, 2017

A Workaround for the MP3 Tagging Problem

I have found a workaround for the problem I was having. To quickly summarize, I use Logic Pro 9 to export projects to wave files. Then I want to convert them to fully tagged MP3 files.

I've been doing the conversion by hand using iTunes, and tagging in iTunes too. My projects tend to be in higher sample rates and bit depths -- for example, 24-bit, 96KHz. I would use Logic Pro to export the files to MP3 format, and tag them, but I have the following issues:

  1. In Logic Pro 9, if I ask Logic to bounce this project to an MP3 file, it does a long series of conversions and the end result is that I get an MP3 file at 48KHz, which is not what I want. There does not seem to be an option to force it to use 44.1KHz.
  2. In Logic Pro 9, you can also ask Logic to tag your file, but if you supply long fields, it will truncate them. I think this is because it supports a somewhat out-of-date version of the ID3 standard, while iTunes supports a later version which supports longer fields.

So why not just upgrade to Logic Pro X? Well, first, I'm not sure if this would actually fix the problem. At the moment, money is a bit tight. And I'm recording on a 2009 "3,1" Mac Mini. It works great, although it is slow. I don't think installing Logic Pro X on this machine is likely to make my projects easier. Most likely, Pro X eats considerably more memory and CPU and disc space than Logic Pro 9. So the plan is to make do, as much as possible, with what I have, until I can do some major upgrades, including replacing the computer.

Anyhow, to work around these issues with Logic Pro 9, I've been bouncing to a WAVE file, then bringing the 16-bit, 44.1KHz WAVE file into iTunes, creating an MP3 using iTunes, then tagging it by hand.

I wanted to see if I could do some of these steps on the command line, so I could do it in a script, a BBEdit worksheet, or even a Makefile. I'd like to automate that somewhat, not so much because I'm spending that much time producing podcasts, but because all these steps are error-prone. I'd also like to automate, at least partially, the generation of the entries in the podcast feed file. I'm always screwing up the time zone offset in dates, or forgetting to update the size of the file in bytes. It would be nice to have a script to do the grunt work, especially since I am often making versions to test, before I am happy enough with them to add them to the live podcast feed.

So I was trying to use LAME to do the encoding and tagging, but I discovered that iTunes would not import the "comment" field in the MP3 files created and tagged by LAME.

I asked Dan Benjamin on Twitter, and was happy that he replied, but he just wrote "Why not just bounce correctly from Logic?"

Maybe that works for him, but as I explained above, and in the link I sent him, it doesn't work for me, because I wind up with MP3 files encoded at 48KHz. I don't want to get too far into the weeds here, but I believe that making 48KHz MP3 files for podcasts are fairly pointless for most users, since they will need to be resampled on playback and resampling is lossy. For most listeners playing the files back on typical devices, 48KHz is a waste of storage space and will not provide a quality boost over a 44.1KHz file.

I also want to be able to use comment fields like this:

This work by Paul R. Potts is released under the Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported License ( See for more information.

And not have them truncated.

In the Hydrogen Audio forum I got a couple of useful replies, but no solutions as such. The root of the problem seems to be that iTunes silently fails to import certain types of comment fields in MP3 tags. I don't want to go too far down the ID3 rabbit hole, but it seems like if the language specified for the comment field is "XXX," iTunes will not import it.

When LAME writes an ID3v2 comment tag, it seems to set the language to either some unicode string, or if the command-line switch --id3v2-latin1 is used, to "XXX." There doesn't seem to be an option to set it to something else. In either case, iTunes will not import this field.

My wife Grace said "your encoder is lame."

I tried to use the id3v2 command-line tool to add the tags to my MP3 file instead. Since I'm making a script, I have no qualms about using two command-line tools instead of one, if that works. But id3v2 seems to have the same problem. It supports the --id3v2-only switch, but there does not seem to be any equivalent of the --id3v2-latin1 switch, so I can't get it to write an iTunes-compatible comment field either.

My workaround was to rebuild LAME, replacing several hard-coded instances of "XXX" with "eng." This is not exactly a bug to report, since I'm not sure that LAME is actually "wrong" per se, according to the standard. But I can't fix the issue in iTunes. And like it or not, if I want maximum compatibility, I have to generate files that work well with iTunes.

A better solution would probably be to give LAME more options. Specifically for this problem an option to set the comment language would be nice. I would hesitate to add a specific switch like --workarounditunes which just forced the comment language to "eng," but maybe the ability to set the comment language would be useful for other folks, while providing a workaround for this compatibility problem.

Ypsilanti, Michigan
August 12, 2017

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