I need to convert approximately 15000 FLAC files to MP3 as a one time job.
It is a large audio archive containing 50 years worth of interviews, talks-shows, radio-speeches and monologues belonging to the radio-station I do volunteer work for.
As of 2017 all new stuff is recorded straight in MP3, but we have a huge library of older analog material that got digitized to FLAC in 2018.
(I only got involved later. If I had been there I would have saved everything in both formats from the start.)

I'm looking for a MacOS batch-convert utility (command-line only would be ok too) that is free (this is a short on cash non-profit volunteer organization) and that can do the conversion including the ID3 tags in the FLAC files.
The ID3 metadata is very important to keep: loosing that during the conversion is NOT acceptable.
Typical batch-size would be ideally be 300-400 files in a single run.
Performance (or lack there of) is not a consideration. We have plenty of time.

This is a Mac only outfit, but I'm willing to consider Windows or Linux software if there is nothing available for MacOS. I can setup a VM with Windows or Linux if needed, but I like to avoid that if possible: Our available Macs are aging and not blessed with a lot of RAM.

I've been Googling around but most software seems to be limited use trail-ware that needs payment before it can be used properly. And there is a lot of downloads from dubious sources. Other software seems old and not working on MacOS Catalina at all.

Anybody knows of a good converter?

  • Take a look at FFmpeg, it contains a command-line tool that most likely does what you want. Writing a simple Bash script to convert all your files shouldn't be that hard to do.
    – wb9688
    Sep 1, 2020 at 11:54
  • @wb9688 I know about ffmpeg and I can wriote bash scripts, but I have had serious issues in the past with ffmpeg not handling all ID3 tags well, which makes it a no-go for me.
    – Tonny
    Sep 1, 2020 at 12:04
  • FFmpeg should handle ID3v2 by default now and there probably are command line options for getting ID3v1 as well. 90% of other converters are just wrappers around FFmpeg, so I'd say to just try FFmpeg on one of the files and if it works, write a simple Bash script to do that command for all of the files.
    – wb9688
    Sep 1, 2020 at 12:09
  • @wb9688 I will most definitely look into ffmpeg. It has been a few years I last used it for something like this. Maybe it is better know.
    – Tonny
    Sep 1, 2020 at 13:57

1 Answer 1


There is a free app named Adaptor that will do what you want and runs in batch mode.

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