"How did you do that?" A friend of mine asked a few weeks ago when he saw me right-click a file, click "Get Spectrogram" and watch an image like the one above appear on my screen. I had just downloaded a file from Soulseek^[1] and wanted to verify whether the purported AIFF file was actually legitimate or a bad transcode. Once I confirmed it was genuine, I right-clicked again and converted it to 320kbps MP3—all without leaving Finder.

I had achieved this by using a feature of macOS called "Quick Actions". Quick Actions, introduced in macOS High Sierra, allow you to build your own plug-ins that can be applied in other apps. They can be used by right-clicking files, folders, or text, and can even have keyboard shortcuts assigned to them. They're extremely powerful tools that allow me to do all kinds of tasks on my computer. As a DJ and music collector, I use Quick Actions to help me convert files and verify if the files I have are what they claim to be.

If you already know what transcodes are and how you can detect them, skip ahead to the installation guide.

Why audio quality matters for DJs

If you've ever heard a song sound great on your laptop speakers but terrible when a DJ plays it out, you've probably experienced the difference audio quality makes. Club sound systems are unforgiving. They'll expose every loss of fidelity in a low-quality file.

MP3 is a "lossy" compression format, meaning the compression algorithm causes actual loss of audio data. The lower the bitrate (represented in kbps) of an MP3, the more audio data loss and the lower the sound quality. The general rule of thumb is that music you plan to play as a DJ should at the very least be 320kbps MP3. Some DJs only play lossless music (WAV, AIFF, or FLAC), but this does take up more storage space.

Most of the music in my Rekordbox library is 320kbps MP3. For some important tracks, I prefer to have it in lossless AIFF. I don't put FLAC files into Rekordbox because some older CDJ models do not support FLAC. As a result, I often find myself converting file types, and I wanted a quick way to do so directly from Finder.

The problem with bad transcodes

Some files you may find on the internet may be "bad transcodes" (or just "transcodes" for short). These are files that claim to be lossless or a certain bitrate MP3, but are in fact not.

The first time a file is converted to a lossy format, audio information is permanently lost and can never be recovered through further conversion. Bad transcodes can be created by converting a lossy format more than once (for example converting a 128kbps file to 320kbps, or vice versa), or by converting a lossy format file back to a lossless format.

In general, if I'm buying music from an online marketplace like Bandcamp or Beatport, I can trust that a WAV or AIFF is actually lossless and a 320kbps MP3 is actually a 320kbps MP3. However, I never trust the quality of a file I download from Soulseek. You would be surprised how many times I find that a supposedly lossless or 320kbps file from Soulseek is actually an upconverted 128kbps YouTube rip.

What does a bad transcode look like?

Audio files can be represented visually through a graph called a spectrogram. A spectrogram shows which frequencies are represented in an audio signal over time. Since lossy formats generally remove audio information at higher frequencies, we can often see the difference between a transcode and a valid file in the spectrogram.

The image below shows two versions of the same song that both claim to be "320kbps". One is a genuine 320kbps MP3, and the other is a bad transcode (a 128kbps file that was converted up to 320kbps):

Notice how the genuine 320kbps file has frequencies extending all the way up to 20kHz, while the bad transcode has a sharp cutoff around 16kHz. This cutoff is a dead giveaway that the file was originally encoded at a lower bitrate.

If you want more information on spectrograms, check out Redacted Interview Prep for a good guide.

My workflow

My general workflow when I download a file is to first analyze the spectrogram to verify the file is not a bad transcode. If the file I downloaded is truly a lossless AIFF or FLAC, I then convert it to the desired format. To speed up this workflow, I have created 3 Quick Actions:

1. Get Spectrogram - generates and shows a spectrogram image for the selected file
2. Convert to MP3 (320) - converts audio files to 320kbps MP3
3. Convert to AIFF - converts audio files to lossless AIFF

Installation guide

This installation guide will walk you through how to install sox and ffmpeg. If you already have these installed or have a preferred way to install command line tools, you can skip ahead to Install The Quick Actions.

Caveats:

• Setting up these Quick Actions will require you to use the Terminal to install some programs. It's pretty easy, and I will walk you through it.

• Quick Actions are a Mac-only feature, but maybe Windows and Linux distros have similar concepts. The scripts that these Quick Actions use could still be useful to you regardless of what platform you're on.

Opening up Terminal

You can find the Terminal on the Mac by opening the Applications folder, then going to the Utilities folder, and finally double-clicking on Terminal.

Installing Homebrew

Homebrew is a command-line package manager macOS. It allows you to install the programs you will need to run these Quick Actions in the Terminal.

To install Homebrew, run this command in your Terminal:

/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"

Installing ffmpeg and sox

ffmpeg is a software package that allows users to convert and modify audio and video files. The Convert to MP3 and Convert to AIFF scripts use it.

sox or Sound eXchange is an audio editing software. It is what we use to generate the spectrogram.

In Terminal, run this command.

brew install ffmpeg sox

Install the Quick Actions

Quick Actions can be edited and installed in the Automator app, which is installed by default on Mac.

You can download the Quick Actions here. If you're not on macOS and would just like to use the scripts, you can copy them from this GitHub Gist.

Once you've unzipped automator-actions-for-djs.zip, you should see a folder with 3 files, one for each Quick Action. To install, double click each of them and click "Install" on the dialog that shows up.

🎉 Hooray! The Quick Actions should now be available to use. Right-click any audio file in Finder to use them.

What's next?

With these three Quick Actions installed, you'll be able to quickly verify and convert audio files right from Finder. No more guessing whether that "lossless" file is actually what it claims to be, and no more opening separate apps just to convert between formats.

Quick Actions can be a powerful tool for all kinds of problems, so I encourage you to try and find your own ways to save time by experimenting with them!

Questions or issues? Feel free to email me if you run into any problems setting these up. I'll try my best to keep this article updated with any problems people bring up.

Found this helpful? Consider buying me a coffee to support more DJ tools and tutorials!

I'm really excited to share that I will be playing at System Activate, a new rite of the Motherbeat, in Central Vermont this summer.

Close friends will know that my first (known) experience with the Motherbeat was at Eris Drew's set at TUF til Dawn in 2017. It is what motivated me to start DJing again. I am so thankful for the journey it set me out on.

Naturally, when I received the invitation to play, my first reaction was to start bawling.

I'm already so anxious to share music with friends new and old at this experimental, intentional rave. Be sure to check out the site and read more about the idea.

https://systemactivate.com

As people talk about moving away from social media and look towards other paths to community on the web, I have been thinking about how many people and businesses have forgotten about the importance of making their own websites.

I know plenty of people who promote themselves online but don't have any web presence beyond social media. For a couple of years, even I let my website fall into neglect.

Like most other musicians, DJs, and business owners, I've felt like leaving social media is nearly impossible. It's where I announce shows, promote my projects, connect with like-minded people, and have fun. The idea of moving away from it is terrifying... what if all those connections disappear?

But the connections we build through Instagram, Tiktok, and Twitter are not entirely our own. They filter through obfuscated algorithms that dictate what people see. We worry about getting "shadowbanned" or wonder why our event flyer isn't getting as much engagement. We re-structure our speech and our content to try and satisfy the algorithm. Meanwhile, we're fed addictive content, often at the cost of our well-being. If we step out of line, we risk our content being removed or fading into digital obscurity.

I always have gone to the web for connection and for fun. But this? This isn't cool or fun at all.

The solution isn't just hopping over to a new platform. Substack is not just a way to send newsletters, it's another social media platform that does not ban Nazis. Medium is a terrible platform to read on. And even though I use Bluesky, it's just Twitter methadone. We can't trust platforms to stay good.

We can only make the web better by doing it ourselves.

Make a website. Make a blog with an RSS feed. Start an e-mail list. Visit your friends' websites.

Be cool. Have fun. 😎