Forecast by Marco Arment — What It Is, How It Works, and Why Podcasters Should Take a Look

How to Create Podcast Chapters for Your Show

You can download Forecast for free over at

Marco Arment created and shared a Mac app called Forecast for adding chapters to podcast episodes, and it’s great.

How MP3 chapters work in the Overcast iPad app

Forecast is also an MP3 encoder: It takes a .wav file and turns it into an MP3 (quickly, Marco says, by using all the available processor cores in your computer). It also has some other cool features that I’ll share with you in a minute.

🖥 👉 Watch my full screencast tutorial for Forecast here:

How Does It Work?

After downloading and opening Forecast, you’ll need a .wav file to import into the app. You can either click the Import Audio button in the top left and find your file in the Finder, or drag and drop your file into the Import Button area of the app.

As soon as you import the .wav file, Forecast will start encoding it as an MP3. This is a great feature and a huge time saver, because you can add the other information while the file is being encoded. Great touch, Mr. Arment.

Next, add your podcast title, episode title, and the summary of the episode.

Adding Chapters with Markers

Forecast makes it really easy to add podcast chapters with time-stamps. Simply drop a marker in your editing software for the start of each chapter. So you can mark the intro, your sponsor, and the main topics.

Forecast even gives you the option to export the audio for your sponsor read chapters (called “Airchecks”) so your sponsors can hear how well you sold their product or service to your listeners.

If you’d like to try including chapters in your podcast, start by thinking of the different sections of your show (or questions if you’re doing an interview show) as chapters. Then while you’re recording or editing, drop markers in the right place.

When you’re done editing your episode and you export your .wav file and import it into Forecast, all your markers should show up as chapters with timestamps. You can then add custom square images and URLs for each chapter if you’d like.

Setting Up an Automated Workflow with Hazel

If you’d like to save a step or two, create a rule in Hazel that watches a folder on your hard drive for new .wav files.

Create a rule that says when Hazel sees a new .wav file in that folder, open it with the Forecast application.

There are some other things that you can do with Hazel and Keyboard Maestro related to automating your podcast export/tagging process, but I’ll save those for another tutorial.

Does Forecast Save Time When Exporting?

I was curious about how long it would take Forecast to encode an MP3 file versus how long it would Logic Pro X to export the same MP3.

I performed this test on my main computer, a stock 2016 13" Macbook Pro without a touchbar (2.0ghz i5, 8gb of ram, 250gb SSD). I’m going to guess that encoding would be faster on a Macbook with more cores.

There were a couple plugins used on each track, nothing hardcore (Izotope plugins, while great, also add a lot of time when exporting a file).

  1. First test was bouncing a stereo .wav file with Logic Pro X. Time was 2 minutes, 30 seconds. Not bad. This is time we’ll include with Forecast’s total time since Forecast needs a .wav file as an input.
  2. Second test was Logic Pro X bouncing a .mp3 file: 3 minutes, 24 seconds. So Logic took about an extra minute to convert the .wav file to a .mp3 file.
  3. Third test was Forecast encoding .wav to .mp3: 40 seconds. Add Logic’s 2 minutes and 30 seconds to that and you end up with 3 minutes and 10 seconds.

So it looks like Logic for the .wav + Forecast for the .mp3 file is a little faster than Logic by itself, but there’s another thing to consider: Logic Pro X has occasionally been outputting corrupted MP3 files for me. I have no idea why, but one or two out of every ten MP3 files I export from Logic is screwed up and has to be re-bounced. It’s just something I’ve dealt with in the past, but I don’t really want to deal with re-bouncing files anymore.

Since Forecast seems to be more reliable than Logic Pro X when it comes to exporting MP3 files, it will save me a few minutes each week at the very least. I imagine that Forecast will save full-time podcast editors a lot of time.

Silence Warnings

Another feature of Forecast that I really like: It will give you a list of long silences that might be unintentional, which will help you spot mistakes (like leaving 30 minutes of silence at the end of an episode, which is something that I’ve done on a few occasions). This is a useful feature and shows that Marco is trying to solve real problems that podcasters face with this app.

Wrapping Up

I’ve started using Forecast to tag and add chapters to Dribbble’s Overtime podcast, and I’ve been really pleased with the results, although it looks like some podcast apps don’t currently display the chapters. I’m interested to see if other podcasters start including chapters with their podcasts.

Update: Apple Podcasts will be supporting chapters in iOS 12.

Big thanks to Marco for creating and sharing a useful tool for podcasters.

You can download Forecast here.

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