We work hard on our podcasts and we want to make the most out of the work we do. The best kind of content for us is usually evergreen – stuff that will remain true for years. Evergreen podcast episodes help us build a consistent body of work we can point to. Plus it means we’re not having to chase the latest headline or daily hashtag to get traction.
But while the ideas and messages we send out are often timeless, we need our podcast to work for us. An episode recorded three years ago probably doesn’t reflect our work today. So how can we keep our ideas evergreen while giving us the opportunity to talk about what we’re doing right now?
Introducing DAI: dynamic ad insertion
The MP3 format for podcast audio is pretty basic. There’s a bit of metadata at the top of the file, then a stream of bytes that represent the audio. We can stitch MP3 files together and even break them up, with no noticeable effect.
If you’ve ever listened to a podcast from Gimlet, Earwolf, Wondery, or any big network, you’ve heard a dynamically-inserted ad. In some cases you might not even realise it. But it’s not just the big NPRs that do it.
The Adventure Zone moved to dynamic ads back in 2020. Doug Loves Movies started at around a similar time too. I use it for the Podcode podcast, and in my latest project where I help podcasters solve problems. And it’s something I’m encouraging more purpose-driven podcasters to do.
Here comes the science
Here’s how it works for the podcaster:
You specify certain points within your file where dynamic content can be inserted. These are
You separately upload your dynamic “ads” to a library, and tag it. That way your media host knows what to insert where.
You activate a campaign (a set of ads) either manually, or automatically. An automatic campaign can run within a given timeframe. Not all hosts support automatic campaigns, so if yours doesn’t, put a date in your calendar to deactivate your old campaign, and switch to the new one.
Then on the listener’s side:
The listener’s podcast player requests an episode.
As the episode is downloading, the media host injects ads at the points you chose.
Once the ad has been inserted, the original media stream resumes.
I don’t carry ads on my podcast – how is this useful?
This isn’t about advertising for other companies or services. You can use DAI strictly to promote your own work.
Here’s an example. Let’s say you’re a coach, and you have an episode about NLP. It regularly gets a few hundred downloads per month. You’ve got the usual calls-to-action to visit your website or sign up to your newsletter. Now let’s say you’re looking to run a group coaching programme, and you want to put a cohort together. You can record a message about the programme, and have it injected at a specific point in your NLP episode.
Here’s another. A theatre has a podcast that tells the story of their historic building. You have a limited run series, and you’re no longer making episodes, but people still find them on your homepage. At the halfway mark of each episode, you have a space to alert listeners about your latest stage show.
You don’t need to re-edit each episode
Your media host will do the editing for you, so as long as you’ve specified in each episode where ads should go, you’re done. You just need to record any new ads, check the volume levels match, and preview a couple of episodes. Here, you’re listening for any clumsy-sounding transitions between content and ad.
You might already be publishing episodes with timely content baked in. In that case, check to see if your host supports “ad painting” or similar. Ad painting lets you specify a region of audio, remove it, and replace it with content from your ad library.
It’s fiddly to begin with, but you’ll get the hang of it
Some media hosts do a better job than others of letting you specify the insertion point. Captivate uses a graphical interface where you can zoom in to the waveform. This is handy if you need to pinpoint a moment of silence. Transistor (whom I use) don’t currently offer that, but my editing app Descript gives me accurate timecodes.
It adds an extra step to your workflow, but once you’ve got the hang of it, it gets easier. The extra 5 minutes of jiggery-pokery is worth it for an evergreen episode that’s also up-to-date with your latest offerings.
Some tips and caveats
Never place ads directly at the beginning or end of an episode.
You need to demonstrate some value or hook the listener in before you think about drawing their attention to something else.
Ads at the very end of an episode are rarely played, as listeners will have already moved on to the next thing.
Instead, pick points near to the beginning and end for your pre- and post-roll ads. For example, if you have a cold open – a brief bit of speech before the main body of the episode – that’s a great place for a pre-roll. A post-roll ad is better placed before you start wrapping up the show, telling people where to find your guest, etc. If your media host won’t let you place a post-roll ad that far from the end of an episode, ignore the post-roll segment and just insert another mid-roll point.
Some DAI systems are more advanced than others. Some are truly dynamic in that they inject the ad right as the listener’s player is downloading the episode. That technique is usually reserved for external ad campaigns where the ad might differ from one device to another. For example, there are ads running on Conan O’Brien’s show for US audiences that don’t play in the UK.
You’re more likely to use a host that “processes” each episode when the active ad campaign changes, or you move insertion point. In this case, the host bakes the ads fully into the episode file, storing it as a separate copy. They’ll keep the original, but serve the one with ads to listeners.
Keep your timecodes accurate. A timecode is a point in time for a piece of media, so it’s what we use to tell our media host when to insert an ad. It’s usually specified in
HH:MM:SS.mmm (hours, minutes, seconds, microseconds). You need to be accurate to the microsecond, so if you’re copying timecodes, check for a decimal point followed by a number. Otherwise you’ll cut the conversation half-way through a word!
The tech is pretty primitive. You can’t fade in and out of dynamically-inserted segments, or let one bit of audio overlap another. Also, there’s always a fraction of a second at the beginning of a bit of MP3 data. That means the switch from content to ad won’t be gapless.
And finally, always listen back to check your transitions. Ensure the insertion point is in the right place, and make adjustments if needed.
How to put DAI to work in your show
Check with your media host to see if they support dynamic ad insertion. If they don’t, and if it’s not in their roadmap, consider a move. Captivate is by far the most affordable and flexible option right now.
Next, think about your next episode and where you can put in some dynamic content. Consider how you flow in and out of segments, so that the ad feels natural and not tacked on. You’re looking to build trust with your audience, so don’t undermine it with a misaligned message.
Once you have an episode ready to go and where the ads feel natural, think about your back catalogue. Consider re-editing old episodes so that you can add those smooth transitions. If you can’t, pick points in the transitions between one thought and another.
Test your finished episodes out on a few people. Don’t ask them specifically about the ad content, but hint that you’re looking for anything that might be odd or out-of-place.