Flex: Ad markers

Let Acast know where to place ads

Updated over a week ago

To access monetisation through Flex means you will need to deliver details of where you would like ads to be stitched into the audio files. These placements are then read by our system, which will then place the correct number of ads and sponsorships into the audio based on your show's ad settings.

Types of Ad Slots

Ads can either be placed in the pre-roll, mid-roll or post-roll - 3 defined positions within the audio file. Within each placement, any number combination of Ads or Sponsorship can be delivered.

Sponsorships - these are narrator or host read messages, delivered against every listen on a show over a given period of time.

Ads - Ads are brand messages delivered over a range of shows, targeted by audience of context, and paced to deliver to an impression goal over time.

Specific order of ads and sponsorships in each placement:

In each ad marker placed in your episode, a mixture of ads and sponsorships can be played in a specified order.

  • Pre-roll: Ads are placed before sponsorship, so the sponsorship runs seamlessly into the content when placed at the start of the episode

  • Mid-roll: Ads are placed before sponsorship

  • Post-roll: Sponsorship are placed for ads, so the sponsorship is heard along with the episode content when placed at the end of the episode.

Ad marker placement options

To position your ad slots within the episodes, you can use ID3 tags embedded within the audio file or encrypted XML information sent directly on the RSS feed.

ID3 Tags

Ad markers can be placed by inserting the ad break position in an ID3v2 tag within the MP3 file. The ad marker can be added to any field in the ID3v2 header of the MP3 file in your preferred editing software.

The ID3v2 tag can have any name but should use the following format:


[slot] has one of these values:

  • PRE: for positioning of a pre-roll

  • 1: for positioning of a mid-roll

  • POST: for positioning of a post-roll

[time] is expressed either as an integer in milliseconds from the start, or in HH:MM:SS:mmm format (where mmm stands for milliseconds).

Multiple ad breaks can be included, with each separated by a semicolon in the ID3 tag.

Example 1: For a mid-roll ad break at 1 hour 23 minutes 10 seconds and 200 milliseconds:


Example 2: Ad break at 1 hour 23 minutes 10 seconds and 200 milliseconds:


Example 3: Pre-roll at the two-second mark, mid-roll at 35 minutes 12 seconds and 456 milliseconds:


Pre- and post-roll ID3 tags are optional. If not set, a pre-roll will automatically be added at the 0 position, and a post-roll at the end of the episode.

Mid-roll ID3 tags are also optional. However, if no mid-roll marker is set, no mid-roll ad or sponsorship will be served in that episode.

Encrypted XML

A payload can be added inside the RSS item at the episode level, with the position of the ads and some additional, advanced settings for the file.

A payload can also be added at the show level to act as the default for all episodes.

See here for more information.

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