Output Audio

There are two primary methods of outputting audio from bots:

Platform Support

Google Meet:white-check-mark:
Microsoft Teams:white-check-mark:
Cisco Webex:white-check-mark:
Slack Huddles:x:

Audio Format

Audio should be provided as an mp3 encoded as a base 64 string.

MP3 files can easily be converted to a b64 string using CLI tools such as ffmpeg or an online tool such as b64Guru.

Outputting Audio

Using automatic_audio_output

Create Bot accepts an automatic_audio_output configuration for automatically outputting audio when the bot starts recording, with the option to repeat the audio when participants join.

data allows you to specify the mp3 the bot should play.

  • kind - The type of data encoded in the b64 string (Currently only mp3 is supported)
  • b64_data - Data encoded in Base64 format, using the standard alphabet (as specified here)

replay_on_participant_join can be optionally used to repeat the audio whenever someone joins.

  • debounce_mode: Debounce mode ("trailing" or "leading")
    • leading: The debounce timer will start counting down when the first participant joins.
    • trailing: The debounce timer will start counting down when the last participant joins.
  • debounce_interval: The amount of time to wait for additional participants to join before replaying the audio.
  • disable_after: The number of seconds after which the audio will no longer replay when new participants join. This parameter is useful to prevent the bot from interrupting a meeting, if a late participant joins.

automatic_audio_output example

// POST https://api.recall.ai/api/v1/bot/
  "automatic_audio_output": {
    "in_call_recording": {
      "data": {
        "kind": "mp3",
        "b64_data": "..."
      "replay_on_participant_join": {
        "debounce_mode": "trailing",
        "debounce_interval": 10, 
        "disable_after": 60

Using the above configuration as an example, let's say we have the following scenario:

  • Participant 1 is there a bit early and joins right before the bot starts recording.
  • 5 seconds after recording starts, Participant 2 joins.
  • 5 seconds later, Participant 3 joins.
  • Participant 4 is running late, and joins the call three minutes after recording starts.

In this scenario, Participants 1 and 4's experiences are fairly straightforward.

  • Participant 1 hears the audio played when the bot starts recording.
  • Participant 4 never hears the audio played since they joined 180 seconds after the bot started recording, which is greater than the disabled_after value of 60.

Participants 2 and 3 will experience something slightly different based on the debounce_mode:

  • In trailing mode, the audio would play 10 seconds after Participant 3 joins (15 seconds after Participant 2 joins).
  • If we set the debounce_mode to leading, however, the audio will play 10 seconds after Participant 2 joins (5 seconds after Participant 3 joins).

Using the Output Audio endpoint

If your use case requires more manual control over outputting bot audio, you can use the Output Audio endpoint.

This endpoint takes the same parameters as the bot configuration objects above:

// POST https://api.recall.ai/api/v1/bot/{id}/output_audio/
  "kind": "mp3",
  "b64_data": "..." // b64 encoded string