What is the expected payload format to send audio to Plivo?

Plivo expects the audio to stream in a specific format. Below is the expected payload to send audio to Plivo.

{
  "event": "playAudio",
  "media": {
    "contentType": "audio/x-l16 or audio/x-mulaw",
    "sampleRate": 8000,
    "payload": "base64 encoded raw audio.."
  }
}

• contentType: can be (audio/x-l16, audio/x-mulaw)
• sampleRate: 8000 or 16000
• payload: base64 encoded raw audio