Twilio Media Stream Save Audio File

This codebase provides a simple Node.js library class that makes it easy to save Twilio media streams to a local audio file in wav format.

Purpose

I was playing around with the Twilio Media Streams and wanted to easily save the phone call to a local wav file after the call completed. I did a quick Google search and found someone on StackOverflow (Inspired by user @tdeo: https://stackoverflow.com/questions/58439005/is-there-any-way-to-save-mulaw-audio-stream-from-twilio-in-a-file) who had provided code snippet for writing a Mulaw header for a WAV-file compatible with twilio format.

To make this a bit simpler I have taken this code snippet and converted it into a Node.js (CommonJS) class library for easier usage.

If you need to save a Twilio Media Stream phone call to a local audio file when the call completes then this library should help you.

Example Usage

const TwilioMediaStreamSaveAudioFile = require("twilio-media-stream-save-audio-file");

const mediaStreamSaver = new TwilioMediaStreamSaveAudioFile({
  saveLocation: __dirname,
  saveFilename: "my-twilio-media-stream-output",
  onSaved: () => console.log("File was saved!"),
});

wss.on("connection", (ws) => {
  console.log("New connection initiated!");

  ws.on("message", (message) => {
    const msg = JSON.parse(message);
    switch (msg.event) {
      case "connected":
        console.log("A new call has connected");
        break;
      case "start":
        console.log(`Starting media stream...`);
        mediaStreamSaver.twilioStreamStart();
        break;
      case "media":
        console.log("Receiving audio...");
        mediaStreamSaver.twilioStreamMedia(msg.media.payload);
        break;
      case "stop":
        console.log("Call has ended");
        mediaStreamSaver.twilioStreamStop();
        break;
      default:
        break;
    }
  });
});

Options

When you instantiate the library you can pass in the following options. They are not required and all optional.

• saveLocation - (Optional) Defaults to the local dir using __dirname. You can set any path you wish. Make sure path exists.

• saveFilename - (Optional) Defaults to the current date timestamp using Date.now(). You can set any filename you wish.

• onSaved - (Optional) This is a optional callback function that you can provide if you want to be notified when the audio wav file has been saved.

Notes

• Inside the connected websocket message event make sure to call each of the corresponding methods for the incoming Twilio Media Stream message events:

  Twilio Media Stream Message Event: start

  • mediaStreamSaver.twilioStreamStart()

  Twilio Media Stream Message Event: media

  • mediaStreamSaver.twilioStreamMedia(twilioMediaPayload)

  Twilio Media Stream Message Event: stop

  • mediaStreamSaver.twilioStreamStop()

For getting started on how Twilio media streams work, check out Twilio.

Author

👤 Jremi [email protected]

• Website: http://stackoverflow.com/users/1062503/jremi
• Github: @jremi

Made with ❤️ in San Diego