custom-audio-config

How to pass different audio codecs

Sometimes you need to pass different audio codecs when passing the audio. This example shows how to pass them. The ones currently supported are

[OPUS](https://opus-codec.org/):
  - Supported Sample Rates -- 16000Hz, 24000Hz,48000Hz
  - Both CBR (Constant Bitrate) and VBR (Variable Bitrate) are supported
  - Support for in-band FEC

  [SPEEX](https://www.speex.org/):
    - Supported Sample Rates -- 16000Hz
    - VBR is not supported

  [LINEAR16](https://tools.ietf.org/html/rfc2586)
    - Supported Sample Rates -- 44100Hz

  [MULAW](https://en.wikipedia.org/wiki/G.711#%CE%BC-law)
    - Supported Sample Rates -- 8000Hz

NOTE: We recommend using OPUS as compared to other codecs because it provides the most flexibility in terms of audio transportation and also has packet retransmission mechanisms like FEC which work well especially in low-bandwidth scenarios.

Getting started

Open .env file and add your APP_ID, APP_SECRET, SUMMARY_EMAIL. You can get APP_ID and APP_SECRET from https://platform.symbl.ai

We will use symbl-node package.

require('dotenv').config()

const {sdk} = require('symbl-node')

Let's start by initialising symbl-node sdk

await sdk.init({
  appId: process.env.APP_ID,
  appSecret: process.env.APP_SECRET,
  basePath: 'https://api.symbl.ai',
})

Now after we initialised, we need to start the connection by running

const connection = await sdk.startEndpoint(endpointConfig)

So how do you pass custom codecs? It's as simple as passing custom audio config

          endpoint: {
            //*****************Custom Audio Config******************
            audioConfig: {
              encoding: 'OPUS',
              sampleRate: 16000,
            },
            //******************************************************
            type: 'pstn',
            phoneNumber: process.env.DEFAULT_PHONE_NUMBER,
          },

If you have a requirement to use a codec not included in the ones above or have any other queries, please drop an e-mail to support@symbl.ai