Create get-started-volume-indicator.md

Author: sloanster

articles/communication-services/quickstarts/voice-video-calling/get-started-volume-indicator.md

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+---
+title: Quickstart - Add volume indicator to your Web calling app
+titleSuffix: An Azure Communication Services quickstart
+description: In this quickstart, you'll learn how to add raw media access calling capabilities to your app using Azure Communication Services.
+author: sloanster
+
+ms.author: micahvivion
+ms.date: 1/18/2023
+ms.topic: quickstart
+ms.service: azure-communication-services
+ms.subservice: calling
+ms.custom: mode-other
+---
+
+As a developer you can have control over checking microphone volume in Javascript
+
+## Prerequisites
+[!INCLUDE [Public Preview](../../../../includes/public-preview-include-document.md)]
+
+>[!IMPORTANT]
+> The quick start examples here are available starting on the public preview version [1.9.1-beta.1](https://www.npmjs.com/package/@azure/communication-calling/v/1.9.1-beta.1) of the calling Web SDK. Make sure to use that version or newer when trying this quickstart.
+
+## Checking the audio stream olume
+### Description
+
+As a developer it can be nice to have the ability to check the microphone volume in Javascript. This quickstart shows examples of how to do this in ACS WebJS.
+
+#### Architecture
+##### Pre/Post Call
+ACS Already has raw audio stream access api built over TsCall on Device Manager this can be used to expose audio gain for precall/incall Microphone volume.
+```javascript
+export interface LocalAudioStream {
+    getMediaStreamTrack(): Promise<MediaStreamTrack>;
+    switchSource(source: AudioDeviceInfo | MediaStreamTrack): Promise<void>;
+    dispose();
+}
+export interface RemoteAudioStream {
+    getMediaStreamTrack(): Promise<MediaStreamTrack>;
+}
+```
+ACS will expose another API on local and remote audio streams to get Microphone volume built over Raw Audio access API, to get Volume (gain) of selected Microphone
+```javascript
+export interface LocalAudioStream {
+     getVolume(): Promise<Volume>;
+...
+}
+
+export interface RemoteAudioStream {
+     getVolume(): Promise<Volume>;
+...
+}
+
+export interface Volume extends Disposable{				
+      off(event: 'levelChanged', listener: PropertyChangedEvent): void;		
+      on(event: 'levelChanged', listener: PropertyChangedEvent): void;
+      readonly level: number;		
+  }
+```
+The volume is a number ranging from 0 to 100
+It's sampled every 200ms to get near realtime value of volume
+####  Example usage
+Sample code to get volume of selected microphone
+
+need call getVolume on audioSourceChanged for local audio stream
+
+```javascript
+
+const volumeIndicator = await new SDK.LocalAudioStream(deviceManager.selectedMicrophone).getVolume();
+volumeIndicator.on('levelChanged', ()=>{
+    console.log(`Volume is ${volumeIndicator.level}`)
+})
+
+
+const remoteAudioStream = call.remoteAudioStreams[0];
+const volumeIndicator = await remoteAudioStream.getVolume();
+volumeIndicator.on('levelChanged', ()=>{
+    console.log(`Volume is ${volumeIndicator.level}`)
+})
+
+```
+
+#### Telemetry for localAudioStream
+best effort to send telemetry, from localAudioStream
+if call client is not initialized before LocalAudioStream, no telemetry will be sent
+
+For MediaStreamTrack telemetry only from the first created call client will be sent
+cc1, new local stream ... everything works fine
+cc1, new local stream gets latched to telemetry logger from cc1, cc2, new local stream will not send data