Add volume modification to dispatcher

src/client/voice/dispatcher/StreamDispatcher.js

@@ -21,6 +21,7 @@ class StreamDispatcher extends EventEmitter {
     };
     this._startStreaming();
     this._triggered = false;
+    this._volume = 1;
   }
 
   /**
@@ -59,6 +60,26 @@ class StreamDispatcher extends EventEmitter {
     return packetBuffer;
   }
 
+  _applyVolume(buffer) {
+    if (this._volume === 1) {
+      return buffer;
+    }
+
+    const out = new Buffer(buffer.length);
+
+    for (let i = 0; i < buffer.length; i += 2) {
+      if (i >= buffer.length - 1) {
+        break;
+      }
+
+      const uint = Math.min(32767, Math.max(-32767, Math.floor(this._volume * buffer.readInt16LE(i))));
+
+      out.writeInt16LE(uint, i);
+    }
+
+    return out;
+  }
+
   _send() {
     try {
       if (this._triggered) {
@@ -93,6 +114,8 @@ class StreamDispatcher extends EventEmitter {
         buffer = newBuffer;
       }
 
+      buffer = this._applyVolume(buffer);
+
       data.count++;
       data.sequence = (data.sequence + 1) < (65536) ? data.sequence + 1 : 0;
       data.timestamp = data.timestamp + 4294967295 ? data.timestamp + 960 : 0;
@@ -182,6 +205,39 @@ class StreamDispatcher extends EventEmitter {
     this._triggerTerminalState('end', 'user requested');
   }
 
+  /**
+   * The volume of the stream, relative to the stream's input volume
+   * @type {number}
+   * @readonly
+   */
+  get volume() {
+    return this._volume;
+  }
+
+  /**
+   * Sets the volume relative to the input stream - i.e. 1 is normal, 0.5 is half, 2 is double.
+   * @param {number} volume the volume that you want to set
+   */
+  setVolume(volume) {
+    this._volume = volume;
+  }
+
+  /**
+   * Set the volume in decibels
+   * @param {number} db the decibels
+   */
+  setVolumeDecibels(db) {
+    this._volume = Math.pow(10, db / 20);
+  }
+
+  /**
+   * Set the volume so that a perceived value of 0.5 is half the perceived volume etc.
+   * @param {number} value the value for the volume
+   */
+  setVolumeLogarithmic(value) {
+    this._volume = Math.pow(value, 1.660964);
+  }
+
   /**
    * Stops sending voice packets to the voice connection (stream may still progress however)
    */

test/random.js

@@ -124,13 +124,15 @@ client.on('message', msg => {
 
 const ytdl = require('ytdl-core');
 
+let disp;
+
 client.on('message', msg => {
   if (msg.content.startsWith('/join')) {
     const chan = msg.content.split(' ').slice(1).join(' ');
     msg.channel.guild.channels.get(chan).join()
       .then(conn => {
         msg.reply('done');
-        const disp = conn.player.playStream(ytdl('https://www.youtube.com/watch?v=nbXgHAzUWB0', {filter : 'audioonly'}));
+        disp = conn.player.playStream(ytdl('https://www.youtube.com/watch?v=nbXgHAzUWB0', {filter : 'audioonly'}));
         conn.player.on('debug', console.log);
         conn.player.on('error', err => console.log(123, err));
         const receiver = conn.createReceiver();