How to calculate amplitude with OpenFL - haxe

Question

I was looking for a way to get the audio amplitude of a sound played at a given time, and the OpenFL API proposed the leftPeak and rightPeak methods of the SoundChannel class. After several tests, I could observe the value returned by the method was always the same: 1 (it is supposed to return a value between 0 and 1)!
After searching the source code, I was able to discover that leftPeak and rightPeak were only public properties, set in the constructor of our SoundChannel object, but never updated, and there is no function that explains how to do it.
Could you please support me develop the method to get the amplitude back?
I put the class code just below it, to confirm what I said!
Thank you in advance.
#if !flash
import openfl.events.Event;
import openfl.events.EventDispatcher;
#if lime
import lime.media.AudioSource;
#end
/**
The SoundChannel class controls a sound in an application. Every sound is
assigned to a sound channel, and the application can have multiple sound
channels that are mixed together. The SoundChannel class contains a
`stop()` method, properties for monitoring the amplitude
(volume) of the channel, and a property for assigning a SoundTransform
object to the channel.
#event soundComplete Dispatched when a sound has finished playing.
**/
#if !openfl_debug
#:fileXml('tags="haxe,release"')
#:noDebug
#end
#:access(openfl.media.SoundMixer)
#:final #:keep class SoundChannel extends EventDispatcher
{
/**
The current amplitude(volume) of the left channel, from 0(silent) to 1
(full amplitude).
**/
public var leftPeak(default, null):Float;
/**
When the sound is playing, the `position` property indicates in
milliseconds the current point that is being played in the sound file.
When the sound is stopped or paused, the `position` property
indicates the last point that was played in the sound file.
A common use case is to save the value of the `position`
property when the sound is stopped. You can resume the sound later by
restarting it from that saved position.
If the sound is looped, `position` is reset to 0 at the
beginning of each loop.
**/
public var position(get, set):Float;
/**
The current amplitude(volume) of the right channel, from 0(silent) to 1
(full amplitude).
**/
public var rightPeak(default, null):Float;
/**
The SoundTransform object assigned to the sound channel. A SoundTransform
object includes properties for setting volume, panning, left speaker
assignment, and right speaker assignment.
**/
public var soundTransform(get, set):SoundTransform;
#:noCompletion private var __isValid:Bool;
#:noCompletion private var __soundTransform:SoundTransform;
#if lime
#:noCompletion private var __source:AudioSource;
#end
#if openfljs
#:noCompletion private static function __init__()
{
untyped Object.defineProperties(SoundChannel.prototype, {
"position": {
get: untyped __js__("function () { return this.get_position (); }"),
set: untyped __js__("function (v) { return this.set_position (v); }")
},
"soundTransform": {
get: untyped __js__("function () { return this.get_soundTransform (); }"),
set: untyped __js__("function (v) { return this.set_soundTransform (v); }")
},
});
}
#end
#:noCompletion private function new(source:#if lime AudioSource #else Dynamic #end = null, soundTransform:SoundTransform = null):Void
{
super(this);
leftPeak = 1;
rightPeak = 1;
if (soundTransform != null)
{
__soundTransform = soundTransform;
}
else
{
__soundTransform = new SoundTransform();
}
#if lime
if (source != null)
{
__source = source;
__source.onComplete.add(source_onComplete);
__isValid = true;
__source.play();
}
#end
SoundMixer.__registerSoundChannel(this);
}
/**
Stops the sound playing in the channel.
**/
public function stop():Void
{
SoundMixer.__unregisterSoundChannel(this);
if (!__isValid) return;
#if lime
__source.stop();
#end
__dispose();
}
#:noCompletion private function __dispose():Void
{
if (!__isValid) return;
#if lime
__source.onComplete.remove(source_onComplete);
__source.dispose();
__source = null;
#end
__isValid = false;
}
#:noCompletion private function __updateTransform():Void
{
this.soundTransform = soundTransform;
}
// Get & Set Methods
#:noCompletion private function get_position():Float
{
if (!__isValid) return 0;
#if lime
return __source.currentTime + __source.offset;
#else
return 0;
#end
}
#:noCompletion private function set_position(value:Float):Float
{
if (!__isValid) return 0;
#if lime
__source.currentTime = Std.int(value) - __source.offset;
#end
return value;
}
#:noCompletion private function get_soundTransform():SoundTransform
{
return __soundTransform.clone();
}
#:noCompletion private function set_soundTransform(value:SoundTransform):SoundTransform
{
if (value != null)
{
__soundTransform.pan = value.pan;
__soundTransform.volume = value.volume;
var pan = SoundMixer.__soundTransform.pan + __soundTransform.pan;
if (pan < -1) pan = -1;
if (pan > 1) pan = 1;
var volume = SoundMixer.__soundTransform.volume * __soundTransform.volume;
if (__isValid)
{
#if lime
__source.gain = volume;
var position = __source.position;
position.x = pan;
position.z = -1 * Math.sqrt(1 - Math.pow(pan, 2));
__source.position = position;
return value;
#end
}
}
return value;
}
// Event Handlers
#:noCompletion private function source_onComplete():Void
{
SoundMixer.__unregisterSoundChannel(this);
__dispose();
dispatchEvent(new Event(Event.SOUND_COMPLETE));
}
}
#else
typedef SoundChannel = flash.media.SoundChannel;
#end