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Assets/AVProVideo/Runtime/Scripts/Components/AudioChannelMixer.cs

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+using UnityEngine;
+
+//-----------------------------------------------------------------------------
+// Copyright 2019-2022 RenderHeads Ltd.  All rights reserved.
+//-----------------------------------------------------------------------------
+
+namespace RenderHeads.Media.AVProVideo
+{
+	/// Allows per-channel volume control
+	/// Currently supported on Windows and UWP (Media Foundation API only), macOS, iOS, tvOS and Android (ExoPlayer API only)
+	[AddComponentMenu("AVPro Video/Audio Channel Mixer", 401)]
+	[HelpURL("https://www.renderheads.com/products/avpro-video/")]
+	public class AudioChannelMixer : MonoBehaviour
+	{
+		const int MaxChannels = 8;
+
+		[Range(0f, 1f)]
+		[SerializeField] float[] _channels = null;
+
+		/// Range 0.0 to 1.0
+		public float[] Channel
+		{
+			get { return _channels; }
+			set { _channels = value; }
+		}
+
+		void Reset()
+		{
+			_channels = new float[MaxChannels];
+			for (int i = 0; i < MaxChannels; i++)
+			{
+				_channels[i] = 1f;
+			}
+		}
+
+		void ChangeChannelCount(int numChannels)
+		{
+			float[] channels = new float[numChannels];
+			if (_channels != null && _channels.Length != 0)
+			{
+				for (int i = 0; i < channels.Length; i++)
+				{
+					if (i < _channels.Length)
+					{
+						channels[i] = _channels[i];
+					}
+					else
+					{
+						channels[i] = 1f;
+					}
+				}
+			}
+			else
+			{
+				for (int i = 0; i < numChannels; i++)
+				{
+					channels[i] = 1f;
+				}
+			}
+			_channels = channels;
+		}
+
+		void OnAudioFilterRead(float[] data, int channels)
+		{
+			if (channels != _channels.Length)
+			{
+				ChangeChannelCount(channels);
+			}
+			int k = 0;
+			int numSamples = data.Length / channels;
+			for (int j = 0; j < numSamples; j++)
+			{
+				for (int i = 0; i < channels; i++)
+				{
+					data[k] *= _channels[i];
+					k++;
+				}
+			}
+		}
+	}
+}