Add support for .mp3 files.

OpenRA.Mods.Common/AudioLoaders/Mp3Loader.cs

@@ -0,0 +1,60 @@
+#region Copyright & License Information
+/*
+ * Copyright 2007-2021 The OpenRA Developers (see AUTHORS)
+ * This file is part of OpenRA, which is free software. It is made
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version. For more
+ * information, see COPYING.
+ */
+#endregion
+
+using System.IO;
+using MP3Sharp;
+using OpenRA.Primitives;
+
+namespace OpenRA.Mods.Common.AudioLoaders
+{
+	public class Mp3Loader : ISoundLoader
+	{
+		bool ISoundLoader.TryParseSound(Stream stream, out ISoundFormat sound)
+		{
+			try
+			{
+				sound = new Mp3Format(stream);
+				return true;
+			}
+			catch
+			{
+				// Not a (supported) MP3
+			}
+
+			sound = null;
+			return false;
+		}
+	}
+
+	public sealed class Mp3Format : ISoundFormat
+	{
+		public int Channels { get { return mp3.ChannelCount; } }
+		public int SampleBits { get { return 16; } }
+		public int SampleRate { get { return mp3.Frequency; } }
+		public float LengthInSeconds { get { return mp3.Length * 8f / (2f * Channels * SampleRate); } }
+		public Stream GetPCMInputStream() { return new MP3Stream(Clone(this)); }
+		public void Dispose() { mp3.Dispose(); }
+
+		readonly MP3Stream mp3;
+		readonly Stream stream;
+
+		public Mp3Format(Stream stream)
+		{
+			mp3 = new MP3Stream(stream);
+			this.stream = stream;
+		}
+
+		Stream Clone(Mp3Format cloneFrom)
+		{
+			return SegmentStream.CreateWithoutOwningStream(cloneFrom.stream, 0, (int)cloneFrom.stream.Length);
+		}
+	}
+}