Initial commit: OpenRA game engine

Fork from OpenRA/OpenRA with one-click launch script (start-ra.cmd)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

OpenRA.Mods.Common/AudioLoaders/Mp3Loader.cs

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+#region Copyright & License Information
+/*
+ * Copyright (c) The OpenRA Developers and Contributors
+ * 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;
+using System.IO;
+using MP3Sharp;
+using OpenRA.Primitives;
+
+namespace OpenRA.Mods.Common.AudioLoaders
+{
+	public class Mp3Loader : ISoundLoader
+	{
+		static bool IsMp3(Stream s)
+		{
+			var start = s.Position;
+
+			// First try: MP3 may have ID3 meta data in front.
+			var idTag = s.ReadASCII(3);
+			s.Position = start;
+
+			if (idTag == "ID3")
+				return true;
+
+			// Second try: MP3 without metadata, starts with MPEG chunk.
+			var frameSync = s.ReadUInt16();
+			s.Position = start;
+
+			if (frameSync == 0xfbff)
+				return true;
+
+			// Neither found, not an MP3!
+			return false;
+		}
+
+		bool ISoundLoader.TryParseSound(Stream stream, out ISoundFormat sound)
+		{
+			try
+			{
+				if (IsMp3(stream))
+				{
+					sound = new Mp3Format(stream);
+					return true;
+				}
+			}
+			catch
+			{
+				// Not a (supported) MP3
+			}
+
+			sound = null;
+			return false;
+		}
+	}
+
+	public sealed class Mp3Format : ISoundFormat
+	{
+		public int Channels => mp3.ChannelCount;
+		public int SampleBits => 16;
+		public int SampleRate => mp3.Frequency;
+		public float LengthInSeconds { get; }
+		public Stream GetPCMInputStream() { return new MP3Stream(Clone(this)); }
+		public void Dispose() { mp3.Dispose(); }
+
+		readonly MP3Stream mp3;
+		readonly Stream stream;
+
+		public Mp3Format(Stream stream)
+		{
+			var startPosition = stream.Position;
+			try
+			{
+				mp3 = new MP3Stream(stream);
+				this.stream = stream;
+
+				// Make a first guess based on the file size and bitrate
+				// This should be fine for constant bitrate files
+				LengthInSeconds = mp3.Length * 8f / (2f * Channels * SampleRate);
+
+				try
+				{
+					// Attempt to parse a more accurate length from the file metadata;
+					LengthInSeconds = (float)new TagLib.Mpeg.AudioFile(new StreamAbstraction(stream)).Properties.Duration.TotalSeconds;
+				}
+				catch { }
+			}
+			finally
+			{
+				stream.Position = startPosition;
+			}
+		}
+
+		static Stream Clone(Mp3Format cloneFrom)
+		{
+			return SegmentStream.CreateWithoutOwningStream(cloneFrom.stream, 0, (int)cloneFrom.stream.Length);
+		}
+
+		public class StreamAbstraction : TagLib.File.IFileAbstraction
+		{
+			public StreamAbstraction(Stream s)
+			{
+				ReadStream = s;
+			}
+
+			public Stream ReadStream { get; }
+
+			public Stream WriteStream => throw new NotImplementedException();
+
+			public void CloseStream(Stream stream) { }
+			public string Name => "";
+		}
+	}
+}