OpenRA/OpenRA.Mods.Common/FileFormats/AudReader.cs

#region Copyright & License Information
/*
 * Copyright 2007-2018 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;
using System.Collections.Generic;
using System.IO;
using OpenRA.Primitives;

namespace OpenRA.Mods.Common.FileFormats
{
	[Flags]
	enum SoundFlags
	{
		Stereo = 0x1,
		_16Bit = 0x2,
	}

	enum SoundFormat
	{
		WestwoodCompressed = 1,
		ImaAdpcm = 99,
	}

	struct Chunk
	{
		public int CompressedSize;
		public int OutputSize;

		public static Chunk Read(Stream s)
		{
			Chunk c;
			c.CompressedSize = s.ReadUInt16();
			c.OutputSize = s.ReadUInt16();

			if (s.ReadUInt32() != 0xdeaf)
				throw new InvalidDataException("Chunk header is bogus");
			return c;
		}
	}

	public static class AudReader
	{
		static readonly int[] IndexAdjust = { -1, -1, -1, -1, 2, 4, 6, 8 };
		static readonly int[] StepTable =
		{
			7, 8, 9, 10, 11, 12, 13, 14, 16,
			17, 19, 21, 23, 25, 28, 31, 34, 37,
			41, 45, 50, 55, 60, 66, 73, 80, 88,
			97, 107, 118, 130, 143, 157, 173, 190, 209,
			230, 253, 279, 307, 337, 371, 408, 449, 494,
			544, 598, 658, 724, 796, 876, 963, 1060, 1166,
			1282, 1411, 1552, 1707, 1878, 2066, 2272, 2499, 2749,
			3024, 3327, 3660, 4026, 4428, 4871, 5358, 5894, 6484,
			7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899, 15289,
			16818, 18500, 20350, 22385, 24623, 27086, 29794, 32767
		};

		static short DecodeSample(byte b, ref int index, ref int current)
		{
			var sb = (b & 8) != 0;
			b &= 7;

			var delta = (StepTable[index] * b) / 4 + StepTable[index] / 8;
			if (sb) delta = -delta;

			current += delta;
			if (current > short.MaxValue) current = short.MaxValue;
			if (current < short.MinValue) current = short.MinValue;

			index += IndexAdjust[b];
			if (index < 0) index = 0;
			if (index > 88) index = 88;

			return (short)current;
		}

		public static byte[] LoadSound(byte[] raw, ref int index)
		{
			var s = new MemoryStream(raw);
			var dataSize = raw.Length;
			var outputSize = raw.Length * 4;

			var output = new byte[outputSize];
			var offset = 0;
			var currentSample = 0;

			while (dataSize-- > 0)
			{
				var b = s.ReadUInt8();

				var t = DecodeSample(b, ref index, ref currentSample);
				output[offset++] = (byte)t;
				output[offset++] = (byte)(t >> 8);

				t = DecodeSample((byte)(b >> 4), ref index, ref currentSample);
				output[offset++] = (byte)t;
				output[offset++] = (byte)(t >> 8);
			}

			return output;
		}

		public static float SoundLength(Stream s)
		{
			var sampleRate = s.ReadUInt16();
			/*var dataSize = */ s.ReadInt32();
			var outputSize = s.ReadInt32();
			var flags = (SoundFlags)s.ReadByte();

			var samples = outputSize;
			if ((flags & SoundFlags.Stereo) != 0) samples /= 2;
			if ((flags & SoundFlags._16Bit) != 0) samples /= 2;
			return (float)samples / sampleRate;
		}

		public static bool LoadSound(Stream s, out Func<Stream> result, out int sampleRate)
		{
			result = null;
			var startPosition = s.Position;
			try
			{
				sampleRate = s.ReadUInt16();
				var dataSize = s.ReadInt32();
				var outputSize = s.ReadInt32();

				var readFlag = s.ReadByte();
				if (!Enum.IsDefined(typeof(SoundFlags), readFlag))
					return false;

				var readFormat = s.ReadByte();
				if (!Enum.IsDefined(typeof(SoundFormat), readFormat))
					return false;

				var offsetPosition = s.Position;

				result = () =>
				{
					var audioStream = SegmentStream.CreateWithoutOwningStream(s, offsetPosition, (int)(s.Length - offsetPosition));
					return new AudStream(audioStream, outputSize, dataSize);
				};
			}
			finally
			{
				s.Position = startPosition;
			}

			return true;
		}

		sealed class AudStream : ReadOnlyAdapterStream
		{
			readonly int outputSize;
			int dataSize;

			int currentSample;
			int baseOffset;
			int index;

			public AudStream(Stream stream, int outputSize, int dataSize) : base(stream)
			{
				this.outputSize = outputSize;
				this.dataSize = dataSize;
			}

			public override long Length
			{
				get { return outputSize; }
			}

			protected override bool BufferData(Stream baseStream, Queue<byte> data)
			{
				if (dataSize <= 0)
					return true;

				var chunk = Chunk.Read(baseStream);
				for (var n = 0; n < chunk.CompressedSize; n++)
				{
					var b = baseStream.ReadUInt8();

					var t = DecodeSample(b, ref index, ref currentSample);
					data.Enqueue((byte)t);
					data.Enqueue((byte)(t >> 8));
					baseOffset += 2;

					if (baseOffset < outputSize)
					{
						/* possible that only half of the final byte is used! */
						t = DecodeSample((byte)(b >> 4), ref index, ref currentSample);
						data.Enqueue((byte)t);
						data.Enqueue((byte)(t >> 8));
						baseOffset += 2;
					}
				}

				dataSize -= 8 + chunk.CompressedSize;

				return dataSize <= 0;
			}
		}
	}
}