121 lines
2.7 KiB
C#
121 lines
2.7 KiB
C#
#region Copyright & License Information
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/*
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* Copyright (c) The OpenRA Developers and Contributors
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* This file is part of OpenRA, which is free software. It is made
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* available to you under the terms of the GNU General Public License
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* as published by the Free Software Foundation, either version 3 of
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* the License, or (at your option) any later version. For more
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* information, see COPYING.
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*/
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#endregion
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using System;
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using System.IO;
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using MP3Sharp;
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using OpenRA.Primitives;
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namespace OpenRA.Mods.Common.AudioLoaders
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{
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public class Mp3Loader : ISoundLoader
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{
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static bool IsMp3(Stream s)
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{
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var start = s.Position;
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// First try: MP3 may have ID3 meta data in front.
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var idTag = s.ReadASCII(3);
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s.Position = start;
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if (idTag == "ID3")
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return true;
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// Second try: MP3 without metadata, starts with MPEG chunk.
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var frameSync = s.ReadUInt16();
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s.Position = start;
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if (frameSync == 0xfbff)
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return true;
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// Neither found, not an MP3!
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return false;
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}
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bool ISoundLoader.TryParseSound(Stream stream, out ISoundFormat sound)
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{
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try
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{
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if (IsMp3(stream))
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{
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sound = new Mp3Format(stream);
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return true;
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}
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}
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catch
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{
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// Not a (supported) MP3
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}
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sound = null;
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return false;
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}
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}
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public sealed class Mp3Format : ISoundFormat
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{
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public int Channels => mp3.ChannelCount;
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public int SampleBits => 16;
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public int SampleRate => mp3.Frequency;
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public float LengthInSeconds { get; }
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public Stream GetPCMInputStream() { return new MP3Stream(Clone(this)); }
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public void Dispose() { mp3.Dispose(); }
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readonly MP3Stream mp3;
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readonly Stream stream;
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public Mp3Format(Stream stream)
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{
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var startPosition = stream.Position;
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try
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{
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mp3 = new MP3Stream(stream);
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this.stream = stream;
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// Make a first guess based on the file size and bitrate
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// This should be fine for constant bitrate files
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LengthInSeconds = mp3.Length * 8f / (2f * Channels * SampleRate);
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try
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{
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// Attempt to parse a more accurate length from the file metadata;
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LengthInSeconds = (float)new TagLib.Mpeg.AudioFile(new StreamAbstraction(stream)).Properties.Duration.TotalSeconds;
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}
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catch { }
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}
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finally
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{
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stream.Position = startPosition;
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}
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}
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static Stream Clone(Mp3Format cloneFrom)
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{
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return SegmentStream.CreateWithoutOwningStream(cloneFrom.stream, 0, (int)cloneFrom.stream.Length);
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}
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public class StreamAbstraction : TagLib.File.IFileAbstraction
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{
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public StreamAbstraction(Stream s)
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{
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ReadStream = s;
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}
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public Stream ReadStream { get; }
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public Stream WriteStream => throw new NotImplementedException();
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public void CloseStream(Stream stream) { }
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public string Name => "";
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}
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}
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}
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