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Added mu-law and a-law encoders and decoders

pull/1/head
markheath 14 years ago
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14b2ee58dd
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bdeacad8d8
5 changed files with 255 additions and 0 deletions
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  1. 63
      NAudio/Codecs/ALawDecoder.cs
  2. 65
      NAudio/Codecs/ALawEncoder.cs
  3. 65
      NAudio/Codecs/MuLawDecoder.cs
  4. 58
      NAudio/Codecs/MuLawEncoder.cs
  5. 4
      NAudio/NAudio.csproj

63
NAudio/Codecs/ALawDecoder.cs
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@ -0,0 +1,63 @@
using System;
using System.Collections.Generic;
using System.Text;
namespace NAudio.Codecs
{
/// <summary>
/// a-law decoder
/// based on code from:
/// http://hazelware.luggle.com/tutorials/mulawcompression.html
/// </summary>
public class ALawDecoder
{
/// <summary>
/// only 512 bytes required, so just use a lookup
/// </summary>
private static readonly short[] ALawDecompressTable = new short[256]
{
-5504, -5248, -6016, -5760, -4480, -4224, -4992, -4736,
-7552, -7296, -8064, -7808, -6528, -6272, -7040, -6784,
-2752, -2624, -3008, -2880, -2240, -2112, -2496, -2368,
-3776, -3648, -4032, -3904, -3264, -3136, -3520, -3392,
-22016,-20992,-24064,-23040,-17920,-16896,-19968,-18944,
-30208,-29184,-32256,-31232,-26112,-25088,-28160,-27136,
-11008,-10496,-12032,-11520,-8960, -8448, -9984, -9472,
-15104,-14592,-16128,-15616,-13056,-12544,-14080,-13568,
-344, -328, -376, -360, -280, -264, -312, -296,
-472, -456, -504, -488, -408, -392, -440, -424,
-88, -72, -120, -104, -24, -8, -56, -40,
-216, -200, -248, -232, -152, -136, -184, -168,
-1376, -1312, -1504, -1440, -1120, -1056, -1248, -1184,
-1888, -1824, -2016, -1952, -1632, -1568, -1760, -1696,
-688, -656, -752, -720, -560, -528, -624, -592,
-944, -912, -1008, -976, -816, -784, -880, -848,
5504, 5248, 6016, 5760, 4480, 4224, 4992, 4736,
7552, 7296, 8064, 7808, 6528, 6272, 7040, 6784,
2752, 2624, 3008, 2880, 2240, 2112, 2496, 2368,
3776, 3648, 4032, 3904, 3264, 3136, 3520, 3392,
22016, 20992, 24064, 23040, 17920, 16896, 19968, 18944,
30208, 29184, 32256, 31232, 26112, 25088, 28160, 27136,
11008, 10496, 12032, 11520, 8960, 8448, 9984, 9472,
15104, 14592, 16128, 15616, 13056, 12544, 14080, 13568,
344, 328, 376, 360, 280, 264, 312, 296,
472, 456, 504, 488, 408, 392, 440, 424,
88, 72, 120, 104, 24, 8, 56, 40,
216, 200, 248, 232, 152, 136, 184, 168,
1376, 1312, 1504, 1440, 1120, 1056, 1248, 1184,
1888, 1824, 2016, 1952, 1632, 1568, 1760, 1696,
688, 656, 752, 720, 560, 528, 624, 592,
944, 912, 1008, 976, 816, 784, 880, 848
};
/// <summary>
/// Converts an a-law encoded byte to a 16 bit linear sample
/// </summary>
/// <param name="muLaw">a-law encoded byte</param>
/// <returns>Linear sample</returns>
public static short ALawToLinearSample(byte aLaw)
{
return ALawDecompressTable[aLaw];
}
}
}

65
NAudio/Codecs/ALawEncoder.cs
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@ -0,0 +1,65 @@
using System;
using System.Collections.Generic;
using System.Text;
namespace NAudio.Codecs
{
/// <summary>
/// A-law encoder
/// </summary>
public static class ALawEncoder
{
private const int cBias = 0x84;
private const int cClip = 32635;
private static readonly byte[] ALawCompressTable = new byte[128]
{
1,1,2,2,3,3,3,3,
4,4,4,4,4,4,4,4,
5,5,5,5,5,5,5,5,
5,5,5,5,5,5,5,5,
6,6,6,6,6,6,6,6,
6,6,6,6,6,6,6,6,
6,6,6,6,6,6,6,6,
6,6,6,6,6,6,6,6,
7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7
};
/// <summary>
/// Encodes a single 16 bit sample to a-law
/// </summary>
/// <param name="sample">16 bit PCM sample</param>
/// <returns>a-law encoded byte</returns>
public static byte LinearToALawSample(short sample)
{
int sign;
int exponent;
int mantissa;
byte compressedByte;
sign = ((~sample) >> 8) & 0x80;
if (sign == 0)
sample = (short)-sample;
if (sample > cClip)
sample = cClip;
if (sample >= 256)
{
exponent = (int)ALawCompressTable[(sample >> 8) & 0x7F];
mantissa = (sample >> (exponent + 3)) & 0x0F;
compressedByte = (byte)((exponent << 4) | mantissa);
}
else
{
compressedByte = (byte)(sample >> 4);
}
compressedByte ^= (byte)(sign ^ 0x55);
return compressedByte;
}
}
}

65
NAudio/Codecs/MuLawDecoder.cs
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@ -0,0 +1,65 @@
using System;
using System.Collections.Generic;
using System.Text;
using NAudio.Wave;
namespace NAudio.Codecs
{
/// <summary>
/// mu-law decoder
/// based on code from:
/// http://hazelware.luggle.com/tutorials/mulawcompression.html
/// </summary>
public static class MuLawDecoder
{
/// <summary>
/// only 512 bytes required, so just use a lookup
/// </summary>
private static readonly short[] MuLawDecompressTable = new short[256]
{
-32124,-31100,-30076,-29052,-28028,-27004,-25980,-24956,
-23932,-22908,-21884,-20860,-19836,-18812,-17788,-16764,
-15996,-15484,-14972,-14460,-13948,-13436,-12924,-12412,
-11900,-11388,-10876,-10364, -9852, -9340, -8828, -8316,
-7932, -7676, -7420, -7164, -6908, -6652, -6396, -6140,
-5884, -5628, -5372, -5116, -4860, -4604, -4348, -4092,
-3900, -3772, -3644, -3516, -3388, -3260, -3132, -3004,
-2876, -2748, -2620, -2492, -2364, -2236, -2108, -1980,
-1884, -1820, -1756, -1692, -1628, -1564, -1500, -1436,
-1372, -1308, -1244, -1180, -1116, -1052, -988, -924,
-876, -844, -812, -780, -748, -716, -684, -652,
-620, -588, -556, -524, -492, -460, -428, -396,
-372, -356, -340, -324, -308, -292, -276, -260,
-244, -228, -212, -196, -180, -164, -148, -132,
-120, -112, -104, -96, -88, -80, -72, -64,
-56, -48, -40, -32, -24, -16, -8, -1,
32124, 31100, 30076, 29052, 28028, 27004, 25980, 24956,
23932, 22908, 21884, 20860, 19836, 18812, 17788, 16764,
15996, 15484, 14972, 14460, 13948, 13436, 12924, 12412,
11900, 11388, 10876, 10364, 9852, 9340, 8828, 8316,
7932, 7676, 7420, 7164, 6908, 6652, 6396, 6140,
5884, 5628, 5372, 5116, 4860, 4604, 4348, 4092,
3900, 3772, 3644, 3516, 3388, 3260, 3132, 3004,
2876, 2748, 2620, 2492, 2364, 2236, 2108, 1980,
1884, 1820, 1756, 1692, 1628, 1564, 1500, 1436,
1372, 1308, 1244, 1180, 1116, 1052, 988, 924,
876, 844, 812, 780, 748, 716, 684, 652,
620, 588, 556, 524, 492, 460, 428, 396,
372, 356, 340, 324, 308, 292, 276, 260,
244, 228, 212, 196, 180, 164, 148, 132,
120, 112, 104, 96, 88, 80, 72, 64,
56, 48, 40, 32, 24, 16, 8, 0
};
/// <summary>
/// Converts a mu-law encoded byte to a 16 bit linear sample
/// </summary>
/// <param name="muLaw">mu-law encoded byte</param>
/// <returns>Linear sample</returns>
public static short MuLawToLinearSample(byte muLaw)
{
return MuLawDecompressTable[muLaw];
}
}
}

58
NAudio/Codecs/MuLawEncoder.cs
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@ -0,0 +1,58 @@
using System;
using System.Collections.Generic;
using System.Text;
using NAudio.Wave;
namespace NAudio.Codecs
{
/// <summary>
/// mu-law encoder
/// based on code from:
/// http://hazelware.luggle.com/tutorials/mulawcompression.html
/// </summary>
public static class MuLawEncoder
{
private const int cBias = 0x84;
private const int cClip = 32635;
private static readonly byte[] MuLawCompressTable = new byte[256]
{
0,0,1,1,2,2,2,2,3,3,3,3,3,3,3,3,
4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,
5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7
};
/// <summary>
/// Encodes a single 16 bit sample to mu-law
/// </summary>
/// <param name="sample">16 bit PCM sample</param>
/// <returns>mu-law encoded byte</returns>
public static byte LinearToMuLawSample(short sample)
{
int sign = (sample >> 8) & 0x80;
if (sign != 0)
sample = (short)-sample;
if (sample > cClip)
sample = cClip;
sample = (short)(sample + cBias);
int exponent = (int)MuLawCompressTable[(sample >> 7) & 0xFF];
int mantissa = (sample >> (exponent + 3)) & 0x0F;
int compressedByte = ~(sign | (exponent << 4) | mantissa);
return (byte)compressedByte;
}
}
}

4
NAudio/NAudio.csproj
View File

@ -72,6 +72,10 @@
<Reference Include="System.Xml" />
</ItemGroup>
<ItemGroup>
<Compile Include="Codecs\ALawDecoder.cs" />
<Compile Include="Codecs\ALawEncoder.cs" />
<Compile Include="Codecs\MuLawDecoder.cs" />
<Compile Include="Codecs\MuLawEncoder.cs" />
<Compile Include="CoreAudioApi\AudioCaptureClient.cs" />
<Compile Include="CoreAudioApi\AudioClient.cs" />
<Compile Include="CoreAudioApi\AudioClientBufferFlags.cs" />

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