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