CODEWITHSUNDEEP
c#c++
bebo
bebo

Reputation: 67

decoding G711 converting from c++ to c#

i try to decoding G711 packet i find this code in c++ but i do not know how to convert this code to c#

this the code

gint16 alaw_exp_table[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};



#include <glib.h>
#include "G711adecode.h"
#include "G711atable.h"

int
decodeG711a(void *input, int inputSizeBytes, void *output, int *outputSizeBytes)
{
  guint8 *dataIn = (guint8 *)input;
  gint16 *dataOut = (gint16 *)output;
  int i;

  for (i=0; i<inputSizeBytes; i++)
  {
    dataOut[i] = alaw_exp_table[dataIn[i]];
  }
  *outputSizeBytes = inputSizeBytes * 2;
  return 0;
}

can any body help me ?

thanks in advance

Upvotes: 0

Views: 600

Answers (2)

David Yaw
David Yaw

Reputation: 27864

Looks like this is a fairly simple lossy encoding of a short array. Since G711 is an audio codec, that makes sense. Just iterate over the input byte array, and put the values from the lookup table in the output short array.

private short[] alaw_exp_table = {/* same data as the C code */};

public short[] decodeG711a(byte[] input)
{
    short[] result = new short[input.Length];

    for (int i = 0; i < input.Length; i++)
    {
        result[i] = alaw_exp_table[input[i]];
    }

    return result;
}

Upvotes: 1

SLaks
SLaks

Reputation: 887453

This is a short[].
You can translate it like any other array:

short[] x = { 1,2,3 };

Upvotes: 2

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