add description to ambisonics converter program

#include "tinywaveout_c.h"

#include "ambi_convert.h"

/*-------------------------------------------------------------------------------------*

* Ambisonics converter program

*

* gcc ambi_converter.c ../lib_util/ambi_convert.c  -I../lib_util/ -lm -o ambi_converter

*--------------------------------------------------------------------------------------*/

int main( int argc, char *argv[] )

{

        out[j] = &samples_f_out[j * L_FRAME48k];

    }

    if( argc != 5 )

    {

        printf("Ambisonics converter program\n");

        printf("----------------------------------------------------------------------------------\n");

        printf("Usage:\n");

        printf("./ambi_conveter input_file output_file input_convention output_convention\n");

        printf("\n");

        printf("input_convention and output convention must be an integer number in [0,5]\n");

        printf("the following conventions are supported:\n");

        printf("0 : ACN-SN3D\n");

        printf("1 : ACN-N3D\n");

        printf("2 : FuMa-MaxN\n");

        printf("3 : FuMa-FuMa\n");

        printf("4 : SID-SN3D\n");

        printf("5 : SID-N3D\n");

        printf("\n");

        printf("Either the input or the output convention must always be ACN-SN3D!\n");

        return -1;

    }

    fileName_in = argv[1];

    fileName_out = argv[2];

    in_format = atoi( argv[3] );