encode.c

MPEG 2的音频编码软件。喜欢多媒体的开发人员可以看看。

	matricing_fft (buffer, buffer_matr, fr_ps);

    /*
     * After matrixing, "buffer_matr" contains:
     *	buffer_matr[0]	Lo
     *	buffer_matr[1]	Ro
     *	buffer_matr[2]	C
     *	buffer_matr[3]	Ls
     *	buffer_matr[4]	Rs
     *	buffer_matr[5]	L
     *	buffer_matr[6]	R
#ifdef Augmentation_7ch
     *  optional in 7.1 channel augmentation mode
     *	buffer_matr[7]	L7
     *	buffer_matr[8]	R7
     *	buffer_matr[9]	C7
     *	buffer_matr[10]	Lc
     *	buffer_matr[11]	Rc
#endif
     */

    return (samples_read);
}

/*************************************************************************
/*
/* matricing()
/*
/* The five-channel signal must be matricied to guarantee
/* the compatibility to the stereo-decoder.
/* There must be something of the surround information in the
/* two front channels. In a five-channel decoder there will
/* be a dematricing.
/* There must be 7 channels for channel switching 8/10/93, SR
/* 
/* Channel 5 and 6 are the not matriced signals L and R
/*
/* If phantom coding is used the high-frequency part of the
/* center signal is matrixed to left and right.
/* 27/07/95 WtK
/*                                                                         */
/***************************************************************************/

void normalizing (double (*sb_sample)[3][12][32], frame_params *fr_ps)
{
    double matrNorm;	/* factor for normalizing JMZ */
    double matrC;	/* weighting factor for C, Phantom C */
    double matrLsRs;	/* weighting factor for Ls, Rs */
    int stereo = fr_ps->stereo;
    int i, j, k, l;
    
    layer *info = fr_ps->header;
  
    switch (info->matrix)
    {
    /* Changed the factors according to International Standard */
      
    case 0:
    case 2: matrNorm	= 1 / (1 + sqrt(2.0));
	    matrC	= 1 / sqrt(2.0);
	    matrLsRs	= 1 / sqrt(2.0);
	    break;
    case 1: matrNorm	= 1 / (1.5 + 0.5*sqrt(2.0));
	    matrC	= 1 / sqrt(2.0);
	    matrLsRs	= 0.5;
	    break;
    case 3: matrNorm	= 1;
	    matrC	= 1;
	    matrLsRs	= 1;
	    break;
    }


    for (i = 0; i < stereo; i++)
    	for (j = 0; j < 3; j++)
	    for (l = 0; l < 12; l++)
	    	for (k = 0; k < SBLIMIT; k ++)
		    sb_sample[i][j][l][k] *= matrNorm;

    for (j = 0; j < 3; ++j)
	for (l = 0; l < 12; l ++)
	    for (k = 0; k < SBLIMIT; k ++)
		if (fr_ps->config == 320)
		{
		    sb_sample[2][j][l][k] = sb_sample[2][j][l][k] * matrNorm * matrC;
		    sb_sample[3][j][l][k] = sb_sample[3][j][l][k] * matrNorm * matrLsRs;
		    sb_sample[4][j][l][k] = sb_sample[4][j][l][k] * matrNorm * matrLsRs;
		}
		else if (fr_ps->config == 310)
		{
		    sb_sample[2][j][l][k] = sb_sample[2][j][l][k] * matrNorm * matrC;
		    sb_sample[3][j][l][k] = sb_sample[3][j][l][k] * matrNorm * matrLsRs;
		}
		else if (fr_ps->config == 220)
		{
		    sb_sample[2][j][l][k] = sb_sample[2][j][l][k] * matrNorm * matrLsRs;
		    sb_sample[3][j][l][k] = sb_sample[3][j][l][k] * matrNorm * matrLsRs;
		}
		else if (fr_ps->config == 300 || fr_ps->config == 302)
		    sb_sample[2][j][l][k] = sb_sample[2][j][l][k] * matrNorm * matrC;
		else if (fr_ps->config == 210)
		    sb_sample[2][j][l][k] = sb_sample[2][j][l][k] * matrNorm * matrLsRs;
}

void matricing (double (*sb_sample)[3][12][32], frame_params *fr_ps)
{
    double matrPC;	/* weighting factor for Phantom C */
    double mono_surround;
    register double val;
    int i, j, k, l;
    
    layer *info = fr_ps->header;
  
    switch (info->matrix)
    {
    /* Changed the factors according to International Standard */      
    case 0:
    case 1:
    case 2: matrPC	= 1;
	    break;
    case 3: matrPC	= 1 / sqrt(2.0);
	    break;
    }


    for (j = 0; j < 3; ++j)
    {
	for (l = 0; l < 12; l ++)
	{
	    for (k = 0; k < SBLIMIT; k ++)
	    {
		sb_sample[5][j][l][k] = sb_sample[0][j][l][k];
		sb_sample[6][j][l][k] = sb_sample[1][j][l][k];

		if (fr_ps->config == 320)
		{
		    /* 960819 FdB changed matricing */
		    if (info->matrix == 0 || info->matrix == 1)
		    {
			    sb_sample[0][j][l][k] = sb_sample[5][j][l][k] + sb_sample[2][j][l][k] + sb_sample[3][j][l][k];
			    sb_sample[1][j][l][k] = sb_sample[6][j][l][k] + sb_sample[2][j][l][k] + sb_sample[4][j][l][k];
		    }
		    else if (info->matrix == 2)
		    {
			    mono_surround = (sb_sample[3][j][l][k] + sb_sample[4][j][l][k]) / 2.0;
			    sb_sample[0][j][l][k] = sb_sample[5][j][l][k] + sb_sample[2][j][l][k] - mono_surround;
			    sb_sample[1][j][l][k] = sb_sample[6][j][l][k] + sb_sample[2][j][l][k] + mono_surround;
		    }
		    else
		    {
			    sb_sample[0][j][l][k] = sb_sample[5][j][l][k];
			    sb_sample[1][j][l][k] = sb_sample[6][j][l][k];
		    }
		}
		else if (fr_ps->config == 310)
		{
		    /* 960819 FdB changed matricing */
		    if (info->matrix == 0 || info->matrix == 1)
		    {
			    sb_sample[0][j][l][k] = sb_sample[5][j][l][k] + sb_sample[2][j][l][k] + sb_sample[3][j][l][k];
			    sb_sample[1][j][l][k] = sb_sample[6][j][l][k] + sb_sample[2][j][l][k] + sb_sample[3][j][l][k];
		    }
		    else if (info->matrix == 2)
		    {
			    sb_sample[0][j][l][k] = sb_sample[5][j][l][k] + sb_sample[2][j][l][k] - sb_sample[3][j][l][k];
			    sb_sample[1][j][l][k] = sb_sample[6][j][l][k] + sb_sample[2][j][l][k] + sb_sample[3][j][l][k];
		    }
		    else
		    {
			    sb_sample[0][j][l][k] = sb_sample[5][j][l][k];
			    sb_sample[1][j][l][k] = sb_sample[6][j][l][k];
		    }
		}
		else if (fr_ps->config == 220)
		{
		    /* 960819 FdB changed matricing */
		    if (info->matrix == 0 || info->matrix == 1)
		    {
			    sb_sample[0][j][l][k] = sb_sample[5][j][l][k] + sb_sample[2][j][l][k];
			    sb_sample[1][j][l][k] = sb_sample[6][j][l][k] + sb_sample[3][j][l][k];
		    }
		    else if (info->matrix == 3)
		    {
			    sb_sample[0][j][l][k] = sb_sample[5][j][l][k];
			    sb_sample[1][j][l][k] = sb_sample[6][j][l][k];
		    }
		}
		else if (fr_ps->config == 300 || fr_ps->config == 302)
		{
		    /* 960819 FdB changed matricing */
		    if (info->matrix == 0 || info->matrix == 1)
		    {
			    sb_sample[0][j][l][k] = sb_sample[5][j][l][k] + sb_sample[2][j][l][k];
			    sb_sample[1][j][l][k] = sb_sample[6][j][l][k] + sb_sample[2][j][l][k];
		    }
		    else if (info->matrix == 3)
		    {
			    sb_sample[0][j][l][k] = sb_sample[5][j][l][k];
			    sb_sample[1][j][l][k] = sb_sample[6][j][l][k];
		    }
		}
		else if (fr_ps->config == 210)
		{
		    /* 960819 FdB changed matricing */
		    if (info->matrix == 0 || info->matrix == 1)
		    {
			    sb_sample[0][j][l][k] = sb_sample[5][j][l][k] + sb_sample[2][j][l][k];
			    sb_sample[1][j][l][k] = sb_sample[6][j][l][k] + sb_sample[2][j][l][k];
		    }
		    else if (info->matrix == 3)
		    {
			    sb_sample[0][j][l][k] = sb_sample[5][j][l][k];
			    sb_sample[1][j][l][k] = sb_sample[6][j][l][k];
		    }
		}
	    }

	    if (info->center == 3)            /* 27/07/95 WtK */
	    {
		if (info->matrix==3)
		    for (k = 12; k < SBLIMIT; k ++)
		    {
			val = matrPC * sb_sample[2][j][l][k];
			sb_sample[0][j][l][k] += val;
			sb_sample[1][j][l][k] += val;
			sb_sample[2][j][l][k] = 0;
		    }
		else 
		    for (k = 12; k < SBLIMIT; k ++)
		    {
			val = matrPC * sb_sample[2][j][l][k];
			sb_sample[5][j][l][k] += val;
			sb_sample[6][j][l][k] += val;
			sb_sample[2][j][l][k] = 0;
		    }
	    }
	}
    }
}

#ifdef Augmentation_7ch
void normalizing_aug (double (*sb_sample)[3][12][32], frame_params *fr_ps)
{
    double norm;	/* factor for normalizing JMZ */
    double c[7];
    int i, j, k, l;
    
    layer *info = fr_ps->header;
  
    for (i = 0; i < 7; i++)
	c[i] = 1.0;

    switch (info->matrix)
    {
    	/* factors according to International Standard */
    	case 0:
    	case 2: c[2] = c[3] = c[4] = 1.0 / sqrt (2.0);	/* weigh factor for C, Ls and Rs */
	    	break;
    	case 1: c[2] = 1.0 / sqrt (2.0);		/* weigh factor for C            */
		c[3] = c[4] = 0.5;			/* weigh factor for Ls, Rs       */
		break;
    }

    if (info->aug_mtx_proc == 0)
    	/* factors according to 7-ch augmentation */
	/* unweigh factor for LC, RC */
	c[5] = c[6] = 0.75;

    /* normalization factor */
    switch (info->matrix * 10 + info->aug_mtx_proc)
    {
    case 00:
    case 20: norm = 1.0 / (1.75 + 1.25 * sqrt (2.0));
	     break;
    case 10: norm = 1.0 / (2.25 + 0.75 * sqrt (2.0));
	     break;
    case 30: norm = 1.0 / 1.75;
	     break;
    case 01:
    case 21: norm = 1.0 / (2.0 + sqrt (2.0));
	     break;
    case 11: norm = 1.0 / (2.5 + 0.5 * sqrt (2.0));
	     break;
    case 31: norm = 0.5;
	     break;
    case 03:
    case 23: norm = 1.0 / (1.0 + sqrt (2.0));
	     break;
    case 13: norm = 1.0 / (1.5 + 0.5 * sqrt (2.0));
	     break;
    case 33: norm = 1.0;
	     break;
    }

    for (i = 0; i < 7; i++)
	c[i] *= norm;

    /* normalizing */
    for (i = 0; i < 7; i++)
	for (j = 0; j < 3; j++)
	    for (k = 0; k < 12; k++)
		for (l = 0; l < SBLIMIT; l++)
		    sb_sample[i][j][k][l] *= c[i];
}

void matricing_aug (double (*sb_sample)[3][12][32], frame_params *fr_ps)
{
    int i, j, k, l;
    
    layer *info = fr_ps->header;
  
    for (j = 0; j < 3; ++j)
	for (l = 0; l < 12; l ++)
	    for (k = 0; k < SBLIMIT; k ++)
	    {
		/* copy L7, R7, C7, Lc and Rc to sb_sample[7 .. 11] */
		sb_sample[11][j][l][k] = sb_sample[6][j][l][k];
		sb_sample[10][j][l][k] = sb_sample[5][j][l][k];
		sb_sample[ 9][j][l][k] = sb_sample[2][j][l][k];
		sb_sample[ 8][j][l][k] = sb_sample[1][j][l][k];
		sb_sample[ 7][j][l][k] = sb_sample[0][j][l][k];

		/* 960819 FdB changed matricing */
		if (info->aug_mtx_proc == 0 || info->aug_mtx_proc == 1)
		{
		    sb_sample[0][j][l][k] += sb_sample[5][j][l][k];
		    sb_sample[1][j][l][k] += sb_sample[6][j][l][k];
                }
		if (info->aug_mtx_proc == 0)
		    sb_sample[2][j][l][k] += (sb_sample[5][j][l][k] + sb_sample[6][j][l][k]) / 3;
	    }
}
#endif

/*************************************************************************
/*
/* matricing_fft()
/*
/* To get the best results in psychoacoustics there must be both,
/* the matriced and the not matriced signal. This matricing
/* may be in full bandwith.
 *
 * If LFE is not enabled, "buffer" contains:
 *	buffer[0]	L
 *	buffer[1]	R
 *	buffer[2]	C
 *	buffer[3]	Ls
 *	buffer[4]	Rs
 *
 * If LFE is enabled, "buffer" contains:
 *	buffer[0]	L
 *	buffer[1]	R
 *	buffer[2]	C
 *	buffer[3]	LFE
 *	buffer[4]	Ls
 *	buffer[5]	Rs
 *
 * This function matrixes the original audio samples to pass to the
 * psychoacoustic model. The model considers the matrixed and non-
 * matrixed versions of the signal, so both are retained here.
 * 
 * On exit, buffer_matr[0] to buffer_matr[6] contain the channels
 * Lo, Ro, C, Ls, Rs, L, R, respectively.
 *
 **************************************************************************/

void matricing_fft (double (*buffer)[1152],
		    double (*buffer_matr)[1152],
		    frame_params *fr_ps)
{
    double matrNorm;	/* factor for normalizing JMZ */
    double matrC;		/* weighting factor for C */
    double matrLsRs;	/* weighting factor for Ls, Rs */
    double mono_surround;
    int i, j, k, l;
    int lfe, lfe_pos;
    double dummy;
    
    layer *info = fr_ps->header;
    lfe = info->lfe;
    lfe_pos = fr_ps->lfe_pos;

    switch(info->matrix)
    {
    case 0:
    case 2: matrNorm	= 1 / (1 + sqrt(2.0));
	    matrC	= 1 / sqrt(2.0);
	    matrLsRs	= 1 / sqrt(2.0);
	    break;
    case 1: matrNorm	= 1 / (1.5 + 0.5*sqrt(2.0));
	    matrC	= 1 / sqrt(2.0);
	    matrLsRs	= 0.5;
	    break;
    case 3: matrNorm	= 1;
	    matrC	= 1;
	    matrLsRs	= 1;
	    break;
    }

    for (i = 0; i < 1152; i++)
    {
	if (lfe && lfe_pos < 3)
	    buffer_matr[2][i]	= buffer[3][i];
	else
	    buffer_matr[2][i]	= buffer[2][i];
	buffer_matr[3][i]	= buffer[3+lfe][i];
	buffer_matr[4][i]	= buffer[4+lfe][i];
	buffer_matr[5][i]	= buffer[0][i];
	buffer_matr[6][i]	= buffer[1][i];
   
	switch (info->matrix)
	{
	case 0:
	case 1: buffer_matr[0][i] = matrNorm*(buffer[0][i] + matrC*buffer_matr[2][i] + matrLsRs*buffer_matr[3][i]);
		buffer_matr[1][i] = matrNorm*(buffer[1][i] + matrC*buffer_matr[2][i] + matrLsRs*buffer_matr[4][i]);
		break;