297 lines
7.5 KiB
C
297 lines
7.5 KiB
C
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/*____________________________________________________________________________
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FreeAmp - The Free MP3 Player
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MP3 Decoder originally Copyright (C) 1995-1997 Xing Technology
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Corp. http://www.xingtech.com
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Portions Copyright (C) 1998-1999 EMusic.com
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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$Id: msis.c,v 1.4 1999/10/19 07:13:09 elrod Exp $
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____________________________________________________________________________*/
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/**** msis.c ***************************************************
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Layer III
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antialias, ms and is stereo precessing
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**** is_process assumes never switch
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from short to long in is region *****
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is_process does ms or stereo in "forbidded sf regions"
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//ms_mode = 0
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lr[0][i][0] = 1.0f;
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lr[0][i][1] = 0.0f;
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// ms_mode = 1, in is bands is routine does ms processing
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lr[1][i][0] = 1.0f;
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lr[1][i][1] = 1.0f;
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******************************************************************/
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#include <stdlib.h>
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#include <stdio.h>
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#include <float.h>
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#include <math.h>
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#include "L3.h"
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#include "mp3struct.h"
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typedef float ARRAY2[2];
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typedef float ARRAY8_2[8][2];
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float csa[8][2]; /* antialias */ // effectively constant
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/* pMP3Stream->nBand[0] = long, pMP3Stream->nBand[1] = short */
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////@@@@extern int pMP3Stream->nBand[2][22];
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////@@@@extern int pMP3Stream->sfBandIndex[2][22]; /* [long/short][cb] */
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/* intensity stereo */
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/* if ms mode quant pre-scales all values by 1.0/sqrt(2.0) ms_mode in table
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compensates */
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static float lr[2][8][2]; /* [ms_mode 0/1][sf][left/right] */ // effectively constant
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/* intensity stereo MPEG2 */
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/* lr2[intensity_scale][ms_mode][sflen_offset+sf][left/right] */
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typedef float ARRAY2_64_2[2][64][2];
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typedef float ARRAY64_2[64][2];
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static float lr2[2][2][64][2]; // effectively constant
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/*===============================================================*/
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ARRAY2 *alias_init_addr()
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{
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return csa;
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}
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/*-----------------------------------------------------------*/
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ARRAY8_2 *msis_init_addr()
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{
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/*-------
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pi = 4.0*atan(1.0);
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t = pi/12.0;
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for(i=0;i<7;i++) {
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s = sin(i*t);
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c = cos(i*t);
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// ms_mode = 0
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lr[0][i][0] = (float)(s/(s+c));
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lr[0][i][1] = (float)(c/(s+c));
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// ms_mode = 1
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lr[1][i][0] = (float)(sqrt(2.0)*(s/(s+c)));
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lr[1][i][1] = (float)(sqrt(2.0)*(c/(s+c)));
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}
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//sf = 7
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//ms_mode = 0
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lr[0][i][0] = 1.0f;
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lr[0][i][1] = 0.0f;
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// ms_mode = 1, in is bands is routine does ms processing
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lr[1][i][0] = 1.0f;
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lr[1][i][1] = 1.0f;
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------------*/
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return lr;
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}
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/*-------------------------------------------------------------*/
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ARRAY2_64_2 *msis_init_addr_MPEG2()
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{
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return lr2;
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}
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/*===============================================================*/
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void antialias(float x[], int n)
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{
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int i, k;
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float a, b;
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for (k = 0; k < n; k++)
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{
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for (i = 0; i < 8; i++)
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{
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a = x[17 - i];
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b = x[18 + i];
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x[17 - i] = a * csa[i][0] - b * csa[i][1];
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x[18 + i] = b * csa[i][0] + a * csa[i][1];
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}
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x += 18;
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}
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}
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/*===============================================================*/
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void ms_process(float x[][1152], int n) /* sum-difference stereo */
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{
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int i;
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float xl, xr;
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/*-- note: sqrt(2) done scaling by dequant ---*/
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for (i = 0; i < n; i++)
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{
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xl = x[0][i] + x[1][i];
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xr = x[0][i] - x[1][i];
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x[0][i] = xl;
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x[1][i] = xr;
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}
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return;
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}
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/*===============================================================*/
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void is_process_MPEG1(float x[][1152], /* intensity stereo */
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SCALEFACT * sf,
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CB_INFO cb_info[2], /* [ch] */
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int nsamp, int ms_mode)
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{
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int i, j, n, cb, w;
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float fl, fr;
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int m;
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int isf;
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float fls[3], frs[3];
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int cb0;
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cb0 = cb_info[1].cbmax; /* start at end of right */
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i = pMP3Stream->sfBandIndex[cb_info[1].cbtype][cb0];
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cb0++;
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m = nsamp - i; /* process to len of left */
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if (cb_info[1].cbtype)
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goto short_blocks;
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/*------------------------*/
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/* long_blocks: */
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for (cb = cb0; cb < 21; cb++)
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{
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isf = sf->l[cb];
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n = pMP3Stream->nBand[0][cb];
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fl = lr[ms_mode][isf][0];
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fr = lr[ms_mode][isf][1];
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for (j = 0; j < n; j++, i++)
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{
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if (--m < 0)
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goto exit;
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x[1][i] = fr * x[0][i];
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x[0][i] = fl * x[0][i];
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}
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}
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return;
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/*------------------------*/
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short_blocks:
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for (cb = cb0; cb < 12; cb++)
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{
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for (w = 0; w < 3; w++)
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{
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isf = sf->s[w][cb];
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fls[w] = lr[ms_mode][isf][0];
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frs[w] = lr[ms_mode][isf][1];
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}
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n = pMP3Stream->nBand[1][cb];
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for (j = 0; j < n; j++)
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{
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m -= 3;
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if (m < 0)
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goto exit;
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x[1][i] = frs[0] * x[0][i];
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x[0][i] = fls[0] * x[0][i];
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x[1][1 + i] = frs[1] * x[0][1 + i];
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x[0][1 + i] = fls[1] * x[0][1 + i];
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x[1][2 + i] = frs[2] * x[0][2 + i];
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x[0][2 + i] = fls[2] * x[0][2 + i];
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i += 3;
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}
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}
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exit:
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return;
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}
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/*===============================================================*/
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void is_process_MPEG2(float x[][1152], /* intensity stereo */
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SCALEFACT * sf,
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CB_INFO cb_info[2], /* [ch] */
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IS_SF_INFO * is_sf_info,
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int nsamp, int ms_mode)
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{
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int i, j, k, n, cb, w;
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float fl, fr;
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int m;
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int isf;
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int il[21];
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int tmp;
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int r;
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ARRAY2 *lr;
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int cb0, cb1;
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lr = lr2[is_sf_info->intensity_scale][ms_mode];
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if (cb_info[1].cbtype)
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goto short_blocks;
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/*------------------------*/
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/* long_blocks: */
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cb0 = cb_info[1].cbmax; /* start at end of right */
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i = pMP3Stream->sfBandIndex[0][cb0];
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m = nsamp - i; /* process to len of left */
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/* gen sf info */
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for (k = r = 0; r < 3; r++)
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{
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tmp = (1 << is_sf_info->slen[r]) - 1;
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for (j = 0; j < is_sf_info->nr[r]; j++, k++)
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il[k] = tmp;
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}
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for (cb = cb0 + 1; cb < 21; cb++)
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{
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isf = il[cb] + sf->l[cb];
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fl = lr[isf][0];
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fr = lr[isf][1];
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n = pMP3Stream->nBand[0][cb];
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for (j = 0; j < n; j++, i++)
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{
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if (--m < 0)
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goto exit;
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x[1][i] = fr * x[0][i];
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x[0][i] = fl * x[0][i];
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}
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}
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return;
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/*------------------------*/
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short_blocks:
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for (k = r = 0; r < 3; r++)
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{
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tmp = (1 << is_sf_info->slen[r]) - 1;
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for (j = 0; j < is_sf_info->nr[r]; j++, k++)
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il[k] = tmp;
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}
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for (w = 0; w < 3; w++)
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{
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cb0 = cb_info[1].cbmax_s[w]; /* start at end of right */
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i = pMP3Stream->sfBandIndex[1][cb0] + w;
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cb1 = cb_info[0].cbmax_s[w]; /* process to end of left */
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for (cb = cb0 + 1; cb <= cb1; cb++)
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{
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isf = il[cb] + sf->s[w][cb];
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fl = lr[isf][0];
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fr = lr[isf][1];
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n = pMP3Stream->nBand[1][cb];
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for (j = 0; j < n; j++)
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{
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x[1][i] = fr * x[0][i];
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x[0][i] = fl * x[0][i];
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i += 3;
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}
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}
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}
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exit:
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return;
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}
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/*===============================================================*/
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