/*____________________________________________________________________________ FreeAmp - The Free MP3 Player MP3 Decoder originally Copyright (C) 1995-1997 Xing Technology Corp. http://www.xingtech.com Portions Copyright (C) 1998-1999 EMusic.com This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. $Id: msis.c,v 1.4 1999/10/19 07:13:09 elrod Exp $ ____________________________________________________________________________*/ /**** msis.c *************************************************** Layer III antialias, ms and is stereo precessing **** is_process assumes never switch from short to long in is region ***** is_process does ms or stereo in "forbidded sf regions" //ms_mode = 0 lr[0][i][0] = 1.0f; lr[0][i][1] = 0.0f; // ms_mode = 1, in is bands is routine does ms processing lr[1][i][0] = 1.0f; lr[1][i][1] = 1.0f; ******************************************************************/ #include #include #include #include #include "l3.h" #include "mp3struct.h" typedef float ARRAY2[2]; typedef float ARRAY8_2[8][2]; float csa[8][2]; /* antialias */ // effectively constant /* pMP3Stream->nBand[0] = long, pMP3Stream->nBand[1] = short */ ////@@@@extern int pMP3Stream->nBand[2][22]; ////@@@@extern int pMP3Stream->sfBandIndex[2][22]; /* [long/short][cb] */ /* intensity stereo */ /* if ms mode quant pre-scales all values by 1.0/sqrt(2.0) ms_mode in table compensates */ static float lr[2][8][2]; /* [ms_mode 0/1][sf][left/right] */ // effectively constant /* intensity stereo MPEG2 */ /* lr2[intensity_scale][ms_mode][sflen_offset+sf][left/right] */ typedef float ARRAY2_64_2[2][64][2]; typedef float ARRAY64_2[64][2]; static float lr2[2][2][64][2]; // effectively constant /*===============================================================*/ ARRAY2 *alias_init_addr() { return csa; } /*-----------------------------------------------------------*/ ARRAY8_2 *msis_init_addr() { /*------- pi = 4.0*atan(1.0); t = pi/12.0; for(i=0;i<7;i++) { s = sin(i*t); c = cos(i*t); // ms_mode = 0 lr[0][i][0] = (float)(s/(s+c)); lr[0][i][1] = (float)(c/(s+c)); // ms_mode = 1 lr[1][i][0] = (float)(sqrt(2.0)*(s/(s+c))); lr[1][i][1] = (float)(sqrt(2.0)*(c/(s+c))); } //sf = 7 //ms_mode = 0 lr[0][i][0] = 1.0f; lr[0][i][1] = 0.0f; // ms_mode = 1, in is bands is routine does ms processing lr[1][i][0] = 1.0f; lr[1][i][1] = 1.0f; ------------*/ return lr; } /*-------------------------------------------------------------*/ ARRAY2_64_2 *msis_init_addr_MPEG2() { return lr2; } /*===============================================================*/ void antialias(float x[], int n) { int i, k; float a, b; for (k = 0; k < n; k++) { for (i = 0; i < 8; i++) { a = x[17 - i]; b = x[18 + i]; x[17 - i] = a * csa[i][0] - b * csa[i][1]; x[18 + i] = b * csa[i][0] + a * csa[i][1]; } x += 18; } } /*===============================================================*/ void ms_process(float x[][1152], int n) /* sum-difference stereo */ { int i; float xl, xr; /*-- note: sqrt(2) done scaling by dequant ---*/ for (i = 0; i < n; i++) { xl = x[0][i] + x[1][i]; xr = x[0][i] - x[1][i]; x[0][i] = xl; x[1][i] = xr; } return; } /*===============================================================*/ void is_process_MPEG1(float x[][1152], /* intensity stereo */ SCALEFACT * sf, CB_INFO cb_info[2], /* [ch] */ int nsamp, int ms_mode) { int i, j, n, cb, w; float fl, fr; int m; int isf; float fls[3], frs[3]; int cb0; cb0 = cb_info[1].cbmax; /* start at end of right */ i = pMP3Stream->sfBandIndex[cb_info[1].cbtype][cb0]; cb0++; m = nsamp - i; /* process to len of left */ if (cb_info[1].cbtype) goto short_blocks; /*------------------------*/ /* long_blocks: */ for (cb = cb0; cb < 21; cb++) { isf = sf->l[cb]; n = pMP3Stream->nBand[0][cb]; fl = lr[ms_mode][isf][0]; fr = lr[ms_mode][isf][1]; for (j = 0; j < n; j++, i++) { if (--m < 0) goto exit; x[1][i] = fr * x[0][i]; x[0][i] = fl * x[0][i]; } } return; /*------------------------*/ short_blocks: for (cb = cb0; cb < 12; cb++) { for (w = 0; w < 3; w++) { isf = sf->s[w][cb]; fls[w] = lr[ms_mode][isf][0]; frs[w] = lr[ms_mode][isf][1]; } n = pMP3Stream->nBand[1][cb]; for (j = 0; j < n; j++) { m -= 3; if (m < 0) goto exit; x[1][i] = frs[0] * x[0][i]; x[0][i] = fls[0] * x[0][i]; x[1][1 + i] = frs[1] * x[0][1 + i]; x[0][1 + i] = fls[1] * x[0][1 + i]; x[1][2 + i] = frs[2] * x[0][2 + i]; x[0][2 + i] = fls[2] * x[0][2 + i]; i += 3; } } exit: return; } /*===============================================================*/ void is_process_MPEG2(float x[][1152], /* intensity stereo */ SCALEFACT * sf, CB_INFO cb_info[2], /* [ch] */ IS_SF_INFO * is_sf_info, int nsamp, int ms_mode) { int i, j, k, n, cb, w; float fl, fr; int m; int isf; int il[21]; int tmp; int r; ARRAY2 *lr; int cb0, cb1; lr = lr2[is_sf_info->intensity_scale][ms_mode]; if (cb_info[1].cbtype) goto short_blocks; /*------------------------*/ /* long_blocks: */ cb0 = cb_info[1].cbmax; /* start at end of right */ i = pMP3Stream->sfBandIndex[0][cb0]; m = nsamp - i; /* process to len of left */ /* gen sf info */ for (k = r = 0; r < 3; r++) { tmp = (1 << is_sf_info->slen[r]) - 1; for (j = 0; j < is_sf_info->nr[r]; j++, k++) il[k] = tmp; } for (cb = cb0 + 1; cb < 21; cb++) { isf = il[cb] + sf->l[cb]; fl = lr[isf][0]; fr = lr[isf][1]; n = pMP3Stream->nBand[0][cb]; for (j = 0; j < n; j++, i++) { if (--m < 0) goto exit; x[1][i] = fr * x[0][i]; x[0][i] = fl * x[0][i]; } } return; /*------------------------*/ short_blocks: for (k = r = 0; r < 3; r++) { tmp = (1 << is_sf_info->slen[r]) - 1; for (j = 0; j < is_sf_info->nr[r]; j++, k++) il[k] = tmp; } for (w = 0; w < 3; w++) { cb0 = cb_info[1].cbmax_s[w]; /* start at end of right */ i = pMP3Stream->sfBandIndex[1][cb0] + w; cb1 = cb_info[0].cbmax_s[w]; /* process to end of left */ for (cb = cb0 + 1; cb <= cb1; cb++) { isf = il[cb] + sf->s[w][cb]; fl = lr[isf][0]; fr = lr[isf][1]; n = pMP3Stream->nBand[1][cb]; for (j = 0; j < n; j++) { x[1][i] = fr * x[0][i]; x[0][i] = fl * x[0][i]; i += 3; } } } exit: return; } /*===============================================================*/