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+/*
+ *
+ * downmix.c
+ *
+ * Copyright (C) Aaron Holtzman - Sept 1999
+ *
+ * Originally based on code by Yuqing Deng.
+ *
+ * This file is part of ac3dec, a free Dolby AC-3 stream decoder.
+ *
+ * ac3dec 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, or (at your option)
+ * any later version.
+ *
+ * ac3dec 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 GNU Make; see the file COPYING. If not, write to
+ * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ *
+ */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <math.h>
+#include "ac3.h"
+#include "ac3_internal.h"
+
+
+#include "decode.h"
+#include "downmix.h"
+#include "debug.h"
+
+
+//Pre-scaled downmix coefficients
+static float cmixlev_lut[4] = { 0.2928, 0.2468, 0.2071, 0.2468 };
+static float smixlev_lut[4] = { 0.2928, 0.2071, 0.0 , 0.2071 };
+
+static void
+downmix_3f_2r_to_2ch(bsi_t* bsi, stream_samples_t samples,sint_16 *s16_samples)
+{
+ uint_32 j;
+ float right_tmp;
+ float left_tmp;
+ float clev,slev;
+ float *centre = 0, *left = 0, *right = 0, *left_sur = 0, *right_sur = 0;
+
+ left = samples[0];
+ centre = samples[1];
+ right = samples[2];
+ left_sur = samples[3];
+ right_sur = samples[4];
+
+ clev = cmixlev_lut[bsi->cmixlev];
+ slev = smixlev_lut[bsi->surmixlev];
+
+#if defined DOLBY_SURROUND
+ for (j = 0; j < 256; j++)
+ {
+ right_tmp = *left_sur++ + *right_sur++;
+ left_tmp = 1.4142f * *left++ + *centre - right_tmp;
+ right_tmp += 1.4142f * *right++ + *centre++;
+
+ s16_samples[j * 2 ] = (sint_16) (left_tmp * 16000.0f);
+ s16_samples[j * 2 + 1] = (sint_16) (right_tmp * 16000.0f);
+ }
+#else
+ for (j = 0; j < 256; j++)
+ {
+ left_tmp = 0.4142f * *left++ + clev * *centre + slev * *left_sur++;
+ right_tmp= 0.4142f * *right++ + clev * *centre++ + slev * *right_sur++;
+
+ s16_samples[j * 2 ] = (sint_16) (left_tmp * 32767.0f);
+ s16_samples[j * 2 + 1] = (sint_16) (right_tmp * 32767.0f);
+ }
+#endif
+}
+
+static void
+downmix_2f_2r_to_2ch(bsi_t* bsi, stream_samples_t samples,sint_16 *s16_samples)
+{
+ uint_32 j;
+ float right_tmp;
+ float left_tmp;
+ float slev;
+ float *left = 0, *right = 0, *left_sur = 0, *right_sur = 0;
+
+ left = samples[0];
+ right = samples[1];
+ left_sur = samples[2];
+ right_sur = samples[3];
+
+ slev = smixlev_lut[bsi->surmixlev];
+
+ for (j = 0; j < 256; j++)
+ {
+ left_tmp = 0.4142f * *left++ + slev * *left_sur++;
+ right_tmp= 0.4142f * *right++ + slev * *right_sur++;
+
+ s16_samples[j * 2 ] = (sint_16) (left_tmp * 32767.0f);
+ s16_samples[j * 2 + 1] = (sint_16) (right_tmp * 32767.0f);
+ }
+}
+
+static void
+downmix_3f_1r_to_2ch(bsi_t* bsi, stream_samples_t samples,sint_16 *s16_samples)
+{
+ uint_32 j;
+ float right_tmp;
+ float left_tmp;
+ float clev,slev;
+ float *centre = 0, *left = 0, *right = 0, *sur = 0;
+
+ left = samples[0];
+ centre = samples[1];
+ right = samples[2];
+ //Mono surround
+ sur = samples[3];
+
+ clev = cmixlev_lut[bsi->cmixlev];
+ slev = smixlev_lut[bsi->surmixlev];
+
+ for (j = 0; j < 256; j++)
+ {
+ left_tmp = 0.4142f * *left++ + clev * *centre++ + slev * *sur;
+ right_tmp= 0.4142f * *right++ + clev * *centre + slev * *sur++;
+
+ s16_samples[j * 2 ] = (sint_16) (left_tmp * 32767.0f);
+ s16_samples[j * 2 + 1] = (sint_16) (right_tmp * 32767.0f);
+ }
+}
+
+
+static void
+downmix_2f_1r_to_2ch(bsi_t* bsi, stream_samples_t samples,sint_16 *s16_samples)
+{
+ uint_32 j;
+ float right_tmp;
+ float left_tmp;
+ float slev;
+ float *left = 0, *right = 0, *sur = 0;
+
+ left = samples[0];
+ right = samples[1];
+ //Mono surround
+ sur = samples[2];
+
+ slev = smixlev_lut[bsi->surmixlev];
+
+ for (j = 0; j < 256; j++)
+ {
+ left_tmp = 0.4142f * *left++ + slev * *sur;
+ right_tmp= 0.4142f * *right++ + slev * *sur++;
+
+ s16_samples[j * 2 ] = (sint_16) (left_tmp * 32767.0f);
+ s16_samples[j * 2 + 1] = (sint_16) (right_tmp * 32767.0f);
+ }
+}
+
+static void
+downmix_3f_0r_to_2ch(bsi_t* bsi, stream_samples_t samples,sint_16 *s16_samples)
+{
+ uint_32 j;
+ float right_tmp;
+ float left_tmp;
+ float clev;
+ float *centre = 0, *left = 0, *right = 0;
+
+ left = samples[0];
+ centre = samples[1];
+ right = samples[2];
+
+ clev = cmixlev_lut[bsi->cmixlev];
+
+ for (j = 0; j < 256; j++)
+ {
+ left_tmp = 0.4142f * *left++ + clev * *centre;
+ right_tmp= 0.4142f * *right++ + clev * *centre++;
+
+ s16_samples[j * 2 ] = (sint_16) (left_tmp * 32767.0f);
+ s16_samples[j * 2 + 1] = (sint_16) (right_tmp * 32767.0f);
+ }
+}
+
+static void
+downmix_2f_0r_to_2ch(bsi_t* bsi, stream_samples_t samples,sint_16 *s16_samples)
+{
+ uint_32 j;
+ float *left = 0, *right = 0;
+
+ left = samples[0];
+ right = samples[1];
+
+ for (j = 0; j < 256; j++)
+ {
+ s16_samples[j * 2 ] = (sint_16) (*left++ * 32767.0f);
+ s16_samples[j * 2 + 1] = (sint_16) (*right++ * 32767.0f);
+ }
+}
+
+static void
+downmix_1f_0r_to_2ch(float *centre,sint_16 *s16_samples)
+{
+ uint_32 j;
+ float tmp;
+
+ //Mono program!
+
+ for (j = 0; j < 256; j++)
+ {
+ tmp = 32767.0f * 0.7071f * *centre++;
+
+ s16_samples[j * 2 ] = s16_samples[j * 2 + 1] = (sint_16) tmp;
+ }
+}
+
+//
+// Downmix into 2 or 4 channels (4 ch isn't in quite yet)
+//
+// The downmix function names have the following format
+//
+// downmix_Xf_Yr_to_[2|4]ch[_dolby]
+//
+// where X = number of front channels
+// Y = number of rear channels
+// [2|4] = number of output channels
+// [_dolby] = with or without dolby surround mix
+//
+
+void downmix(bsi_t* bsi, stream_samples_t samples,sint_16 *s16_samples)
+{
+ if(bsi->acmod > 7)
+ dprintf("(downmix) invalid acmod number\n");
+
+ //
+ //There are two main cases, with or without Dolby Surround
+ //
+ if(ac3_config.flags & AC3_DOLBY_SURR_ENABLE)
+ {
+ fprintf(stderr,"Dolby Surround Mixes not currently enabled\n");
+ exit(1);
+ }
+
+ //Non-Dolby surround downmixes
+ switch(bsi->acmod)
+ {
+ // 3/2
+ case 7:
+ downmix_3f_2r_to_2ch(bsi,samples,s16_samples);
+ break;
+
+ // 2/2
+ case 6:
+ downmix_2f_2r_to_2ch(bsi,samples,s16_samples);
+ break;
+
+ // 3/1
+ case 5:
+ downmix_3f_1r_to_2ch(bsi,samples,s16_samples);
+ break;
+
+ // 2/1
+ case 4:
+ downmix_2f_1r_to_2ch(bsi,samples,s16_samples);
+ break;
+
+ // 3/0
+ case 3:
+ downmix_3f_0r_to_2ch(bsi,samples,s16_samples);
+ break;
+
+ case 2:
+ downmix_2f_0r_to_2ch(bsi,samples,s16_samples);
+ break;
+
+ // 1/0
+ case 1:
+ downmix_1f_0r_to_2ch(samples[0],s16_samples);
+ break;
+
+ // 1+1
+ case 0:
+ downmix_1f_0r_to_2ch(samples[ac3_config.dual_mono_ch_sel],s16_samples);
+ break;
+ }
+}
+
+
+
+#if 0
+
+ //the dolby mixes lay here for the time being
+ switch(bsi->acmod)
+ {
+ // 3/2
+ case 7:
+ left = samples[0];
+ centre = samples[1];
+ right = samples[2];
+ left_sur = samples[3];
+ right_sur = samples[4];
+
+ for (j = 0; j < 256; j++)
+ {
+ right_tmp = 0.2265f * *left_sur++ + 0.2265f * *right_sur++;
+ left_tmp = -1 * right_tmp;
+ right_tmp += 0.3204f * *right++ + 0.2265f * *centre;
+ left_tmp += 0.3204f * *left++ + 0.2265f * *centre++;
+
+ samples[1][j] = right_tmp;
+ samples[0][j] = left_tmp;
+ }
+
+ break;
+
+ // 2/2
+ case 6:
+ left = samples[0];
+ right = samples[1];
+ left_sur = samples[2];
+ right_sur = samples[3];
+
+ for (j = 0; j < 256; j++)
+ {
+ right_tmp = 0.2265f * *left_sur++ + 0.2265f * *right_sur++;
+ left_tmp = -1 * right_tmp;
+ right_tmp += 0.3204f * *right++;
+ left_tmp += 0.3204f * *left++ ;
+
+ samples[1][j] = right_tmp;
+ samples[0][j] = left_tmp;
+ }
+ break;
+
+ // 3/1
+ case 5:
+ left = samples[0];
+ centre = samples[1];
+ right = samples[2];
+ //Mono surround
+ right_sur = samples[3];
+
+ for (j = 0; j < 256; j++)
+ {
+ right_tmp = 0.2265f * *right_sur++;
+ left_tmp = -1 * right_tmp;
+ right_tmp += 0.3204f * *right++ + 0.2265f * *centre;
+ left_tmp += 0.3204f * *left++ + 0.2265f * *centre++;
+
+ samples[1][j] = right_tmp;
+ samples[0][j] = left_tmp;
+ }
+ break;
+
+ // 2/1
+ case 4:
+ left = samples[0];
+ right = samples[1];
+ //Mono surround
+ right_sur = samples[2];
+
+ for (j = 0; j < 256; j++)
+ {
+ right_tmp = 0.2265f * *right_sur++;
+ left_tmp = -1 * right_tmp;
+ right_tmp += 0.3204f * *right++;
+ left_tmp += 0.3204f * *left++;
+
+ samples[1][j] = right_tmp;
+ samples[0][j] = left_tmp;
+ }
+ break;
+
+ // 3/0
+ case 3:
+ left = samples[0];
+ centre = samples[1];
+ right = samples[2];
+
+ for (j = 0; j < 256; j++)
+ {
+ right_tmp = 0.3204f * *right++ + 0.2265f * *centre;
+ left_tmp = 0.3204f * *left++ + 0.2265f * *centre++;
+
+ samples[1][j] = right_tmp;
+ samples[0][j] = left_tmp;
+ }
+ break;
+
+ // 2/0
+ case 2:
+ //Do nothing!
+ break;
+
+ // 1/0
+ case 1:
+ //Mono program!
+ right = samples[0];
+
+ for (j = 0; j < 256; j++)
+ {
+ right_tmp = 0.7071f * *right++;
+
+ samples[1][j] = right_tmp;
+ samples[0][j] = right_tmp;
+ }
+
+ break;
+
+ // 1+1
+ case 0:
+ //Dual mono, output selected by user
+ right = samples[ac3_config.dual_mono_ch_sel];
+
+ for (j = 0; j < 256; j++)
+ {
+ right_tmp = 0.7071f * *right++;
+
+ samples[1][j] = right_tmp;
+ samples[0][j] = right_tmp;
+ }
+ break;
+#endif
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