ref: 2fbc12a1a1ee88dc8e023bcdb71a6e6f440781aa
dir: /libfaac/joint.c/
/*
* FAAC - Freeware Advanced Audio Coder
* Copyright (C) 2001 Menno Bakker
*
* 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* $Id: joint.c,v 1.3 2001/02/28 18:39:34 menno Exp $
*/
#include "channels.h"
#include "util.h"
void MSEncode(CoderInfo *coderInfo,
ChannelInfo *channelInfo,
double *spectrum[MAX_CHANNELS],
unsigned int numberOfChannels,
unsigned int msenable)
{
unsigned int chanNum;
int sfbNum;
int lineNum;
double sum,diff;
/* Look for channel_pair_elements */
for (chanNum=0;chanNum<numberOfChannels;chanNum++) {
if (channelInfo[chanNum].present) {
if ((channelInfo[chanNum].cpe)&&(channelInfo[chanNum].ch_is_left)) {
int leftChan=chanNum;
int rightChan = channelInfo[chanNum].paired_ch;
channelInfo[leftChan].msInfo.is_present = 0;
channelInfo[rightChan].msInfo.is_present = 0;
/* Perform MS if block_types are the same */
if ((coderInfo[leftChan].block_type==coderInfo[rightChan].block_type)&&(msenable)) {
int numGroups;
int maxSfb;
int g,w,line_offset;
int startWindow,stopWindow;
MSInfo *msInfoL;
MSInfo *msInfoR;
channelInfo[leftChan].common_window = 1; /* Use common window */
channelInfo[leftChan].msInfo.is_present = 1;
channelInfo[rightChan].msInfo.is_present = 1;
numGroups = coderInfo[leftChan].num_window_groups;
maxSfb = coderInfo[leftChan].max_sfb;
w=0;
/* Determine which bands should be enabled */
msInfoL = &(channelInfo[leftChan].msInfo);
msInfoR = &(channelInfo[rightChan].msInfo);
/* Perform sum and differencing on bands in which ms_used flag */
/* has been set. */
if (coderInfo[leftChan].block_type == ONLY_SHORT_WINDOW) {
line_offset=0;
startWindow = 0;
for (g=0;g<numGroups;g++) {
int numWindows = coderInfo[leftChan].window_group_length[g];
stopWindow = startWindow + numWindows;
for (sfbNum=0;sfbNum<maxSfb;sfbNum++) {
/* Enable MS mask */
int use_ms = 1;
for (w=startWindow;w<stopWindow;w++) {
use_ms = min(use_ms, msInfoL->ms_usedS[w][sfbNum]);
}
msInfoL->ms_used[g*maxSfb+sfbNum] = use_ms; /* write this to bitstream */
msInfoR->ms_used[g*maxSfb+sfbNum] = use_ms;
for (w=startWindow;w<stopWindow;w++) {
msInfoL->ms_usedS[w][sfbNum] = use_ms;
msInfoR->ms_usedS[w][sfbNum] = use_ms;
}
for (w=startWindow;w<stopWindow;w++) {
if (msInfoL->ms_usedS[w][sfbNum]) {
for (lineNum = coderInfo[leftChan].sfb_offset[sfbNum];
lineNum < coderInfo[leftChan].sfb_offset[sfbNum+1];
lineNum++)
{
line_offset = w*BLOCK_LEN_SHORT;
sum=spectrum[leftChan][line_offset+lineNum]+spectrum[rightChan][line_offset+lineNum];
diff=spectrum[leftChan][line_offset+lineNum]-spectrum[rightChan][line_offset+lineNum];
spectrum[leftChan][line_offset+lineNum] = 0.5 * sum;
spectrum[rightChan][line_offset+lineNum] = 0.5 * diff;
}
}
}
}
startWindow = stopWindow;
}
} else {
for (sfbNum = 0;sfbNum < maxSfb; sfbNum++) {
msInfoR->ms_used[sfbNum] = msInfoL->ms_used[sfbNum];
/* Enable MS mask */
if (msInfoL->ms_used[sfbNum]) {
for (lineNum = coderInfo[leftChan].sfb_offset[sfbNum];
lineNum < coderInfo[leftChan].sfb_offset[sfbNum+1];
lineNum++)
{
sum=spectrum[leftChan][lineNum]+spectrum[rightChan][lineNum];
diff=spectrum[leftChan][lineNum]-spectrum[rightChan][lineNum];
spectrum[leftChan][lineNum] = 0.5 * sum;
spectrum[rightChan][lineNum] = 0.5 * diff;
}
}
}
}
}
}
}
}
}