ref: f462a48362fda61eba348d50b22892ca2be6b563
dir: /libfaac/channels.c/
/*
* FAAC - Freeware Advanced Audio Coder
* Copyright (C) 2001 Menno Bakker
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* $Id: channels.c,v 1.4 2001/06/08 18:01:09 menno Exp $
*/
#include "channels.h"
#include "coder.h"
#include "util.h"
/* If LFE present */
/* Num channels # of SCE's # of CPE's #of LFE's */
/* ============ ========== ========== ========= */
/* 1 1 0 0 */
/* 2 0 1 0 */
/* 3 1 1 0 */
/* 4 1 1 1 */
/* 5 1 2 0 */
/* For more than 5 channels, use the following elements: */
/* 2*N 1 2*(N-1) 1 */
/* 2*N+1 1 2*N 0 */
/* */
/* Else: */
/* */
/* Num channels # of SCE's # of CPE's #of LFE's */
/* ============ ========== ========== ========= */
/* 1 1 0 0 */
/* 2 0 1 0 */
/* 3 1 1 0 */
/* 4 2 1 0 */
/* 5 1 2 0 */
/* For more than 5 channels, use the following elements: */
/* 2*N 2 2*(N-1) 0 */
/* 2*N+1 1 2*N 0 */
void GetChannelInfo(ChannelInfo *channelInfo, int numChannels, int useLfe)
{
int sceTag = 0;
int lfeTag = 0;
int cpeTag = 0;
int numChannelsLeft = numChannels;
/* First element is sce, except for 2 channel case */
if (numChannelsLeft != 2) {
channelInfo[numChannels-numChannelsLeft].present = 1;
channelInfo[numChannels-numChannelsLeft].tag = sceTag++;
channelInfo[numChannels-numChannelsLeft].cpe = 0;
channelInfo[numChannels-numChannelsLeft].lfe = 0;
numChannelsLeft--;
}
/* Next elements are cpe's */
while (numChannelsLeft > 1) {
/* Left channel info */
channelInfo[numChannels-numChannelsLeft].present = 1;
channelInfo[numChannels-numChannelsLeft].tag = cpeTag++;
channelInfo[numChannels-numChannelsLeft].cpe = 1;
channelInfo[numChannels-numChannelsLeft].common_window = 0;
channelInfo[numChannels-numChannelsLeft].ch_is_left = 1;
channelInfo[numChannels-numChannelsLeft].paired_ch = numChannels-numChannelsLeft+1;
channelInfo[numChannels-numChannelsLeft].lfe = 0;
numChannelsLeft--;
/* Right channel info */
channelInfo[numChannels-numChannelsLeft].present = 1;
channelInfo[numChannels-numChannelsLeft].cpe = 1;
channelInfo[numChannels-numChannelsLeft].common_window = 0;
channelInfo[numChannels-numChannelsLeft].ch_is_left = 0;
channelInfo[numChannels-numChannelsLeft].paired_ch = numChannels-numChannelsLeft-1;
channelInfo[numChannels-numChannelsLeft].lfe = 0;
numChannelsLeft--;
}
/* Is there another channel left ? */
if (numChannelsLeft) {
if (useLfe) {
channelInfo[numChannels-numChannelsLeft].present = 1;
channelInfo[numChannels-numChannelsLeft].tag = lfeTag++;
channelInfo[numChannels-numChannelsLeft].cpe = 0;
channelInfo[numChannels-numChannelsLeft].lfe = 1;
} else {
channelInfo[numChannels-numChannelsLeft].present = 1;
channelInfo[numChannels-numChannelsLeft].tag = sceTag++;
channelInfo[numChannels-numChannelsLeft].cpe = 0;
channelInfo[numChannels-numChannelsLeft].lfe = 0;
}
numChannelsLeft--;
}
}