shithub: aacenc

ref: 88c21b018c8eb827016538ae1c338941e2a70afd
dir: /mc_enc.c/

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#include "mc_enc.h"

void DetermineChInfo(Ch_Info* chInfo, int numChannels, int lfePresent) {
   
  /* 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           */

	int sceTag=0;
	int lfeTag=0;
	int cpeTag=0;
	int numChannelsLeft=numChannels;

	
	/* First element is sce, except for 2 channel case */
	if (numChannelsLeft!=2) {
		chInfo[numChannels-numChannelsLeft].present = 1;
		chInfo[numChannels-numChannelsLeft].tag=sceTag++;
		chInfo[numChannels-numChannelsLeft].cpe=0;
		chInfo[numChannels-numChannelsLeft].lfe=0;    
		numChannelsLeft--;
	}

	/* Next elements are cpe's */
	while (numChannelsLeft>1) {
		/* Left channel info */
		chInfo[numChannels-numChannelsLeft].present = 1;
		chInfo[numChannels-numChannelsLeft].tag=cpeTag++;
		chInfo[numChannels-numChannelsLeft].cpe=1;
		chInfo[numChannels-numChannelsLeft].common_window=0;
		chInfo[numChannels-numChannelsLeft].ch_is_left=1;
		chInfo[numChannels-numChannelsLeft].paired_ch=numChannels-numChannelsLeft+1;
		chInfo[numChannels-numChannelsLeft].lfe=0;    
		numChannelsLeft--;
		
		/* Right channel info */
		chInfo[numChannels-numChannelsLeft].present = 1;
		chInfo[numChannels-numChannelsLeft].cpe=1;
		chInfo[numChannels-numChannelsLeft].common_window=0;
		chInfo[numChannels-numChannelsLeft].ch_is_left=0;
		chInfo[numChannels-numChannelsLeft].paired_ch=numChannels-numChannelsLeft-1;
		chInfo[numChannels-numChannelsLeft].lfe=0;
		numChannelsLeft--;
	}

	/* Is there another channel left ? */
	if (numChannelsLeft) {
		if (lfePresent) { 
			chInfo[numChannels-numChannelsLeft].present = 1;
			chInfo[numChannels-numChannelsLeft].tag=lfeTag++;
			chInfo[numChannels-numChannelsLeft].cpe=0;
			chInfo[numChannels-numChannelsLeft].lfe=1; 
		} else {
			chInfo[numChannels-numChannelsLeft].present = 1;
			chInfo[numChannels-numChannelsLeft].tag=sceTag++;
			chInfo[numChannels-numChannelsLeft].cpe=0;
			chInfo[numChannels-numChannelsLeft].lfe=0;
		}
		numChannelsLeft--;
	}
}