transform_pcm.c

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#include "config.h"
#include "transform_pcm.h"

#include <stdint.h>
#include <math.h>

#define UNUSED(x) (void)(x)     

#ifndef MIN
# define MIN(a,b) (((a) < (b)) ? (a) : (b))
#endif

#ifndef MAX
# define MAX(a,b) (((a) > (b)) ? (a) : (b))
#endif

inline signed short int pcm_float_to_int(float f)
{
        return (signed short int)(MIN(MAX(floorf(f * 32767.f + .5f), -32768), 32767));
}

inline signed short int pcm_int16_to_int(int i)
{
        return (signed short int)(MIN(MAX(i, -32768), 32767));
}

/*
input channel order:                  used for: mono stereo 2.1 4.0 5.0 5.1 6.1 7.1
float *pcm_fl   1: front left/left stereo               X    X   X   X   X   X   X
float *pcm_fr   2: front right/right stereo             X    X   X   X   X   X   X
float *pcm_fc   3: (front)center/mono            X           X       X   X   X   X
float *pcm_rc   4: rear center                                               X
float *pcm_sl   5: side left                                                 X   X
float *pcm_sr   6: side right                                                X   X
float *pcm_rl   7: rear left                                     X   X   X       X
float *pcm_rr   8: rear right                                    X   X   X       X
float *pcm_lfe  9: LFE                                                   X   X   X

output channel order:
signed int16_t *pcmout_l        1: left stereo
signed int16_t *pcmout_r        2: right stereo
*/

int transform_to_stereo(long int samples, int channels, float *pcm_fl, float *pcm_fr, float *pcm_fc, float *pcm_rc, float *pcm_sl, float *pcm_sr, float *pcm_rl, float *pcm_rr, float *pcm_lfe, signed short int *pcmout_l, signed short int *pcmout_r)
{
        UNUSED(pcm_fc);
        UNUSED(pcm_rc);
        UNUSED(pcm_sl);
        UNUSED(pcm_sr);
        UNUSED(pcm_rl);
        UNUSED(pcm_rr);
        UNUSED(pcm_lfe);
        long int s;

        for(s = 0; s < samples; s++)
        {
                switch(channels)
                {
                    case 1:
                        pcmout_l[s] = pcmout_r[s] = pcm_float_to_int(pcm_fc[s]);
                        break;
                    case 2:
                    default:
                        pcmout_l[s] = pcm_float_to_int(pcm_fl[s]);
                        pcmout_r[s] = pcm_float_to_int(pcm_fr[s]);
                        break;
                }
        }
        return s + 1;
}