ref: 4fda6b01424aab5f6c5b13b1bd01697c899b6fcd
dir: /silk/stereo_decode_pred.c/
/***********************************************************************
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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***********************************************************************/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "main.h"
/* Decode mid/side predictors */
void silk_stereo_decode_pred(
ec_dec *psRangeDec, /* I/O Compressor data structure */
opus_int32 pred_Q13[] /* O Predictors */
)
{
opus_int n, ix[ 2 ][ 3 ];
opus_int32 low_Q13, step_Q13;
/* Entropy decoding */
n = ec_dec_icdf( psRangeDec, silk_stereo_pred_joint_iCDF, 8 );
ix[ 0 ][ 2 ] = silk_DIV32_16( n, 5 );
ix[ 1 ][ 2 ] = n - 5 * ix[ 0 ][ 2 ];
for( n = 0; n < 2; n++ ) {
ix[ n ][ 0 ] = ec_dec_icdf( psRangeDec, silk_uniform3_iCDF, 8 );
ix[ n ][ 1 ] = ec_dec_icdf( psRangeDec, silk_uniform5_iCDF, 8 );
}
/* Dequantize */
for( n = 0; n < 2; n++ ) {
ix[ n ][ 0 ] += 3 * ix[ n ][ 2 ];
low_Q13 = silk_stereo_pred_quant_Q13[ ix[ n ][ 0 ] ];
step_Q13 = silk_SMULWB( silk_stereo_pred_quant_Q13[ ix[ n ][ 0 ] + 1 ] - low_Q13,
SILK_FIX_CONST( 0.5 / STEREO_QUANT_SUB_STEPS, 16 ) );
pred_Q13[ n ] = silk_SMLABB( low_Q13, step_Q13, 2 * ix[ n ][ 1 ] + 1 );
}
/* Subtract second from first predictor (helps when actually applying these) */
pred_Q13[ 0 ] -= pred_Q13[ 1 ];
}
/* Decode mid-only flag */
void silk_stereo_decode_mid_only(
ec_dec *psRangeDec, /* I/O Compressor data structure */
opus_int *decode_only_mid /* O Flag that only mid channel has been coded */
)
{
/* Decode flag that only mid channel is coded */
*decode_only_mid = ec_dec_icdf( psRangeDec, silk_stereo_only_code_mid_iCDF, 8 );
}