godot/drivers/opus/silk/float/process_gains_FLP.c

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#include "opus/opus_config.h"

#include "opus/silk/float/main_FLP.h"
#include "opus/silk/tuning_parameters.h"

/* Processing of gains */
void silk_process_gains_FLP(
    silk_encoder_state_FLP          *psEnc,                             /* I/O  Encoder state FLP                           */
    silk_encoder_control_FLP        *psEncCtrl,                         /* I/O  Encoder control FLP                         */
    opus_int                        condCoding                          /* I    The type of conditional coding to use       */
)
{
    silk_shape_state_FLP *psShapeSt = &psEnc->sShape;
    opus_int     k;
    opus_int32   pGains_Q16[ MAX_NB_SUBFR ];
    silk_float   s, InvMaxSqrVal, gain, quant_offset;

    /* Gain reduction when LTP coding gain is high */
    if( psEnc->sCmn.indices.signalType == TYPE_VOICED ) {
        s = 1.0f - 0.5f * silk_sigmoid( 0.25f * ( psEncCtrl->LTPredCodGain - 12.0f ) );
        for( k = 0; k < psEnc->sCmn.nb_subfr; k++ ) {
            psEncCtrl->Gains[ k ] *= s;
        }
    }

    /* Limit the quantized signal */
    InvMaxSqrVal = ( silk_float )( pow( 2.0f, 0.33f * ( 21.0f - psEnc->sCmn.SNR_dB_Q7 * ( 1 / 128.0f ) ) ) / psEnc->sCmn.subfr_length );

    for( k = 0; k < psEnc->sCmn.nb_subfr; k++ ) {
        /* Soft limit on ratio residual energy and squared gains */
        gain = psEncCtrl->Gains[ k ];
        gain = ( silk_float )sqrt( gain * gain + psEncCtrl->ResNrg[ k ] * InvMaxSqrVal );
        psEncCtrl->Gains[ k ] = silk_min_float( gain, 32767.0f );
    }

    /* Prepare gains for noise shaping quantization */
    for( k = 0; k < psEnc->sCmn.nb_subfr; k++ ) {
        pGains_Q16[ k ] = (opus_int32)( psEncCtrl->Gains[ k ] * 65536.0f );
    }

    /* Save unquantized gains and gain Index */
    silk_memcpy( psEncCtrl->GainsUnq_Q16, pGains_Q16, psEnc->sCmn.nb_subfr * sizeof( opus_int32 ) );
    psEncCtrl->lastGainIndexPrev = psShapeSt->LastGainIndex;

    /* Quantize gains */
    silk_gains_quant( psEnc->sCmn.indices.GainsIndices, pGains_Q16,
            &psShapeSt->LastGainIndex, condCoding == CODE_CONDITIONALLY, psEnc->sCmn.nb_subfr );

    /* Overwrite unquantized gains with quantized gains and convert back to Q0 from Q16 */
    for( k = 0; k < psEnc->sCmn.nb_subfr; k++ ) {
        psEncCtrl->Gains[ k ] = pGains_Q16[ k ] / 65536.0f;
    }

    /* Set quantizer offset for voiced signals. Larger offset when LTP coding gain is low or tilt is high (ie low-pass) */
    if( psEnc->sCmn.indices.signalType == TYPE_VOICED ) {
        if( psEncCtrl->LTPredCodGain + psEnc->sCmn.input_tilt_Q15 * ( 1.0f / 32768.0f ) > 1.0f ) {
            psEnc->sCmn.indices.quantOffsetType = 0;
        } else {
            psEnc->sCmn.indices.quantOffsetType = 1;
        }
    }

    /* Quantizer boundary adjustment */
    quant_offset = silk_Quantization_Offsets_Q10[ psEnc->sCmn.indices.signalType >> 1 ][ psEnc->sCmn.indices.quantOffsetType ] / 1024.0f;
    psEncCtrl->Lambda = LAMBDA_OFFSET
                      + LAMBDA_DELAYED_DECISIONS * psEnc->sCmn.nStatesDelayedDecision
                      + LAMBDA_SPEECH_ACT        * psEnc->sCmn.speech_activity_Q8 * ( 1.0f /  256.0f )
                      + LAMBDA_INPUT_QUALITY     * psEncCtrl->input_quality
                      + LAMBDA_CODING_QUALITY    * psEncCtrl->coding_quality
                      + LAMBDA_QUANT_OFFSET      * quant_offset;

    silk_assert( psEncCtrl->Lambda > 0.0f );
    silk_assert( psEncCtrl->Lambda < 2.0f );
}