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/*
* Compare two audio signals and compute weighted SNR difference
*/

#ifdef _WIN32
#define _CRT_SECURE_NO_DEPRECATE    1
#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>

#include "SKP_Silk_SigProc_FIX.h"

#define FRAME_LENGTH_MS         10
#define WIN_LENGTH_MS           20
#define BW_EXPANSION            0.7f

#define MAX_FS_KHZ              24
#define LPC_ORDER               10
#define SNR_THRESHOLD           15.0

#ifdef  __cplusplus
extern "C"
{
#endif
/* Internally used functions */
void Autocorrelation( 
    SKP_float *results,                 /* o    result (length correlationCount)            */
    const SKP_float *inputData,         /* i    input data to correlate                     */
    SKP_int inputDataSize,              /* i    length of input                             */
    SKP_int correlationCount            /* i    number of correlation taps to compute       */
);

/* inner product of two SKP_float arrays, with result as double */
double Inner_product( 
    const SKP_float     *data1, 
    const SKP_float     *data2, 
    SKP_int             dataSize
);
/* Solve the normal equations using the Levinson-Durbin recursion */
SKP_float Levinsondurbin(               /* O    prediction error energy                     */
    SKP_float       A[],                /* O    prediction coefficients [order]             */
    const SKP_float corr[],             /* I    input auto-correlations [order + 1]         */
    const SKP_int   order               /* I    prediction order                            */
);

/* Chirp (bw expand) LP AR filter */
void Bwexpander( 
    SKP_float *ar,                      /* io   AR filter to be expanded (without leading 1)    */
    const SKP_int d,                    /* i    length of ar                                    */
    const SKP_float chirp               /* i    chirp factor (typically in range (0..1) )       */
);

#ifdef  __cplusplus
}
#endif

static void print_usage(char* argv[]) {
    printf("\nusage: %s ref.pcm test.pcm [settings]\n", argv[ 0 ]);
    printf("\nref.pcm       : Reference file");
    printf("\ntest.pcm      : File to be tested, should be of same length as ref.pcm");
    printf("\n   settings:");
    printf("\n-diff         : Only determine bit-exactness");
    printf("\n-fs <Hz>      : Sampling rate in Hz, max: %d; default: 24000", MAX_FS_KHZ * 1000 );
    printf("\n");
}


int main(int argc, char* argv[])
{
    SKP_int   args, n, i, counterRef, counterTest;
    char      testInFileName[150], refInFileName[150];
    FILE      *refInFile, *testInFile;
    SKP_int   nFrames = 0, isUnequal = 0;
    SKP_int   diff = 0, Fs_kHz;
    SKP_int32 Fs_Hz = 24000;
    SKP_float c, refWhtnd, testWhtnd, refNrg, diffNrg;
    double    SNR = 0.0;
    SKP_int16 refIn[WIN_LENGTH_MS * MAX_FS_KHZ], testIn[WIN_LENGTH_MS * MAX_FS_KHZ];
    SKP_float refWin[WIN_LENGTH_MS * MAX_FS_KHZ], testWin[WIN_LENGTH_MS * MAX_FS_KHZ];
    SKP_float autoCorr[LPC_ORDER + 1], LPC_Coef[LPC_ORDER];

    if (argc < 3) {
        print_usage(argv);
        exit(0);
    } 

    /* get arguments */
    args = 1;
    strcpy(refInFileName, argv[args]);
    args++;
    strcpy(testInFileName, argv[args]);
    args++;
    while(args < argc ) {
        if (SKP_STR_CASEINSENSITIVE_COMPARE(argv[args], "-diff") == 0) {
            diff = 1;
            args++;
        }else if (SKP_STR_CASEINSENSITIVE_COMPARE(argv[args], "-fs") == 0) {
            sscanf(argv[args+1], "%d", &Fs_Hz);
            args += 2;
        } else {
            printf("Error: unrecognized setting: %s\n\n", argv[args]);
            print_usage(argv);
            exit(0);
        }
    }

    Fs_kHz = SKP_DIV32_16( Fs_Hz, 1000 );

    if( Fs_kHz > MAX_FS_KHZ ) {
        printf("Error: sampling rate too high: %d\n\n", Fs_kHz);
        print_usage(argv);
        exit(0);
    }

    printf("Reference:  %s\n", refInFileName);
    //printf("Test:       %s\n", testInFileName);

    /* open files */
    refInFile = fopen(refInFileName, "rb");
    if (refInFile==NULL) {
        printf("Error: could not open input file %s\n", refInFileName);
        exit(0);
    } 
    testInFile = fopen(testInFileName, "rb");
    if (testInFile==NULL) {
        printf("Error: could not open input file %s\n", testInFileName);
        exit(0);
    }

    SKP_memset( refIn,  0, sizeof(refIn) );
    SKP_memset( testIn, 0, sizeof(testIn) );

    while(1) {
        /* Read inputs */
        counterRef  = (SKP_int)fread(&refIn[(WIN_LENGTH_MS - FRAME_LENGTH_MS) * Fs_kHz], 
            sizeof(SKP_int16), FRAME_LENGTH_MS * Fs_kHz, refInFile);
        counterTest = (SKP_int)fread(&testIn[(WIN_LENGTH_MS - FRAME_LENGTH_MS) * Fs_kHz], 
            sizeof(SKP_int16), FRAME_LENGTH_MS * Fs_kHz, testInFile);
        if(counterRef != FRAME_LENGTH_MS * Fs_kHz || counterTest != FRAME_LENGTH_MS * Fs_kHz){
            break;
        }

        /* test for bit-exactness */
        for( n = 0; n < FRAME_LENGTH_MS * Fs_kHz; n++ ) {
            if( refIn[(WIN_LENGTH_MS - FRAME_LENGTH_MS) * Fs_kHz + n] != 
                testIn[(WIN_LENGTH_MS - FRAME_LENGTH_MS) * Fs_kHz + n] ) {
                    isUnequal = 1;
                    break;
            }
        }

        /* apply sine window */
        for( n = 0; n < WIN_LENGTH_MS * Fs_kHz; n++ ) {
            c = (SKP_float)sin( 3.14159265 * (n + 1) / (WIN_LENGTH_MS * Fs_kHz + 1) );
            refWin[n]  = refIn[n]  * c;
            testWin[n] = testIn[n] * c;
        }

        /* LPC analysis on reference signal */

        /* Calculate auto correlation */
        Autocorrelation(autoCorr, refWin, WIN_LENGTH_MS * Fs_kHz, LPC_ORDER + 1);

        /* Add white noise */
        autoCorr[ 0 ] += autoCorr[ 0 ] * 1e-6f + 1.0f; 

        /* Convert correlations to prediction coefficients */
        Levinsondurbin(LPC_Coef, autoCorr, LPC_ORDER);

        /* Bandwdith expansion */
        Bwexpander(LPC_Coef, LPC_ORDER, BW_EXPANSION);

        /* Filter both signals */
        refNrg = 1.0f;
        diffNrg = 1e-10f;
        for( n = (WIN_LENGTH_MS - FRAME_LENGTH_MS) / 2 * Fs_kHz; 
             n < (WIN_LENGTH_MS + FRAME_LENGTH_MS) / 2 * Fs_kHz; n++ ) {
                refWhtnd = refIn[n];
                testWhtnd = testIn[n];
                for( i = 0; i < LPC_ORDER; i++ ) {
                    refWhtnd  -= LPC_Coef[ i ] * refIn[n - i - 1];
                    testWhtnd -= LPC_Coef[ i ] * testIn[n - i - 1];
                }
                refNrg += refWhtnd * refWhtnd;
                diffNrg += (refWhtnd - testWhtnd) * (refWhtnd - testWhtnd);
        }

        /* weighted SNR */
        if( refNrg > FRAME_LENGTH_MS * Fs_kHz ) {
            SNR += 10.0 * log10( refNrg / diffNrg );
            nFrames++;
        }

        /* Update Buffer */
        SKP_memmove( refIn,  &refIn[FRAME_LENGTH_MS * Fs_kHz],  (WIN_LENGTH_MS - FRAME_LENGTH_MS) * Fs_kHz * sizeof(SKP_int16));
        SKP_memmove( testIn, &testIn[FRAME_LENGTH_MS * Fs_kHz], (WIN_LENGTH_MS - FRAME_LENGTH_MS) * Fs_kHz * sizeof(SKP_int16));
    }

    if( diff ) {
        if( isUnequal ) {
            printf("Signals differ\n");
        } else {
            if(counterRef != counterTest){
                printf("Warning: signals differ in length\n");
            }
            printf("Signals are bit-exact\n");
        }
    } else {
        if( nFrames == 0 ) {
            printf("At least one signal too short or not loud enough\n");
            exit(0);
        }
        if(counterRef != counterTest){
            printf("Warning: signals differ in length\n");
        }
        if( isUnequal == 0 ) {
            printf("Signals are bit-exact          PASS\n");
        } else {
            printf("Average weighted SNR: %4.1f dB  ", SNR / nFrames);
            if( SNR / nFrames < SNR_THRESHOLD ) {
                printf("FAIL\n");
            } else {
                printf("PASS\n");
            }
        }
    }
    printf("\n");

    /* Close Files */
    fclose(refInFile);
    fclose(testInFile);

    return 0;
}

/* compute autocorrelation */
void Autocorrelation( 
    SKP_float *results,                 /* o    result (length correlationCount)            */
    const SKP_float *inputData,         /* i    input data to correlate                     */
    SKP_int inputDataSize,              /* i    length of input                             */
    SKP_int correlationCount            /* i    number of correlation taps to compute       */
)
{
    SKP_int i;

    if (correlationCount > inputDataSize) {
        correlationCount = inputDataSize;
    }

    for( i = 0; i < correlationCount; i++ ) {
        results[ i ] =  (SKP_float)Inner_product( inputData, inputData + i, inputDataSize - i );
    }
}

/* inner product of two SKP_float arrays, with result as double */
double Inner_product( 
    const SKP_float     *data1, 
    const SKP_float     *data2, 
    SKP_int             dataSize
)
{
    SKP_int  i, dataSize4;
    double   result;

    /* 4x unrolled loop */
    result = 0.0f;
    dataSize4 = dataSize & 0xFFFC;
    for( i = 0; i < dataSize4; i += 4 ) {
        result += data1[ i + 0 ] * data2[ i + 0 ] + 
                  data1[ i + 1 ] * data2[ i + 1 ] +
                  data1[ i + 2 ] * data2[ i + 2 ] +
                  data1[ i + 3 ] * data2[ i + 3 ];
    }

    /* add any remaining products */
    for( ; i < dataSize; i++ ) {
        result += data1[ i ] * data2[ i ];
    }

    return result;
}

/* Solve the normal equations using the Levinson-Durbin recursion */
SKP_float Levinsondurbin(               /* O    prediction error energy                     */
    SKP_float       A[],                /* O    prediction coefficients [order]             */
    const SKP_float corr[],             /* I    input auto-correlations [order + 1]         */
    const SKP_int   order               /* I    prediction order                            */
)
{
    SKP_int   i, mHalf, m;
    SKP_float min_nrg, nrg, t, km, Atmp1, Atmp2;
    
    min_nrg = 1e-12f * corr[ 0 ] + 1e-9f;
    nrg = corr[ 0 ];
    nrg = SKP_max(min_nrg, nrg);
    A[ 0 ] = corr[ 1 ] / nrg;
    nrg -= A[ 0 ] * corr[ 1 ];
    nrg = SKP_max(min_nrg, nrg);

    for( m = 1; m < order; m++ )
    {
        t = corr[ m + 1 ];
        for( i = 0; i < m; i++ ) {
            t -= A[ i ] * corr[ m - i ];
        }

        /* reflection coefficient */
        km = t / nrg;

        /* residual energy */
        nrg -= km * t;
        nrg = SKP_max(min_nrg, nrg);

        mHalf = m >> 1;
        for( i = 0; i < mHalf; i++ ) {
            Atmp1 = A[ i ];
            Atmp2 = A[ m - i - 1 ];
            A[ m - i - 1 ] -= km * Atmp1;
            A[ i ]         -= km * Atmp2;
        }
        if( m & 1 ) {
            A[ mHalf ]     -= km * A[ mHalf ];
        }
        A[ m ] = km;
    }

    /* return the residual energy */
    return nrg;
}

/* Chirp (bw expand) LP AR filter */
void Bwexpander( 
    SKP_float *ar,                      /* io   AR filter to be expanded (without leading 1)    */
    const SKP_int d,                    /* i    length of ar                                    */
    const SKP_float chirp               /* i    chirp factor (typically in range (0..1) )       */
)
{
    SKP_int   i;
    SKP_float cfac = chirp;

    for( i = 0; i < d - 1; i++ ) {
        ar[ i ] *=  cfac;
        cfac    *=  chirp;
    }
    ar[ d - 1 ] *=  cfac;
}
