Wrong DCT with MKL DCT function

Question

I am giving 8x8 input to my MKL based Discrete Cosine Transform (DCT) code :

"fileinput.txt" INPUT:

255    255    255    255    255    255    255    255
255    255    255    255    255    255    255    255
255    255    255    255    255    255    255    255
255    255    255    255    255    255    255    255
255    255    255    255    255    255    255    255
255    255    255    255    255    255    255    255
255    255    255    255    255    255    255    255
255    255    255    255    255    255    255    255

DCT OUTPUT FROM BELOW CODE as :

32385      -727.349243  -619.955444 -458.675903 -267.323547 -74.151535  92.318069   207.505844
764.404419  717.50531   602.316772  435.846893  242.6754    51.322887   -109.956779 -217.350159
-762.619629 -706.582764 -583.869446 -412.598663 -218.058334 -28.972321  126.74057   226.088898
759.648132  694.603516  564.651367  388.979492  193.525208  7.147152    -142.635284 -233.70639
-755.498901 -681.59967  -544.712891 -365.049927 -169.138    14.096443   157.598663  240.180206
750.180115  667.597656  524.094971  340.860809  144.948898  -34.714363  -171.600922 -245.499771
-743.705566 -652.633789 -502.85144  -316.473694 -121.019257 54.652824   184.604614  249.648224
736.088623  636.739502  481.026154  291.940552  97.400169   -73.870857  -196.583725 -252.620102

EXPECTED OUTPUT:

16320      8.331551    -8.493903    8.775995    -9.19324    9.772106    -10.552611  11.595706
8.332954    0.004307    -0.004317   0.004504    -0.00472    0.004989    -0.005391   0.00592
-8.494178   -0.004317   0.004454    -0.004576   0.004765    -0.005109   0.005472    -0.006031
8.776941    0.004504    -0.004545   0.004746    -0.004965   0.005248    -0.005666   0.006251
-9.193484   -0.004659   0.004811    -0.00495    0.005198    -0.005507   0.005955    -0.006519
9.771847    0.005035    -0.005079   0.005241    -0.005522   0.005852    -0.006314   0.00696
-10.552428  -0.005383   0.005533    -0.005627   0.00591    -0.006314    0.006844    -0.007483
11.59587    0.005882    -0.00605    0.006274    -0.006557   0.006974    -0.007506   0.008264

CODE:

#include <time.h>
#include <stdlib.h>
#include "mkl.h"
#include "iostream"
using namespace std;

int main(int argc, char* argv[]){
    float *dpar;
    float *out;
    MKL_INT *ipar;
    MKL_INT tt_type,stat,n_1,nn;
    FILE *fp;

    fp = fopen( "D:\\fileinput.txt","r" );


    if(fp == NULL){
        cout<<"file not created properly"<<endl;
    }
    printf("\n===== DCT CODE ======== \n");
    DFTI_DESCRIPTOR_HANDLE handle = 0;
    int n = 64;//8x8 matrix;
    nn = (MKL_INT)n;
    tt_type = MKL_COSINE_TRANSFORM;

    n_1 = nn + 1 ;
    out = (float*)malloc((n+1)*sizeof(float));
    dpar= (float*)malloc((5*n_1/2+2)*sizeof(float));
    ipar= (MKL_INT*)malloc((128)*sizeof(int));
    s_init_trig_transform(&n_1,&tt_type,ipar,dpar,&stat);
    for (int srcSize =0 ;srcSize< n ; srcSize++)
    {
        fscanf(fp,"%f\n",&out[srcSize]);
    }
    fclose(fp);
    if (stat != 0)
    {
        printf("\n============================================================================\n");
        printf("FFTW2MKL FATAL ERROR: MKL TT initialization has failed with status=%d\n",(MKL_INT)stat);
        printf("Please refer to the Trigonometric Transform Routines Section of MKL Manual\n");
        printf("to find what went wrong...\n");
        printf("============================================================================\n");
        return NULL;
    }
    ipar[10] = 1;    //nx, that is, the number of intervals along the x-axis, in the Cartesian case.
    ipar[11] = 1;    //ny, that is, the number of intervals along the x-axis, in the Cartesian case.
    ipar[14] = n_1;  //specifies the internal partitioning of the dpar array.
    ipar[15] = 1;    //value of ipar[14]+1,Specifies the internal partitioning of the dpar array.
    s_commit_trig_transform(out,&handle,ipar,dpar,&stat);
    if (stat != 0)
    {
        printf("\n============================================================================\n");
        printf("FFTW2MKL FATAL ERROR: MKL TT commit step has failed with status=%d\n",(MKL_INT)stat);
        printf("Please refer to the Trigonometric Transform Routines Section of MKL Manual\n");
        printf("to find what went wrong...\n");
        printf("============================================================================\n");
        return NULL;
    }
    s_forward_trig_transform(out,&handle,ipar,dpar,&stat);
    if (stat != 0)
    {
        printf("\n============================================================================\n");
        printf("FFTW2MKL FATAL ERROR: MKL TT commit step has failed with status=%d\n",(MKL_INT)stat);
        printf("Please refer to the Trigonometric Transform Routines Section of MKL Manual\n");
        printf("to find what went wrong...\n");
        printf("============================================================================\n");
        return NULL;
    }

    free_trig_transform(&handle,ipar,&stat);
    printf("\n===== DCT GOT OVER ======== \n");


    return 0;

}

Can you please guide me To find out the mistake that I am doing inside my code

this is C++ code, so the 'C' tag should be removed – user3629249 Dec 24 '14 at 18:04 — user3629249, Dec 24 '14 at 18:04

score 0 · Answer 1 · answered Dec 24 '14 at 18:45

More of a question than an answer. Are these 4 lines correct?

ipar[10] = 1;    //nx, that is, the number of intervals along the x-axis,
ipar[11] = 1;    //ny, that is, the number of intervals along the x-axis,
ipar[14] = n_1;  //specifies the internal partitioning of the dpar array.
ipar[15] = 1;    //value of ipar[14]+1,Specifies the ... of the dpar array.

In the first two cases, is the number of intervals really 1?

In the fourth case, the comment says that ipar[15] is the value of ipar[14]+1 = n_1 + 1 = nn + 2 = n + 2 = 66, although we don't know what happens to n_1 in s_init_trig_transform().

Weather Vane,whether number of interval along x axis means 8 and for y axis 8 (as he mentioned n = 64;//8X8 ) ?? — Ashwin, Dec 25 '14 at 04:29

Wrong DCT with MKL DCT function

1 Answers1