MDCT conversion, part I.

libcelt/kiss_fftr.c

@@ -84,7 +84,6 @@ void kiss_fftr(kiss_fftr_cfg st,const kiss_fft_scalar *timedata,kiss_fft_scalar
    /* input buffer timedata is stored row-wise */
    int k,ncfft;
    kiss_fft_cpx f2k,f1k,tdc,tw;
-   celt_word32_t f1kr, f1ki, twr, twi;
 
    ncfft = st->substate->nfft;
 

libcelt/mdct.c

@@ -50,11 +50,14 @@
 #include "kiss_fft.h"
 #include <math.h>
 #include "os_support.h"
+#include "_kiss_fft_guts.h"
 
 #ifndef M_PI
 #define M_PI 3.14159263
 #endif
 
+#undef S_MUL
+#define S_MUL(a,b) ((a)*(b))
 void mdct_init(mdct_lookup *l,int N)
 {
    int i;
@@ -67,7 +70,6 @@ void mdct_init(mdct_lookup *l,int N)
    /* We have enough points that sine isn't necessary */
    for (i=0;i<N2;i++)
       l->trig[i] = cos(2*M_PI*(i+1./8.)/N);
-   l->scale = 1./N4;
 }
 
 void mdct_clear(mdct_lookup *l)
@@ -76,36 +78,36 @@ void mdct_clear(mdct_lookup *l)
    celt_free(l->trig);
 }
 
-void mdct_forward(mdct_lookup *l, celt_sig_t *in, celt_sig_t *out)
+void mdct_forward(mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar *out)
 {
    int i;
    int N, N2, N4, N8;
-   VARDECL(celt_sig_t *f);
+   VARDECL(kiss_fft_scalar *f);
    N = l->n;
    N2 = N/2;
    N4 = N/4;
    N8 = N/8;
-   ALLOC(f, N2, celt_sig_t);
+   ALLOC(f, N2, kiss_fft_scalar);
    
    /* Consider the input to be compused of four blocks: [a, b, c, d] */
    /* Shuffle, fold, pre-rotate (part 1) */
    for(i=0;i<N8;i++)
    {
-      float re, im;
+      kiss_fft_scalar re, im;
       /* Real part arranged as -d-cR, Imag part arranged as -b+aR*/
       re = -.5*(in[N2+N4+2*i] + in[N2+N4-2*i-1]);
       im = -.5*(in[N4+2*i]    - in[N4-2*i-1]);
-      out[2*i]   = re*l->trig[i]  -  im*l->trig[i+N4];
-      out[2*i+1] = im*l->trig[i]  +  re*l->trig[i+N4];
+      out[2*i]   = S_MUL(re,l->trig[i])  -  S_MUL(im,l->trig[i+N4]);
+      out[2*i+1] = S_MUL(im,l->trig[i])  +  S_MUL(re,l->trig[i+N4]);
    }
    for(;i<N4;i++)
    {
-      float re, im;
+      kiss_fft_scalar re, im;
       /* Real part arranged as a-bR, Imag part arranged as -c-dR */
       re =  .5*(in[2*i-N4] - in[N2+N4-2*i-1]);
       im = -.5*(in[N4+2*i] + in[N+N4-2*i-1]);
-      out[2*i]   = re*l->trig[i]  -  im*l->trig[i+N4];
-      out[2*i+1] = im*l->trig[i]  +  re*l->trig[i+N4];
+      out[2*i]   = S_MUL(re,l->trig[i])  -  S_MUL(im,l->trig[i+N4]);
+      out[2*i+1] = S_MUL(im,l->trig[i])  +  S_MUL(re,l->trig[i+N4]);
    }
 
    /* N/4 complex FFT, which should normally down-scale by 4/N (but doesn't now) */
@@ -114,28 +116,28 @@ void mdct_forward(mdct_lookup *l, celt_sig_t *in, celt_sig_t *out)
    /* Post-rotate and apply the scaling if the FFT doesn't to it itself */
    for(i=0;i<N4;i++)
    {
-      out[2*i]      = -f[2*i+1]*l->trig[i+N4] + f[2*i]  *l->trig[i];
-      out[N2-1-2*i] = -f[2*i]  *l->trig[i+N4] - f[2*i+1]*l->trig[i];
+      out[2*i]      = -S_MUL(f[2*i+1],l->trig[i+N4]) + S_MUL(f[2*i]  ,l->trig[i]);
+      out[N2-1-2*i] = -S_MUL(f[2*i]  ,l->trig[i+N4]) - S_MUL(f[2*i+1],l->trig[i]);
    }
 }
 
 
-void mdct_backward(mdct_lookup *l, celt_sig_t *in, celt_sig_t *out)
+void mdct_backward(mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar *out)
 {
    int i;
    int N, N2, N4, N8;
-   VARDECL(celt_sig_t *f);
+   VARDECL(kiss_fft_scalar *f);
    N = l->n;
    N2 = N/2;
    N4 = N/4;
    N8 = N/8;
-   ALLOC(f, N2, celt_sig_t);
+   ALLOC(f, N2, kiss_fft_scalar);
    
    /* Pre-rotate */
    for(i=0;i<N4;i++) 
    {
-      out[2*i]   = -in[N2-2*i-1] * l->trig[i]    - in[2*i]*l->trig[i+N4];
-      out[2*i+1] =  in[N2-2*i-1] * l->trig[i+N4] - in[2*i]*l->trig[i];
+      out[2*i]   = -S_MUL(in[N2-2*i-1], l->trig[i])    - S_MUL(in[2*i],l->trig[i+N4]);
+      out[2*i+1] =  S_MUL(in[N2-2*i-1], l->trig[i+N4]) - S_MUL(in[2*i],l->trig[i]);
    }
 
    /* Inverse N/4 complex FFT. This one should *not* downscale even in fixed-point */
@@ -144,12 +146,12 @@ void mdct_backward(mdct_lookup *l, celt_sig_t *in, celt_sig_t *out)
    /* Post-rotate */
    for(i=0;i<N4;i++)
    {
-      float re, im;
+      kiss_fft_scalar re, im;
       re = f[2*i];
       im = f[2*i+1];
       /* We'd scale up by 2 here, but instead it's done when mixing the windows */
-      f[2*i]   = re*l->trig[i] + im*l->trig[i+N4];
-      f[2*i+1] = im*l->trig[i] - re*l->trig[i+N4];
+      f[2*i]   = S_MUL(re,l->trig[i]) + S_MUL(im,l->trig[i+N4]);
+      f[2*i+1] = S_MUL(im,l->trig[i]) - S_MUL(re,l->trig[i+N4]);
    }
    /* De-shuffle the components for the middle of the window only */
    for(i = 0; i < N4; i++)

libcelt/mdct.h

@@ -48,15 +48,14 @@ typedef struct {
    int n;
    kiss_fft_cfg kfft;
    float *trig;
-   float scale;
 } mdct_lookup;
 
 void mdct_init(mdct_lookup *l,int N);
 void mdct_clear(mdct_lookup *l);
 
 /** Compute a forward MDCT and scale by 2/N */
-void mdct_forward(mdct_lookup *l, celt_sig_t *in, celt_sig_t *out);
+void mdct_forward(mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar *out);
 
 /** Compute a backward MDCT (no scaling) */
-void mdct_backward(mdct_lookup *l, celt_sig_t *in, celt_sig_t *out);
+void mdct_backward(mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar *out);
 

tests/mdct-test.c

@@ -6,7 +6,7 @@
 #include "mdct.h"
 
 int ret = 0;
-void check(float  * in,float  * out,int nfft,int isinverse)
+void check(kiss_fft_scalar  * in,kiss_fft_scalar  * out,int nfft,int isinverse)
 {
     int bin,k;
     double errpow=0,sigpow=0;
@@ -36,7 +36,7 @@ void check(float  * in,float  * out,int nfft,int isinverse)
     }
 }
 
-void check_inv(float  * in,float  * out,int nfft,int isinverse)
+void check_inv(kiss_fft_scalar  * in,kiss_fft_scalar  * out,int nfft,int isinverse)
 {
    int bin,k;
    double errpow=0,sigpow=0;
@@ -70,10 +70,10 @@ void check_inv(float  * in,float  * out,int nfft,int isinverse)
 void test1d(int nfft,int isinverse)
 {
     mdct_lookup cfg;
-    size_t buflen = sizeof(float)*nfft;
+    size_t buflen = sizeof(kiss_fft_scalar)*nfft;
 
-    float  * in = (float*)malloc(buflen);
-    float  * out= (float*)malloc(buflen);
+    kiss_fft_scalar  * in = (kiss_fft_scalar*)malloc(buflen);
+    kiss_fft_scalar  * out= (kiss_fft_scalar*)malloc(buflen);
     int k;
 
     mdct_init(&cfg, nfft);
@@ -83,8 +83,7 @@ void test1d(int nfft,int isinverse)
 
 #ifdef DOUBLE_PRECISION
     for (k=0;k<nfft;++k) {
-       in[k].r *= 65536;
-       in[k].i *= 65536;
+       in[k] *= 32768;
     }
 #endif