mdct_backward now does the WOLA, so there isn't much left in compute_inv_mdcts
[opus.git] / libcelt / mdct.c
index 37a8562..075ab5e 100644 (file)
@@ -86,7 +86,14 @@ void mdct_clear(mdct_lookup *l)
    celt_free(l->trig);
 }
 
-void mdct_forward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar * restrict out)
+/* Only divide by half if float. In fixed-point, it's included in the shift */
+#ifdef FIXED_POINT
+#define FL_HALF(x) (x)
+#else
+#define FL_HALF(x) (.5f*(x))
+#endif
+
+void mdct_forward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar * restrict out, const celt_word16_t *window, int overlap)
 {
    int i;
    int N, N2, N4;
@@ -98,40 +105,57 @@ void mdct_forward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar * r
    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) */
+   /* Window, shuffle, fold */
    {
       /* Temp pointers to make it really clear to the compiler what we're doing */
-      const kiss_fft_scalar * restrict xp1 = in+N4;
-      const kiss_fft_scalar * restrict xp2 = in+N2+N4-1;
+      const kiss_fft_scalar * restrict xp1 = in+(overlap>>1);
+      const kiss_fft_scalar * restrict xp2 = in+N2-1+(overlap>>1);
       kiss_fft_scalar * restrict yp = out;
-      kiss_fft_scalar *t = &l->trig[0];
-      for(i=0;i<N/8;i++)
+      const celt_word16_t * restrict wp1 = window+(overlap>>1);
+      const celt_word16_t * restrict wp2 = window+(overlap>>1)-1;
+      for(i=0;i<(overlap>>2);i++)
       {
-         kiss_fft_scalar re, im;
          /* Real part arranged as -d-cR, Imag part arranged as -b+aR*/
-         re = -HALF32(xp1[N2] + *xp2);
-         im = -HALF32(*xp1    - xp2[-N2]);
+         *yp++ = -FL_HALF(MULT16_32_Q16(*wp2, xp1[N2]) + MULT16_32_Q16(*wp1,*xp2));
+         *yp++ = -FL_HALF(MULT16_32_Q16(*wp1, *xp1)    - MULT16_32_Q16(*wp2, xp2[-N2]));
+         xp1+=2;
+         xp2-=2;
+         wp1+=2;
+         wp2-=2;
+      }
+      wp1 = window;
+      wp2 = window+overlap-1;
+      for(;i<N4-(overlap>>2);i++)
+      {
+         /* Real part arranged as a-bR, Imag part arranged as -c-dR */
+         *yp++ = -HALF32(*xp2);
+         *yp++ = -HALF32(*xp1);
          xp1+=2;
          xp2-=2;
-         /* We could remove the HALF32 above and just use MULT16_32_Q16 below
-            (MIXED_PRECISION only) */
-         *yp++ = S_MUL(re,t[0])  -  S_MUL(im,t[N4]);
-         *yp++ = S_MUL(im,t[0])  +  S_MUL(re,t[N4]);
-        t++;
       }
       for(;i<N4;i++)
       {
-         kiss_fft_scalar re, im;
          /* Real part arranged as a-bR, Imag part arranged as -c-dR */
-         re =  HALF32(xp1[-N2] - *xp2);
-         im = -HALF32(*xp1 + xp2[N2]);
+         *yp++ =  FL_HALF(MULT16_32_Q16(*wp1, xp1[-N2]) - MULT16_32_Q16(*wp2, *xp2));
+         *yp++ = -FL_HALF(MULT16_32_Q16(*wp2, *xp1)     + MULT16_32_Q16(*wp1, xp2[N2]));
          xp1+=2;
          xp2-=2;
-         /* We could remove the HALF32 above and just use MULT16_32_Q16 below
-            (MIXED_PRECISION only) */
+         wp1+=2;
+         wp2-=2;
+      }
+   }
+   /* Pre-rotation */
+   {
+      kiss_fft_scalar * restrict yp = out;
+      kiss_fft_scalar *t = &l->trig[0];
+      for(i=0;i<N4;i++)
+      {
+         kiss_fft_scalar re, im;
+         re = yp[0];
+         im = yp[1];
          *yp++ = S_MUL(re,t[0])  -  S_MUL(im,t[N4]);
          *yp++ = S_MUL(im,t[0])  +  S_MUL(re,t[N4]);
-        t++;
+         t++;
       }
    }
 
@@ -153,30 +177,32 @@ void mdct_forward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar * r
          fp += 2;
          yp1 += 2;
          yp2 -= 2;
-        t++;
+         t++;
       }
    }
    RESTORE_STACK;
 }
 
 
-void mdct_backward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar * restrict out)
+void mdct_backward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar * restrict out, const celt_word16_t * restrict window, int overlap)
 {
    int i;
    int N, N2, N4;
    VARDECL(kiss_fft_scalar, f);
+   VARDECL(kiss_fft_scalar, f2);
    SAVE_STACK;
    N = l->n;
    N2 = N>>1;
    N4 = N>>2;
    ALLOC(f, N2, kiss_fft_scalar);
+   ALLOC(f2, N2, kiss_fft_scalar);
    
    /* Pre-rotate */
    {
       /* Temp pointers to make it really clear to the compiler what we're doing */
       const kiss_fft_scalar * restrict xp1 = in;
       const kiss_fft_scalar * restrict xp2 = in+N2-1;
-      kiss_fft_scalar * restrict yp = out;
+      kiss_fft_scalar * restrict yp = f2;
       kiss_fft_scalar *t = &l->trig[0];
       for(i=0;i<N4;i++) 
       {
@@ -184,36 +210,38 @@ void mdct_backward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar *
          *yp++ =  S_MUL(*xp2, t[N4]) - S_MUL(*xp1,t[0]);
          xp1+=2;
          xp2-=2;
-        t++;
+         t++;
       }
    }
 
    /* Inverse N/4 complex FFT. This one should *not* downscale even in fixed-point */
-   cpx32_ifft(l->kfft, out, f, N4);
+   cpx32_ifft(l->kfft, f2, f, N4);
    
    /* Post-rotate */
    {
       kiss_fft_scalar * restrict fp = f;
+      kiss_fft_scalar *t = &l->trig[0];
+
       for(i=0;i<N4;i++)
       {
          kiss_fft_scalar re, im;
          re = fp[0];
          im = fp[1];
          /* We'd scale up by 2 here, but instead it's done when mixing the windows */
-         fp[0] = S_MUL(re,l->trig[i]) + S_MUL(im,l->trig[i+N4]);
-         fp[1] = S_MUL(im,l->trig[i]) - S_MUL(re,l->trig[i+N4]);
-         fp += 2;
+         *fp++ = S_MUL(re,*t) + S_MUL(im,t[N4]);
+         *fp++ = S_MUL(im,*t) - S_MUL(re,t[N4]);
+         t++;
       }
    }
    /* De-shuffle the components for the middle of the window only */
    {
       const kiss_fft_scalar * restrict fp1 = f;
       const kiss_fft_scalar * restrict fp2 = f+N2-1;
-      kiss_fft_scalar * restrict yp = out+N4;
+      kiss_fft_scalar * restrict yp = f2;
       for(i = 0; i < N4; i++)
       {
-         *yp++ =-*fp1;
-         *yp++ = *fp2;
+         *yp++ =-*fp1*2;
+         *yp++ = *fp2*2;
          fp1 += 2;
          fp2 -= 2;
       }
@@ -221,14 +249,47 @@ void mdct_backward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar *
 
    /* Mirror on both sides for TDAC */
    {
-      const kiss_fft_scalar * restrict xp1 = out+N2-1;
-      const kiss_fft_scalar * restrict xp2 = out+N2;
-      kiss_fft_scalar * restrict yp1 = out;
-      kiss_fft_scalar * restrict yp2 = out+N-1;
-      for(i = 0; i < N4; i++)
+      kiss_fft_scalar * restrict fp1 = f2+N4-1;
+      kiss_fft_scalar * restrict xp1 = out+N2-1;
+      kiss_fft_scalar * restrict yp1 = out+N4-overlap/2;
+      const celt_word16_t * restrict wp1 = window;
+      const celt_word16_t * restrict wp2 = window+overlap-1;
+      for(i = 0; i< N4-overlap/2; i++)
+      {
+         *xp1 = *fp1;
+         xp1--;
+         fp1--;
+      }
+      for(; i < N4; i++)
+      {
+         kiss_fft_scalar x1;
+         x1 = *fp1--;
+         *yp1++ +=-MULT16_32_Q15(*wp1, x1);
+         *xp1-- += MULT16_32_Q15(*wp2, x1);
+         wp1++;
+         wp2--;
+      }
+   }
+   {
+      kiss_fft_scalar * restrict fp2 = f2+N4;
+      kiss_fft_scalar * restrict xp2 = out+N2;
+      kiss_fft_scalar * restrict yp2 = out+N-1-(N4-overlap/2);
+      const celt_word16_t * restrict wp1 = window;
+      const celt_word16_t * restrict wp2 = window+overlap-1;
+      for(i = 0; i< N4-overlap/2; i++)
+      {
+         *xp2 = *fp2;
+         xp2++;
+         fp2++;
+      }
+      for(; i < N4; i++)
       {
-         *yp1++ =-*xp1--;
-         *yp2-- = *xp2++;
+         kiss_fft_scalar x2;
+         x2 = *fp2++;
+         *yp2--  = MULT16_32_Q15(*wp1, x2);
+         *xp2++  = MULT16_32_Q15(*wp2, x2);
+         wp1++;
+         wp2--;
       }
    }
    RESTORE_STACK;