* introducing dct248 into the DSP context.

   * simple/accurate implementation of dct248
   * DV encoding now supports 2-4-8 DCT
   * DV encoding gets a bit faster (but still miles away
     from what I think it could do)
   * misc. DV codec cleanups

Originally committed as revision 2425 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 127 insertions, 0 deletions

diff --git a/libavcodec/jfdctint.c b/libavcodec/jfdctint.c
index 702d0a9476..d5797bddff 100644
--- a/libavcodec/jfdctint.c
+++ b/libavcodec/jfdctint.c
@@ -295,3 +295,130 @@ ff_jpeg_fdct_islow (DCTELEM * data)
     dataptr++;			/* advance pointer to next column */
   }
 }
+
+/*
+ * The secret of DCT2-4-8 is really simple -- you do the usual 1-DCT
+ * on the rows and then, instead of doing even and odd, part on the colums
+ * you do even part two times.
+ */
+GLOBAL(void)
+ff_fdct248_islow (DCTELEM * data)
+{
+  int32_t tmp0, tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7;
+  int32_t tmp10, tmp11, tmp12, tmp13;
+  int32_t z1, z2, z3, z4, z5;
+  DCTELEM *dataptr;
+  int ctr;
+  SHIFT_TEMPS
+
+  /* Pass 1: process rows. */
+  /* Note results are scaled up by sqrt(8) compared to a true DCT; */
+  /* furthermore, we scale the results by 2**PASS1_BITS. */
+
+  dataptr = data;
+  for (ctr = DCTSIZE-1; ctr >= 0; ctr--) {
+    tmp0 = dataptr[0] + dataptr[7];
+    tmp7 = dataptr[0] - dataptr[7];
+    tmp1 = dataptr[1] + dataptr[6];
+    tmp6 = dataptr[1] - dataptr[6];
+    tmp2 = dataptr[2] + dataptr[5];
+    tmp5 = dataptr[2] - dataptr[5];
+    tmp3 = dataptr[3] + dataptr[4];
+    tmp4 = dataptr[3] - dataptr[4];
+    
+    /* Even part per LL&M figure 1 --- note that published figure is faulty;
+     * rotator "sqrt(2)*c1" should be "sqrt(2)*c6".
+     */
+    
+    tmp10 = tmp0 + tmp3;
+    tmp13 = tmp0 - tmp3;
+    tmp11 = tmp1 + tmp2;
+    tmp12 = tmp1 - tmp2;
+    
+    dataptr[0] = (DCTELEM) ((tmp10 + tmp11) << PASS1_BITS);
+    dataptr[4] = (DCTELEM) ((tmp10 - tmp11) << PASS1_BITS);
+    
+    z1 = MULTIPLY(tmp12 + tmp13, FIX_0_541196100);
+    dataptr[2] = (DCTELEM) DESCALE(z1 + MULTIPLY(tmp13, FIX_0_765366865),
+				   CONST_BITS-PASS1_BITS);
+    dataptr[6] = (DCTELEM) DESCALE(z1 + MULTIPLY(tmp12, - FIX_1_847759065),
+				   CONST_BITS-PASS1_BITS);
+    
+    /* Odd part per figure 8 --- note paper omits factor of sqrt(2).
+     * cK represents cos(K*pi/16).
+     * i0..i3 in the paper are tmp4..tmp7 here.
+     */
+    
+    z1 = tmp4 + tmp7;
+    z2 = tmp5 + tmp6;
+    z3 = tmp4 + tmp6;
+    z4 = tmp5 + tmp7;
+    z5 = MULTIPLY(z3 + z4, FIX_1_175875602); /* sqrt(2) * c3 */
+    
+    tmp4 = MULTIPLY(tmp4, FIX_0_298631336); /* sqrt(2) * (-c1+c3+c5-c7) */
+    tmp5 = MULTIPLY(tmp5, FIX_2_053119869); /* sqrt(2) * ( c1+c3-c5+c7) */
+    tmp6 = MULTIPLY(tmp6, FIX_3_072711026); /* sqrt(2) * ( c1+c3+c5-c7) */
+    tmp7 = MULTIPLY(tmp7, FIX_1_501321110); /* sqrt(2) * ( c1+c3-c5-c7) */
+    z1 = MULTIPLY(z1, - FIX_0_899976223); /* sqrt(2) * (c7-c3) */
+    z2 = MULTIPLY(z2, - FIX_2_562915447); /* sqrt(2) * (-c1-c3) */
+    z3 = MULTIPLY(z3, - FIX_1_961570560); /* sqrt(2) * (-c3-c5) */
+    z4 = MULTIPLY(z4, - FIX_0_390180644); /* sqrt(2) * (c5-c3) */
+    
+    z3 += z5;
+    z4 += z5;
+    
+    dataptr[7] = (DCTELEM) DESCALE(tmp4 + z1 + z3, CONST_BITS-PASS1_BITS);
+    dataptr[5] = (DCTELEM) DESCALE(tmp5 + z2 + z4, CONST_BITS-PASS1_BITS);
+    dataptr[3] = (DCTELEM) DESCALE(tmp6 + z2 + z3, CONST_BITS-PASS1_BITS);
+    dataptr[1] = (DCTELEM) DESCALE(tmp7 + z1 + z4, CONST_BITS-PASS1_BITS);
+    
+    dataptr += DCTSIZE;		/* advance pointer to next row */
+  }
+
+  /* Pass 2: process columns.
+   * We remove the PASS1_BITS scaling, but leave the results scaled up
+   * by an overall factor of 8.
+   */
+
+  dataptr = data;
+  for (ctr = DCTSIZE-1; ctr >= 0; ctr--) {
+     tmp0 = dataptr[DCTSIZE*0] + dataptr[DCTSIZE*1];
+     tmp1 = dataptr[DCTSIZE*2] + dataptr[DCTSIZE*3];
+     tmp2 = dataptr[DCTSIZE*4] + dataptr[DCTSIZE*5];
+     tmp3 = dataptr[DCTSIZE*6] + dataptr[DCTSIZE*7];
+     tmp4 = dataptr[DCTSIZE*0] - dataptr[DCTSIZE*1];
+     tmp5 = dataptr[DCTSIZE*2] - dataptr[DCTSIZE*3];
+     tmp6 = dataptr[DCTSIZE*4] - dataptr[DCTSIZE*5];
+     tmp7 = dataptr[DCTSIZE*6] - dataptr[DCTSIZE*7];
+      
+     tmp10 = tmp0 + tmp3;
+     tmp11 = tmp1 + tmp2;
+     tmp12 = tmp1 - tmp2;
+     tmp13 = tmp0 - tmp3;
+     
+     dataptr[DCTSIZE*0] = (DCTELEM) DESCALE(tmp10 + tmp11, PASS1_BITS);
+     dataptr[DCTSIZE*4] = (DCTELEM) DESCALE(tmp10 - tmp11, PASS1_BITS);
+     
+     z1 = MULTIPLY(tmp12 + tmp13, FIX_0_541196100);
+     dataptr[DCTSIZE*2] = (DCTELEM) DESCALE(z1 + MULTIPLY(tmp13, FIX_0_765366865),
+				            CONST_BITS+PASS1_BITS);
+     dataptr[DCTSIZE*6] = (DCTELEM) DESCALE(z1 + MULTIPLY(tmp12, - FIX_1_847759065),
+				            CONST_BITS+PASS1_BITS);
+
+     tmp10 = tmp4 + tmp7;
+     tmp11 = tmp5 + tmp6;
+     tmp12 = tmp5 - tmp6;
+     tmp13 = tmp4 - tmp7;
+
+     dataptr[DCTSIZE*1] = (DCTELEM) DESCALE(tmp10 + tmp11, PASS1_BITS);
+     dataptr[DCTSIZE*5] = (DCTELEM) DESCALE(tmp10 - tmp11, PASS1_BITS);
+     
+     z1 = MULTIPLY(tmp12 + tmp13, FIX_0_541196100);
+     dataptr[DCTSIZE*3] = (DCTELEM) DESCALE(z1 + MULTIPLY(tmp13, FIX_0_765366865),
+				            CONST_BITS+PASS1_BITS);
+     dataptr[DCTSIZE*7] = (DCTELEM) DESCALE(z1 + MULTIPLY(tmp12, - FIX_1_847759065),
+				            CONST_BITS+PASS1_BITS);
+    
+     dataptr++;			/* advance pointer to next column */
+  }
+}