Add lossless compression mode.

This commit adds lossless compression capability to the experimental
branch. The lossless experiment can be enabled using --enable-lossless
in configure. When the experiment is enabled, the encoder will use
lossless compression mode by command line option --lossless, and the
decoder automatically recognizes a losslessly encoded clip and decodes
accordingly.

To achieve the lossless coding, this commit has changed the following:
    1. To encode at lossless mode, encoder forces the use of unit
quantizer, i.e, Q 0, where effective quantization is 1. Encoder also
disables the usage of 8x8 transform and allows only 4x4 transform;
    2. At Q 0, the first order 4x4  DCT/IDCT have been switched over
to a pair of forward and inverse Walsh-Hadamard Transform
(http://goo.gl/EIsfy),  with proper scaling applied to match the range
of the original 4x4 DCT/IDCT pair;
    3. At Q 0, the second order remains to use the previous
walsh-hadamard transform pair. However, to maintain the reversibility
in second order transform at Q 0, scaling down is applied to first
order DC coefficients prior to forward transform, and scaling up is
applied to the second order output prior to quantization. Symmetric
upscaling and downscaling are added around inverse second order
transform;
    4. At lossless mode, encoder also disables a number of minor
features to ensure no loss is introduced, these features includes:
        a. Trellis quantization optimization
        b. Loop filtering
        c. Aggressive zero-binning, rounding and zero-bin boosting
        d. Mode based zero-bin boosting

Lossless coding test was performed on all clips within the derf set,
to verify that the commit has achieved lossless compression for all
clips. The average compression ratio is around 2.57 to 1.
(http://goo.gl/dEShs)

Change-Id: Ia3aba7dd09df40dd590f93b9aba134defbc64e34

1 files changed, 158 insertions, 0 deletions

diff --git a/vp8/common/idctllm.c b/vp8/common/idctllm.c
index 75ce8d44d..acb856d53 100644
--- a/vp8/common/idctllm.c
+++ b/vp8/common/idctllm.c
@@ -23,6 +23,7 @@
  *         x * sqrt(2) * cos (pi/8) = x + x * (sqrt(2) *cos(pi/8)-1).
  **************************************************************************/
 #include "vpx_ports/config.h"
+#include "vp8/common/idct.h"
 
 
 #include <math.h>
@@ -195,6 +196,163 @@ void vp8_short_inv_walsh4x4_1_c(short *in, short *out)
     }
 }
 
+#if CONFIG_LOSSLESS
+void vp8_short_inv_walsh4x4_lossless_c(short *input, short *output)
+{
+    int i;
+    int a1, b1, c1, d1;
+    short *ip = input;
+    short *op = output;
+
+    for (i = 0; i < 4; i++)
+    {
+        a1 = ((ip[0] + ip[3]))>>Y2_WHT_UPSCALE_FACTOR;
+        b1 = ((ip[1] + ip[2]))>>Y2_WHT_UPSCALE_FACTOR;
+        c1 = ((ip[1] - ip[2]))>>Y2_WHT_UPSCALE_FACTOR;
+        d1 = ((ip[0] - ip[3]))>>Y2_WHT_UPSCALE_FACTOR;
+
+        op[0] = (a1 + b1 + 1)>>1;
+        op[1] = (c1 + d1)>>1;
+        op[2] = (a1 - b1)>>1;
+        op[3] = (d1 - c1)>>1;
+
+        ip += 4;
+        op += 4;
+    }
+
+    ip = output;
+    op = output;
+    for (i = 0; i < 4; i++)
+    {
+        a1 = ip[0] + ip[12];
+        b1 = ip[4] + ip[8];
+        c1 = ip[4] - ip[8];
+        d1 = ip[0] - ip[12];
+
+
+        op[0] = ((a1 + b1 + 1)>>1)<<Y2_WHT_UPSCALE_FACTOR;
+        op[4] = ((c1 + d1)>>1)<<Y2_WHT_UPSCALE_FACTOR;
+        op[8] = ((a1 - b1)>>1)<<Y2_WHT_UPSCALE_FACTOR;
+        op[12]= ((d1 - c1)>>1)<<Y2_WHT_UPSCALE_FACTOR;
+
+        ip++;
+        op++;
+    }
+}
+
+void vp8_short_inv_walsh4x4_1_lossless_c(short *in, short *out)
+{
+    int i;
+    short tmp[4];
+    short *ip = in;
+    short *op = tmp;
+
+    op[0] =((ip[0]>>Y2_WHT_UPSCALE_FACTOR)+ 1)>>1;
+    op[1] = op[2] = op[3] = ((ip[0]>>Y2_WHT_UPSCALE_FACTOR)>>1);
+
+    ip = tmp;
+    op = out;
+    for(i = 0; i<4; i++)
+    {
+        op[0] =((ip[0]+ 1)>>1)<<Y2_WHT_UPSCALE_FACTOR;
+        op[4] = op[8] = op[12] = ((ip[0]>>1))<<Y2_WHT_UPSCALE_FACTOR;
+        ip ++;
+        op ++;
+    }
+}
+
+void vp8_short_inv_walsh4x4_x8_c(short *input, short *output, int pitch)
+{
+    int i;
+    int a1, b1, c1, d1;
+    short *ip = input;
+    short *op = output;
+    int shortpitch = pitch >> 1;
+
+    for (i = 0; i < 4; i++)
+    {
+        a1 = ((ip[0] + ip[3]))>>WHT_UPSCALE_FACTOR;
+        b1 = ((ip[1] + ip[2]))>>WHT_UPSCALE_FACTOR;
+        c1 = ((ip[1] - ip[2]))>>WHT_UPSCALE_FACTOR;
+        d1 = ((ip[0] - ip[3]))>>WHT_UPSCALE_FACTOR;
+
+        op[0] = (a1 + b1 + 1)>>1;
+        op[1] = (c1 + d1)>>1;
+        op[2] = (a1 - b1)>>1;
+        op[3] = (d1 - c1)>>1;
+
+        ip += 4;
+        op += shortpitch;
+    }
+
+    ip = output;
+    op = output;
+    for (i = 0; i < 4; i++)
+    {
+        a1 = ip[shortpitch*0] + ip[shortpitch*3];
+        b1 = ip[shortpitch*1] + ip[shortpitch*2];
+        c1 = ip[shortpitch*1] - ip[shortpitch*2];
+        d1 = ip[shortpitch*0] - ip[shortpitch*3];
+
+
+        op[shortpitch*0] = (a1 + b1 + 1)>>1;
+        op[shortpitch*1] = (c1 + d1)>>1;
+        op[shortpitch*2] = (a1 - b1)>>1;
+        op[shortpitch*3] = (d1 - c1)>>1;
+
+        ip++;
+        op++;
+    }
+}
+
+void vp8_short_inv_walsh4x4_1_x8_c(short *in, short *out, int pitch)
+{
+    int i;
+    short tmp[4];
+    short *ip = in;
+    short *op = tmp;
+    int shortpitch = pitch >> 1;
+
+    op[0] =((ip[0]>>WHT_UPSCALE_FACTOR) + 1)>>1;
+    op[1] = op[2] = op[3] = ((ip[0]>>WHT_UPSCALE_FACTOR)>>1);
+
+
+    ip = tmp;
+    op = out;
+    for(i = 0; i<4; i++)
+    {
+        op[shortpitch*0] =(ip[0]+ 1)>>1;
+        op[shortpitch*1] = op[shortpitch*2] = op[shortpitch*3] = ip[0]>>1;
+        ip ++;
+        op ++;
+    }
+}
+
+void vp8_dc_only_inv_walsh_add_c(short input_dc, unsigned char *pred_ptr, unsigned char *dst_ptr, int pitch, int stride)
+{
+    int r, c;
+    short tmp[16];
+    vp8_short_inv_walsh4x4_1_x8_c( &input_dc, tmp, 4<<1);
+
+    for (r = 0; r < 4; r++)
+        {
+          for (c = 0; c < 4; c++)
+            {
+                int a = tmp[r*4 + c] + pred_ptr[c] ;
+                if (a < 0)
+                    a = 0;
+
+                if (a > 255)
+                    a = 255;
+
+                dst_ptr[c] = (unsigned char) a ;
+            }
+
+            dst_ptr += stride;
+            pred_ptr += pitch;
+        }
+}
+#endif
 
 void vp8_dc_only_idct_add_8x8_c(short input_dc,
                                 unsigned char *pred_ptr,