added separate entropy context for alt_ref

This commit added code to keep track of separate entropy contexts for
normal frames and alt ref frames. The underly assumption was that the
two type of frames have different entropy characteristics given they
typically have quite different quantization levels. By keeping entropy
contexts separate, it helps the entropy context distribution to be more
closely adapted to each frame type.

Tests on derf set showed a good and very consistent gain on all clips
on all metrics, avg psnr: 0.89%, overall psnr: 0.84% and ssim 0.93%.

http://www.corp.google.com/~yaowu/no_crawl/mulcontext.html

Change-Id: I15bc9697f6ff7829042911fe0c62930585d7e65d

3 files changed, 40 insertions, 5 deletions

diff --git a/vp8/decoder/decodemv.c b/vp8/decoder/decodemv.c
index 68044f4d5..7e3137fd2 100644
--- a/vp8/decoder/decodemv.c
+++ b/vp8/decoder/decodemv.c
@@ -854,4 +854,4 @@ void vp8_decode_mode_mvs(VP8D_COMP *pbi)
 #endif
 
 
-}
+}
\ No newline at end of file
diff --git a/vp8/decoder/decodframe.c b/vp8/decoder/decodframe.c
index 5e8925286..f3da2d0b5 100644
--- a/vp8/decoder/decodframe.c
+++ b/vp8/decoder/decodframe.c
@@ -830,9 +830,16 @@ static void init_frame(VP8D_COMP *pbi)
          */
         pc->ref_frame_sign_bias[GOLDEN_FRAME] = 0;
         pc->ref_frame_sign_bias[ALTREF_FRAME] = 0;
+
+#if CONFIG_MULCONTEXT
+        vpx_memcpy(&pc->lfc, &pc->fc, sizeof(pc->fc));
+        vpx_memcpy(&pc->lfc_a, &pc->fc, sizeof(pc->fc));
+#endif
+
     }
     else
     {
+
         if (!pc->use_bilinear_mc_filter)
             pc->mcomp_filter_type = SIXTAP;
         else
@@ -1206,6 +1213,13 @@ int vp8_decode_frame(VP8D_COMP *pbi)
             pc->refresh_alt_ref_frame = 0;
 #endif
 
+#if CONFIG_MULCONTEXT
+        if(pc->refresh_alt_ref_frame)
+            vpx_memcpy(&pc->fc, &pc->lfc_a, sizeof(pc->fc));
+        else
+            vpx_memcpy(&pc->fc, &pc->lfc, sizeof(pc->fc));
+#endif
+
         /* Buffer to buffer copy flags. */
         pc->copy_buffer_to_gf = 0;
 
@@ -1391,12 +1405,21 @@ int vp8_decode_frame(VP8D_COMP *pbi)
     {
         pc->last_kf_gf_q = pc->base_qindex;
     }
-
+#if CONFIG_MULCONTEXT
+    if(pc->refresh_entropy_probs)
+    {
+        if(pc->refresh_alt_ref_frame)
+            vpx_memcpy(&pc->lfc_a, &pc->fc, sizeof(pc->fc));
+        else
+            vpx_memcpy(&pc->lfc, &pc->fc, sizeof(pc->fc));
+    }
+#else
     if (pc->refresh_entropy_probs == 0)
     {
         vpx_memcpy(&pc->fc, &pc->lfc, sizeof(pc->fc));
         pbi->independent_partitions = prev_independent_partitions;
     }
+#endif
 
 #ifdef PACKET_TESTING
     {
diff --git a/vp8/decoder/onyxd_if.c b/vp8/decoder/onyxd_if.c
index a45d692d0..7862cbf90 100644
--- a/vp8/decoder/onyxd_if.c
+++ b/vp8/decoder/onyxd_if.c
@@ -80,6 +80,7 @@ void vp8_recon_write_yuv_frame(char *name, YV12_BUFFER_CONFIG *s)
     fclose(yuv_file);
 }
 #endif
+//#define WRITE_RECON_BUFFER 1
 #if WRITE_RECON_BUFFER
 void write_dx_frame_to_file(YV12_BUFFER_CONFIG *frame, int this_frame)
 {
@@ -93,21 +94,24 @@ void write_dx_frame_to_file(YV12_BUFFER_CONFIG *frame, int this_frame)
     yframe = fopen(filename, "wb");
 
     for (i = 0; i < frame->y_height; i++)
-        fwrite(frame->y_buffer + i * frame->y_stride, frame->y_width, 1, yframe);
+        fwrite(frame->y_buffer + i * frame->y_stride,
+            frame->y_width, 1, yframe);
 
     fclose(yframe);
     sprintf(filename, "dx\\u%04d.raw", this_frame);
     yframe = fopen(filename, "wb");
 
     for (i = 0; i < frame->uv_height; i++)
-        fwrite(frame->u_buffer + i * frame->uv_stride, frame->uv_width, 1, yframe);
+        fwrite(frame->u_buffer + i * frame->uv_stride,
+            frame->uv_width, 1, yframe);
 
     fclose(yframe);
     sprintf(filename, "dx\\v%04d.raw", this_frame);
     yframe = fopen(filename, "wb");
 
     for (i = 0; i < frame->uv_height; i++)
-        fwrite(frame->v_buffer + i * frame->uv_stride, frame->uv_width, 1, yframe);
+        fwrite(frame->v_buffer + i * frame->uv_stride,
+            frame->uv_width, 1, yframe);
 
     fclose(yframe);
 }
@@ -579,9 +583,17 @@ int vp8dx_receive_compressed_data(VP8D_PTR ptr, unsigned long size, const unsign
 
 #if WRITE_RECON_BUFFER
         if(cm->show_frame)
+<<<<<<< HEAD
             write_dx_frame_to_file(cm->frame_to_show, cm->current_video_frame);
         else
             write_dx_frame_to_file(cm->frame_to_show, cm->current_video_frame+1000);
+=======
+            write_dx_frame_to_file(cm->frame_to_show,
+                cm->current_video_frame);
+        else
+            write_dx_frame_to_file(cm->frame_to_show,
+                cm->current_video_frame+1000);
+>>>>>>> added separate entropy context for alt_ref
 #endif
 
         if(cm->filter_level)