fixed a bug of context overwritten by key frame recoding

The recoding loop save and restore frame coding context for recodes.
However in recoding of key frames, some of the coding context saved
was stale from last encoded inter frame. The save/restore sometimes
overwrites the re-inintialized coding context with saved context
from last frame, resulting in encoder/decoder mismatch

Change-Id: I354ae2f71074d142602d51d06544c05a2462caaf

vp8/encoder/ratectrl.c

@@ -222,9 +222,9 @@ void vp8_restore_coding_context(VP8_COMP *cpi)
 void vp8_setup_key_frame(VP8_COMP *cpi)
 {
     // Setup for Key frame:
-
     vp8_default_coef_probs(& cpi->common);
     vp8_kf_default_bmode_probs(cpi->common.kf_bmode_prob);
+    vp8_init_mbmode_probs(& cpi->common);
 
     vpx_memcpy(cpi->common.fc.mvc, vp8_default_mv_context, sizeof(vp8_default_mv_context));
     {
@@ -263,6 +263,18 @@ void vp8_setup_key_frame(VP8_COMP *cpi)
     vpx_memcpy( cpi->common.vp8_mode_contexts,
                 default_vp8_mode_contexts,
                 sizeof(default_vp8_mode_contexts));
+
+    /* make sure coding_context is correct in key frame recode */
+    {
+        CODING_CONTEXT *const cc = & cpi->coding_context;
+
+        vp8_copy(cc->mvc,      cpi->common.fc.mvc);
+#if CONFIG_HIGH_PRECISION_MV
+        vp8_copy(cc->mvc_hp,      cpi->common.fc.mvc_hp);
+#endif
+        vp8_copy(cc->ymode_prob,   cpi->common.fc.ymode_prob);
+        vp8_copy(cc->uv_mode_prob,  cpi->common.fc.uv_mode_prob);
+    }
 }
 void vp8_setup_inter_frame(VP8_COMP *cpi)
 {