reset segement map on key frame

This is to fix a decoder crash when decoder skips a number of frame to
continue decoding from a later key frame.

Change-Id: I3ba116eba6c3440e0528a21f53745f694302e4ad

vp9/decoder/vp9_decodframe.c

@@ -40,7 +40,7 @@
 
 #define COEFCOUNT_TESTING
 
-// #define DEC_DEBUG
+//#define DEC_DEBUG
 #ifdef DEC_DEBUG
 int dec_debug = 0;
 #endif
@@ -1311,7 +1311,10 @@ static void init_frame(VP9D_COMP *pbi) {
   MACROBLOCKD *const xd  = &pbi->mb;
 
   if (pc->frame_type == KEY_FRAME) {
-    /* Various keyframe initializations */
+
+    if (pc->last_frame_seg_map)
+      vpx_memset(pc->last_frame_seg_map, 0, (pc->mb_rows * pc->mb_cols));
+
     vp9_init_mv_probs(pc);
 
     vp9_init_mbmode_probs(pc);
@@ -1354,6 +1357,7 @@ static void init_frame(VP9D_COMP *pbi) {
     vp9_update_mode_info_border(pc, pc->mip);
     vp9_update_mode_info_in_image(pc, pc->mi);
 
+
   } else {
 
     if (!pc->use_bilinear_mc_filter)
@@ -1600,6 +1604,7 @@ int vp9_decode_frame(VP9D_COMP *pbi, const unsigned char **p_data_end) {
     pc->ref_pred_probs[0] = 120;
     pc->ref_pred_probs[1] = 80;
     pc->ref_pred_probs[2] = 40;
+
   } else {
     for (i = 0; i < PREDICTION_PROBS; i++) {
       if (vp9_read_bit(&header_bc))

vp9/encoder/vp9_ratectrl.c

@@ -255,6 +255,9 @@ void vp9_setup_key_frame(VP9_COMP *cpi) {
   vp9_init_mbmode_probs(& cpi->common);
   vp9_default_bmode_probs(cm->fc.bmode_prob);
 
+  if(cm->last_frame_seg_map)
+    vpx_memset(cm->last_frame_seg_map, 0, (cm->mb_rows * cm->mb_cols));
+
   vp9_init_mv_probs(& cpi->common);
 
   // cpi->common.filter_level = 0;      // Reset every key frame.