Re-design drl index coding to remove ctx parsing dep

Re-design the dynamic motion vector index coding system to remove
the context parsing dependency on the reconstructed motion vectors.

Change-Id: I01dd6eda239a0bed32d8dc98f0f10f18249a76d4

av1/common/mvref_common.c

@@ -757,6 +757,7 @@ static void setup_ref_mv_list(const AV1_COMMON *cm, const MACROBLOCKD *xd,
   nearest_match = ref_match_count;
   nearest_refmv_count = *refmv_count;
 
+  ref_mv_stack[0].weight = 0;
   for (idx = 0; idx < nearest_refmv_count; ++idx)
     ref_mv_stack[idx].weight += REF_CAT_LEVEL;
 

av1/common/mvref_common.h

@@ -367,6 +367,13 @@ static INLINE int16_t av1_mode_context_analyzer(
 
 static INLINE uint8_t av1_drl_ctx(const CANDIDATE_MV *ref_mv_stack,
                                   int ref_idx) {
+#if CONFIG_OPT_REF_MV
+  if (ref_mv_stack[0].weight >= REF_CAT_LEVEL)
+    return 0;
+  else
+    return 2;
+#endif
+
   if (ref_mv_stack[ref_idx].weight >= REF_CAT_LEVEL &&
       ref_mv_stack[ref_idx + 1].weight >= REF_CAT_LEVEL)
     return 0;

av1/decoder/decodemv.c

@@ -257,7 +257,7 @@ static void read_drl_idx(FRAME_CONTEXT *ec_ctx, MACROBLOCKD *xd,
   if (mbmi->mode == NEWMV || mbmi->mode == NEW_NEWMV) {
     int idx;
     for (idx = 0; idx < 2; ++idx) {
-      if (xd->ref_mv_count[ref_frame_type] > idx + 1) {
+      if (xd->ref_mv_count[ref_frame_type] > idx + 1 || CONFIG_OPT_REF_MV) {
         uint8_t drl_ctx = av1_drl_ctx(xd->ref_mv_stack[ref_frame_type], idx);
         int drl_idx = aom_read_symbol(r, ec_ctx->drl_cdf[drl_ctx], 2, ACCT_STR);
         mbmi->ref_mv_idx = idx + drl_idx;
@@ -272,7 +272,7 @@ static void read_drl_idx(FRAME_CONTEXT *ec_ctx, MACROBLOCKD *xd,
     // TODO(jingning): Unify the two syntax decoding loops after the NEARESTMV
     // mode is factored in.
     for (idx = 1; idx < 3; ++idx) {
-      if (xd->ref_mv_count[ref_frame_type] > idx + 1) {
+      if (xd->ref_mv_count[ref_frame_type] > idx + 1 || CONFIG_OPT_REF_MV) {
         uint8_t drl_ctx = av1_drl_ctx(xd->ref_mv_stack[ref_frame_type], idx);
         int drl_idx = aom_read_symbol(r, ec_ctx->drl_cdf[drl_ctx], 2, ACCT_STR);
         mbmi->ref_mv_idx = idx + drl_idx - 1;

av1/encoder/bitstream.c

@@ -149,7 +149,8 @@ static void write_drl_idx(FRAME_CONTEXT *ec_ctx, const MB_MODE_INFO *mbmi,
   if (new_mv) {
     int idx;
     for (idx = 0; idx < 2; ++idx) {
-      if (mbmi_ext->ref_mv_count[ref_frame_type] > idx + 1) {
+      if (mbmi_ext->ref_mv_count[ref_frame_type] > idx + 1 ||
+          CONFIG_OPT_REF_MV) {
         uint8_t drl_ctx =
             av1_drl_ctx(mbmi_ext->ref_mv_stack[ref_frame_type], idx);
 
@@ -165,7 +166,8 @@ static void write_drl_idx(FRAME_CONTEXT *ec_ctx, const MB_MODE_INFO *mbmi,
     int idx;
     // TODO(jingning): Temporary solution to compensate the NEARESTMV offset.
     for (idx = 1; idx < 3; ++idx) {
-      if (mbmi_ext->ref_mv_count[ref_frame_type] > idx + 1) {
+      if (mbmi_ext->ref_mv_count[ref_frame_type] > idx + 1 ||
+          CONFIG_OPT_REF_MV) {
         uint8_t drl_ctx =
             av1_drl_ctx(mbmi_ext->ref_mv_stack[ref_frame_type], idx);
         aom_write_symbol(w, mbmi->ref_mv_idx != (idx - 1),