Revert "Set unused reference frames to first ref"

This reverts commit e7f33a53cf404bbb3688af9b13375b5c090daae4.

Change-Id: I54e807220885cb78af6f3c6e48b3eb2c9f1e70b4

3 files changed, 43 insertions, 51 deletions

diff --git a/vp9/encoder/vp9_bitstream.c b/vp9/encoder/vp9_bitstream.c
index 7644930c1..99cc2ee83 100644
--- a/vp9/encoder/vp9_bitstream.c
+++ b/vp9/encoder/vp9_bitstream.c
@@ -1241,21 +1241,12 @@ static void write_uncompressed_header(VP9_COMP *cpi,
       vpx_wb_write_literal(wb, vp9_get_refresh_mask(cpi), REF_FRAMES);
       write_frame_size(cm, wb);
     } else {
-      static const int flag_list[4] = { 0, VP9_LAST_FLAG, VP9_GOLD_FLAG,
-                                        VP9_ALT_FLAG };
-      const MV_REFERENCE_FRAME first_ref = get_first_ref_frame(cpi);
-      const int first_ref_map_idx = get_ref_frame_map_idx(cpi, first_ref);
       MV_REFERENCE_FRAME ref_frame;
       vpx_wb_write_literal(wb, vp9_get_refresh_mask(cpi), REF_FRAMES);
-
-      // If a reference frame is not referenced, then set the index for that
-      // reference to the first one used/referenced.
-      for (ref_frame = LAST_FRAME; ref_frame < MAX_REF_FRAMES; ++ref_frame) {
-        const int referenced = cpi->ref_frame_flags & flag_list[ref_frame];
-        const int map_idx = referenced ? get_ref_frame_map_idx(cpi, ref_frame)
-                                       : first_ref_map_idx;
-        assert(map_idx != INVALID_IDX);
-        vpx_wb_write_literal(wb, map_idx, REF_FRAMES_LOG2);
+      for (ref_frame = LAST_FRAME; ref_frame <= ALTREF_FRAME; ++ref_frame) {
+        assert(get_ref_frame_map_idx(cpi, ref_frame) != INVALID_IDX);
+        vpx_wb_write_literal(wb, get_ref_frame_map_idx(cpi, ref_frame),
+                             REF_FRAMES_LOG2);
         vpx_wb_write_bit(wb, cm->ref_frame_sign_bias[ref_frame]);
       }
 
diff --git a/vp9/encoder/vp9_encoder.h b/vp9/encoder/vp9_encoder.h
index 1bca7ded7..9774a64cc 100644
--- a/vp9/encoder/vp9_encoder.h
+++ b/vp9/encoder/vp9_encoder.h
@@ -1196,24 +1196,14 @@ static INLINE int frame_is_kf_gf_arf(const VP9_COMP *cpi) {
          (cpi->refresh_golden_frame && !cpi->rc.is_src_frame_alt_ref);
 }
 
-static INLINE MV_REFERENCE_FRAME get_first_ref_frame(VP9_COMP *const cpi) {
-  static const int flag_list[4] = { 0, VP9_LAST_FLAG, VP9_GOLD_FLAG,
-                                    VP9_ALT_FLAG };
-  MV_REFERENCE_FRAME ref_frame = LAST_FRAME;
-  while (ref_frame < MAX_REF_FRAMES) {
-    if (cpi->ref_frame_flags & flag_list[ref_frame]) break;
-    ref_frame++;
-  }
-  return ref_frame;
-}
-
 static INLINE int get_ref_frame_map_idx(const VP9_COMP *cpi,
                                         MV_REFERENCE_FRAME ref_frame) {
-  switch (ref_frame) {
-    case LAST_FRAME: return cpi->lst_fb_idx;
-    case GOLDEN_FRAME: return cpi->gld_fb_idx;
-    case ALTREF_FRAME: return cpi->alt_fb_idx;
-    default: return INVALID_IDX;
+  if (ref_frame == LAST_FRAME) {
+    return cpi->lst_fb_idx;
+  } else if (ref_frame == GOLDEN_FRAME) {
+    return cpi->gld_fb_idx;
+  } else {
+    return cpi->alt_fb_idx;
   }
 }
 
diff --git a/vp9/encoder/vp9_svc_layercontext.c b/vp9/encoder/vp9_svc_layercontext.c
index f01cb17a2..ad3a8f7af 100644
--- a/vp9/encoder/vp9_svc_layercontext.c
+++ b/vp9/encoder/vp9_svc_layercontext.c
@@ -73,7 +73,7 @@ void vp9_init_layer_context(VP9_COMP *const cpi) {
     svc->downsample_filter_type[sl] = BILINEAR;
     svc->downsample_filter_phase[sl] = 8;  // Set to 8 for averaging filter.
     svc->framedrop_thresh[sl] = oxcf->drop_frames_water_mark;
-    svc->fb_idx_upd_tl0[sl] = INVALID_IDX;
+    svc->fb_idx_upd_tl0[sl] = -1;
     svc->drop_count[sl] = 0;
     svc->spatial_layer_sync[sl] = 0;
     svc->force_drop_constrained_from_above[sl] = 0;
@@ -462,22 +462,33 @@ static void reset_fb_idx_unused(VP9_COMP *const cpi) {
   // fb_idx for that reference to the first one used/referenced.
   // This is to avoid setting fb_idx for a reference to a slot that is not
   // used/needed (i.e., since that reference is not referenced or refreshed).
-  const MV_REFERENCE_FRAME first_ref = get_first_ref_frame(cpi);
-  const int map_idx = get_ref_frame_map_idx(cpi, first_ref);
-  if (map_idx != INVALID_IDX) {
-    if (!(cpi->ref_frame_flags & VP9_LAST_FLAG ||
-          cpi->ext_refresh_last_frame)) {
-      cpi->lst_fb_idx = map_idx;
-    }
-    if (!(cpi->ref_frame_flags & VP9_GOLD_FLAG ||
-          cpi->ext_refresh_golden_frame)) {
-      cpi->gld_fb_idx = map_idx;
-    }
-    if (!(cpi->ref_frame_flags & VP9_ALT_FLAG ||
-          cpi->ext_refresh_alt_ref_frame)) {
-      cpi->alt_fb_idx = map_idx;
+  static const int flag_list[4] = { 0, VP9_LAST_FLAG, VP9_GOLD_FLAG,
+                                    VP9_ALT_FLAG };
+  MV_REFERENCE_FRAME ref_frame;
+  MV_REFERENCE_FRAME first_ref = 0;
+  int first_fb_idx = 0;
+  int fb_idx[3] = { cpi->lst_fb_idx, cpi->gld_fb_idx, cpi->alt_fb_idx };
+  for (ref_frame = LAST_FRAME; ref_frame <= ALTREF_FRAME; ref_frame++) {
+    if (cpi->ref_frame_flags & flag_list[ref_frame]) {
+      first_ref = ref_frame;
+      first_fb_idx = fb_idx[ref_frame - 1];
+      break;
     }
   }
+  if (first_ref > 0) {
+    if (first_ref != LAST_FRAME &&
+        !(cpi->ref_frame_flags & flag_list[LAST_FRAME]) &&
+        !cpi->ext_refresh_last_frame)
+      cpi->lst_fb_idx = first_fb_idx;
+    else if (first_ref != GOLDEN_FRAME &&
+             !(cpi->ref_frame_flags & flag_list[GOLDEN_FRAME]) &&
+             !cpi->ext_refresh_golden_frame)
+      cpi->gld_fb_idx = first_fb_idx;
+    else if (first_ref != ALTREF_FRAME &&
+             !(cpi->ref_frame_flags & flag_list[ALTREF_FRAME]) &&
+             !cpi->ext_refresh_alt_ref_frame)
+      cpi->alt_fb_idx = first_fb_idx;
+  }
 }
 
 // Never refresh any reference frame buffers on top temporal layers in
@@ -705,9 +716,9 @@ static void set_flags_and_fb_idx_bypass_via_set_ref_frame_config(
   int sl = svc->spatial_layer_id = svc->spatial_layer_to_encode;
   cpi->svc.temporal_layer_id = cpi->svc.temporal_layer_id_per_spatial[sl];
   cpi->ext_refresh_frame_flags_pending = 1;
-  if (svc->reference_last[sl]) cpi->lst_fb_idx = svc->lst_fb_idx[sl];
-  if (svc->reference_golden[sl]) cpi->gld_fb_idx = svc->gld_fb_idx[sl];
-  if (svc->reference_altref[sl]) cpi->alt_fb_idx = svc->alt_fb_idx[sl];
+  cpi->lst_fb_idx = svc->lst_fb_idx[sl];
+  cpi->gld_fb_idx = svc->gld_fb_idx[sl];
+  cpi->alt_fb_idx = svc->alt_fb_idx[sl];
   cpi->ext_refresh_last_frame = 0;
   cpi->ext_refresh_golden_frame = 0;
   cpi->ext_refresh_alt_ref_frame = 0;
@@ -864,9 +875,9 @@ int vp9_one_pass_cbr_svc_start_layer(VP9_COMP *const cpi) {
     // flags are passed via the encode call (bypass mode). Issue is that we're
     // resetting ext_refresh_frame_flags_pending to 0 on frame drops.
     if (svc->temporal_layering_mode != VP9E_TEMPORAL_LAYERING_MODE_BYPASS) {
-      memset(&svc->lst_fb_idx, INVALID_IDX, sizeof(svc->lst_fb_idx));
-      memset(&svc->gld_fb_idx, INVALID_IDX, sizeof(svc->lst_fb_idx));
-      memset(&svc->alt_fb_idx, INVALID_IDX, sizeof(svc->lst_fb_idx));
+      memset(&svc->lst_fb_idx, -1, sizeof(svc->lst_fb_idx));
+      memset(&svc->gld_fb_idx, -1, sizeof(svc->lst_fb_idx));
+      memset(&svc->alt_fb_idx, -1, sizeof(svc->lst_fb_idx));
       // These are set by API before the superframe is encoded and they are
       // passed to encoder layer by layer. Don't reset them on layer 0 in bypass
       // mode.
@@ -959,7 +970,7 @@ int vp9_one_pass_cbr_svc_start_layer(VP9_COMP *const cpi) {
 
   if (svc->temporal_layering_mode != VP9E_TEMPORAL_LAYERING_MODE_BYPASS &&
       svc->last_layer_dropped[svc->spatial_layer_id] &&
-      svc->fb_idx_upd_tl0[svc->spatial_layer_id] != INVALID_IDX &&
+      svc->fb_idx_upd_tl0[svc->spatial_layer_id] != -1 &&
       !svc->layer_context[svc->temporal_layer_id].is_key_frame) {
     // For fixed/non-flexible mode, if the previous frame (same spatial layer
     // from previous superframe) was dropped, make sure the lst_fb_idx