Further dual arf changes: multi_arf_allowed.

Add multi_arf_allowed flag.
Re-initialize buffer indices every kf.
Add some const indicators.

Change-Id: If86c39153517c427182691d2d4d4b7e90594be71

vp9/encoder/vp9_bitstream.c

@@ -890,7 +890,7 @@ static void write_tile_info(VP9_COMMON *cm, struct vp9_write_bit_buffer *wb) {
 }
 
 static int get_refresh_mask(VP9_COMP *cpi) {
-    if (!cpi->multi_arf_enabled && cpi->refresh_golden_frame &&
+    if (!cpi->multi_arf_allowed && cpi->refresh_golden_frame &&
         cpi->rc.is_src_frame_alt_ref && !cpi->use_svc) {
       // Preserve the previously existing golden frame and update the frame in
       // the alt ref slot instead. This is highly specific to the use of
@@ -906,7 +906,7 @@ static int get_refresh_mask(VP9_COMP *cpi) {
       int arf_idx = cpi->alt_fb_idx;
 
       if ((cpi->pass == 2) && cpi->multi_arf_enabled) {
-        GF_GROUP *gf_group = &cpi->twopass.gf_group;
+        const GF_GROUP *const gf_group = &cpi->twopass.gf_group;
         arf_idx = gf_group->arf_update_idx[gf_group->index];
       }
       return (cpi->refresh_last_frame << cpi->lst_fb_idx) |

vp9/encoder/vp9_encoder.c

@@ -490,6 +490,12 @@ static void set_tile_limits(VP9_COMP *cpi) {
   cm->log2_tile_rows = cpi->oxcf.tile_rows;
 }
 
+static void init_buffer_indices(VP9_COMP *cpi) {
+  cpi->lst_fb_idx = 0;
+  cpi->gld_fb_idx = 1;
+  cpi->alt_fb_idx = 2;
+}
+
 static void init_config(struct VP9_COMP *cpi, VP9EncoderConfig *oxcf) {
   VP9_COMMON *const cm = &cpi->common;
 
@@ -519,9 +525,7 @@ static void init_config(struct VP9_COMP *cpi, VP9EncoderConfig *oxcf) {
 
   cpi->static_mb_pct = 0;
 
-  cpi->lst_fb_idx = 0;
-  cpi->gld_fb_idx = 1;
-  cpi->alt_fb_idx = 2;
+  init_buffer_indices(cpi);
 
   set_tile_limits(cpi);
 }
@@ -762,10 +766,23 @@ VP9_COMP *vp9_create_compressor(VP9EncoderConfig *oxcf) {
 
   cpi->refresh_alt_ref_frame = 0;
 
-  if (cpi->pass == 2)
-    cpi->multi_arf_enabled = 0;
-  else
+  // Note that at the moment multi_arf will not work with svc.
+  // For the current check in all the execution paths are defaulted to 0
+  // pending further tuning and testing. The code is left in place here
+  // as a place holder in regard to the required paths.
+  if (cpi->pass == 2) {
+    if (cpi->use_svc) {
+      cpi->multi_arf_allowed = 0;
+      cpi->multi_arf_enabled = 0;
+    } else {
+      // Disable by default for now.
+      cpi->multi_arf_allowed = 0;
+      cpi->multi_arf_enabled = 0;
+    }
+  } else {
+    cpi->multi_arf_allowed = 0;
     cpi->multi_arf_enabled = 0;
+  }
 
   cpi->b_calculate_psnr = CONFIG_INTERNAL_STATS;
 #if CONFIG_INTERNAL_STATS
@@ -1475,9 +1492,8 @@ void vp9_update_reference_frames(VP9_COMP *cpi) {
                &cm->ref_frame_map[cpi->gld_fb_idx], cm->new_fb_idx);
     ref_cnt_fb(cm->frame_bufs,
                &cm->ref_frame_map[cpi->alt_fb_idx], cm->new_fb_idx);
-  }
-  else if (!cpi->multi_arf_enabled && cpi->refresh_golden_frame &&
-           cpi->rc.is_src_frame_alt_ref && !cpi->use_svc) {
+  } else if (!cpi->multi_arf_allowed && cpi->refresh_golden_frame &&
+             cpi->rc.is_src_frame_alt_ref && !cpi->use_svc) {
     /* Preserve the previously existing golden frame and update the frame in
      * the alt ref slot instead. This is highly specific to the current use of
      * alt-ref as a forward reference, and this needs to be generalized as
@@ -1495,11 +1511,11 @@ void vp9_update_reference_frames(VP9_COMP *cpi) {
     tmp = cpi->alt_fb_idx;
     cpi->alt_fb_idx = cpi->gld_fb_idx;
     cpi->gld_fb_idx = tmp;
-  }  else { /* For non key/golden frames */
+  } else { /* For non key/golden frames */
     if (cpi->refresh_alt_ref_frame) {
       int arf_idx = cpi->alt_fb_idx;
       if ((cpi->pass == 2) && cpi->multi_arf_enabled) {
-        GF_GROUP *gf_group = &cpi->twopass.gf_group;
+        const GF_GROUP *const gf_group = &cpi->twopass.gf_group;
         arf_idx = gf_group->arf_update_idx[gf_group->index];
       }
 
@@ -2372,7 +2388,7 @@ static void is_src_altref(VP9_COMP *cpi) {
   RATE_CONTROL *const rc = &cpi->rc;
 
   if (cpi->pass == 2) {
-    GF_GROUP *gf_group = &cpi->twopass.gf_group;
+    const GF_GROUP *const gf_group = &cpi->twopass.gf_group;
     rc->is_src_frame_alt_ref =
       (gf_group->update_type[gf_group->index] == OVERLAY_UPDATE);
   } else {
@@ -2518,10 +2534,13 @@ int vp9_get_compressed_data(VP9_COMP *cpi, unsigned int *frame_flags,
   cm->frame_bufs[cm->new_fb_idx].ref_count--;
   cm->new_fb_idx = get_free_fb(cm);
 
-  if (cpi->multi_arf_enabled && (cm->frame_type != KEY_FRAME) &&
-      (cpi->pass == 2)) {
-    const GF_GROUP *const gf_group = &cpi->twopass.gf_group;
-    cpi->alt_fb_idx = gf_group->arf_ref_idx[gf_group->index];
+  if (!cpi->use_svc && cpi->multi_arf_allowed) {
+    if (cm->frame_type == KEY_FRAME) {
+      init_buffer_indices(cpi);
+    } else if (cpi->pass == 2) {
+      const GF_GROUP *const gf_group = &cpi->twopass.gf_group;
+      cpi->alt_fb_idx = gf_group->arf_ref_idx[gf_group->index];
+    }
   }
 
   cpi->frame_flags = *frame_flags;

vp9/encoder/vp9_encoder.h

@@ -416,6 +416,7 @@ typedef struct VP9_COMP {
   PC_TREE *pc_root;
   int partition_cost[PARTITION_CONTEXTS][PARTITION_TYPES];
 
+  int multi_arf_allowed;
   int multi_arf_enabled;
 
 #if CONFIG_DENOISING

vp9/encoder/vp9_firstpass.c

@@ -1400,11 +1400,13 @@ static void allocate_gf_group_bits(VP9_COMP *cpi, int64_t gf_group_bits,
     ++frame_index;
   }
 
-  if (rc->source_alt_ref_pending && cpi->multi_arf_enabled) {
-    twopass->gf_group.bit_allocation[2] =
-      twopass->gf_group.bit_allocation[middle_frame_idx] + mid_boost_bits;
-    twopass->gf_group.update_type[middle_frame_idx] = OVERLAY_UPDATE;
-    twopass->gf_group.bit_allocation[middle_frame_idx] = 0;
+  if (rc->source_alt_ref_pending) {
+    if (cpi->multi_arf_enabled) {
+      twopass->gf_group.bit_allocation[2] =
+        twopass->gf_group.bit_allocation[middle_frame_idx] + mid_boost_bits;
+      twopass->gf_group.update_type[middle_frame_idx] = OVERLAY_UPDATE;
+      twopass->gf_group.bit_allocation[middle_frame_idx] = 0;
+    }
 
     // Configure the overlay frame at the end of the sequence that will also
     // be the start frame of the next group. The reason for doing this here