SVC 1 pass mode: Constrain inter mode search within superframe.

Keep track of frame indexes for the references, and
constrain inter mode search for reference with same
temporal alignment.

Improves speed by about ~15%, no noticeable loss in
compression performance.

Change-Id: I5c407a8acca921234060c4fcef4afd7d734201c8

vp9/encoder/vp9_encoder.c

@@ -2793,6 +2793,22 @@ void vp9_update_reference_frames(VP9_COMP *cpi) {
                                    cpi->resize_pending);
   }
 #endif
+  if (is_one_pass_cbr_svc(cpi)) {
+    // Keep track of frame index for each reference frame.
+    SVC *const svc = &cpi->svc;
+    if (cm->frame_type == KEY_FRAME) {
+      svc->ref_frame_index[cpi->lst_fb_idx] = svc->current_superframe;
+      svc->ref_frame_index[cpi->gld_fb_idx] = svc->current_superframe;
+      svc->ref_frame_index[cpi->alt_fb_idx] = svc->current_superframe;
+    } else {
+      if (cpi->refresh_last_frame)
+        svc->ref_frame_index[cpi->lst_fb_idx] = svc->current_superframe;
+      if (cpi->refresh_golden_frame)
+        svc->ref_frame_index[cpi->gld_fb_idx] = svc->current_superframe;
+      if (cpi->refresh_alt_ref_frame)
+        svc->ref_frame_index[cpi->alt_fb_idx] = svc->current_superframe;
+    }
+  }
 }
 
 static void loopfilter_frame(VP9_COMP *cpi, VP9_COMMON *cm) {

vp9/encoder/vp9_pickmode.c

@@ -1094,6 +1094,7 @@ void vp9_pick_inter_mode(VP9_COMP *cpi, MACROBLOCK *x,
                          BLOCK_SIZE bsize, PICK_MODE_CONTEXT *ctx) {
   VP9_COMMON *const cm = &cpi->common;
   SPEED_FEATURES *const sf = &cpi->sf;
+  const SVC *const svc = &cpi->svc;
   TileInfo *const tile_info = &tile_data->tile_info;
   MACROBLOCKD *const xd = &x->e_mbd;
   MB_MODE_INFO *const mbmi = &xd->mi[0]->mbmi;
@@ -1143,6 +1144,7 @@ void vp9_pick_inter_mode(VP9_COMP *cpi, MACROBLOCK *x,
   int best_pred_sad = INT_MAX;
   int best_early_term = 0;
   int ref_frame_cost[MAX_REF_FRAMES];
+  int svc_force_zero_mode[3] = {0};
 #if CONFIG_VP9_TEMPORAL_DENOISING
   int64_t zero_last_cost_orig = INT64_MAX;
 #endif
@@ -1196,6 +1198,17 @@ void vp9_pick_inter_mode(VP9_COMP *cpi, MACROBLOCK *x,
   } else {
     usable_ref_frame = GOLDEN_FRAME;
   }
+
+  // If the reference is temporally aligned with current superframe
+  // (e.g., spatial reference within superframe), constrain the inter mode:
+  // for now only test zero motion.
+  if (cpi->use_svc && svc ->force_zero_mode_spatial_ref) {
+    if (svc->ref_frame_index[cpi->lst_fb_idx] == svc->current_superframe)
+      svc_force_zero_mode[LAST_FRAME - 1] = 1;
+    if (svc->ref_frame_index[cpi->gld_fb_idx] == svc->current_superframe)
+      svc_force_zero_mode[GOLDEN_FRAME - 1] = 1;
+  }
+
   for (ref_frame = LAST_FRAME; ref_frame <= usable_ref_frame; ++ref_frame) {
     const YV12_BUFFER_CONFIG *yv12 = get_ref_frame_buffer(cpi, ref_frame);
 
@@ -1248,8 +1261,13 @@ void vp9_pick_inter_mode(VP9_COMP *cpi, MACROBLOCK *x,
       continue;
 
     ref_frame = ref_mode_set[idx].ref_frame;
-    if (cpi->use_svc)
+    if (cpi->use_svc) {
       ref_frame = ref_mode_set_svc[idx].ref_frame;
+      if (svc_force_zero_mode[ref_frame - 1] &&
+          frame_mv[this_mode][ref_frame].as_int != 0)
+        continue;
+    }
+
     if (!(cpi->ref_frame_flags & flag_list[ref_frame]))
       continue;
     if (const_motion[ref_frame] && this_mode == NEARMV)

vp9/encoder/vp9_svc_layercontext.c

@@ -25,13 +25,17 @@ void vp9_init_layer_context(VP9_COMP *const cpi) {
   const VP9EncoderConfig *const oxcf = &cpi->oxcf;
   int mi_rows = cpi->common.mi_rows;
   int mi_cols = cpi->common.mi_cols;
-  int sl, tl;
+  int sl, tl, i;
   int alt_ref_idx = svc->number_spatial_layers;
 
   svc->spatial_layer_id = 0;
   svc->temporal_layer_id = 0;
   svc->first_spatial_layer_to_encode = 0;
   svc->rc_drop_superframe = 0;
+  svc->force_zero_mode_spatial_ref = 0;
+  svc->current_superframe = 0;
+  for (i = 0; i < REF_FRAMES; ++i)
+    svc->ref_frame_index[i] = -1;
 
   if (cpi->oxcf.error_resilient_mode == 0 && cpi->oxcf.pass == 2) {
     if (vpx_realloc_frame_buffer(&cpi->svc.empty_frame.img,
@@ -353,6 +357,8 @@ void vp9_inc_frame_in_layer(VP9_COMP *const cpi) {
                               cpi->svc.number_temporal_layers];
   ++lc->current_video_frame_in_layer;
   ++lc->frames_from_key_frame;
+  if (cpi->svc.spatial_layer_id == cpi->svc.number_spatial_layers - 1)
+    ++cpi->svc.current_superframe;
 }
 
 int vp9_is_upper_layer_key_frame(const VP9_COMP *const cpi) {
@@ -542,6 +548,7 @@ static void set_flags_and_fb_idx_for_temporal_mode_noLayering(
 int vp9_one_pass_cbr_svc_start_layer(VP9_COMP *const cpi) {
   int width = 0, height = 0;
   LAYER_CONTEXT *lc = NULL;
+  cpi->svc.force_zero_mode_spatial_ref = 1;
 
   if (cpi->svc.temporal_layering_mode == VP9E_TEMPORAL_LAYERING_MODE_0212) {
     set_flags_and_fb_idx_for_temporal_mode3(cpi);

vp9/encoder/vp9_svc_layercontext.h

@@ -83,6 +83,9 @@ typedef struct {
   int ext_lst_fb_idx[VPX_MAX_LAYERS];
   int ext_gld_fb_idx[VPX_MAX_LAYERS];
   int ext_alt_fb_idx[VPX_MAX_LAYERS];
+  int ref_frame_index[REF_FRAMES];
+  int force_zero_mode_spatial_ref;
+  int current_superframe;
 } SVC;
 
 struct VP9_COMP;