Add extra altref option for hierarchical structure

This CL is to hook up the implemented hierarchical structure
construction as well as its corresponding bitrate allocation
functionality with the defining of a GF group.

Currently the hierarchical structure is off by default. Hence this CL
has no impact on coding performance.

Change-Id: I9e1ddfd877559e99072c23970f7fe103b64ed9ee

diff --git a/vp9/encoder/vp9_encoder.h b/vp9/encoder/vp9_encoder.h
index a3d39266fd400b34cc2e4fb0d53704b45f97c4c8..ec02a78ee22d0bab2fd7873fcd8e04c06873c486 100644 (file)
--- a/vp9/encoder/vp9_encoder.h
+++ b/vp9/encoder/vp9_encoder.h
@@ -758,9 +758,7 @@ typedef struct VP9_COMP {
   int num_extra_arfs;
   int arf_pos_in_gf[MAX_EXT_ARFS + 1];
   int arf_pos_for_ovrly[MAX_EXT_ARFS + 1];
-
   int extra_arf_allowed;
-  int bwd_ref_allowed;
 
   vpx_roi_map_t roi;
 } VP9_COMP;

diff --git a/vp9/encoder/vp9_firstpass.c b/vp9/encoder/vp9_firstpass.c
index 5828d2436403f94cfc9e67f68c960fd8b8c4ed87..6717d961d7572589ff208f2efe2f96b243eed61a 100644 (file)
--- a/vp9/encoder/vp9_firstpass.c
+++ b/vp9/encoder/vp9_firstpass.c
@@ -2135,7 +2135,7 @@ static void define_gf_multi_arf_structure(VP9_COMP *cpi) {
   // (3) The bi-predictive group interval is strictly smaller than the
   //     golden group interval.
   const int is_bipred_enabled =
-      cpi->bwd_ref_allowed && rc->source_alt_ref_pending &&
+      cpi->extra_arf_allowed && rc->source_alt_ref_pending &&
       rc->bipred_group_interval &&
       rc->bipred_group_interval <=
           (rc->baseline_gf_interval - rc->source_alt_ref_pending);
@@ -2523,6 +2523,8 @@ static void allocate_gf_multi_arf_bits(VP9_COMP *cpi, int64_t gf_group_bits,
       target_frame_size -= last_frame_reduction;
     }
 
+    // TODO(zoeliu): Further check whether following is needed for
+    //               hierarchical GF group structure.
     if (rc->source_alt_ref_pending && cpi->multi_arf_enabled) {
       target_frame_size -= (target_frame_size >> 4);
     }
@@ -2539,8 +2541,8 @@ static void allocate_gf_multi_arf_bits(VP9_COMP *cpi, int64_t gf_group_bits,
       gf_group->bit_allocation[frame_index] =
           target_frame_size - (target_frame_size >> 1);
     } else if (gf_group->update_type[frame_index] == BIPRED_UPDATE) {
-      // TODO(zoeliu): To investigate whether the allocated bits on
-      // BIPRED_UPDATE frames need to be further adjusted.
+      // TODO(zoeliu): Investigate whether the allocated bits on BIPRED_UPDATE
+      //               frames need to be further adjusted.
       gf_group->bit_allocation[frame_index] = target_frame_size;
     } else {
       assert(gf_group->update_type[frame_index] == LF_UPDATE ||
@@ -2753,6 +2755,8 @@ static void define_gf_group(VP9_COMP *cpi, FIRSTPASS_STATS *this_frame) {
   const int is_key_frame = frame_is_intra_only(cm);
   const int arf_active_or_kf = is_key_frame || rc->source_alt_ref_active;
 
+  int disable_bwd_extarf;
+
   // Reset the GF group data structures unless this is a key
   // frame in which case it will already have been done.
   if (is_key_frame == 0) {
@@ -2933,6 +2937,39 @@ static void define_gf_group(VP9_COMP *cpi, FIRSTPASS_STATS *this_frame) {
 
   rc->frames_till_gf_update_due = rc->baseline_gf_interval;
 
+  // TODO(zoeliu): Turn on the option to disable extra ALTREFs for still GF
+  //               groups.
+  // Disable extra altrefs for "still" gf group:
+  //   zero_motion_accumulator: minimum percentage of (0,0) motion;
+  //   avg_sr_coded_error:      average of the SSE per pixel of each frame;
+  //   avg_raw_err_stdev:       average of the standard deviation of (0,0)
+  //                            motion error per block of each frame.
+#if 0
+  assert(num_mbs > 0);
+  disable_bwd_extarf =
+      (zero_motion_accumulator > MIN_ZERO_MOTION &&
+       avg_sr_coded_error / num_mbs < MAX_SR_CODED_ERROR &&
+       avg_raw_err_stdev < MAX_RAW_ERR_VAR);
+#else
+  disable_bwd_extarf = 0;
+#endif  // 0
+
+  if (disable_bwd_extarf) cpi->extra_arf_allowed = 0;
+
+  if (!cpi->extra_arf_allowed) {
+    cpi->num_extra_arfs = 0;
+  } else {
+    // Compute how many extra alt_refs we can have
+    cpi->num_extra_arfs = get_number_of_extra_arfs(rc->baseline_gf_interval,
+                                                   rc->source_alt_ref_pending);
+  }
+  // Currently at maximum two extra ARFs' are allowed
+  assert(cpi->num_extra_arfs <= MAX_EXT_ARFS);
+
+  rc->bipred_group_interval = BFG_INTERVAL;
+  // The minimum bi-predictive frame group interval is 2.
+  if (rc->bipred_group_interval < 2) rc->bipred_group_interval = 0;
+
   // Reset the file position.
   reset_fpf_position(twopass, start_pos);
 
@@ -2984,13 +3021,7 @@ static void define_gf_group(VP9_COMP *cpi, FIRSTPASS_STATS *this_frame) {
   twopass->kf_group_error_left -= gf_group_err;
 
   // Allocate bits to each of the frames in the GF group.
-  cpi->bwd_ref_allowed = 0;
-  cpi->extra_arf_allowed = 0;
-
-  cpi->num_extra_arfs = 0;
-  cpi->num_extra_arfs = cpi->extra_arf_allowed ? cpi->num_extra_arfs : 0;
-
-  if (cpi->bwd_ref_allowed) {
+  if (cpi->extra_arf_allowed) {
     allocate_gf_multi_arf_bits(cpi, gf_group_bits, gf_arf_bits);
   } else {
     allocate_gf_group_bits(cpi, gf_group_bits, gf_arf_bits);

diff --git a/vp9/encoder/vp9_firstpass.h b/vp9/encoder/vp9_firstpass.h
index 958dc128de18ed426d2cf952efb6899dbc06bec9..404175d92962fb5ba03e925617dcf1fa1a41169e 100644 (file)
--- a/vp9/encoder/vp9_firstpass.h
+++ b/vp9/encoder/vp9_firstpass.h
@@ -11,6 +11,8 @@
 #ifndef VP9_ENCODER_VP9_FIRSTPASS_H_
 #define VP9_ENCODER_VP9_FIRSTPASS_H_
 
+#include <assert.h>
+
 #include "vp9/encoder/vp9_lookahead.h"
 #include "vp9/encoder/vp9_ratectrl.h"
 
@@ -41,7 +43,12 @@ typedef struct {
 
 #define INVALID_ROW -1
 
+// Length of the bi-predictive frame group (BFG)
+// NOTE: Currently each BFG contains one backward ref (BWF) frame plus a certain
+//       number of bi-predictive frames.
+#define BFG_INTERVAL 2
 #define MAX_EXT_ARFS 2
+#define MIN_EXT_ARF_INTERVAL 4
 
 typedef struct {
   double frame_mb_intra_factor;
@@ -210,6 +217,17 @@ void vp9_twopass_postencode_update(struct VP9_COMP *cpi);
 void calculate_coded_size(struct VP9_COMP *cpi, int *scaled_frame_width,
                           int *scaled_frame_height);
 
+static INLINE int get_number_of_extra_arfs(int interval, int arf_pending) {
+  assert(MAX_EXT_ARFS > 0);
+  if (arf_pending) {
+    if (interval >= MIN_EXT_ARF_INTERVAL * (MAX_EXT_ARFS + 1))
+      return MAX_EXT_ARFS;
+    else if (interval >= MIN_EXT_ARF_INTERVAL * MAX_EXT_ARFS)
+      return MAX_EXT_ARFS - 1;
+  }
+  return 0;
+}
+
 #ifdef __cplusplus
 }  // extern "C"
 #endif