Merge changes Ia82cef79,I7324a75a,I7b66daad,I73344451,I91dc210f,I5945b5ce into experimental

* changes:
  Use alt-ref frame context for keyframes
  Preserve the previous golden frame on golden updates
  Generalize and increase frame coding contexts
  Start to anonymize reference frames
  Update encoder to use fb_idx_ref_cnt
  Remove buffer-to-buffer copy logic

vp9/common/vp9_alloccommon.c

@@ -80,7 +80,6 @@ int vp9_alloc_frame_buffers(VP9_COMMON *oci, int width, int height) {
 
   for (i = 0; i < NUM_YV12_BUFFERS; i++) {
     oci->fb_idx_ref_cnt[i] = 0;
-    oci->yv12_fb[i].flags = 0;
     if (vp8_yv12_alloc_frame_buffer(&oci->yv12_fb[i], width, height,
                                     VP9BORDERINPIXELS) < 0) {
       vp9_de_alloc_frame_buffers(oci);
@@ -88,15 +87,16 @@ int vp9_alloc_frame_buffers(VP9_COMMON *oci, int width, int height) {
     }
   }
 
-  oci->new_fb_idx = 0;
-  oci->lst_fb_idx = 1;
-  oci->gld_fb_idx = 2;
-  oci->alt_fb_idx = 3;
+  oci->new_fb_idx = NUM_YV12_BUFFERS - 1;
+  oci->fb_idx_ref_cnt[oci->new_fb_idx] = 1;
 
-  oci->fb_idx_ref_cnt[0] = 1;
-  oci->fb_idx_ref_cnt[1] = 1;
-  oci->fb_idx_ref_cnt[2] = 1;
-  oci->fb_idx_ref_cnt[3] = 1;
+  for (i = 0; i < 3; i++)
+    oci->active_ref_idx[i] = i;
+
+  for (i = 0; i < NUM_REF_FRAMES; i++) {
+    oci->ref_frame_map[i] = i;
+    oci->fb_idx_ref_cnt[i] = 1;
+  }
 
   if (vp8_yv12_alloc_frame_buffer(&oci->temp_scale_frame, width, 16,
                                   VP9BORDERINPIXELS) < 0) {
@@ -204,9 +204,6 @@ void vp9_create_common(VP9_COMMON *oci) {
   /* Initialise reference frame sign bias structure to defaults */
   vpx_memset(oci->ref_frame_sign_bias, 0, sizeof(oci->ref_frame_sign_bias));
 
-  /* Default disable buffer to buffer copying */
-  oci->copy_buffer_to_gf = 0;
-  oci->copy_buffer_to_arf = 0;
   oci->kf_ymode_probs_update = 0;
 }
 

vp9/common/vp9_onyxc_int.h

@@ -37,7 +37,12 @@ void vp9_initialize_common(void);
 
 #define QINDEX_RANGE (MAXQ + 1)
 
-#define NUM_YV12_BUFFERS 4
+#define NUM_REF_FRAMES 3
+#define NUM_REF_FRAMES_LG2 2
+#define NUM_YV12_BUFFERS (NUM_REF_FRAMES + 1)
+
+#define NUM_FRAME_CONTEXTS_LG2 2
+#define NUM_FRAME_CONTEXTS (1 << NUM_FRAME_CONTEXTS_LG2)
 
 #define COMP_PRED_CONTEXTS   2
 
@@ -142,8 +147,14 @@ typedef struct VP9Common {
   YV12_BUFFER_CONFIG *frame_to_show;
 
   YV12_BUFFER_CONFIG yv12_fb[NUM_YV12_BUFFERS];
-  int fb_idx_ref_cnt[NUM_YV12_BUFFERS];
-  int new_fb_idx, lst_fb_idx, gld_fb_idx, alt_fb_idx;
+  int fb_idx_ref_cnt[NUM_YV12_BUFFERS]; /* reference counts */
+  int ref_frame_map[NUM_REF_FRAMES]; /* maps fb_idx to reference slot */
+
+  /* TODO(jkoleszar): could expand active_ref_idx to 4, with 0 as intra, and
+   * roll new_fb_idx into it.
+   */
+  int active_ref_idx[3]; /* each frame can reference 3 buffers */
+  int new_fb_idx;
 
   YV12_BUFFER_CONFIG post_proc_buffer;
   YV12_BUFFER_CONFIG temp_scale_frame;
@@ -202,13 +213,6 @@ typedef struct VP9Common {
   int last_sharpness_level;
   int sharpness_level;
 
-  int refresh_last_frame;       /* Two state 0 = NO, 1 = YES */
-  int refresh_golden_frame;     /* Two state 0 = NO, 1 = YES */
-  int refresh_alt_ref_frame;     /* Two state 0 = NO, 1 = YES */
-
-  int copy_buffer_to_gf;         /* 0 none, 1 Last to GF, 2 ARF to GF */
-  int copy_buffer_to_arf;        /* 0 none, 1 Last to ARF, 2 GF to ARF */
-
   int refresh_entropy_probs;    /* Two state 0 = NO, 1 = YES */
 
   int ref_frame_sign_bias[MAX_REF_FRAMES];    /* Two state 0, 1 */
@@ -250,9 +254,9 @@ typedef struct VP9Common {
 
   vp9_prob mbskip_pred_probs[MBSKIP_CONTEXTS];
 
-  FRAME_CONTEXT lfc_a; /* last alt ref entropy */
-  FRAME_CONTEXT lfc; /* last frame entropy */
   FRAME_CONTEXT fc;  /* this frame entropy */
+  FRAME_CONTEXT frame_contexts[NUM_FRAME_CONTEXTS];
+  unsigned int  frame_context_idx; /* Context to use/update */
 
   unsigned int current_video_frame;
   int near_boffset[3];
@@ -274,4 +278,24 @@ typedef struct VP9Common {
 
 } VP9_COMMON;
 
+static int get_free_fb(VP9_COMMON *cm) {
+  int i;
+  for (i = 0; i < NUM_YV12_BUFFERS; i++)
+    if (cm->fb_idx_ref_cnt[i] == 0)
+      break;
+
+  assert(i < NUM_YV12_BUFFERS);
+  cm->fb_idx_ref_cnt[i] = 1;
+  return i;
+}
+
+static void ref_cnt_fb(int *buf, int *idx, int new_idx) {
+  if (buf[*idx] > 0)
+    buf[*idx]--;
+
+  *idx = new_idx;
+
+  buf[new_idx]++;
+}
+
 #endif  // VP9_COMMON_VP9_ONYXC_INT_H_

vp9/decoder/vp9_decodemv.c

@@ -730,12 +730,7 @@ static void read_mb_modes_mv(VP9D_COMP *pbi, MODE_INFO *mi, MB_MODE_INFO *mbmi,
       int ref_fb_idx;
 
       /* Select the appropriate reference frame for this MB */
-      if (ref_frame == LAST_FRAME)
-        ref_fb_idx = cm->lst_fb_idx;
-      else if (ref_frame == GOLDEN_FRAME)
-        ref_fb_idx = cm->gld_fb_idx;
-      else
-        ref_fb_idx = cm->alt_fb_idx;
+      ref_fb_idx = cm->active_ref_idx[ref_frame - 1];
 
       recon_y_stride = cm->yv12_fb[ref_fb_idx].y_stride  ;
       recon_uv_stride = cm->yv12_fb[ref_fb_idx].uv_stride;
@@ -818,13 +813,7 @@ static void read_mb_modes_mv(VP9D_COMP *pbi, MODE_INFO *mi, MB_MODE_INFO *mbmi,
       if (mbmi->second_ref_frame > 0) {
         int second_ref_fb_idx;
         /* Select the appropriate reference frame for this MB */
-        if (mbmi->second_ref_frame == LAST_FRAME)
-          second_ref_fb_idx = cm->lst_fb_idx;
-        else if (mbmi->second_ref_frame ==
-          GOLDEN_FRAME)
-          second_ref_fb_idx = cm->gld_fb_idx;
-        else
-          second_ref_fb_idx = cm->alt_fb_idx;
+        second_ref_fb_idx = cm->active_ref_idx[mbmi->second_ref_frame - 1];
 
         xd->second_pre.y_buffer =
           cm->yv12_fb[second_ref_fb_idx].y_buffer + recon_yoffset;

vp9/decoder/vp9_decodframe.c

@@ -1091,12 +1091,7 @@ static void set_refs(VP9D_COMP *pbi, int block_size,
     int ref_fb_idx, ref_yoffset, ref_uvoffset, ref_y_stride, ref_uv_stride;
 
     /* Select the appropriate reference frame for this MB */
-    if (mbmi->ref_frame == LAST_FRAME)
-      ref_fb_idx = cm->lst_fb_idx;
-    else if (mbmi->ref_frame == GOLDEN_FRAME)
-      ref_fb_idx = cm->gld_fb_idx;
-    else
-      ref_fb_idx = cm->alt_fb_idx;
+    ref_fb_idx = cm->active_ref_idx[mbmi->ref_frame - 1];
 
     ref_y_stride = cm->yv12_fb[ref_fb_idx].y_stride;
     ref_yoffset = mb_row * 16 * ref_y_stride + 16 * mb_col;
@@ -1113,12 +1108,7 @@ static void set_refs(VP9D_COMP *pbi, int block_size,
       int second_ref_fb_idx;
 
       /* Select the appropriate reference frame for this MB */
-      if (mbmi->second_ref_frame == LAST_FRAME)
-        second_ref_fb_idx = cm->lst_fb_idx;
-      else if (mbmi->second_ref_frame == GOLDEN_FRAME)
-        second_ref_fb_idx = cm->gld_fb_idx;
-      else
-        second_ref_fb_idx = cm->alt_fb_idx;
+      second_ref_fb_idx = cm->active_ref_idx[mbmi->second_ref_frame - 1];
 
       xd->second_pre.y_buffer =
           cm->yv12_fb[second_ref_fb_idx].y_buffer + ref_yoffset;
@@ -1265,6 +1255,7 @@ static void init_frame(VP9D_COMP *pbi) {
   MACROBLOCKD *const xd  = &pbi->mb;
 
   if (pc->frame_type == KEY_FRAME) {
+    int i;
 
     if (pc->last_frame_seg_map)
       vpx_memset(pc->last_frame_seg_map, 0, (pc->mb_rows * pc->mb_cols));
@@ -1288,10 +1279,7 @@ static void init_frame(VP9D_COMP *pbi) {
     vpx_memset(xd->mode_lf_deltas, 0, sizeof(xd->mode_lf_deltas));
 
     /* All buffers are implicitly updated on key frames. */
-    pc->refresh_golden_frame = 1;
-    pc->refresh_alt_ref_frame = 1;
-    pc->copy_buffer_to_gf = 0;
-    pc->copy_buffer_to_arf = 0;
+    pbi->refresh_frame_flags = (1 << NUM_REF_FRAMES) - 1;
 
     /* Note that Golden and Altref modes cannot be used on a key frame so
      * ref_frame_sign_bias[] is undefined and meaningless
@@ -1300,8 +1288,9 @@ static void init_frame(VP9D_COMP *pbi) {
     pc->ref_frame_sign_bias[ALTREF_FRAME] = 0;
 
     vp9_init_mode_contexts(&pbi->common);
-    vpx_memcpy(&pc->lfc, &pc->fc, sizeof(pc->fc));
-    vpx_memcpy(&pc->lfc_a, &pc->fc, sizeof(pc->fc));
+
+    for (i = 0; i < NUM_FRAME_CONTEXTS; i++)
+      vpx_memcpy(&pc->frame_contexts[i], &pc->fc, sizeof(pc->fc));
 
     vpx_memset(pc->prev_mip, 0,
                (pc->mb_cols + 1) * (pc->mb_rows + 1)* sizeof(MODE_INFO));
@@ -1645,27 +1634,20 @@ int vp9_decode_frame(VP9D_COMP *pbi, const unsigned char **p_data_end) {
    * For all non key frames the GF and ARF refresh flags and sign bias
    * flags must be set explicitly.
    */
-  if (pc->frame_type != KEY_FRAME) {
+  if (pc->frame_type == KEY_FRAME) {
+    pc->active_ref_idx[0] = pc->new_fb_idx;
+    pc->active_ref_idx[1] = pc->new_fb_idx;
+    pc->active_ref_idx[2] = pc->new_fb_idx;
+  } else {
     /* Should the GF or ARF be updated from the current frame */
-    pc->refresh_golden_frame = vp9_read_bit(&header_bc);
-    pc->refresh_alt_ref_frame = vp9_read_bit(&header_bc);
-
-    if (pc->refresh_alt_ref_frame) {
-      vpx_memcpy(&pc->fc, &pc->lfc_a, sizeof(pc->fc));
-    } else {
-      vpx_memcpy(&pc->fc, &pc->lfc, sizeof(pc->fc));
-    }
-
-    /* Buffer to buffer copy flags. */
-    pc->copy_buffer_to_gf = 0;
+    pbi->refresh_frame_flags = vp9_read_literal(&header_bc, NUM_REF_FRAMES);
 
-    if (!pc->refresh_golden_frame)
-      pc->copy_buffer_to_gf = vp9_read_literal(&header_bc, 2);
+    /* Select active reference frames */
+    for (i = 0; i < 3; i++) {
+      int ref_frame_num = vp9_read_literal(&header_bc, NUM_REF_FRAMES_LG2);
 
-    pc->copy_buffer_to_arf = 0;
-
-    if (!pc->refresh_alt_ref_frame)
-      pc->copy_buffer_to_arf = vp9_read_literal(&header_bc, 2);
+      pc->active_ref_idx[i] = pc->ref_frame_map[ref_frame_num];
+    }
 
     pc->ref_frame_sign_bias[GOLDEN_FRAME] = vp9_read_bit(&header_bc);
     pc->ref_frame_sign_bias[ALTREF_FRAME] = vp9_read_bit(&header_bc);
@@ -1686,12 +1668,9 @@ int vp9_decode_frame(VP9D_COMP *pbi, const unsigned char **p_data_end) {
   }
 
   pc->refresh_entropy_probs = vp9_read_bit(&header_bc);
-  if (pc->refresh_entropy_probs == 0) {
-    vpx_memcpy(&pc->lfc, &pc->fc, sizeof(pc->fc));
-  }
-
-  pc->refresh_last_frame = (pc->frame_type == KEY_FRAME)
-                           || vp9_read_bit(&header_bc);
+  pc->frame_context_idx = vp9_read_literal(&header_bc, NUM_FRAME_CONTEXTS_LG2);
+  vpx_memcpy(&pc->fc, &pc->frame_contexts[pc->frame_context_idx],
+             sizeof(pc->fc));
 
   // Read inter mode probability context updates
   if (pc->frame_type != KEY_FRAME) {
@@ -1735,12 +1714,10 @@ int vp9_decode_frame(VP9D_COMP *pbi, const unsigned char **p_data_end) {
 
   if (0) {
     FILE *z = fopen("decodestats.stt", "a");
-    fprintf(z, "%6d F:%d,G:%d,A:%d,L:%d,Q:%d\n",
+    fprintf(z, "%6d F:%d,R:%d,Q:%d\n",
             pc->current_video_frame,
             pc->frame_type,
-            pc->refresh_golden_frame,
-            pc->refresh_alt_ref_frame,
-            pc->refresh_last_frame,
+            pbi->refresh_frame_flags,
             pc->base_qindex);
     fclose(z);
   }
@@ -1792,8 +1769,11 @@ int vp9_decode_frame(VP9D_COMP *pbi, const unsigned char **p_data_end) {
 
   read_coef_probs(pbi, &header_bc);
 
-  vpx_memcpy(&xd->pre, &pc->yv12_fb[pc->lst_fb_idx], sizeof(YV12_BUFFER_CONFIG));
-  vpx_memcpy(&xd->dst, &pc->yv12_fb[pc->new_fb_idx], sizeof(YV12_BUFFER_CONFIG));
+  /* Initialize xd pointers. Any reference should do for xd->pre, so use 0. */
+  vpx_memcpy(&xd->pre, &pc->yv12_fb[pc->active_ref_idx[0]],
+             sizeof(YV12_BUFFER_CONFIG));
+  vpx_memcpy(&xd->dst, &pc->yv12_fb[pc->new_fb_idx],
+             sizeof(YV12_BUFFER_CONFIG));
 
   // Create the segmentation map structure and set to 0
   if (!pc->last_frame_seg_map)
@@ -1845,16 +1825,9 @@ int vp9_decode_frame(VP9D_COMP *pbi, const unsigned char **p_data_end) {
     vp9_update_mode_context(&pbi->common);
   }
 
-  /* If this was a kf or Gf note the Q used */
-  if ((pc->frame_type == KEY_FRAME) ||
-      pc->refresh_golden_frame || pc->refresh_alt_ref_frame) {
-    pc->last_kf_gf_q = pc->base_qindex;
-  }
   if (pc->refresh_entropy_probs) {
-    if (pc->refresh_alt_ref_frame)
-      vpx_memcpy(&pc->lfc_a, &pc->fc, sizeof(pc->fc));
-    else
-      vpx_memcpy(&pc->lfc, &pc->fc, sizeof(pc->fc));
+    vpx_memcpy(&pc->frame_contexts[pc->frame_context_idx], &pc->fc,
+               sizeof(pc->fc));
   }
 
 #ifdef PACKET_TESTING

vp9/decoder/vp9_onyxd_if.c

@@ -30,9 +30,6 @@
 #include "vp9/decoder/vp9_detokenize.h"
 #include "./vpx_scale_rtcd.h"
 
-static int get_free_fb(VP9_COMMON *cm);
-static void ref_cnt_fb(int *buf, int *idx, int new_idx);
-
 #define WRITE_RECON_BUFFER 0
 #if WRITE_RECON_BUFFER == 1
 static void recon_write_yuv_frame(char *name, YV12_BUFFER_CONFIG *s) {
@@ -168,12 +165,13 @@ vpx_codec_err_t vp9_get_reference_dec(VP9D_PTR ptr, VP9_REFFRAME ref_frame_flag,
   VP9_COMMON *cm = &pbi->common;
   int ref_fb_idx;
 
+  /* TODO(jkoleszar): The decoder doesn't have any real knowledge of what the
+   * encoder is using the frame buffers for. This is just a stub to keep the
+   * vpxenc --test-decode functionality working, and will be replaced in a
+   * later commit that adds VP9-specific controls for this functionality.
+   */
   if (ref_frame_flag == VP9_LAST_FLAG)
-    ref_fb_idx = cm->lst_fb_idx;
-  else if (ref_frame_flag == VP9_GOLD_FLAG)
-    ref_fb_idx = cm->gld_fb_idx;
-  else if (ref_frame_flag == VP9_ALT_FLAG)
-    ref_fb_idx = cm->alt_fb_idx;
+    ref_fb_idx = pbi->common.new_fb_idx;
   else {
     vpx_internal_error(&pbi->common.error, VPX_CODEC_ERROR,
                        "Invalid reference frame");
@@ -200,12 +198,17 @@ vpx_codec_err_t vp9_set_reference_dec(VP9D_PTR ptr, VP9_REFFRAME ref_frame_flag,
   int *ref_fb_ptr = NULL;
   int free_fb;
 
+  /* TODO(jkoleszar): The decoder doesn't have any real knowledge of what the
+   * encoder is using the frame buffers for. This is just a stub to keep the
+   * vpxenc --test-decode functionality working, and will be replaced in a
+   * later commit that adds VP9-specific controls for this functionality.
+   */
   if (ref_frame_flag == VP9_LAST_FLAG)
-    ref_fb_ptr = &cm->lst_fb_idx;
+    ref_fb_ptr = &pbi->common.active_ref_idx[0];
   else if (ref_frame_flag == VP9_GOLD_FLAG)
-    ref_fb_ptr = &cm->gld_fb_idx;
+    ref_fb_ptr = &pbi->common.active_ref_idx[1];
   else if (ref_frame_flag == VP9_ALT_FLAG)
-    ref_fb_ptr = &cm->alt_fb_idx;
+    ref_fb_ptr = &pbi->common.active_ref_idx[2];
   else {
     vpx_internal_error(&pbi->common.error, VPX_CODEC_ERROR,
                        "Invalid reference frame");
@@ -234,77 +237,25 @@ vpx_codec_err_t vp9_set_reference_dec(VP9D_PTR ptr, VP9_REFFRAME ref_frame_flag,
 }
 
 
-static int get_free_fb(VP9_COMMON *cm) {
-  int i;
-  for (i = 0; i < NUM_YV12_BUFFERS; i++)
-    if (cm->fb_idx_ref_cnt[i] == 0)
-      break;
-
-  assert(i < NUM_YV12_BUFFERS);
-  cm->fb_idx_ref_cnt[i] = 1;
-  return i;
-}
-
-static void ref_cnt_fb(int *buf, int *idx, int new_idx) {
-  if (buf[*idx] > 0)
-    buf[*idx]--;
-
-  *idx = new_idx;
-
-  buf[new_idx]++;
-}
-
-/* If any buffer copy / swapping is signalled it should be done here. */
-static int swap_frame_buffers(VP9_COMMON *cm) {
-  int err = 0;
-
-  /* The alternate reference frame or golden frame can be updated
-   *  using the new, last, or golden/alt ref frame.  If it
-   *  is updated using the newly decoded frame it is a refresh.
-   *  An update using the last or golden/alt ref frame is a copy.
-   */
-  if (cm->copy_buffer_to_arf) {
-    int new_fb = 0;
+/* If any buffer updating is signalled it should be done here. */
+static void swap_frame_buffers(VP9D_COMP *pbi) {
+  int ref_index = 0, mask;
 
-    if (cm->copy_buffer_to_arf == 1)
-      new_fb = cm->lst_fb_idx;
-    else if (cm->copy_buffer_to_arf == 2)
-      new_fb = cm->gld_fb_idx;
-    else
-      err = -1;
-
-    ref_cnt_fb(cm->fb_idx_ref_cnt, &cm->alt_fb_idx, new_fb);
-  }
-
-  if (cm->copy_buffer_to_gf) {
-    int new_fb = 0;
-
-    if (cm->copy_buffer_to_gf == 1)
-      new_fb = cm->lst_fb_idx;
-    else if (cm->copy_buffer_to_gf == 2)
-      new_fb = cm->alt_fb_idx;
-    else
-      err = -1;
-
-    ref_cnt_fb(cm->fb_idx_ref_cnt, &cm->gld_fb_idx, new_fb);
+  for (mask = pbi->refresh_frame_flags; mask; mask >>= 1) {
+    if (mask & 1) {
+      ref_cnt_fb(pbi->common.fb_idx_ref_cnt,
+                 &pbi->common.ref_frame_map[ref_index],
+                 pbi->common.new_fb_idx);
+    }
+    ++ref_index;
   }
 
-  if (cm->refresh_golden_frame)
-    ref_cnt_fb(cm->fb_idx_ref_cnt, &cm->gld_fb_idx, cm->new_fb_idx);
-
-  if (cm->refresh_alt_ref_frame)
-    ref_cnt_fb(cm->fb_idx_ref_cnt, &cm->alt_fb_idx, cm->new_fb_idx);
+  pbi->common.frame_to_show = &pbi->common.yv12_fb[pbi->common.new_fb_idx];
+  pbi->common.fb_idx_ref_cnt[pbi->common.new_fb_idx]--;
 
-  if (cm->refresh_last_frame) {
-    ref_cnt_fb(cm->fb_idx_ref_cnt, &cm->lst_fb_idx, cm->new_fb_idx);
-
-    cm->frame_to_show = &cm->yv12_fb[cm->lst_fb_idx];
-  } else
-    cm->frame_to_show = &cm->yv12_fb[cm->new_fb_idx];
-
-  cm->fb_idx_ref_cnt[cm->new_fb_idx]--;
-
-  return err;
+  /* Invalidate these references until the next frame starts. */
+  for (ref_index = 0; ref_index < 3; ref_index++)
+    pbi->common.active_ref_idx[ref_index] = INT_MAX;
 }
 
 int vp9_receive_compressed_data(VP9D_PTR ptr, unsigned long size,
@@ -332,8 +283,12 @@ int vp9_receive_compressed_data(VP9D_PTR ptr, unsigned long size,
      * We do not know if the missing frame(s) was supposed to update
      * any of the reference buffers, but we act conservative and
      * mark only the last buffer as corrupted.
+     *
+     * TODO(jkoleszar): Error concealment is undefined and non-normative
+     * at this point, but if it becomes so, [0] may not always be the correct
+     * thing to do here.
      */
-    cm->yv12_fb[cm->lst_fb_idx].corrupted = 1;
+    cm->yv12_fb[cm->active_ref_idx[0]].corrupted = 1;
   }
 
   cm->new_fb_idx = get_free_fb(cm);
@@ -344,8 +299,12 @@ int vp9_receive_compressed_data(VP9D_PTR ptr, unsigned long size,
     /* We do not know if the missing frame(s) was supposed to update
      * any of the reference buffers, but we act conservative and
      * mark only the last buffer as corrupted.
+     *
+     * TODO(jkoleszar): Error concealment is undefined and non-normative
+     * at this point, but if it becomes so, [0] may not always be the correct
+     * thing to do here.
      */
-    cm->yv12_fb[cm->lst_fb_idx].corrupted = 1;
+    cm->yv12_fb[cm->active_ref_idx[0]].corrupted = 1;
 
     if (cm->fb_idx_ref_cnt[cm->new_fb_idx] > 0)
       cm->fb_idx_ref_cnt[cm->new_fb_idx]--;
@@ -365,11 +324,7 @@ int vp9_receive_compressed_data(VP9D_PTR ptr, unsigned long size,
   }
 
   {
-    if (swap_frame_buffers(cm)) {
-      pbi->common.error.error_code = VPX_CODEC_ERROR;
-      pbi->common.error.setjmp = 0;
-      return -1;
-    }
+    swap_frame_buffers(pbi);
 
 #if WRITE_RECON_BUFFER == 2
     if (cm->show_frame)

vp9/decoder/vp9_onyxd_int.h

@@ -76,6 +76,7 @@ typedef struct VP9Decompressor {
   vp9_dequant_idct_add_y_block_fn_t    idct_add_y_block;
   vp9_dequant_idct_add_uv_block_fn_t   idct_add_uv_block;
 
+  int refresh_frame_flags;
   vp9_prob prob_skip_false;
 
   int decoded_key_frame;

vp9/encoder/vp9_bitstream.c

@@ -1772,22 +1772,30 @@ void vp9_pack_bitstream(VP9_COMP *cpi, unsigned char *dest,
 
   // When there is a key frame all reference buffers are updated using the new key frame
   if (pc->frame_type != KEY_FRAME) {
-    // Should the GF or ARF be updated using the transmitted frame or buffer
-    vp9_write_bit(&header_bc, pc->refresh_golden_frame);
-    vp9_write_bit(&header_bc, pc->refresh_alt_ref_frame);
-
-    // For inter frames the current default behavior is that when
-    // cm->refresh_golden_frame is set we copy the old GF over to
-    // the ARF buffer. This is purely an encoder decision at present.
-    if (pc->refresh_golden_frame)
-      pc->copy_buffer_to_arf  = 2;
+    int refresh_mask;
 
-    // If not being updated from current frame should either GF or ARF be updated from another buffer
-    if (!pc->refresh_golden_frame)
-      vp9_write_literal(&header_bc, pc->copy_buffer_to_gf, 2);
-
-    if (!pc->refresh_alt_ref_frame)
-      vp9_write_literal(&header_bc, pc->copy_buffer_to_arf, 2);
+    // Should the GF or ARF be updated using the transmitted frame or buffer
+    if (cpi->refresh_golden_frame && !cpi->refresh_alt_ref_frame) {
+      /* Preserve the previously existing golden frame and update the frame in
+       * the alt ref slot instead. This is highly specific to the use of
+       * alt-ref as a forward reference, and this needs to be generalized as
+       * other uses are implemented (like RTC/temporal scaling)
+       *
+       * gld_fb_idx and alt_fb_idx need to be swapped for future frames, but
+       * that happens in vp9_onyx_if.c:update_reference_frames() so that it can
+       * be done outside of the recode loop.
+       */
+      refresh_mask = (cpi->refresh_last_frame << cpi->lst_fb_idx) |
+                     (cpi->refresh_golden_frame << cpi->alt_fb_idx);
+    } else {
+      refresh_mask = (cpi->refresh_last_frame << cpi->lst_fb_idx) |
+                     (cpi->refresh_golden_frame << cpi->gld_fb_idx) |
+                     (cpi->refresh_alt_ref_frame << cpi->alt_fb_idx);
+    }
+    vp9_write_literal(&header_bc, refresh_mask, NUM_REF_FRAMES);
+    vp9_write_literal(&header_bc, cpi->lst_fb_idx, NUM_REF_FRAMES_LG2);
+    vp9_write_literal(&header_bc, cpi->gld_fb_idx, NUM_REF_FRAMES_LG2);
+    vp9_write_literal(&header_bc, cpi->alt_fb_idx, NUM_REF_FRAMES_LG2);
 
     // Indicate reference frame sign bias for Golden and ARF frames (always 0 for last frame buffer)
     vp9_write_bit(&header_bc, pc->ref_frame_sign_bias[GOLDEN_FRAME]);
@@ -1832,9 +1840,8 @@ void vp9_pack_bitstream(VP9_COMP *cpi, unsigned char *dest,
   }
 
   vp9_write_bit(&header_bc, pc->refresh_entropy_probs);
-
-  if (pc->frame_type != KEY_FRAME)
-    vp9_write_bit(&header_bc, pc->refresh_last_frame);
+  vp9_write_literal(&header_bc, pc->frame_context_idx,
+                    NUM_FRAME_CONTEXTS_LG2);
 
 #ifdef ENTROPY_STATS
   if (pc->frame_type == INTER_FRAME)

vp9/encoder/vp9_encodeframe.c

@@ -640,7 +640,7 @@ static void set_offsets(VP9_COMP *cpi,
   const int src_uv_stride = x->src.uv_stride;
   const int src_yoffset = 16 * mb_row * src_y_stride + 16 * mb_col;
   const int src_uvoffset = 8 * mb_row * src_uv_stride + 8 * mb_col;
-  const int ref_fb_idx = cm->lst_fb_idx;
+  const int ref_fb_idx = cm->active_ref_idx[cpi->lst_fb_idx];
   const int ref_y_stride = cm->yv12_fb[ref_fb_idx].y_stride;
   const int ref_uv_stride = cm->yv12_fb[ref_fb_idx].uv_stride;
   const int idx_map = mb_row * cm->mb_cols + mb_col;
@@ -1205,7 +1205,7 @@ static void init_encode_frame_mb_context(VP9_COMP *cpi) {
 
   // Copy data over into macro block data structures.
   x->src = *cpi->Source;
-  xd->pre = cm->yv12_fb[cm->lst_fb_idx];
+  xd->pre = cm->yv12_fb[cm->active_ref_idx[cpi->lst_fb_idx]];
   xd->dst = cm->yv12_fb[cm->new_fb_idx];
 
   // set up frame for intra coded blocks
@@ -1526,9 +1526,9 @@ void vp9_encode_frame(VP9_COMP *cpi) {
      */
     if (cpi->common.frame_type == KEY_FRAME)
       frame_type = 0;
-    else if (cpi->is_src_frame_alt_ref && cpi->common.refresh_golden_frame)
+    else if (cpi->is_src_frame_alt_ref && cpi->refresh_golden_frame)
       frame_type = 3;
-    else if (cpi->common.refresh_golden_frame || cpi->common.refresh_alt_ref_frame)
+    else if (cpi->refresh_golden_frame || cpi->refresh_alt_ref_frame)
       frame_type = 1;
     else
       frame_type = 2;
@@ -2086,11 +2086,11 @@ static void encode_macroblock(VP9_COMP *cpi, TOKENEXTRA **t,
     assert(cm->frame_type != KEY_FRAME);
 
     if (mbmi->ref_frame == LAST_FRAME)
-      ref_fb_idx = cpi->common.lst_fb_idx;
+      ref_fb_idx = cpi->common.active_ref_idx[cpi->lst_fb_idx];
     else if (mbmi->ref_frame == GOLDEN_FRAME)
-      ref_fb_idx = cpi->common.gld_fb_idx;
+      ref_fb_idx = cpi->common.active_ref_idx[cpi->gld_fb_idx];
     else
-      ref_fb_idx = cpi->common.alt_fb_idx;
+      ref_fb_idx = cpi->common.active_ref_idx[cpi->alt_fb_idx];
 
     xd->pre.y_buffer = cpi->common.yv12_fb[ref_fb_idx].y_buffer + recon_yoffset;
     xd->pre.u_buffer = cpi->common.yv12_fb[ref_fb_idx].u_buffer + recon_uvoffs