Extend number of reference buffers to 8.

The number of reference buffers is extended to 8 and
a reference sign-bias added for the LAST_FRAME.

Whilst the number of reference buffers used by an
individual frame remains unchanged at 3, these may
now be selected from 8 possible buffers.

Change-Id: I2d247b9c1c2b3a339d6c9fac125e81ba373f75a7

vp9/common/vp9_entropymode.c

@@ -771,8 +771,7 @@ void vp9_setup_past_independence(VP9_COMMON *cm, MACROBLOCKD *xd) {
   vp9_update_mode_info_border(cm, cm->prev_mip);
   vp9_update_mode_info_in_image(cm, cm->prev_mi);
 
-  cm->ref_frame_sign_bias[GOLDEN_FRAME] = 0;
-  cm->ref_frame_sign_bias[ALTREF_FRAME] = 0;
+  vpx_memset(cm->ref_frame_sign_bias, 0, sizeof(cm->ref_frame_sign_bias));
 
   cm->frame_context_idx = 0;
 }

vp9/common/vp9_onyxc_int.h

@@ -32,13 +32,9 @@
 
 void vp9_initialize_common(void);
 
-#if CONFIG_MULTIPLE_ARF
+// Define the number of candidate reference buffers.
 #define NUM_REF_FRAMES 8
 #define NUM_REF_FRAMES_LG2 3
-#else
-#define NUM_REF_FRAMES 3
-#define NUM_REF_FRAMES_LG2 2
-#endif
 
 #define ALLOWED_REFS_PER_FRAME 3
 

vp9/decoder/vp9_decodframe.c

@@ -1278,8 +1278,11 @@ int vp9_decode_frame(VP9D_COMP *pbi, const uint8_t **p_data_end) {
         vp9_setup_scale_factors_for_frame(sf, fb, pc->width, pc->height);
     }
 
-    pc->ref_frame_sign_bias[GOLDEN_FRAME] = vp9_read_bit(&header_bc);
-    pc->ref_frame_sign_bias[ALTREF_FRAME] = vp9_read_bit(&header_bc);
+    // Read the sign bias for each reference frame buffer.
+    for (i = 0; i < ALLOWED_REFS_PER_FRAME; ++i) {
+      pc->ref_frame_sign_bias[i + 1] = vp9_read_bit(&header_bc);
+    }
+
     xd->allow_high_precision_mv = vp9_read_bit(&header_bc);
     pc->mcomp_filter_type = read_mcomp_filter_type(&header_bc);
 

vp9/encoder/vp9_bitstream.c

@@ -1985,9 +1985,10 @@ void vp9_pack_bitstream(VP9_COMP *cpi, uint8_t *dest, unsigned long *size) {
     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]);
-    vp9_write_bit(&header_bc, pc->ref_frame_sign_bias[ALTREF_FRAME]);
+    // Indicate the sign bias for each reference frame buffer.
+    for (i = 0; i < ALLOWED_REFS_PER_FRAME; ++i) {
+      vp9_write_bit(&header_bc, pc->ref_frame_sign_bias[LAST_FRAME + i]);
+    }
 
     // Signal whether to allow high MV precision
     vp9_write_bit(&header_bc, (xd->allow_high_precision_mv) ? 1 : 0);