Experiment for mid group second arf.

This patch implements a mechanism for inserting a second
arf at the mid position of arf groups.

It is currently disabled by default using the flag multi_arf_enabled.

Results are currently down somewhat in initial testing if
multi-arf is enabled. Most of the loss is attributable to the
fact that code to preserve the previous golden frame
(in the arf buffer) in cases where we are coding an overlay
frame, is currently disabled in the multi-arf case.

Change-Id: I1d777318ca09f147db2e8c86d7315fe86168c865

1 files changed, 7 insertions, 2 deletions

diff --git a/vp9/encoder/vp9_bitstream.c b/vp9/encoder/vp9_bitstream.c
index 76f5e7bbe..80787e567 100644
--- a/vp9/encoder/vp9_bitstream.c
+++ b/vp9/encoder/vp9_bitstream.c
@@ -895,8 +895,8 @@ static int get_refresh_mask(VP9_COMP *cpi) {
     if (!cpi->multi_arf_enabled && cpi->refresh_golden_frame &&
         !cpi->refresh_alt_ref_frame) {
 #else
-    if (cpi->refresh_golden_frame && !cpi->refresh_alt_ref_frame &&
-        !cpi->use_svc) {
+    if (!cpi->multi_arf_enabled && cpi->refresh_golden_frame &&
+        cpi->rc.is_src_frame_alt_ref && !cpi->use_svc) {
 #endif
       // Preserve the previously existing golden frame and update the frame in
       // the alt ref slot instead. This is highly specific to the use of
@@ -919,6 +919,11 @@ static int get_refresh_mask(VP9_COMP *cpi) {
             cpi->arf_buffer_idx[sn];
       }
 #endif
+      if ((cpi->pass == 2) && cpi->multi_arf_enabled) {
+        GF_GROUP *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) |
              (cpi->refresh_golden_frame << cpi->gld_fb_idx) |
              (cpi->refresh_alt_ref_frame << arf_idx);