[twopass temporal svc] Fix decoding error on seek.

Don't put small empty frame in front of a key frame. We will
put key frame flag in webm container if there's a visible key
frame. But there will be decoding error when we seek to here
if we put the small empty frame, which will be inter frame,
in front of it.

Change-Id: Id50c2c1fd31da0405ff6faa7375cc2f49c55402d

1 files changed, 5 insertions, 1 deletions

diff --git a/vp9/encoder/vp9_svc_layercontext.c b/vp9/encoder/vp9_svc_layercontext.c
index 31e93be65..ef6174ec6 100644
--- a/vp9/encoder/vp9_svc_layercontext.c
+++ b/vp9/encoder/vp9_svc_layercontext.c
@@ -279,6 +279,7 @@ static void get_layer_resolution(const int width_org, const int height_org,
 int vp9_svc_start_frame(VP9_COMP *const cpi) {
   int width = 0, height = 0;
   LAYER_CONTEXT *lc;
+  struct lookahead_entry *buf;
   int count = 1 << (cpi->svc.number_temporal_layers - 1);
 
   cpi->svc.spatial_layer_id = cpi->svc.spatial_layer_to_encode;
@@ -339,8 +340,11 @@ int vp9_svc_start_frame(VP9_COMP *const cpi) {
   // since its previous frame could be changed during decoding time. The idea is
   // we put a empty invisible frame in front of them, then we will not use
   // prev_mi when encoding these frames.
+
+  buf = vp9_lookahead_peek(cpi->lookahead, 0);
   if (cpi->oxcf.error_resilient_mode == 0 && cpi->oxcf.pass == 2 &&
-      cpi->svc.encode_empty_frame_state == NEED_TO_ENCODE) {
+      cpi->svc.encode_empty_frame_state == NEED_TO_ENCODE &&
+      lc->rc.frames_to_key != 0 && !(buf->flags & VPX_EFLAG_FORCE_KF)) {
     if ((cpi->svc.number_temporal_layers > 1 &&
          cpi->svc.temporal_layer_id < cpi->svc.number_temporal_layers - 1) ||
         (cpi->svc.number_spatial_layers > 1 &&