vp9-svc: Fix to frame dropping in svc mode.

Don't advance the svc frame counters on dropped frame,
since this can break the referencing scheme and lead
to a crash/assert.

Updated svc-datarate unittest to add a lower bitrate test.

Change only affects 1 pass cbr svc, with frame dropper enabled.

Change-Id: Ibb7530b7a587a9344d46898d9286fd9e2ef0779c

1 files changed, 6 insertions, 2 deletions

diff --git a/vp9/encoder/vp9_encoder.c b/vp9/encoder/vp9_encoder.c
index ac7c6deee..9ebc3a482 100644
--- a/vp9/encoder/vp9_encoder.c
+++ b/vp9/encoder/vp9_encoder.c
@@ -3999,8 +3999,12 @@ static void encode_frame_to_data_rate(VP9_COMP *cpi,
       ++cm->current_video_frame;
       cpi->ext_refresh_frame_flags_pending = 0;
       cpi->svc.rc_drop_superframe = 1;
-      if (cpi->use_svc)
-        vp9_inc_frame_in_layer(cpi);
+      // TODO(marpan): Advancing the svc counters on dropped frames can break
+      // the referencing scheme for the fixed svc patterns defined in
+      // vp9_one_pass_cbr_svc_start_layer(). Look into fixing this issue, but
+      // for now, don't advance the svc frame counters on dropped frame.
+      // if (cpi->use_svc)
+      //   vp9_inc_frame_in_layer(cpi);
       return;
     }
   }