ref: e07b141da0e41fcfd6d069604376eade3a321fe9
parent: 5d8877a9445c8517ffef5d5773d4e7fe850ad875
parent: 3606b78108f8db4b8cfc2ae7fed8de34be8d21e2
author: paulwilkins <paulwilkins@google.com>
date: Tue Apr 21 22:29:17 EDT 2015
Merge "Modified test for auto key frame detection."
--- a/vp9/encoder/vp9_firstpass.c
+++ b/vp9/encoder/vp9_firstpass.c
@@ -2049,29 +2049,61 @@
}
}
-// TODO(PGW) Re-examine the use of II ration in this code in the light of#
-// changes elsewhere
+// Threshold for use of the lagging second reference frame. High second ref
+// usage may point to a transient event like a flash or occlusion rather than
+// a real scene cut.
+#define SECOND_REF_USEAGE_THRESH 0.1
+// Minimum % intra coding observed in first pass (1.0 = 100%)
+#define MIN_INTRA_LEVEL 0.25
+// Minimum ratio between the % of intra coding and inter coding in the first
+// pass after discounting neutral blocks (discounting neutral blocks in this
+// way helps catch scene cuts in clips with very flat areas or letter box
+// format clips with image padding.
+#define INTRA_VS_INTER_THRESH 2.0
+// Hard threshold where the first pass chooses intra for almost all blocks.
+// In such a case even if the frame is not a scene cut coding a key frame
+// may be a good option.
+#define VERY_LOW_INTER_THRESH 0.05
+// Maximum threshold for the relative ratio of intra error score vs best
+// inter error score.
+#define KF_II_ERR_THRESHOLD 2.5
+// In real scene cuts there is almost always a sharp change in the intra
+// or inter error score.
+#define ERR_CHANGE_THRESHOLD 0.4
+// For real scene cuts we expect an improvment in the intra inter error
+// ratio in the next frame.
+#define II_IMPROVEMENT_THRESHOLD 3.5
#define KF_II_MAX 128.0
+
static int test_candidate_kf(TWO_PASS *twopass,
const FIRSTPASS_STATS *last_frame,
const FIRSTPASS_STATS *this_frame,
const FIRSTPASS_STATS *next_frame) {int is_viable_kf = 0;
+ double pcnt_intra = 1.0 - this_frame->pcnt_inter;
+ double modified_pcnt_inter =
+ this_frame->pcnt_inter - this_frame->pcnt_neutral;
// Does the frame satisfy the primary criteria of a key frame?
+ // See above for an explanation of the test criteria.
// If so, then examine how well it predicts subsequent frames.
- if ((this_frame->pcnt_second_ref < 0.10) &&
- (next_frame->pcnt_second_ref < 0.10) &&
- ((this_frame->pcnt_inter < 0.05) ||
- (((this_frame->pcnt_inter - this_frame->pcnt_neutral) < 0.35) &&
+ if ((this_frame->pcnt_second_ref < SECOND_REF_USEAGE_THRESH) &&
+ (next_frame->pcnt_second_ref < SECOND_REF_USEAGE_THRESH) &&
+ ((this_frame->pcnt_inter < VERY_LOW_INTER_THRESH) ||
+ ((pcnt_intra > MIN_INTRA_LEVEL) &&
+ (pcnt_intra > (INTRA_VS_INTER_THRESH * modified_pcnt_inter)) &&
((this_frame->intra_error /
- DOUBLE_DIVIDE_CHECK(this_frame->coded_error)) < 2.5) &&
+ DOUBLE_DIVIDE_CHECK(this_frame->coded_error)) <
+ KF_II_ERR_THRESHOLD) &&
((fabs(last_frame->coded_error - this_frame->coded_error) /
- DOUBLE_DIVIDE_CHECK(this_frame->coded_error) > 0.40) ||
+ DOUBLE_DIVIDE_CHECK(this_frame->coded_error) >
+ ERR_CHANGE_THRESHOLD) ||
(fabs(last_frame->intra_error - this_frame->intra_error) /
- DOUBLE_DIVIDE_CHECK(this_frame->intra_error) > 0.40) ||
+ DOUBLE_DIVIDE_CHECK(this_frame->intra_error) >
+ ERR_CHANGE_THRESHOLD) ||
((next_frame->intra_error /
- DOUBLE_DIVIDE_CHECK(next_frame->coded_error)) > 3.5))))) {+ DOUBLE_DIVIDE_CHECK(next_frame->coded_error)) >
+ II_IMPROVEMENT_THRESHOLD))))) {int i;
const FIRSTPASS_STATS *start_pos = twopass->stats_in;
FIRSTPASS_STATS local_next_frame = *next_frame;