Bug in clamping of base_frame_target.

Bug relating to issue:- http://b/25090786

base_frame_target is supposed to track the idealized bit
allocation based on error score and not the actual bits
allocated to each frame.

The clamping of this value based on the VBR min and max pct values
was causing a bug where in some cases the loop that adjusts the
active max quantizer for each GF group was running out of bits at
the end of a KF group. This caused a spike in Q and some ugly artifacts.

A second change makes sure that the calculation of the active
Q range for a group DOES, however, take account of clamping.

Change-Id: I31035e97d18853530b0874b433c1da7703f607d1

diff --git a/vp9/encoder/vp9_firstpass.c b/vp9/encoder/vp9_firstpass.c
index a6b5ebb0137082db55c6fe49a2d01a92af412437..e81c569bf8788ace55501566af8146332a5d6679 100644 (file)
--- a/vp9/encoder/vp9_firstpass.c
+++ b/vp9/encoder/vp9_firstpass.c
@@ -1183,10 +1183,13 @@ static int get_twopass_worst_quality(const VP9_COMP *cpi,
                                      double group_weight_factor) {
   const RATE_CONTROL *const rc = &cpi->rc;
   const VP9EncoderConfig *const oxcf = &cpi->oxcf;
+  // Clamp the target rate to VBR min / max limts.
+  const int target_rate =
+      vp9_rc_clamp_pframe_target_size(cpi, section_target_bandwidth);
 
   inactive_zone = fclamp(inactive_zone, 0.0, 1.0);
 
-  if (section_target_bandwidth <= 0) {
+  if (target_rate <= 0) {
     return rc->worst_quality;  // Highest value allowed
   } else {
     const int num_mbs = (cpi->oxcf.resize_mode != RESIZE_NONE)
@@ -1195,7 +1198,7 @@ static int get_twopass_worst_quality(const VP9_COMP *cpi,
     const double av_err_per_mb = section_err / active_mbs;
     const double speed_term = 1.0 + 0.04 * oxcf->speed;
     const double ediv_size_correction = (double)num_mbs / EDIV_SIZE_FACTOR;
-    const int target_norm_bits_per_mb = ((uint64_t)section_target_bandwidth <<
+    const int target_norm_bits_per_mb = ((uint64_t)target_rate <<
                                          BPER_MB_NORMBITS) / active_mbs;
 
     int q;
@@ -2737,11 +2740,6 @@ void vp9_rc_get_second_pass_params(VP9_COMP *cpi) {
   }
 
   target_rate = gf_group->bit_allocation[gf_group->index];
-  if (cpi->common.frame_type == KEY_FRAME)
-    target_rate = vp9_rc_clamp_iframe_target_size(cpi, target_rate);
-  else
-    target_rate = vp9_rc_clamp_pframe_target_size(cpi, target_rate);
-
   rc->base_frame_target = target_rate;
 
   {

diff --git a/vp9/encoder/vp9_ratectrl.c b/vp9/encoder/vp9_ratectrl.c
index 1d13199f276c73a0733b6eb5bbe2c3d4c7599631..d70068570e8e31ae4a42e7bbe3c5e17981fb99b6 100644 (file)
--- a/vp9/encoder/vp9_ratectrl.c
+++ b/vp9/encoder/vp9_ratectrl.c
@@ -1816,6 +1816,11 @@ void vp9_set_target_rate(VP9_COMP *cpi) {
   RATE_CONTROL *const rc = &cpi->rc;
   int target_rate = rc->base_frame_target;
 
+  if (cpi->common.frame_type == KEY_FRAME)
+    target_rate = vp9_rc_clamp_iframe_target_size(cpi, target_rate);
+  else
+    target_rate = vp9_rc_clamp_pframe_target_size(cpi, target_rate);
+
   // Correction to rate target based on prior over or under shoot.
   if (cpi->oxcf.rc_mode == VPX_VBR || cpi->oxcf.rc_mode == VPX_CQ)
     vbr_rate_correction(cpi, &target_rate);