shithub: libvpx

Info  •  Files  •  Log  •  Branches

Change to get_twopass_worst_quality()

Change to the calculation of the error divisor used in
get_twopass_worst_quality(). This follows on from other
changes to the rate control that impact the output of this
function.

Change-Id: I414fa9aa1e6a68a64dccea17c3712f44b8a0c10c

--- a/vp9/encoder/vp9_firstpass.c

+++ b/vp9/encoder/vp9_firstpass.c

@@ -236,13 +236,6 @@

   section->duration   -= frame->duration;

 }

-// Calculate the linear size relative to a baseline of 1080P

-#define BASE_SIZE 2073600.0  // 1920x1080

-static double get_linear_size_factor(const VP9_COMP *cpi) {

-  const double this_area = cpi->initial_width * cpi->initial_height;

-  return pow(this_area / BASE_SIZE, 0.5);

-}

-

 // Calculate an active area of the image that discounts formatting

 // bars and partially discounts other 0 energy areas.

 #define MIN_ACTIVE_AREA 0.5

@@ -1247,7 +1240,7 @@

   return fclamp(pow(error_term, power_term), 0.05, 5.0);

 }

-#define ERR_DIVISOR         100.0

+#define ERR_DIVISOR         115.0

 static int get_twopass_worst_quality(VP9_COMP *cpi,

                                      const double section_err,

                                      double inactive_zone,

@@ -1270,7 +1263,6 @@

     const int active_mbs = VPXMAX(1, num_mbs - (int)(num_mbs * inactive_zone));

     const double av_err_per_mb = section_err / active_mbs;

     const double speed_term = 1.0 + 0.04 * oxcf->speed;

-    double ediv_size_correction;

     double last_group_rate_err;

     const int target_norm_bits_per_mb = ((uint64_t)target_rate <<

                                          BPER_MB_NORMBITS) / active_mbs;

@@ -1280,17 +1272,6 @@

     if (is_two_pass_svc(cpi) && cpi->svc.spatial_layer_id > 0)

       is_svc_upper_layer = 1;

-    // Larger image formats are expected to be a little harder to code

-    // relatively given the same prediction error score. This in part at

-    // least relates to the increased size and hence coding overheads of

-    // motion vectors. Some account of this is made through adjustment of

-    // the error divisor.

-    ediv_size_correction =

-        VPXMAX(0.2, VPXMIN(5.0, get_linear_size_factor(cpi)));

-    if (ediv_size_correction < 1.0)

-      ediv_size_correction = -(1.0 / ediv_size_correction);

-    ediv_size_correction *= 4.0;

-

     // based on recent history adjust expectations of bits per macroblock.

     last_group_rate_err = (double)twopass->rolling_arf_group_actual_bits /

         DOUBLE_DIVIDE_CHECK((double)twopass->rolling_arf_group_target_bits);

@@ -1305,7 +1286,7 @@

     for (q = rc->best_quality; q < rc->worst_quality; ++q) {

       const double factor =

           calc_correction_factor(av_err_per_mb,

-                                 ERR_DIVISOR - ediv_size_correction,

+                                 ERR_DIVISOR,

                                  is_svc_upper_layer ? SVC_FACTOR_PT_LOW :

                                  FACTOR_PT_LOW, FACTOR_PT_HIGH, q,

                                  cpi->common.bit_depth);

@@ -2675,7 +2656,6 @@

   RATE_CONTROL *const rc = &cpi->rc;

   TWO_PASS *const twopass = &cpi->twopass;

   GF_GROUP *const gf_group = &twopass->gf_group;

-  int frames_left;

   FIRSTPASS_STATS this_frame;

   int target_rate;

@@ -2682,14 +2662,6 @@

   LAYER_CONTEXT *const lc = is_two_pass_svc(cpi) ?

         &cpi->svc.layer_context[cpi->svc.spatial_layer_id] : 0;

-  if (lc != NULL) {

-    frames_left = (int)(twopass->total_stats.count -

-                  lc->current_video_frame_in_layer);

-  } else {

-    frames_left = (int)(twopass->total_stats.count -

-                  cm->current_video_frame);

-  }

-

   if (!twopass->stats_in)

     return;

@@ -2731,6 +2703,9 @@

     twopass->active_worst_quality = cpi->oxcf.cq_level;

   } else if (cm->current_video_frame == 0 ||

              (lc != NULL && lc->current_video_frame_in_layer == 0)) {

+    const int frames_left = (int)(twopass->total_stats.count -

+        ((lc != NULL) ? lc->current_video_frame_in_layer

+                      : cm->current_video_frame));

     // Special case code for first frame.

     const int section_target_bandwidth = (int)(twopass->bits_left /

                                                frames_left);