Two Pass VBR change

Further experiment with restriction of the Q range.

This uses the average non KF/GF/ARF quantizer,  instead
of just relying on the initial value. It is not such a strong constraint
but there may be a reduced risk of rate misses.

Change-Id: I424fe782a37a2f4e18c70805e240db55bfaa25ec

2 files changed, 43 insertions, 22 deletions

diff --git a/vp8/encoder/firstpass.c b/vp8/encoder/firstpass.c
index 48899162d..4d259c676 100644
--- a/vp8/encoder/firstpass.c
+++ b/vp8/encoder/firstpass.c
@@ -989,6 +989,19 @@ static int estimate_max_q(VP8_COMP *cpi, double section_err, int section_target_
         //Q = cpi->oxcf.cq_target_quality;
     }
 
+    // Adjust maxq_min_limit and maxq_max_limit limits based on
+    // averaga q observed in clip for non kf/gf.arf frames
+    // Give average a chance to settle though.
+    if ( (cpi->ni_frames >
+                  ((unsigned int)cpi->total_stats->count >> 8)) &&
+         (cpi->ni_frames > 150) )
+    {
+        cpi->maxq_max_limit = ((cpi->ni_av_qi + 32) < cpi->worst_quality)
+                                  ? (cpi->ni_av_qi + 32) : cpi->worst_quality;
+        cpi->maxq_min_limit = ((cpi->ni_av_qi - 32) > cpi->best_quality)
+                                  ? (cpi->ni_av_qi - 32) : cpi->best_quality;
+    }
+
     return Q;
 }
 static int estimate_q(VP8_COMP *cpi, double section_err, int section_target_bandwitdh, int Height, int Width)
@@ -2121,7 +2134,7 @@ void vp8_second_pass(VP8_COMP *cpi)
                                 cpi->common.Width);
 
         // Limit the maxq value returned subsequently.
-        // This increases the risk of overspend if the initial
+        // This increases the risk of overspend or underspend if the initial
         // estimate for the clip is bad, but helps prevent excessive
         // variation in Q, especially near the end of a clip
         // where for example a small overspend may cause Q to crash
diff --git a/vp8/encoder/onyx_if.c b/vp8/encoder/onyx_if.c
index ee461c610..2d9e8011b 100644
--- a/vp8/encoder/onyx_if.c
+++ b/vp8/encoder/onyx_if.c
@@ -4442,30 +4442,38 @@ static void encode_frame_to_data_rate
     {
         cpi->ni_frames++;
 
-        // Calculate the average Q for normal inter frames (not key or GFU frames)
-        // This is used as a basis for setting active worst quality.
-        if (cpi->ni_frames > 150)
+        // Calculate the average Q for normal inter frames (not key or GFU
+        // frames).
+        if ( cpi->pass == 2 )
         {
             cpi->ni_tot_qi += Q;
             cpi->ni_av_qi = (cpi->ni_tot_qi / cpi->ni_frames);
         }
-        // Early in the clip ... average the current frame Q value with the default
-        // entered by the user as a dampening measure
         else
         {
-            cpi->ni_tot_qi += Q;
-            cpi->ni_av_qi = ((cpi->ni_tot_qi / cpi->ni_frames) + cpi->worst_quality + 1) / 2;
-        }
-
-        // If the average Q is higher than what was used in the last frame
-        // (after going through the recode loop to keep the frame size within range)
-        // then use the last frame value - 1.
-        // The -1 is designed to stop Q and hence the data rate, from progressively
-        // falling away during difficult sections, but at the same time reduce the number of
-        // itterations around the recode loop.
-        if (Q > cpi->ni_av_qi)
-            cpi->ni_av_qi = Q - 1;
+            // Damp value for first few frames
+            if (cpi->ni_frames > 150 )
+            {
+                cpi->ni_tot_qi += Q;
+                cpi->ni_av_qi = (cpi->ni_tot_qi / cpi->ni_frames);
+            }
+            // For one pass, early in the clip ... average the current frame Q
+            // value with the worstq entered by the user as a dampening measure
+            else
+            {
+                cpi->ni_tot_qi += Q;
+                cpi->ni_av_qi = ((cpi->ni_tot_qi / cpi->ni_frames) + cpi->worst_quality + 1) / 2;
+            }
 
+            // If the average Q is higher than what was used in the last frame
+            // (after going through the recode loop to keep the frame size within range)
+            // then use the last frame value - 1.
+            // The -1 is designed to stop Q and hence the data rate, from progressively
+            // falling away during difficult sections, but at the same time reduce the number of
+            // itterations around the recode loop.
+            if (Q > cpi->ni_av_qi)
+                cpi->ni_av_qi = Q - 1;
+        }
     }
 
 #if 0
@@ -4559,7 +4567,7 @@ static void encode_frame_to_data_rate
 
         if (cpi->total_coded_error_left != 0.0)
             fprintf(f, "%10d %10d %10d %10d %10d %10d %10d %10d %6ld %6ld"
-                       "%6ld %6ld %5ld %5ld %5ld %8ld %8.2f %10d %10.3f"
+                       "%6ld %6ld %6ld %5ld %5ld %5ld %8ld %8.2f %10d %10.3f"
                        "%10.3f %8ld\n",
                        cpi->common.current_video_frame, cpi->this_frame_target,
                        cpi->projected_frame_size,
@@ -4568,7 +4576,7 @@ static void encode_frame_to_data_rate
                        (cpi->oxcf.starting_buffer_level-cpi->bits_off_target),
                        (int)cpi->total_actual_bits, cm->base_qindex,
                        cpi->active_best_quality, cpi->active_worst_quality,
-                       cpi->cq_target_quality, cpi->zbin_over_quant,
+                       cpi->ni_av_qi, cpi->cq_target_quality, cpi->zbin_over_quant,
                        //cpi->avg_frame_qindex, cpi->zbin_over_quant,
                        cm->refresh_golden_frame, cm->refresh_alt_ref_frame,
                        cm->frame_type, cpi->gfu_boost,
@@ -4578,7 +4586,7 @@ static void encode_frame_to_data_rate
                        cpi->tot_recode_hits);
         else
             fprintf(f, "%10d %10d %10d %10d %10d %10d %10d %10d %6ld %6ld"
-                       "%6ld %6ld %5ld %5ld %5ld %8ld %8.2f %10d %10.3f"
+                       "%6ld %6ld %6ld %5ld %5ld %5ld %8ld %8.2f %10d %10.3f"
                        "%8ld\n",
                        cpi->common.current_video_frame,
                        cpi->this_frame_target, cpi->projected_frame_size,
@@ -4587,7 +4595,7 @@ static void encode_frame_to_data_rate
                        (cpi->oxcf.starting_buffer_level-cpi->bits_off_target),
                        (int)cpi->total_actual_bits, cm->base_qindex,
                        cpi->active_best_quality, cpi->active_worst_quality,
-                       cpi->cq_target_quality, cpi->zbin_over_quant,
+                       cpi->ni_av_qi, cpi->cq_target_quality, cpi->zbin_over_quant,
                        //cpi->avg_frame_qindex, cpi->zbin_over_quant,
                        cm->refresh_golden_frame, cm->refresh_alt_ref_frame,
                        cm->frame_type, cpi->gfu_boost,