shithub: libvpx

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Further q estimate adjustment.

Slightly reduces the mean tendency to undershoot target
rate in vbr, especially when using the memory less mode
and when recodes are disabled.

The effect is primarily at low q.

Change-Id: I59a593b99522cc7da31b4134d1c8a65f5b7b7c53

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

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

@@ -954,7 +954,7 @@

   const double error_term = err_per_mb / err_divisor;

   // Adjustment based on actual quantizer to power term.

-  const double power_term = MIN(vp9_convert_qindex_to_q(q) * 0.01 + pt_low,

+  const double power_term = MIN(vp9_convert_qindex_to_q(q) * 0.0125 + pt_low,

                                 pt_high);

   // Calculate correction factor

@@ -1014,7 +1014,7 @@

     int bits_per_mb_at_this_q;

     err_correction_factor = calc_correction_factor(err_per_mb,

-                                                   ERR_DIVISOR, 0.4, 0.90, q);

+                                                   ERR_DIVISOR, 0.5, 0.90, q);

     bits_per_mb_at_this_q = vp9_rc_bits_per_mb(INTER_FRAME, q,

                                                err_correction_factor);

@@ -1064,7 +1064,7 @@

     // Error per MB based correction factor

     err_correction_factor =

-      calc_correction_factor(err_per_mb, 100.0, 0.4, 0.90, q) * clip_iifactor;

+      calc_correction_factor(err_per_mb, 100.0, 0.5, 0.90, q) * clip_iifactor;

     bits_per_mb_at_this_q =

       vp9_rc_bits_per_mb(INTER_FRAME, q, err_correction_factor);