libvpx: Pull from upstream

source/libvpx/vp9/encoder/vp9_ratectrl.c

 /*
  *  Copyright (c) 2010 The WebM project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 1591 matching lines @@
   for (i = rc->best_quality; i < rc->worst_quality; ++i) {
     if (vp9_rc_bits_per_mb(frame_type, i, 1.0, bit_depth) <=
         target_bits_per_mb) {
       target_index = i;
       break;
     }
   }
   return target_index - qindex;
 }
 
-void vp9_rc_set_gf_max_interval(const VP9_COMP *const cpi,
-                                RATE_CONTROL *const rc) {
+#define MIN_GF_INTERVAL     4
+#define MAX_GF_INTERVAL     16
+void vp9_rc_set_gf_interval_range(const VP9_COMP *const cpi,
+                                  RATE_CONTROL *const rc) {
   const VP9EncoderConfig *const oxcf = &cpi->oxcf;
-  // Set Maximum gf/arf interval
-  rc->max_gf_interval = 16;
+
+  // Set a minimum interval.
+  rc->min_gf_interval =
+    MIN(MAX_GF_INTERVAL, MAX(MIN_GF_INTERVAL, (int)(cpi->framerate * 0.125)));
+
+  // Set Maximum gf/arf interval.
+  rc->max_gf_interval =
+    MIN(MAX_GF_INTERVAL, (int)(cpi->framerate * 0.75));
+  // Round up to next even number if odd.
+  rc->max_gf_interval += (rc->max_gf_interval & 0x01);
 
   // Extended interval for genuinely static scenes
   rc->static_scene_max_gf_interval = MAX_LAG_BUFFERS * 2;
 
   if (is_altref_enabled(cpi)) {
     if (rc->static_scene_max_gf_interval > oxcf->lag_in_frames - 1)
       rc->static_scene_max_gf_interval = oxcf->lag_in_frames - 1;
   }
 
   if (rc->max_gf_interval > rc->static_scene_max_gf_interval)
     rc->max_gf_interval = rc->static_scene_max_gf_interval;
+
+  // Clamp min to max
+  rc->min_gf_interval = MIN(rc->min_gf_interval, rc->max_gf_interval);
 }
 
 void vp9_rc_update_framerate(VP9_COMP *cpi) {
   const VP9_COMMON *const cm = &cpi->common;
   const VP9EncoderConfig *const oxcf = &cpi->oxcf;
   RATE_CONTROL *const rc = &cpi->rc;
   int vbr_max_bits;
 
   rc->avg_frame_bandwidth = (int)(oxcf->target_bandwidth / cpi->framerate);
   rc->min_frame_bandwidth = (int)(rc->avg_frame_bandwidth *
                                 oxcf->two_pass_vbrmin_section / 100);
 
   rc->min_frame_bandwidth = MAX(rc->min_frame_bandwidth, FRAME_OVERHEAD_BITS);
 
   // A maximum bitrate for a frame is defined.
   // The baseline for this aligns with HW implementations that
   // can support decode of 1080P content up to a bitrate of MAX_MB_RATE bits
   // per 16x16 MB (averaged over a frame). However this limit is extended if
   // a very high rate is given on the command line or the the rate cannnot
   // be acheived because of a user specificed max q (e.g. when the user
   // specifies lossless encode.
   vbr_max_bits = (int)(((int64_t)rc->avg_frame_bandwidth *
                      oxcf->two_pass_vbrmax_section) / 100);
   rc->max_frame_bandwidth = MAX(MAX((cm->MBs * MAX_MB_RATE), MAXRATE_1080P),
                                     vbr_max_bits);
 
-  vp9_rc_set_gf_max_interval(cpi, rc);
+  vp9_rc_set_gf_interval_range(cpi, rc);
 }
 
 #define VBR_PCT_ADJUSTMENT_LIMIT 50
 // For VBR...adjustment to the frame target based on error from previous frames
 static void vbr_rate_correction(VP9_COMP *cpi,
                                 int *this_frame_target,
                                 int64_t vbr_bits_off_target) {
   int max_delta;
   double position_factor = 1.0;
 
@@ skipping 21 matching lines @@
 
 void vp9_set_target_rate(VP9_COMP *cpi) {
   RATE_CONTROL *const rc = &cpi->rc;
   int target_rate = rc->base_frame_target;
 
   // 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, rc->vbr_bits_off_target);
   vp9_rc_set_frame_target(cpi, target_rate);
 }