shithub: libvpx

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vp9: Reset rc flags on some configuration changes.

For large dynamic changes in target avg_frame_bandwidth, or
a change in resolution, via the update in change_config()),
reset the under/overshoot flags (rc_1_frame, rc_2_frame)
to prevent constraining the QP for the first few frames
following the change.

For SVC use the spatial stream avg_frame_bandwidth in
reset condition.

For the avg_frame_bandwidth condition, use fairly large
threshold (~50%) for now in reset.

This allows for better/faster QP response if, for example,
application dynamically changes bitrate by large amount.

Change-Id: Ib6e3761732d956949d79c9247e50dba744a535c0

--- a/vp9/encoder/vp9_encoder.c

+++ b/vp9/encoder/vp9_encoder.c

@@ -1853,6 +1853,8 @@

            cm->mi_rows * cm->mi_cols * sizeof(*cpi->consec_zero_mv));

     if (cpi->oxcf.aq_mode == CYCLIC_REFRESH_AQ)

       vp9_cyclic_refresh_reset_resize(cpi);

+    rc->rc_1_frame = 0;

+    rc->rc_2_frame = 0;

   }

   if ((cpi->svc.number_temporal_layers > 1 && cpi->oxcf.rc_mode == VPX_CBR) ||

@@ -1861,6 +1863,21 @@

        cpi->oxcf.pass != 1)) {

     vp9_update_layer_context_change_config(cpi,

                                            (int)cpi->oxcf.target_bandwidth);

+  }

+

+  // Check for resetting the rc flags (rc_1_frame, rc_2_frame) if the

+  // configuration change has a large change in avg_frame_bandwidth.

+  // For SVC check for resetting based on spatial layer average bandwidth.

+  if (cm->current_video_frame > 0) {

+    if (cpi->use_svc) {

+      vp9_svc_check_reset_layer_rc_flag(cpi);

+    } else {

+      if (rc->avg_frame_bandwidth > (3 * rc->last_avg_frame_bandwidth >> 1) ||

+          rc->avg_frame_bandwidth < (rc->last_avg_frame_bandwidth >> 1)) {

+        rc->rc_1_frame = 0;

+        rc->rc_2_frame = 0;

+      }

+    }

   }

   cpi->alt_ref_source = NULL;

--- a/vp9/encoder/vp9_ratectrl.c

+++ b/vp9/encoder/vp9_ratectrl.c

@@ -1488,6 +1488,8 @@

     cpi->rc.last_frame_is_src_altref = cpi->rc.is_src_frame_alt_ref;

   }

   if (cm->frame_type != KEY_FRAME) rc->reset_high_source_sad = 0;

+

+  rc->last_avg_frame_bandwidth = rc->avg_frame_bandwidth;

 }

 void vp9_rc_postencode_update_drop_frame(VP9_COMP *cpi) {

--- a/vp9/encoder/vp9_ratectrl.h

+++ b/vp9/encoder/vp9_ratectrl.h

@@ -152,6 +152,8 @@

   int rc_2_frame;

   int q_1_frame;

   int q_2_frame;

+  // Keep track of the last target average frame bandwidth.

+  int last_avg_frame_bandwidth;

   // Auto frame-scaling variables.

   FRAME_SCALE_LEVEL frame_size_selector;

--- a/vp9/encoder/vp9_svc_layercontext.c

+++ b/vp9/encoder/vp9_svc_layercontext.c

@@ -862,3 +862,26 @@

   vp9_update_temporal_layer_framerate(cpi);

   vp9_restore_layer_context(cpi);

 }

+

+void vp9_svc_check_reset_layer_rc_flag(VP9_COMP *const cpi) {

+  SVC *svc = &cpi->svc;

+  int sl, tl;

+  for (sl = 0; sl < svc->number_spatial_layers; ++sl) {

+    // Check for reset based on avg_frame_bandwidth for spatial layer sl.

+    int layer = LAYER_IDS_TO_IDX(sl, svc->number_temporal_layers - 1,

+                                 svc->number_temporal_layers);

+    LAYER_CONTEXT *lc = &svc->layer_context[layer];

+    RATE_CONTROL *lrc = &lc->rc;

+    if (lrc->avg_frame_bandwidth > (3 * lrc->last_avg_frame_bandwidth >> 1) ||

+        lrc->avg_frame_bandwidth < (lrc->last_avg_frame_bandwidth >> 1)) {

+      // Reset for all temporal layers with spatial layer sl.

+      for (tl = 0; tl < svc->number_temporal_layers; ++tl) {

+        int layer = LAYER_IDS_TO_IDX(sl, tl, svc->number_temporal_layers);

+        LAYER_CONTEXT *lc = &svc->layer_context[layer];

+        RATE_CONTROL *lrc = &lc->rc;

+        lrc->rc_1_frame = 0;

+        lrc->rc_2_frame = 0;

+      }

+    }

+  }

+}

--- a/vp9/encoder/vp9_svc_layercontext.h

+++ b/vp9/encoder/vp9_svc_layercontext.h

@@ -154,6 +154,8 @@

 void vp9_svc_reset_key_frame(struct VP9_COMP *const cpi);

+void vp9_svc_check_reset_layer_rc_flag(struct VP9_COMP *const cpi);

+

 #ifdef __cplusplus

 }  // extern "C"

 #endif