shithub: libvpx

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vp9-svc: Rate control fix for key base layer

After encoding key frame on base spatial layer,
if the overshoot is significant, reset the
avg_frame_qindex[INTER] on base spatial layer for
all temporal layers.

This forces the active_worst_quality to increase
on subsequent frames/layers and reduces frame dropping.

Change-Id: I53a3cd14131d69120e59a649b7ed1bfde3e940ee

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

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

@@ -1800,6 +1800,8 @@

     }

   }

+  if (cpi->use_svc) vp9_svc_adjust_avg_frame_qindex(cpi);

+

   // Keep record of last boosted (KF/KF/ARF) Q value.

   // If the current frame is coded at a lower Q then we also update it.

   // If all mbs in this group are skipped only update if the Q value is

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

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

@@ -1227,3 +1227,25 @@

       cpi->svc.timebase_fac * cpi->svc.duration[cpi->svc.spatial_layer_id];

   vp9_new_framerate(cpi, 10000000.0 / this_duration);

 }

+

+void vp9_svc_adjust_avg_frame_qindex(VP9_COMP *const cpi) {

+  VP9_COMMON *const cm = &cpi->common;

+  SVC *const svc = &cpi->svc;

+  RATE_CONTROL *const rc = &cpi->rc;

+  // On key frames in CBR mode: reset the avg_frame_index for base layer

+  // (to level closer to worst_quality) if the overshoot is significant.

+  // Reset it for all temporal layers on base spatial layer.

+  if (cm->frame_type == KEY_FRAME && cpi->oxcf.rc_mode == VPX_CBR &&

+      rc->projected_frame_size > 3 * rc->avg_frame_bandwidth) {

+    int tl;

+    rc->avg_frame_qindex[INTER_FRAME] =

+        VPXMAX(rc->avg_frame_qindex[INTER_FRAME],

+               (cm->base_qindex + rc->worst_quality) >> 1);

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

+      const int layer = LAYER_IDS_TO_IDX(0, tl, svc->number_temporal_layers);

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

+      RATE_CONTROL *lrc = &lc->rc;

+      lrc->avg_frame_qindex[INTER_FRAME] = rc->avg_frame_qindex[INTER_FRAME];

+    }

+  }

+}

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

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

@@ -262,6 +262,7 @@

 void vp9_svc_adjust_frame_rate(struct VP9_COMP *const cpi);

+void vp9_svc_adjust_avg_frame_qindex(struct VP9_COMP *const cpi);

 #ifdef __cplusplus

 }  // extern "C"

 #endif