With Svc controller do not produce frame that will be dropped anyway

This cover scenario where target bitrate is changed in a middle of
of group of frame after spatial upswitch.
This change should avoid wasting encoder resources to produce those
frames, reduce number of errors
"Encoder produced a frame for layer that wasn't requested"

Bug: webrtc:11999
Change-Id: I06045259b1cee2c21bfdabbafff3892b57c82a84
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/230543
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Reviewed-by: Philip Eliasson <philipel@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#34969}

modules/video_coding/codecs/vp9/libvpx_vp9_encoder.cc

@@ -399,22 +399,72 @@ bool LibvpxVp9Encoder::SetSvcRates(
   }
 
   if (svc_controller_) {
-    VideoBitrateAllocation allocation;
     for (int sid = 0; sid < num_spatial_layers_; ++sid) {
       for (int tid = 0; tid < num_temporal_layers_; ++tid) {
-        allocation.SetBitrate(
+        current_bitrate_allocation_.SetBitrate(
             sid, tid,
             config_->layer_target_bitrate[sid * num_temporal_layers_ + tid] *
                 1000);
       }
     }
-    svc_controller_->OnRatesUpdated(allocation);
-  }
+    svc_controller_->OnRatesUpdated(current_bitrate_allocation_);
+  } else {
     current_bitrate_allocation_ = bitrate_allocation;
+  }
   config_changed_ = true;
   return true;
 }
 
+void LibvpxVp9Encoder::DisableSpatialLayer(int sid) {
+  RTC_DCHECK_LT(sid, num_spatial_layers_);
+  if (config_->ss_target_bitrate[sid] == 0) {
+    return;
+  }
+  config_->ss_target_bitrate[sid] = 0;
+  for (int tid = 0; tid < num_temporal_layers_; ++tid) {
+    config_->layer_target_bitrate[sid * num_temporal_layers_ + tid] = 0;
+  }
+  config_changed_ = true;
+}
+
+void LibvpxVp9Encoder::EnableSpatialLayer(int sid) {
+  RTC_DCHECK_LT(sid, num_spatial_layers_);
+  if (config_->ss_target_bitrate[sid] > 0) {
+    return;
+  }
+  for (int tid = 0; tid < num_temporal_layers_; ++tid) {
+    config_->layer_target_bitrate[sid * num_temporal_layers_ + tid] =
+        current_bitrate_allocation_.GetBitrate(sid, tid) / 1000;
+  }
+  config_->ss_target_bitrate[sid] =
+      current_bitrate_allocation_.GetSpatialLayerSum(sid) / 1000;
+  RTC_DCHECK_GT(config_->ss_target_bitrate[sid], 0);
+  config_changed_ = true;
+}
+
+void LibvpxVp9Encoder::SetActiveSpatialLayers() {
+  // Svc controller may decide to skip a frame at certain spatial layer even
+  // when bitrate for it is non-zero, however libvpx uses configured bitrate as
+  // a signal which layers should be produced.
+  RTC_DCHECK(svc_controller_);
+  RTC_DCHECK(!layer_frames_.empty());
+  RTC_DCHECK(absl::c_is_sorted(
+      layer_frames_, [](const ScalableVideoController::LayerFrameConfig& lhs,
+                        const ScalableVideoController::LayerFrameConfig& rhs) {
+        return lhs.SpatialId() < rhs.SpatialId();
+      }));
+
+  auto frame_it = layer_frames_.begin();
+  for (int sid = 0; sid < num_spatial_layers_; ++sid) {
+    if (frame_it != layer_frames_.end() && frame_it->SpatialId() == sid) {
+      EnableSpatialLayer(sid);
+      ++frame_it;
+    } else {
+      DisableSpatialLayer(sid);
+    }
+  }
+}
+
 void LibvpxVp9Encoder::SetRates(const RateControlParameters& parameters) {
   if (!inited_) {
     RTC_LOG(LS_WARNING) << "SetRates() calll while uninitialzied.";
@@ -978,6 +1028,7 @@ int LibvpxVp9Encoder::Encode(const VideoFrame& input_image,
       layer_id.temporal_layer_id_per_spatial[layer.SpatialId()] =
           layer.TemporalId();
     }
+    SetActiveSpatialLayers();
   }
 
   if (is_svc_ && performance_flags_.use_per_layer_speed) {

modules/video_coding/codecs/vp9/libvpx_vp9_encoder.h

@@ -82,6 +82,12 @@ class LibvpxVp9Encoder : public VP9Encoder {
   bool ExplicitlyConfiguredSpatialLayers() const;
   bool SetSvcRates(const VideoBitrateAllocation& bitrate_allocation);
 
+  // Configures which spatial layers libvpx should encode according to
+  // configuration provided by svc_controller_.
+  void EnableSpatialLayer(int sid);
+  void DisableSpatialLayer(int sid);
+  void SetActiveSpatialLayers();
+
   void GetEncodedLayerFrame(const vpx_codec_cx_pkt* pkt);
 
   // Callback function for outputting packets per spatial layer.