Add fuzzer to validate libvpx vp9 encoder wrapper

Fix simulcast svc controller to reuse dropped frame configuration,
same as full svc and k-svc controllers do.
This fuzzer reminded the issue was still there.

Bug: webrtc:11999
Change-Id: I74156bd743124723562e99deb48de5b5018a81d0
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/212281
Reviewed-by: Erik Språng <sprang@webrtc.org>
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#33568}

modules/video_coding/svc/scalability_structure_simulcast.cc

@@ -137,7 +137,7 @@ ScalabilityStructureSimulcast::NextFrameConfig(bool restart) {
         }
         configs.emplace_back();
         ScalableVideoController::LayerFrameConfig& config = configs.back();
-        config.S(sid).T(0);
+        config.Id(current_pattern).S(sid).T(0);
 
         if (can_reference_t0_frame_for_spatial_id_[sid]) {
           config.ReferenceAndUpdate(BufferIndex(sid, /*tid=*/0));
@@ -155,7 +155,10 @@ ScalabilityStructureSimulcast::NextFrameConfig(bool restart) {
         }
         configs.emplace_back();
         ScalableVideoController::LayerFrameConfig& config = configs.back();
-        config.S(sid).T(1).Reference(BufferIndex(sid, /*tid=*/0));
+        config.Id(current_pattern)
+            .S(sid)
+            .T(1)
+            .Reference(BufferIndex(sid, /*tid=*/0));
         // Save frame only if there is a higher temporal layer that may need it.
         if (num_temporal_layers_ > 2) {
           config.Update(BufferIndex(sid, /*tid=*/1));
@@ -171,7 +174,7 @@ ScalabilityStructureSimulcast::NextFrameConfig(bool restart) {
         }
         configs.emplace_back();
         ScalableVideoController::LayerFrameConfig& config = configs.back();
-        config.S(sid).T(2);
+        config.Id(current_pattern).S(sid).T(2);
         if (can_reference_t1_frame_for_spatial_id_[sid]) {
           config.Reference(BufferIndex(sid, /*tid=*/1));
         } else {
@@ -184,12 +187,12 @@ ScalabilityStructureSimulcast::NextFrameConfig(bool restart) {
       break;
   }
 
-  last_pattern_ = current_pattern;
   return configs;
 }
 
 GenericFrameInfo ScalabilityStructureSimulcast::OnEncodeDone(
     const LayerFrameConfig& config) {
+  last_pattern_ = static_cast<FramePattern>(config.Id());
   if (config.TemporalId() == 1) {
     can_reference_t1_frame_for_spatial_id_.set(config.SpatialId());
   }

test/fuzzers/BUILD.gn

@@ -632,6 +632,30 @@ webrtc_fuzzer_test("vp8_replay_fuzzer") {
   seed_corpus = "corpora/rtpdump-corpus/vp8"
 }
 
+if (rtc_build_libvpx) {
+  webrtc_fuzzer_test("vp9_encoder_references_fuzzer") {
+    sources = [ "vp9_encoder_references_fuzzer.cc" ]
+    deps = [
+      "..:test_support",
+      "../../api:array_view",
+      "../../api/transport:webrtc_key_value_config",
+      "../../api/video:video_frame",
+      "../../api/video_codecs:video_codecs_api",
+      "../../modules/video_coding:frame_dependencies_calculator",
+      "../../modules/video_coding:mock_libvpx_interface",
+      "../../modules/video_coding:webrtc_vp9",
+      "../../rtc_base:safe_compare",
+      rtc_libvpx_dir,
+    ]
+    absl_deps = [
+      "//third_party/abseil-cpp/absl/algorithm:container",
+      "//third_party/abseil-cpp/absl/base:core_headers",
+      "//third_party/abseil-cpp/absl/container:inlined_vector",
+    ]
+    defines = [ "RTC_ENABLE_VP9" ]
+  }
+}
+
 webrtc_fuzzer_test("vp9_replay_fuzzer") {
   sources = [ "vp9_replay_fuzzer.cc" ]
   deps = [

test/fuzzers/vp9_encoder_references_fuzzer.cc

@@ -0,0 +1,480 @@
+/*
+ *  Copyright (c) 2021 The WebRTC 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.
+ */
+
+#include <stdint.h>
+
+#include "absl/algorithm/container.h"
+#include "absl/base/macros.h"
+#include "absl/container/inlined_vector.h"
+#include "api/array_view.h"
+#include "api/transport/webrtc_key_value_config.h"
+#include "api/video/video_frame.h"
+#include "api/video_codecs/video_codec.h"
+#include "api/video_codecs/video_encoder.h"
+#include "modules/video_coding/codecs/interface/mock_libvpx_interface.h"
+#include "modules/video_coding/codecs/vp9/libvpx_vp9_encoder.h"
+#include "modules/video_coding/frame_dependencies_calculator.h"
+#include "rtc_base/numerics/safe_compare.h"
+#include "test/fuzzers/fuzz_data_helper.h"
+#include "test/gmock.h"
+
+// Fuzzer simulates various svc configurations and libvpx encoder droping
+// layer frames.
+// Validates vp9 encoder wrapper produces consistent frame references.
+namespace webrtc {
+namespace {
+
+using test::FuzzDataHelper;
+using ::testing::NiceMock;
+
+class FrameValidator : public EncodedImageCallback {
+ public:
+  ~FrameValidator() override = default;
+
+  Result OnEncodedImage(const EncodedImage& encoded_image,
+                        const CodecSpecificInfo* codec_specific_info) override {
+    RTC_CHECK(codec_specific_info);
+    RTC_CHECK_EQ(codec_specific_info->codecType, kVideoCodecVP9);
+    if (codec_specific_info->codecSpecific.VP9.first_frame_in_picture) {
+      ++picture_id_;
+    }
+    LayerFrame layer_frame;
+    layer_frame.picture_id = picture_id_;
+    layer_frame.spatial_id = encoded_image.SpatialIndex().value_or(0);
+    layer_frame.info = *codec_specific_info;
+    CheckVp9References(layer_frame);
+
+    if (layer_frame.info.generic_frame_info.has_value()) {
+      int64_t frame_id = frames_.size();
+      layer_frame.frame_dependencies =
+          dependencies_calculator_.FromBuffersUsage(
+              frame_id, layer_frame.info.generic_frame_info->encoder_buffers);
+
+      CheckGenericReferences(layer_frame);
+      CheckGenericAndCodecSpecificReferencesAreConsistent(layer_frame);
+    }
+
+    frames_.push_back(std::move(layer_frame));
+    return Result(Result::OK);
+  }
+
+ private:
+  struct LayerFrame {
+    const CodecSpecificInfoVP9& vp9() const { return info.codecSpecific.VP9; }
+    int temporal_id() const {
+      return vp9().temporal_idx == kNoTemporalIdx ? 0 : vp9().temporal_idx;
+    }
+
+    int64_t picture_id;
+    int spatial_id;
+    absl::InlinedVector<int64_t, 5> frame_dependencies;
+    CodecSpecificInfo info;
+  };
+
+  void CheckVp9References(const LayerFrame& layer_frame) {
+    if (layer_frame.vp9().inter_layer_predicted) {
+      RTC_CHECK(!frames_.empty());
+      const LayerFrame& previous_frame = frames_.back();
+      RTC_CHECK(!previous_frame.vp9().non_ref_for_inter_layer_pred);
+      RTC_CHECK_EQ(layer_frame.picture_id, previous_frame.picture_id);
+    }
+    if (!frames_.empty() &&
+        frames_.back().picture_id == layer_frame.picture_id) {
+      RTC_CHECK_GT(layer_frame.spatial_id, frames_.back().spatial_id);
+      // The check below would fail for temporal shift structures. Remove it or
+      // move it to !flexible_mode section when vp9 encoder starts supporting
+      // such structures.
+      RTC_CHECK_EQ(layer_frame.vp9().temporal_idx,
+                   frames_.back().vp9().temporal_idx);
+    }
+    if (!layer_frame.vp9().flexible_mode) {
+      if (layer_frame.vp9().gof.num_frames_in_gof > 0) {
+        gof_.CopyGofInfoVP9(layer_frame.vp9().gof);
+      }
+      RTC_CHECK_EQ(gof_.temporal_idx[layer_frame.vp9().gof_idx],
+                   layer_frame.temporal_id());
+    }
+  }
+
+  void CheckGenericReferences(const LayerFrame& layer_frame) const {
+    const GenericFrameInfo& generic_info = *layer_frame.info.generic_frame_info;
+    for (int64_t dependency_frame_id : layer_frame.frame_dependencies) {
+      RTC_CHECK_GE(dependency_frame_id, 0);
+      const LayerFrame& dependency = frames_[dependency_frame_id];
+      RTC_CHECK(dependency.info.generic_frame_info.has_value());
+      RTC_CHECK_GE(generic_info.spatial_id,
+                   dependency.info.generic_frame_info->spatial_id);
+      RTC_CHECK_GE(generic_info.temporal_id,
+                   dependency.info.generic_frame_info->temporal_id);
+    }
+  }
+
+  void CheckGenericAndCodecSpecificReferencesAreConsistent(
+      const LayerFrame& layer_frame) const {
+    const GenericFrameInfo& generic_info = *layer_frame.info.generic_frame_info;
+    RTC_CHECK_EQ(generic_info.spatial_id, layer_frame.spatial_id);
+    RTC_CHECK_EQ(generic_info.temporal_id, layer_frame.temporal_id());
+    auto picture_id_diffs = rtc::MakeArrayView(layer_frame.vp9().p_diff,
+                                               layer_frame.vp9().num_ref_pics);
+    RTC_CHECK_EQ(layer_frame.frame_dependencies.size(),
+                 picture_id_diffs.size() +
+                     (layer_frame.vp9().inter_layer_predicted ? 1 : 0));
+    for (int64_t dependency_frame_id : layer_frame.frame_dependencies) {
+      RTC_CHECK_GE(dependency_frame_id, 0);
+      const LayerFrame& dependency = frames_[dependency_frame_id];
+      if (dependency.spatial_id != layer_frame.spatial_id) {
+        RTC_CHECK(layer_frame.vp9().inter_layer_predicted);
+        RTC_CHECK_EQ(layer_frame.picture_id, dependency.picture_id);
+        RTC_CHECK_GT(layer_frame.spatial_id, dependency.spatial_id);
+      } else {
+        RTC_CHECK(layer_frame.vp9().inter_pic_predicted);
+        RTC_CHECK_EQ(layer_frame.spatial_id, dependency.spatial_id);
+        RTC_CHECK(absl::c_linear_search(
+            picture_id_diffs, layer_frame.picture_id - dependency.picture_id));
+      }
+    }
+  }
+
+  GofInfoVP9 gof_;
+  int64_t picture_id_;
+  FrameDependenciesCalculator dependencies_calculator_;
+  std::vector<LayerFrame> frames_;
+};
+
+class FieldTrials : public WebRtcKeyValueConfig {
+ public:
+  explicit FieldTrials(FuzzDataHelper& config)
+      : flags_(config.ReadOrDefaultValue<uint8_t>(0)) {}
+
+  ~FieldTrials() override = default;
+  std::string Lookup(absl::string_view key) const override {
+    static constexpr absl::string_view kBinaryFieldTrials[] = {
+        "WebRTC-Vp9DependencyDescriptor",
+        "WebRTC-Vp9ExternalRefCtrl",
+        "WebRTC-Vp9IssueKeyFrameOnLayerDeactivation",
+    };
+    for (size_t i = 0; i < ABSL_ARRAYSIZE(kBinaryFieldTrials); ++i) {
+      if (key == kBinaryFieldTrials[i]) {
+        return (flags_ & (1u << i)) ? "Enabled" : "Disabled";
+      }
+    }
+
+    // Ignore following field trials.
+    if (key == "WebRTC-CongestionWindow" ||
+        key == "WebRTC-UseBaseHeavyVP8TL3RateAllocation" ||
+        key == "WebRTC-SimulcastUpswitchHysteresisPercent" ||
+        key == "WebRTC-SimulcastScreenshareUpswitchHysteresisPercent" ||
+        key == "WebRTC-VideoRateControl" ||
+        key == "WebRTC-VP9-PerformanceFlags" ||
+        key == "WebRTC-VP9VariableFramerateScreenshare" ||
+        key == "WebRTC-VP9QualityScaler") {
+      return "";
+    }
+    // Crash when using unexpected field trial to decide if it should be fuzzed
+    // or have a constant value.
+    RTC_CHECK(false) << "Unfuzzed field trial " << key << "\n";
+  }
+
+ private:
+  const uint8_t flags_;
+};
+
+VideoCodec CodecSettings(FuzzDataHelper& rng) {
+  uint16_t config = rng.ReadOrDefaultValue<uint16_t>(0);
+  // Test up to to 4 spatial and 4 temporal layers.
+  int num_spatial_layers = 1 + (config & 0b11);
+  int num_temporal_layers = 1 + ((config >> 2) & 0b11);
+
+  VideoCodec codec_settings = {};
+  codec_settings.codecType = kVideoCodecVP9;
+  codec_settings.maxFramerate = 30;
+  codec_settings.width = 320 << (num_spatial_layers - 1);
+  codec_settings.height = 180 << (num_spatial_layers - 1);
+  if (num_spatial_layers > 1) {
+    for (int sid = 0; sid < num_spatial_layers; ++sid) {
+      SpatialLayer& spatial_layer = codec_settings.spatialLayers[sid];
+      codec_settings.width = 320 << sid;
+      codec_settings.height = 180 << sid;
+      spatial_layer.maxFramerate = codec_settings.maxFramerate;
+      spatial_layer.numberOfTemporalLayers = num_temporal_layers;
+    }
+  }
+  codec_settings.VP9()->numberOfSpatialLayers = num_spatial_layers;
+  codec_settings.VP9()->numberOfTemporalLayers = num_temporal_layers;
+  int inter_layer_pred = (config >> 4) & 0b11;
+  // There are only 3 valid values.
+  codec_settings.VP9()->interLayerPred = static_cast<InterLayerPredMode>(
+      inter_layer_pred < 3 ? inter_layer_pred : 0);
+  codec_settings.VP9()->flexibleMode = (config & (1u << 6)) != 0;
+  codec_settings.VP9()->frameDroppingOn = (config & (1u << 7)) != 0;
+  codec_settings.mode = VideoCodecMode::kRealtimeVideo;
+  return codec_settings;
+}
+
+VideoEncoder::Settings EncoderSettings() {
+  return VideoEncoder::Settings(VideoEncoder::Capabilities(false),
+                                /*number_of_cores=*/1,
+                                /*max_payload_size=*/0);
+}
+
+struct LibvpxState {
+  LibvpxState() {
+    pkt.kind = VPX_CODEC_CX_FRAME_PKT;
+    pkt.data.frame.buf = pkt_buffer;
+    pkt.data.frame.sz = ABSL_ARRAYSIZE(pkt_buffer);
+    layer_id.spatial_layer_id = -1;
+  }
+
+  uint8_t pkt_buffer[1000] = {};
+  vpx_codec_enc_cfg_t config = {};
+  vpx_codec_priv_output_cx_pkt_cb_pair_t callback = {};
+  vpx_image_t img = {};
+  vpx_svc_ref_frame_config_t ref_config = {};
+  vpx_svc_layer_id_t layer_id = {};
+  vpx_svc_frame_drop_t frame_drop = {};
+  vpx_codec_cx_pkt pkt = {};
+};
+
+class StubLibvpx : public NiceMock<MockLibvpxInterface> {
+ public:
+  explicit StubLibvpx(LibvpxState* state) : state_(state) { RTC_CHECK(state_); }
+
+  vpx_codec_err_t codec_enc_config_default(vpx_codec_iface_t* iface,
+                                           vpx_codec_enc_cfg_t* cfg,
+                                           unsigned int usage) const override {
+    state_->config = *cfg;
+    return VPX_CODEC_OK;
+  }
+
+  vpx_codec_err_t codec_enc_init(vpx_codec_ctx_t* ctx,
+                                 vpx_codec_iface_t* iface,
+                                 const vpx_codec_enc_cfg_t* cfg,
+                                 vpx_codec_flags_t flags) const override {
+    RTC_CHECK(ctx);
+    ctx->err = VPX_CODEC_OK;
+    return VPX_CODEC_OK;
+  }
+
+  vpx_image_t* img_wrap(vpx_image_t* img,
+                        vpx_img_fmt_t fmt,
+                        unsigned int d_w,
+                        unsigned int d_h,
+                        unsigned int stride_align,
+                        unsigned char* img_data) const override {
+    state_->img.fmt = fmt;
+    state_->img.d_w = d_w;
+    state_->img.d_h = d_h;
+    return &state_->img;
+  }
+
+  vpx_codec_err_t codec_encode(vpx_codec_ctx_t* ctx,
+                               const vpx_image_t* img,
+                               vpx_codec_pts_t pts,
+                               uint64_t duration,
+                               vpx_enc_frame_flags_t flags,
+                               uint64_t deadline) const override {
+    if (flags & VPX_EFLAG_FORCE_KF) {
+      state_->pkt.data.frame.flags = VPX_FRAME_IS_KEY;
+    } else {
+      state_->pkt.data.frame.flags = 0;
+    }
+    state_->pkt.data.frame.duration = duration;
+    return VPX_CODEC_OK;
+  }
+
+  vpx_codec_err_t codec_control(vpx_codec_ctx_t* ctx,
+                                vp8e_enc_control_id ctrl_id,
+                                void* param) const override {
+    if (ctrl_id == VP9E_REGISTER_CX_CALLBACK) {
+      state_->callback =
+          *reinterpret_cast<vpx_codec_priv_output_cx_pkt_cb_pair_t*>(param);
+    }
+    return VPX_CODEC_OK;
+  }
+
+  vpx_codec_err_t codec_control(
+      vpx_codec_ctx_t* ctx,
+      vp8e_enc_control_id ctrl_id,
+      vpx_svc_ref_frame_config_t* param) const override {
+    switch (ctrl_id) {
+      case VP9E_SET_SVC_REF_FRAME_CONFIG:
+        state_->ref_config = *param;
+        break;
+      case VP9E_GET_SVC_REF_FRAME_CONFIG:
+        *param = state_->ref_config;
+        break;
+      default:
+        break;
+    }
+    return VPX_CODEC_OK;
+  }
+
+  vpx_codec_err_t codec_control(vpx_codec_ctx_t* ctx,
+                                vp8e_enc_control_id ctrl_id,
+                                vpx_svc_layer_id_t* param) const override {
+    switch (ctrl_id) {
+      case VP9E_SET_SVC_LAYER_ID:
+        state_->layer_id = *param;
+        break;
+      case VP9E_GET_SVC_LAYER_ID:
+        *param = state_->layer_id;
+        break;
+      default:
+        break;
+    }
+    return VPX_CODEC_OK;
+  }
+
+  vpx_codec_err_t codec_control(vpx_codec_ctx_t* ctx,
+                                vp8e_enc_control_id ctrl_id,
+                                vpx_svc_frame_drop_t* param) const override {
+    if (ctrl_id == VP9E_SET_SVC_FRAME_DROP_LAYER) {
+      state_->frame_drop = *param;
+    }
+    return VPX_CODEC_OK;
+  }
+
+  vpx_codec_err_t codec_enc_config_set(
+      vpx_codec_ctx_t* ctx,
+      const vpx_codec_enc_cfg_t* cfg) const override {
+    state_->config = *cfg;
+    return VPX_CODEC_OK;
+  }
+
+ private:
+  LibvpxState* const state_;
+};
+
+enum Actions {
+  kEncode,
+  kSetRates,
+};
+
+// When a layer frame is marked for drop, drops all layer frames from that
+// pictures with larger spatial ids.
+constexpr bool DropAbove(uint8_t layers_mask, int sid) {
+  uint8_t full_mask = (uint8_t{1} << (sid + 1)) - 1;
+  return (layers_mask & full_mask) != full_mask;
+}
+// inline unittests
+static_assert(DropAbove(0b1011, /*sid=*/0) == false, "");
+static_assert(DropAbove(0b1011, /*sid=*/1) == false, "");
+static_assert(DropAbove(0b1011, /*sid=*/2) == true, "");
+static_assert(DropAbove(0b1011, /*sid=*/3) == true, "");
+
+// When a layer frame is marked for drop, drops all layer frames from that
+// pictures with smaller spatial ids.
+constexpr bool DropBelow(uint8_t layers_mask, int sid, int num_layers) {
+  return (layers_mask >> sid) != (1 << (num_layers - sid)) - 1;
+}
+// inline unittests
+static_assert(DropBelow(0b1101, /*sid=*/0, 4) == true, "");
+static_assert(DropBelow(0b1101, /*sid=*/1, 4) == true, "");
+static_assert(DropBelow(0b1101, /*sid=*/2, 4) == false, "");
+static_assert(DropBelow(0b1101, /*sid=*/3, 4) == false, "");
+
+}  // namespace
+
+void FuzzOneInput(const uint8_t* data, size_t size) {
+  FuzzDataHelper helper(rtc::MakeArrayView(data, size));
+
+  FrameValidator validator;
+  FieldTrials field_trials(helper);
+  // Setup call callbacks for the fake
+  LibvpxState state;
+
+  // Initialize encoder
+  LibvpxVp9Encoder encoder(cricket::VideoCodec(),
+                           std::make_unique<StubLibvpx>(&state), field_trials);
+  VideoCodec codec = CodecSettings(helper);
+  if (encoder.InitEncode(&codec, EncoderSettings()) != WEBRTC_VIDEO_CODEC_OK) {
+    return;
+  }
+  RTC_CHECK_EQ(encoder.RegisterEncodeCompleteCallback(&validator),
+               WEBRTC_VIDEO_CODEC_OK);
+  {
+    // Enable all the layers initially. Encoder doesn't support producing
+    // frames when no layers are enabled.
+    LibvpxVp9Encoder::RateControlParameters parameters;
+    parameters.framerate_fps = 30.0;
+    for (int sid = 0; sid < codec.VP9()->numberOfSpatialLayers; ++sid) {
+      for (int tid = 0; tid < codec.VP9()->numberOfTemporalLayers; ++tid) {
+        parameters.bitrate.SetBitrate(sid, tid, 100'000);
+      }
+    }
+    encoder.SetRates(parameters);
+  }
+
+  std::vector<VideoFrameType> frame_types(1);
+  VideoFrame fake_image = VideoFrame::Builder()
+                              .set_video_frame_buffer(I420Buffer::Create(
+                                  int{codec.width}, int{codec.height}))
+                              .build();
+
+  // Start producing frames at random.
+  while (helper.CanReadBytes(1)) {
+    uint8_t action = helper.Read<uint8_t>();
+    switch (action & 0b11) {
+      case kEncode: {
+        // bitmask of the action: SSSS-K00, where
+        // four S bit indicate which spatial layers should be produced,
+        // K bit indicates if frame should be a key frame.
+        frame_types[0] = (action & 0b100) ? VideoFrameType::kVideoFrameKey
+                                          : VideoFrameType::kVideoFrameDelta;
+        encoder.Encode(fake_image, &frame_types);
+        uint8_t encode_spatial_layers = (action >> 4);
+        for (size_t sid = 0; sid < state.config.ss_number_layers; ++sid) {
+          bool drop = true;
+          switch (state.frame_drop.framedrop_mode) {
+            case FULL_SUPERFRAME_DROP:
+              drop = encode_spatial_layers == 0;
+              break;
+            case LAYER_DROP:
+              drop = (encode_spatial_layers & (1 << sid)) == 0;
+              break;
+            case CONSTRAINED_LAYER_DROP:
+              drop = DropBelow(encode_spatial_layers, sid,
+                               state.config.ss_number_layers);
+              break;
+            case CONSTRAINED_FROM_ABOVE_DROP:
+              drop = DropAbove(encode_spatial_layers, sid);
+              break;
+          }
+          if (!drop) {
+            state.layer_id.spatial_layer_id = sid;
+            state.callback.output_cx_pkt(&state.pkt, state.callback.user_priv);
+          }
+        }
+      } break;
+      case kSetRates: {
+        // bitmask of the action: (S3)(S1)(S0)01,
+        // where Sx is number of temporal layers to enable for spatial layer x
+        // In pariculat Sx = 0 indicates spatial layer x should be disabled.
+        LibvpxVp9Encoder::RateControlParameters parameters;
+        parameters.framerate_fps = 30.0;
+        for (int sid = 0; sid < codec.VP9()->numberOfSpatialLayers; ++sid) {
+          int temporal_layers = (action >> ((1 + sid) * 2)) & 0b11;
+          for (int tid = 0; tid < temporal_layers; ++tid) {
+            parameters.bitrate.SetBitrate(sid, tid, 100'000);
+          }
+        }
+        // Ignore allocation that turns off all the layers. in such case
+        // it is up to upper-layer code not to call Encode.
+        if (parameters.bitrate.get_sum_bps() > 0) {
+          encoder.SetRates(parameters);
+        }
+      } break;
+      default:
+        // Unspecificed values are noop.
+        break;
+    }
+  }
+}
+}  // namespace webrtc