/*
 *  Copyright (c) 2020 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 "modules/video_coding/codecs/av1/libaom_av1_encoder.h"

#include <stddef.h>
#include <stdint.h>

#include <memory>
#include <utility>
#include <vector>

#include "absl/algorithm/container.h"
#include "absl/base/macros.h"
#include "absl/base/nullability.h"
#include "absl/strings/match.h"
#include "absl/types/optional.h"
#include "api/environment/environment.h"
#include "api/field_trials_view.h"
#include "api/scoped_refptr.h"
#include "api/video/encoded_image.h"
#include "api/video/i420_buffer.h"
#include "api/video/video_frame.h"
#include "api/video_codecs/scalability_mode.h"
#include "api/video_codecs/video_codec.h"
#include "api/video_codecs/video_encoder.h"
#include "modules/video_coding/include/video_codec_interface.h"
#include "modules/video_coding/include/video_error_codes.h"
#include "modules/video_coding/svc/create_scalability_structure.h"
#include "modules/video_coding/svc/scalable_video_controller.h"
#include "modules/video_coding/svc/scalable_video_controller_no_layering.h"
#include "rtc_base/checks.h"
#include "rtc_base/experiments/encoder_info_settings.h"
#include "rtc_base/logging.h"
#include "third_party/libaom/source/libaom/aom/aom_codec.h"
#include "third_party/libaom/source/libaom/aom/aom_encoder.h"
#include "third_party/libaom/source/libaom/aom/aomcx.h"

#if (defined(WEBRTC_ARCH_ARM) || defined(WEBRTC_ARCH_ARM64)) && \
    (defined(WEBRTC_ANDROID) || defined(WEBRTC_IOS))
#define MOBILE_ARM
#endif

#define SET_ENCODER_PARAM_OR_RETURN_ERROR(param_id, param_value) \
  do {                                                           \
    if (!SetEncoderControlParameters(param_id, param_value)) {   \
      return WEBRTC_VIDEO_CODEC_ERROR;                           \
    }                                                            \
  } while (0)

namespace webrtc {
namespace {

// Encoder configuration parameters
constexpr int kQpMin = 10;
constexpr int kUsageProfile = AOM_USAGE_REALTIME;
constexpr int kMinQindex = 145;  // Min qindex threshold for QP scaling.
constexpr int kMaxQindex = 205;  // Max qindex threshold for QP scaling.
constexpr int kBitDepth = 8;
constexpr int kLagInFrames = 0;  // No look ahead.
constexpr int kRtpTicksPerSecond = 90000;
constexpr double kMinimumFrameRate = 1.0;

aom_superblock_size_t GetSuperblockSize(int width, int height, int threads) {
  int resolution = width * height;
  if (threads >= 4 && resolution >= 960 * 540 && resolution < 1920 * 1080)
    return AOM_SUPERBLOCK_SIZE_64X64;
  else
    return AOM_SUPERBLOCK_SIZE_DYNAMIC;
}

class LibaomAv1Encoder final : public VideoEncoder {
 public:
  LibaomAv1Encoder(const Environment& env, LibaomAv1EncoderSettings settings);
  ~LibaomAv1Encoder();

  int InitEncode(const VideoCodec* codec_settings,
                 const Settings& settings) override;

  int32_t RegisterEncodeCompleteCallback(
      EncodedImageCallback* encoded_image_callback) override;

  int32_t Release() override;

  int32_t Encode(const VideoFrame& frame,
                 const std::vector<VideoFrameType>* frame_types) override;

  void SetRates(const RateControlParameters& parameters) override;

  EncoderInfo GetEncoderInfo() const override;

 private:
  template <typename P>
  bool SetEncoderControlParameters(int param_id, P param_value);

  // Get value to be used for encoder cpu_speed setting
  int GetCpuSpeed(int width, int height);

  // Determine number of encoder threads to use.
  int NumberOfThreads(int width, int height, int number_of_cores);

  bool SvcEnabled() const { return svc_params_.has_value(); }
  // Fills svc_params_ memeber value. Returns false on error.
  bool SetSvcParams(ScalableVideoController::StreamLayersConfig svc_config);
  // Configures the encoder with layer for the next frame.
  void SetSvcLayerId(
      const ScalableVideoController::LayerFrameConfig& layer_frame);
  // Configures the encoder which buffers next frame updates and can reference.
  void SetSvcRefFrameConfig(
      const ScalableVideoController::LayerFrameConfig& layer_frame);
  // If pixel format doesn't match, then reallocate.
  void MaybeRewrapImgWithFormat(const aom_img_fmt_t fmt);

  std::unique_ptr<ScalableVideoController> svc_controller_;
  absl::optional<ScalabilityMode> scalability_mode_;
  bool inited_;
  bool rates_configured_;
  absl::optional<aom_svc_params_t> svc_params_;
  VideoCodec encoder_settings_;
  LibaomAv1EncoderSettings settings_;
  aom_image_t* frame_for_encode_;
  aom_codec_ctx_t ctx_;
  aom_codec_enc_cfg_t cfg_;
  EncodedImageCallback* encoded_image_callback_;
  int64_t timestamp_;
  const LibaomAv1EncoderInfoSettings encoder_info_override_;
  int max_consec_frame_drop_;
};

int32_t VerifyCodecSettings(const VideoCodec& codec_settings) {
  if (codec_settings.width < 1) {
    return WEBRTC_VIDEO_CODEC_ERR_PARAMETER;
  }
  if (codec_settings.height < 1) {
    return WEBRTC_VIDEO_CODEC_ERR_PARAMETER;
  }
  // maxBitrate == 0 represents an unspecified maxBitRate.
  if (codec_settings.maxBitrate > 0 &&
      codec_settings.minBitrate > codec_settings.maxBitrate) {
    return WEBRTC_VIDEO_CODEC_ERR_PARAMETER;
  }
  if (codec_settings.maxBitrate > 0 &&
      codec_settings.startBitrate > codec_settings.maxBitrate) {
    return WEBRTC_VIDEO_CODEC_ERR_PARAMETER;
  }
  if (codec_settings.startBitrate < codec_settings.minBitrate) {
    return WEBRTC_VIDEO_CODEC_ERR_PARAMETER;
  }
  if (codec_settings.maxFramerate < 1) {
    return WEBRTC_VIDEO_CODEC_ERR_PARAMETER;
  }
  if (codec_settings.qpMax < kQpMin || codec_settings.qpMax > 63) {
    return WEBRTC_VIDEO_CODEC_ERR_PARAMETER;
  }
  return WEBRTC_VIDEO_CODEC_OK;
}

int GetMaxConsecutiveFrameDrop(const FieldTrialsView& field_trials) {
  webrtc::FieldTrialParameter<int> maxdrop("maxdrop", 0);
  webrtc::ParseFieldTrial(
      {&maxdrop},
      field_trials.Lookup("WebRTC-LibaomAv1Encoder-MaxConsecFrameDrop"));
  return maxdrop;
}

LibaomAv1Encoder::LibaomAv1Encoder(const Environment& env,
                                   LibaomAv1EncoderSettings settings)
    : inited_(false),
      rates_configured_(false),
      settings_(std::move(settings)),
      frame_for_encode_(nullptr),
      encoded_image_callback_(nullptr),
      timestamp_(0),
      encoder_info_override_(env.field_trials()),
      max_consec_frame_drop_(GetMaxConsecutiveFrameDrop(env.field_trials())) {}

LibaomAv1Encoder::~LibaomAv1Encoder() {
  Release();
}

int LibaomAv1Encoder::InitEncode(const VideoCodec* codec_settings,
                                 const Settings& settings) {
  if (codec_settings == nullptr) {
    RTC_LOG(LS_WARNING) << "No codec settings provided to "
                           "LibaomAv1Encoder.";
    return WEBRTC_VIDEO_CODEC_ERR_PARAMETER;
  }
  if (settings.number_of_cores < 1) {
    return WEBRTC_VIDEO_CODEC_ERR_PARAMETER;
  }
  if (inited_) {
    RTC_LOG(LS_WARNING) << "Initing LibaomAv1Encoder without first releasing.";
    Release();
  }
  encoder_settings_ = *codec_settings;

  // Sanity checks for encoder configuration.
  const int32_t result = VerifyCodecSettings(encoder_settings_);
  if (result < 0) {
    RTC_LOG(LS_WARNING) << "Incorrect codec settings provided to "
                           "LibaomAv1Encoder.";
    return result;
  }
  if (encoder_settings_.numberOfSimulcastStreams > 1) {
    RTC_LOG(LS_WARNING) << "Simulcast is not implemented by LibaomAv1Encoder.";
    return result;
  }
  scalability_mode_ = encoder_settings_.GetScalabilityMode();
  if (!scalability_mode_.has_value()) {
    RTC_LOG(LS_WARNING) << "Scalability mode is not set, using 'L1T1'.";
    scalability_mode_ = ScalabilityMode::kL1T1;
  }
  svc_controller_ = CreateScalabilityStructure(*scalability_mode_);
  if (svc_controller_ == nullptr) {
    RTC_LOG(LS_WARNING) << "Failed to set scalability mode "
                        << static_cast<int>(*scalability_mode_);
    return WEBRTC_VIDEO_CODEC_ERR_PARAMETER;
  }

  if (!SetSvcParams(svc_controller_->StreamConfig())) {
    return WEBRTC_VIDEO_CODEC_ERROR;
  }

  // Initialize encoder configuration structure with default values
  aom_codec_err_t ret =
      aom_codec_enc_config_default(aom_codec_av1_cx(), &cfg_, kUsageProfile);
  if (ret != AOM_CODEC_OK) {
    RTC_LOG(LS_WARNING) << "LibaomAv1Encoder::EncodeInit returned " << ret
                        << " on aom_codec_enc_config_default.";
    return WEBRTC_VIDEO_CODEC_ERROR;
  }

  // Overwrite default config with input encoder settings & RTC-relevant values.
  cfg_.g_w = encoder_settings_.width;
  cfg_.g_h = encoder_settings_.height;
  cfg_.g_threads =
      NumberOfThreads(cfg_.g_w, cfg_.g_h, settings.number_of_cores);
  cfg_.g_timebase.num = 1;
  cfg_.g_timebase.den = kRtpTicksPerSecond;
  cfg_.rc_target_bitrate = encoder_settings_.startBitrate;  // kilobits/sec.
  cfg_.rc_dropframe_thresh = encoder_settings_.GetFrameDropEnabled() ? 30 : 0;
  cfg_.g_input_bit_depth = kBitDepth;
  cfg_.kf_mode = AOM_KF_DISABLED;
  cfg_.rc_min_quantizer = kQpMin;
  cfg_.rc_max_quantizer = encoder_settings_.qpMax;
  cfg_.rc_undershoot_pct = 50;
  cfg_.rc_overshoot_pct = 50;
  cfg_.rc_buf_initial_sz = 600;
  cfg_.rc_buf_optimal_sz = 600;
  cfg_.rc_buf_sz = 1000;
  cfg_.g_usage = kUsageProfile;
  cfg_.g_error_resilient = 0;
  // Low-latency settings.
  cfg_.rc_end_usage = AOM_CBR;          // Constant Bit Rate (CBR) mode
  cfg_.g_pass = AOM_RC_ONE_PASS;        // One-pass rate control
  cfg_.g_lag_in_frames = kLagInFrames;  // No look ahead when lag equals 0.

  if (frame_for_encode_ != nullptr) {
    aom_img_free(frame_for_encode_);
    frame_for_encode_ = nullptr;
  }

  // Flag options: AOM_CODEC_USE_PSNR and AOM_CODEC_USE_HIGHBITDEPTH
  aom_codec_flags_t flags = 0;

  // Initialize an encoder instance.
  ret = aom_codec_enc_init(&ctx_, aom_codec_av1_cx(), &cfg_, flags);
  if (ret != AOM_CODEC_OK) {
    RTC_LOG(LS_WARNING) << "LibaomAv1Encoder::EncodeInit returned " << ret
                        << " on aom_codec_enc_init.";
    return WEBRTC_VIDEO_CODEC_ERROR;
  }
  inited_ = true;

  // Set control parameters
  SET_ENCODER_PARAM_OR_RETURN_ERROR(AOME_SET_CPUUSED,
                                    GetCpuSpeed(cfg_.g_w, cfg_.g_h));
  SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_ENABLE_CDEF, 1);
  SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_ENABLE_TPL_MODEL, 0);
  SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_DELTAQ_MODE, 0);
  SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_ENABLE_ORDER_HINT, 0);
  SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_AQ_MODE, 3);
  SET_ENCODER_PARAM_OR_RETURN_ERROR(AOME_SET_MAX_INTRA_BITRATE_PCT, 300);
  SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_COEFF_COST_UPD_FREQ, 3);
  SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_MODE_COST_UPD_FREQ, 3);
  SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_MV_COST_UPD_FREQ, 3);

  if (codec_settings->mode == VideoCodecMode::kScreensharing) {
    SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_TUNE_CONTENT,
                                      AOM_CONTENT_SCREEN);
    SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_ENABLE_PALETTE, 1);
  } else {
    SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_ENABLE_PALETTE, 0);
  }

  if (codec_settings->mode == VideoCodecMode::kRealtimeVideo &&
      encoder_settings_.GetFrameDropEnabled() && max_consec_frame_drop_ > 0) {
    SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_MAX_CONSEC_FRAME_DROP_CBR,
                                      max_consec_frame_drop_);
  }

  if (cfg_.g_threads == 8) {
    // Values passed to AV1E_SET_TILE_ROWS and AV1E_SET_TILE_COLUMNS are log2()
    // based.
    // Use 4 tile columns x 2 tile rows for 8 threads.
    SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_TILE_ROWS, 1);
    SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_TILE_COLUMNS, 2);
  } else if (cfg_.g_threads == 4) {
    // Use 2 tile columns x 2 tile rows for 4 threads.
    SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_TILE_ROWS, 1);
    SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_TILE_COLUMNS, 1);
  } else {
    SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_TILE_COLUMNS,
                                      static_cast<int>(log2(cfg_.g_threads)));
  }

  SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_ROW_MT, 1);
  SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_ENABLE_OBMC, 0);
  SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_NOISE_SENSITIVITY, 0);
  SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_ENABLE_WARPED_MOTION, 0);
  SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_ENABLE_GLOBAL_MOTION, 0);
  SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_ENABLE_REF_FRAME_MVS, 0);
  SET_ENCODER_PARAM_OR_RETURN_ERROR(
      AV1E_SET_SUPERBLOCK_SIZE,
      GetSuperblockSize(cfg_.g_w, cfg_.g_h, cfg_.g_threads));
  SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_ENABLE_CFL_INTRA, 0);
  SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_ENABLE_SMOOTH_INTRA, 0);
  SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_ENABLE_ANGLE_DELTA, 0);
  SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_ENABLE_FILTER_INTRA, 0);
  SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_INTRA_DEFAULT_TX_ONLY, 1);
  SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_DISABLE_TRELLIS_QUANT, 1);
  SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_ENABLE_DIST_WTD_COMP, 0);
  SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_ENABLE_DIFF_WTD_COMP, 0);
  SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_ENABLE_DUAL_FILTER, 0);
  SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_ENABLE_INTERINTRA_COMP, 0);
  SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_ENABLE_INTERINTRA_WEDGE, 0);
  SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_ENABLE_INTRA_EDGE_FILTER, 0);
  SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_ENABLE_INTRABC, 0);
  SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_ENABLE_MASKED_COMP, 0);
  SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_ENABLE_PAETH_INTRA, 0);
  SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_ENABLE_QM, 0);
  SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_ENABLE_RECT_PARTITIONS, 0);
  SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_ENABLE_RESTORATION, 0);
  SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_ENABLE_SMOOTH_INTERINTRA, 0);
  SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_ENABLE_TX64, 0);
  SET_ENCODER_PARAM_OR_RETURN_ERROR(AV1E_SET_MAX_REFERENCE_FRAMES, 3);

  return WEBRTC_VIDEO_CODEC_OK;
}

template <typename P>
bool LibaomAv1Encoder::SetEncoderControlParameters(int param_id,
                                                   P param_value) {
  aom_codec_err_t error_code = aom_codec_control(&ctx_, param_id, param_value);
  if (error_code != AOM_CODEC_OK) {
    RTC_LOG(LS_WARNING)
        << "LibaomAv1Encoder::SetEncoderControlParameters returned "
        << error_code << " on id:  " << param_id << ".";
  }
  return error_code == AOM_CODEC_OK;
}

// Only positive speeds, range for real-time coding currently is: 6 - 10.
// Speed 11 is used for screen sharing.
// Lower means slower/better quality, higher means fastest/lower quality.
int LibaomAv1Encoder::GetCpuSpeed(int width, int height) {
  if (!settings_.max_pixel_count_to_cpu_speed.empty()) {
    if (auto it =
            settings_.max_pixel_count_to_cpu_speed.lower_bound(width * height);
        it != settings_.max_pixel_count_to_cpu_speed.end()) {
      return it->second;
    }

    return 10;
  } else {
    if (encoder_settings_.mode == VideoCodecMode::kScreensharing) {
      return 11;
    }
    // For smaller resolutions, use lower speed setting (get some coding gain at
    // the cost of increased encoding complexity).
    switch (encoder_settings_.GetVideoEncoderComplexity()) {
      case VideoCodecComplexity::kComplexityHigh:
        if (width * height <= 320 * 180)
          return 8;
        else if (width * height <= 640 * 360)
          return 9;
        else
          return 10;
      case VideoCodecComplexity::kComplexityHigher:
        if (width * height <= 320 * 180)
          return 7;
        else if (width * height <= 640 * 360)
          return 8;
        else if (width * height <= 1280 * 720)
          return 9;
        else
          return 10;
      case VideoCodecComplexity::kComplexityMax:
        if (width * height <= 320 * 180)
          return 6;
        else if (width * height <= 640 * 360)
          return 7;
        else if (width * height <= 1280 * 720)
          return 8;
        else
          return 9;
      default:
        return 10;
    }
  }
}

int LibaomAv1Encoder::NumberOfThreads(int width,
                                      int height,
                                      int number_of_cores) {
  // Keep the number of encoder threads equal to the possible number of
  // column/row tiles, which is (1, 2, 4, 8). See comments below for
  // AV1E_SET_TILE_COLUMNS/ROWS.
  if (width * height > 1280 * 720 && number_of_cores > 8) {
    return 8;
  } else if (width * height >= 640 * 360 && number_of_cores > 4) {
    return 4;
  } else if (width * height >= 320 * 180 && number_of_cores > 2) {
    return 2;
  } else {
// Use 2 threads for low res on ARM.
#ifdef MOBILE_ARM
    if (width * height >= 320 * 180 && number_of_cores > 2) {
      return 2;
    }
#endif
    // 1 thread less than VGA.
    return 1;
  }
}

bool LibaomAv1Encoder::SetSvcParams(
    ScalableVideoController::StreamLayersConfig svc_config) {
  bool svc_enabled =
      svc_config.num_spatial_layers > 1 || svc_config.num_temporal_layers > 1;
  if (!svc_enabled) {
    svc_params_ = absl::nullopt;
    return true;
  }
  if (svc_config.num_spatial_layers < 1 || svc_config.num_spatial_layers > 4) {
    RTC_LOG(LS_WARNING) << "Av1 supports up to 4 spatial layers. "
                        << svc_config.num_spatial_layers << " configured.";
    return false;
  }
  if (svc_config.num_temporal_layers < 1 ||
      svc_config.num_temporal_layers > 8) {
    RTC_LOG(LS_WARNING) << "Av1 supports up to 8 temporal layers. "
                        << svc_config.num_temporal_layers << " configured.";
    return false;
  }
  aom_svc_params_t& svc_params = svc_params_.emplace();
  svc_params.number_spatial_layers = svc_config.num_spatial_layers;
  svc_params.number_temporal_layers = svc_config.num_temporal_layers;

  int num_layers =
      svc_config.num_spatial_layers * svc_config.num_temporal_layers;
  for (int i = 0; i < num_layers; ++i) {
    svc_params.min_quantizers[i] = kQpMin;
    svc_params.max_quantizers[i] = encoder_settings_.qpMax;
  }

  // Assume each temporal layer doubles framerate.
  for (int tid = 0; tid < svc_config.num_temporal_layers; ++tid) {
    svc_params.framerate_factor[tid] =
        1 << (svc_config.num_temporal_layers - tid - 1);
  }

  for (int sid = 0; sid < svc_config.num_spatial_layers; ++sid) {
    svc_params.scaling_factor_num[sid] = svc_config.scaling_factor_num[sid];
    svc_params.scaling_factor_den[sid] = svc_config.scaling_factor_den[sid];
  }

  // svc_params.layer_target_bitrate is set in SetRates() before svc_params is
  // passed to SetEncoderControlParameters(AV1E_SET_SVC_PARAMS).

  return true;
}

void LibaomAv1Encoder::SetSvcLayerId(
    const ScalableVideoController::LayerFrameConfig& layer_frame) {
  aom_svc_layer_id_t layer_id = {};
  layer_id.spatial_layer_id = layer_frame.SpatialId();
  layer_id.temporal_layer_id = layer_frame.TemporalId();
  SetEncoderControlParameters(AV1E_SET_SVC_LAYER_ID, &layer_id);
}

void LibaomAv1Encoder::SetSvcRefFrameConfig(
    const ScalableVideoController::LayerFrameConfig& layer_frame) {
  // Buffer name to use for each layer_frame.buffers position. In particular
  // when there are 2 buffers are referenced, prefer name them last and golden,
  // because av1 bitstream format has dedicated fields for these two names.
  // See last_frame_idx and golden_frame_idx in the av1 spec
  // https://aomediacodec.github.io/av1-spec/av1-spec.pdf
  static constexpr int kPreferedSlotName[] = {0,  // Last
                                              3,  // Golden
                                              1, 2, 4, 5, 6};
  static constexpr int kAv1NumBuffers = 8;

  aom_svc_ref_frame_config_t ref_frame_config = {};
  RTC_CHECK_LE(layer_frame.Buffers().size(), ABSL_ARRAYSIZE(kPreferedSlotName));
  for (size_t i = 0; i < layer_frame.Buffers().size(); ++i) {
    const CodecBufferUsage& buffer = layer_frame.Buffers()[i];
    int slot_name = kPreferedSlotName[i];
    RTC_CHECK_GE(buffer.id, 0);
    RTC_CHECK_LT(buffer.id, kAv1NumBuffers);
    ref_frame_config.ref_idx[slot_name] = buffer.id;
    if (buffer.referenced) {
      ref_frame_config.reference[slot_name] = 1;
    }
    if (buffer.updated) {
      ref_frame_config.refresh[buffer.id] = 1;
    }
  }

  SetEncoderControlParameters(AV1E_SET_SVC_REF_FRAME_CONFIG, &ref_frame_config);
}

int32_t LibaomAv1Encoder::RegisterEncodeCompleteCallback(
    EncodedImageCallback* encoded_image_callback) {
  encoded_image_callback_ = encoded_image_callback;
  return WEBRTC_VIDEO_CODEC_OK;
}

int32_t LibaomAv1Encoder::Release() {
  if (frame_for_encode_ != nullptr) {
    aom_img_free(frame_for_encode_);
    frame_for_encode_ = nullptr;
  }
  if (inited_) {
    if (aom_codec_destroy(&ctx_)) {
      return WEBRTC_VIDEO_CODEC_MEMORY;
    }
    inited_ = false;
  }
  rates_configured_ = false;
  return WEBRTC_VIDEO_CODEC_OK;
}

void LibaomAv1Encoder::MaybeRewrapImgWithFormat(const aom_img_fmt_t fmt) {
  if (!frame_for_encode_) {
    frame_for_encode_ =
        aom_img_wrap(nullptr, fmt, cfg_.g_w, cfg_.g_h, 1, nullptr);

  } else if (frame_for_encode_->fmt != fmt) {
    RTC_LOG(LS_INFO) << "Switching AV1 encoder pixel format to "
                     << (fmt == AOM_IMG_FMT_NV12 ? "NV12" : "I420");
    aom_img_free(frame_for_encode_);
    frame_for_encode_ =
        aom_img_wrap(nullptr, fmt, cfg_.g_w, cfg_.g_h, 1, nullptr);
  }
  // else no-op since the image is already in the right format.
}

int32_t LibaomAv1Encoder::Encode(
    const VideoFrame& frame,
    const std::vector<VideoFrameType>* frame_types) {
  if (!inited_ || encoded_image_callback_ == nullptr || !rates_configured_) {
    return WEBRTC_VIDEO_CODEC_UNINITIALIZED;
  }

  bool keyframe_required =
      frame_types != nullptr &&
      absl::c_linear_search(*frame_types, VideoFrameType::kVideoFrameKey);

  std::vector<ScalableVideoController::LayerFrameConfig> layer_frames =
      svc_controller_->NextFrameConfig(keyframe_required);

  if (layer_frames.empty()) {
    RTC_LOG(LS_ERROR) << "SVCController returned no configuration for a frame.";
    return WEBRTC_VIDEO_CODEC_ERROR;
  }

  rtc::scoped_refptr<VideoFrameBuffer> buffer = frame.video_frame_buffer();
  absl::InlinedVector<VideoFrameBuffer::Type, kMaxPreferredPixelFormats>
      supported_formats = {VideoFrameBuffer::Type::kI420,
                           VideoFrameBuffer::Type::kNV12};
  rtc::scoped_refptr<VideoFrameBuffer> mapped_buffer;
  if (buffer->type() != VideoFrameBuffer::Type::kNative) {
    // `buffer` is already mapped.
    mapped_buffer = buffer;
  } else {
    // Attempt to map to one of the supported formats.
    mapped_buffer = buffer->GetMappedFrameBuffer(supported_formats);
  }

  // Convert input frame to I420, if needed.
  if (!mapped_buffer ||
      (absl::c_find(supported_formats, mapped_buffer->type()) ==
           supported_formats.end() &&
       mapped_buffer->type() != VideoFrameBuffer::Type::kI420A)) {
    rtc::scoped_refptr<I420BufferInterface> converted_buffer(buffer->ToI420());
    if (!converted_buffer) {
      RTC_LOG(LS_ERROR) << "Failed to convert "
                        << VideoFrameBufferTypeToString(
                               frame.video_frame_buffer()->type())
                        << " image to I420. Can't encode frame.";
      return WEBRTC_VIDEO_CODEC_ENCODER_FAILURE;
    }
    RTC_CHECK(converted_buffer->type() == VideoFrameBuffer::Type::kI420 ||
              converted_buffer->type() == VideoFrameBuffer::Type::kI420A);

    mapped_buffer = converted_buffer;
  }

  switch (mapped_buffer->type()) {
    case VideoFrameBuffer::Type::kI420:
    case VideoFrameBuffer::Type::kI420A: {
      // Set frame_for_encode_ data pointers and strides.
      MaybeRewrapImgWithFormat(AOM_IMG_FMT_I420);
      auto i420_buffer = mapped_buffer->GetI420();
      RTC_DCHECK(i420_buffer);
      RTC_CHECK_EQ(i420_buffer->width(), frame_for_encode_->d_w);
      RTC_CHECK_EQ(i420_buffer->height(), frame_for_encode_->d_h);
      frame_for_encode_->planes[AOM_PLANE_Y] =
          const_cast<unsigned char*>(i420_buffer->DataY());
      frame_for_encode_->planes[AOM_PLANE_U] =
          const_cast<unsigned char*>(i420_buffer->DataU());
      frame_for_encode_->planes[AOM_PLANE_V] =
          const_cast<unsigned char*>(i420_buffer->DataV());
      frame_for_encode_->stride[AOM_PLANE_Y] = i420_buffer->StrideY();
      frame_for_encode_->stride[AOM_PLANE_U] = i420_buffer->StrideU();
      frame_for_encode_->stride[AOM_PLANE_V] = i420_buffer->StrideV();
      break;
    }
    case VideoFrameBuffer::Type::kNV12: {
      MaybeRewrapImgWithFormat(AOM_IMG_FMT_NV12);
      const NV12BufferInterface* nv12_buffer = mapped_buffer->GetNV12();
      RTC_DCHECK(nv12_buffer);
      RTC_CHECK_EQ(nv12_buffer->width(), frame_for_encode_->d_w);
      RTC_CHECK_EQ(nv12_buffer->height(), frame_for_encode_->d_h);
      frame_for_encode_->planes[AOM_PLANE_Y] =
          const_cast<unsigned char*>(nv12_buffer->DataY());
      frame_for_encode_->planes[AOM_PLANE_U] =
          const_cast<unsigned char*>(nv12_buffer->DataUV());
      frame_for_encode_->planes[AOM_PLANE_V] = nullptr;
      frame_for_encode_->stride[AOM_PLANE_Y] = nv12_buffer->StrideY();
      frame_for_encode_->stride[AOM_PLANE_U] = nv12_buffer->StrideUV();
      frame_for_encode_->stride[AOM_PLANE_V] = 0;
      break;
    }
    default:
      return WEBRTC_VIDEO_CODEC_ENCODER_FAILURE;
  }

  const uint32_t duration =
      kRtpTicksPerSecond / static_cast<float>(encoder_settings_.maxFramerate);
  timestamp_ += duration;

  const size_t num_spatial_layers =
      svc_params_ ? svc_params_->number_spatial_layers : 1;
  auto next_layer_frame = layer_frames.begin();
  for (size_t i = 0; i < num_spatial_layers; ++i) {
    // The libaom AV1 encoder requires that `aom_codec_encode` is called for
    // every spatial layer, even if the configured bitrate for that layer is
    // zero. For zero bitrate spatial layers no frames will be produced.
    absl::optional<ScalableVideoController::LayerFrameConfig>
        non_encoded_layer_frame;
    ScalableVideoController::LayerFrameConfig* layer_frame;
    if (next_layer_frame != layer_frames.end() &&
        next_layer_frame->SpatialId() == static_cast<int>(i)) {
      layer_frame = &*next_layer_frame;
      ++next_layer_frame;
    } else {
      // For layers that are not encoded only the spatial id matters.
      non_encoded_layer_frame.emplace().S(i);
      layer_frame = &*non_encoded_layer_frame;
    }
    const bool end_of_picture = (next_layer_frame == layer_frames.end());

    aom_enc_frame_flags_t flags =
        layer_frame->IsKeyframe() ? AOM_EFLAG_FORCE_KF : 0;

    if (SvcEnabled()) {
      SetSvcLayerId(*layer_frame);
      SetSvcRefFrameConfig(*layer_frame);
    }

    // Encode a frame. The presentation timestamp `pts` should not use real
    // timestamps from frames or the wall clock, as that can cause the rate
    // controller to misbehave.
    aom_codec_err_t ret =
        aom_codec_encode(&ctx_, frame_for_encode_, timestamp_, duration, flags);
    if (ret != AOM_CODEC_OK) {
      RTC_LOG(LS_WARNING) << "LibaomAv1Encoder::Encode returned " << ret
                          << " on aom_codec_encode.";
      return WEBRTC_VIDEO_CODEC_ERROR;
    }

    if (non_encoded_layer_frame) {
      continue;
    }

    // Get encoded image data.
    EncodedImage encoded_image;
    aom_codec_iter_t iter = nullptr;
    int data_pkt_count = 0;
    while (const aom_codec_cx_pkt_t* pkt =
               aom_codec_get_cx_data(&ctx_, &iter)) {
      if (pkt->kind == AOM_CODEC_CX_FRAME_PKT && pkt->data.frame.sz > 0) {
        if (data_pkt_count > 0) {
          RTC_LOG(LS_WARNING) << "LibaomAv1Encoder::Encoder returned more than "
                                 "one data packet for an input video frame.";
          Release();
        }
        encoded_image.SetEncodedData(EncodedImageBuffer::Create(
            /*data=*/static_cast<const uint8_t*>(pkt->data.frame.buf),
            /*size=*/pkt->data.frame.sz));

        if ((pkt->data.frame.flags & AOM_EFLAG_FORCE_KF) != 0) {
          layer_frame->Keyframe();
        }

        encoded_image._frameType = layer_frame->IsKeyframe()
                                       ? VideoFrameType::kVideoFrameKey
                                       : VideoFrameType::kVideoFrameDelta;
        encoded_image.SetRtpTimestamp(frame.rtp_timestamp());
        encoded_image.SetCaptureTimeIdentifier(frame.capture_time_identifier());
        encoded_image.capture_time_ms_ = frame.render_time_ms();
        encoded_image.rotation_ = frame.rotation();
        encoded_image.content_type_ = VideoContentType::UNSPECIFIED;
        // If encoded image width/height info are added to aom_codec_cx_pkt_t,
        // use those values in lieu of the values in frame.
        if (svc_params_) {
          int n = svc_params_->scaling_factor_num[layer_frame->SpatialId()];
          int d = svc_params_->scaling_factor_den[layer_frame->SpatialId()];
          encoded_image._encodedWidth = cfg_.g_w * n / d;
          encoded_image._encodedHeight = cfg_.g_h * n / d;
          encoded_image.SetSpatialIndex(layer_frame->SpatialId());
          encoded_image.SetTemporalIndex(layer_frame->TemporalId());
        } else {
          encoded_image._encodedWidth = cfg_.g_w;
          encoded_image._encodedHeight = cfg_.g_h;
        }
        encoded_image.timing_.flags = VideoSendTiming::kInvalid;

        int qp = -1;
        SET_ENCODER_PARAM_OR_RETURN_ERROR(AOME_GET_LAST_QUANTIZER, &qp);
        encoded_image.qp_ = qp;

        encoded_image.SetColorSpace(frame.color_space());
        ++data_pkt_count;
      }
    }

    // Deliver encoded image data.
    if (encoded_image.size() > 0) {
      CodecSpecificInfo codec_specific_info;
      codec_specific_info.codecType = kVideoCodecAV1;
      codec_specific_info.end_of_picture = end_of_picture;
      codec_specific_info.scalability_mode = scalability_mode_;
      bool is_keyframe = layer_frame->IsKeyframe();
      codec_specific_info.generic_frame_info =
          svc_controller_->OnEncodeDone(*layer_frame);
      if (is_keyframe && codec_specific_info.generic_frame_info) {
        codec_specific_info.template_structure =
            svc_controller_->DependencyStructure();
        auto& resolutions = codec_specific_info.template_structure->resolutions;
        if (SvcEnabled()) {
          resolutions.resize(svc_params_->number_spatial_layers);
          for (int sid = 0; sid < svc_params_->number_spatial_layers; ++sid) {
            int n = svc_params_->scaling_factor_num[sid];
            int d = svc_params_->scaling_factor_den[sid];
            resolutions[sid] =
                RenderResolution(cfg_.g_w * n / d, cfg_.g_h * n / d);
          }
        } else {
          resolutions = {RenderResolution(cfg_.g_w, cfg_.g_h)};
        }
      }
      encoded_image_callback_->OnEncodedImage(encoded_image,
                                              &codec_specific_info);
    }
  }

  return WEBRTC_VIDEO_CODEC_OK;
}

void LibaomAv1Encoder::SetRates(const RateControlParameters& parameters) {
  if (!inited_) {
    RTC_LOG(LS_WARNING) << "SetRates() while encoder is not initialized";
    return;
  }
  if (parameters.framerate_fps < kMinimumFrameRate) {
    RTC_LOG(LS_WARNING) << "Unsupported framerate (must be >= "
                        << kMinimumFrameRate
                        << " ): " << parameters.framerate_fps;
    return;
  }
  if (parameters.bitrate.get_sum_bps() == 0) {
    RTC_LOG(LS_WARNING) << "Attempt to set target bit rate to zero";
    return;
  }

  // The bitrates caluclated internally in libaom when `AV1E_SET_SVC_PARAMS` is
  // called depends on the currently configured `rc_target_bitrate`. If the
  // total target bitrate is not updated first a division by zero could happen.
  svc_controller_->OnRatesUpdated(parameters.bitrate);
  cfg_.rc_target_bitrate = parameters.bitrate.get_sum_kbps();
  aom_codec_err_t error_code = aom_codec_enc_config_set(&ctx_, &cfg_);
  if (error_code != AOM_CODEC_OK) {
    RTC_LOG(LS_WARNING) << "Error configuring encoder, error code: "
                        << error_code;
  }

  if (SvcEnabled()) {
    for (int sid = 0; sid < svc_params_->number_spatial_layers; ++sid) {
      // libaom bitrate for spatial id S and temporal id T means bitrate
      // of frames with spatial_id=S and temporal_id<=T
      // while `parameters.bitrate` provdies bitrate of frames with
      // spatial_id=S and temporal_id=T
      int accumulated_bitrate_bps = 0;
      for (int tid = 0; tid < svc_params_->number_temporal_layers; ++tid) {
        int layer_index = sid * svc_params_->number_temporal_layers + tid;
        accumulated_bitrate_bps += parameters.bitrate.GetBitrate(sid, tid);
        // `svc_params_->layer_target_bitrate` expects bitrate in kbps.
        svc_params_->layer_target_bitrate[layer_index] =
            accumulated_bitrate_bps / 1000;
      }
    }
    SetEncoderControlParameters(AV1E_SET_SVC_PARAMS, &*svc_params_);
  }

  rates_configured_ = true;

  // Set frame rate to closest integer value.
  encoder_settings_.maxFramerate =
      static_cast<uint32_t>(parameters.framerate_fps + 0.5);
}

VideoEncoder::EncoderInfo LibaomAv1Encoder::GetEncoderInfo() const {
  EncoderInfo info;
  info.supports_native_handle = false;
  info.implementation_name = "libaom";
  info.has_trusted_rate_controller = true;
  info.is_hardware_accelerated = false;
  info.scaling_settings =
      (inited_ && !encoder_settings_.AV1().automatic_resize_on)
          ? VideoEncoder::ScalingSettings::kOff
          : VideoEncoder::ScalingSettings(kMinQindex, kMaxQindex);
  info.preferred_pixel_formats = {VideoFrameBuffer::Type::kI420,
                                  VideoFrameBuffer::Type::kNV12};
  if (SvcEnabled()) {
    for (int sid = 0; sid < svc_params_->number_spatial_layers; ++sid) {
      info.fps_allocation[sid].resize(svc_params_->number_temporal_layers);
      for (int tid = 0; tid < svc_params_->number_temporal_layers; ++tid) {
        info.fps_allocation[sid][tid] = EncoderInfo::kMaxFramerateFraction /
                                        svc_params_->framerate_factor[tid];
      }
    }
  }
  if (!encoder_info_override_.resolution_bitrate_limits().empty()) {
    info.resolution_bitrate_limits =
        encoder_info_override_.resolution_bitrate_limits();
  }
  return info;
}

}  // namespace

absl::Nonnull<std::unique_ptr<VideoEncoder>> CreateLibaomAv1Encoder(
    const Environment& env,
    LibaomAv1EncoderSettings settings) {
  return std::make_unique<LibaomAv1Encoder>(env, std::move(settings));
}

}  // namespace webrtc