From d615704551d0f1e4221bd7d643a19dc92d0d8356 Mon Sep 17 00:00:00 2001
From: Sergey Silkin <ssilkin@webrtc.org>
Date: Wed, 7 Jun 2023 13:45:14 +0200
Subject: [PATCH] Enable frame dropping in libaom AV1 encoder
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Bug: webrtc:15225
Change-Id: Ife16a61d47d7aa2f20548d30c56bf59844de1b26
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/307500
Commit-Queue: Sergey Silkin <ssilkin@webrtc.org>
Reviewed-by: Erik Språng <sprang@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#40236}
---
 modules/video_coding/codecs/av1/BUILD.gn      |  2 ++
 .../codecs/av1/libaom_av1_encoder.cc          | 27 ++++++++++++++-----
 2 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/modules/video_coding/codecs/av1/BUILD.gn b/modules/video_coding/codecs/av1/BUILD.gn
index 54149bcb89..6465306731 100644
--- a/modules/video_coding/codecs/av1/BUILD.gn
+++ b/modules/video_coding/codecs/av1/BUILD.gn
@@ -54,7 +54,9 @@ rtc_library("libaom_av1_encoder") {
   sources = [ "libaom_av1_encoder.cc" ]
   deps = [
     "../..:video_codec_interface",
+    "../../../../api:field_trials_view",
     "../../../../api:scoped_refptr",
+    "../../../../api/transport:field_trial_based_config",
     "../../../../api/video:encoded_image",
     "../../../../api/video:video_frame",
     "../../../../api/video_codecs:scalability_mode",
diff --git a/modules/video_coding/codecs/av1/libaom_av1_encoder.cc b/modules/video_coding/codecs/av1/libaom_av1_encoder.cc
index fe7861c867..d23e2d14d8 100644
--- a/modules/video_coding/codecs/av1/libaom_av1_encoder.cc
+++ b/modules/video_coding/codecs/av1/libaom_av1_encoder.cc
@@ -18,8 +18,11 @@
 
 #include "absl/algorithm/container.h"
 #include "absl/base/macros.h"
+#include "absl/strings/match.h"
 #include "absl/types/optional.h"
+#include "api/field_trials_view.h"
 #include "api/scoped_refptr.h"
+#include "api/transport/field_trial_based_config.h"
 #include "api/video/encoded_image.h"
 #include "api/video/i420_buffer.h"
 #include "api/video/video_frame.h"
@@ -68,8 +71,8 @@ aom_superblock_size_t GetSuperblockSize(int width, int height, int threads) {
 
 class LibaomAv1Encoder final : public VideoEncoder {
  public:
-  explicit LibaomAv1Encoder(
-      const absl::optional<LibaomAv1EncoderAuxConfig>& aux_config);
+  LibaomAv1Encoder(const absl::optional<LibaomAv1EncoderAuxConfig>& aux_config,
+                   const FieldTrialsView& trials);
   ~LibaomAv1Encoder();
 
   int InitEncode(const VideoCodec* codec_settings,
@@ -122,6 +125,9 @@ class LibaomAv1Encoder final : public VideoEncoder {
   EncodedImageCallback* encoded_image_callback_;
   int64_t timestamp_;
   const LibaomAv1EncoderInfoSettings encoder_info_override_;
+  // TODO(webrtc:15225): Kill switch for disabling frame dropping. Remove it
+  // after frame dropping is fully rolled out.
+  bool disable_frame_dropping_;
 };
 
 int32_t VerifyCodecSettings(const VideoCodec& codec_settings) {
@@ -153,13 +159,17 @@ int32_t VerifyCodecSettings(const VideoCodec& codec_settings) {
 }
 
 LibaomAv1Encoder::LibaomAv1Encoder(
-    const absl::optional<LibaomAv1EncoderAuxConfig>& aux_config)
+    const absl::optional<LibaomAv1EncoderAuxConfig>& aux_config,
+    const FieldTrialsView& trials)
     : inited_(false),
       rates_configured_(false),
       aux_config_(aux_config),
       frame_for_encode_(nullptr),
       encoded_image_callback_(nullptr),
-      timestamp_(0) {}
+      timestamp_(0),
+      disable_frame_dropping_(absl::StartsWith(
+          trials.Lookup("WebRTC-LibaomAv1Encoder-DisableFrameDropping"),
+          "Enabled")) {}
 
 LibaomAv1Encoder::~LibaomAv1Encoder() {
   Release();
@@ -225,6 +235,9 @@ int LibaomAv1Encoder::InitEncode(const VideoCodec* codec_settings,
   cfg_.g_timebase.num = 1;
   cfg_.g_timebase.den = kRtpTicksPerSecond;
   cfg_.rc_target_bitrate = encoder_settings_.startBitrate;  // kilobits/sec.
+  cfg_.rc_dropframe_thresh =
+      (!disable_frame_dropping_ && encoder_settings_.GetFrameDropEnabled()) ? 30
+                                                                            : 0;
   cfg_.g_input_bit_depth = kBitDepth;
   cfg_.kf_mode = AOM_KF_DISABLED;
   cfg_.rc_min_quantizer = kQpMin;
@@ -825,12 +838,14 @@ VideoEncoder::EncoderInfo LibaomAv1Encoder::GetEncoderInfo() const {
 }  // namespace
 
 std::unique_ptr<VideoEncoder> CreateLibaomAv1Encoder() {
-  return std::make_unique<LibaomAv1Encoder>(absl::nullopt);
+  return std::make_unique<LibaomAv1Encoder>(absl::nullopt,
+                                            FieldTrialBasedConfig());
 }
 
 std::unique_ptr<VideoEncoder> CreateLibaomAv1Encoder(
     const LibaomAv1EncoderAuxConfig& aux_config) {
-  return std::make_unique<LibaomAv1Encoder>(aux_config);
+  return std::make_unique<LibaomAv1Encoder>(aux_config,
+                                            FieldTrialBasedConfig());
 }
 
 }  // namespace webrtc