From 83d667925fa0af4b1334ae57af02846ebba43497 Mon Sep 17 00:00:00 2001
From: philipel <philipel@webrtc.org>
Date: Tue, 2 Nov 2021 14:34:01 +0100
Subject: [PATCH] Removed unused WebRTC-SupportVP9SVC field trial.

Instead use `parameters_.config.rtp.ssrcs.size()` directly to make decisions about the number of temporal and spatial layer used.

Bug: none
Change-Id: Icba553178ae7fea281c2c67654c510228d9ab5b6
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/237080
Commit-Queue: Philip Eliasson <philipel@webrtc.org>
Reviewed-by: Niels Moller <nisse@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#35299}
---
 media/engine/webrtc_video_engine.cc          | 63 ++------------------
 media/engine/webrtc_video_engine_unittest.cc |  8 ---
 2 files changed, 6 insertions(+), 65 deletions(-)

diff --git a/media/engine/webrtc_video_engine.cc b/media/engine/webrtc_video_engine.cc
index 359cbd3a19..f497d9046e 100644
--- a/media/engine/webrtc_video_engine.cc
+++ b/media/engine/webrtc_video_engine.cc
@@ -345,49 +345,6 @@ static int GetMaxDefaultVideoBitrateKbps(int width,
   return max_bitrate;
 }
 
-bool GetVp9LayersFromFieldTrialGroup(
-    size_t* num_spatial_layers,
-    size_t* num_temporal_layers,
-    const webrtc::WebRtcKeyValueConfig& trials) {
-  std::string group = trials.Lookup("WebRTC-SupportVP9SVC");
-  if (group.empty())
-    return false;
-
-  if (sscanf(group.c_str(), "EnabledByFlag_%zuSL%zuTL", num_spatial_layers,
-             num_temporal_layers) != 2) {
-    return false;
-  }
-  if (*num_spatial_layers > webrtc::kMaxSpatialLayers ||
-      *num_spatial_layers < 1)
-    return false;
-
-  const size_t kMaxTemporalLayers = 3;
-  if (*num_temporal_layers > kMaxTemporalLayers || *num_temporal_layers < 1)
-    return false;
-
-  return true;
-}
-
-absl::optional<size_t> GetVp9SpatialLayersFromFieldTrial(
-    const webrtc::WebRtcKeyValueConfig& trials) {
-  size_t num_sl;
-  size_t num_tl;
-  if (GetVp9LayersFromFieldTrialGroup(&num_sl, &num_tl, trials)) {
-    return num_sl;
-  }
-  return absl::nullopt;
-}
-
-absl::optional<size_t> GetVp9TemporalLayersFromFieldTrial(
-    const webrtc::WebRtcKeyValueConfig& trials) {
-  size_t num_sl;
-  size_t num_tl;
-  if (GetVp9LayersFromFieldTrialGroup(&num_sl, &num_tl, trials)) {
-    return num_tl;
-  }
-  return absl::nullopt;
-}
-
 // Returns its smallest positive argument. If neither argument is positive,
 // returns an arbitrary nonpositive value.
 int MinPositive(int a, int b) {
@@ -541,22 +498,14 @@ WebRtcVideoChannel::WebRtcVideoSendStream::ConfigureVideoEncoderSettings(
   if (absl::EqualsIgnoreCase(codec.name, kVp9CodecName)) {
     webrtc::VideoCodecVP9 vp9_settings =
         webrtc::VideoEncoder::GetDefaultVp9Settings();
-    const size_t default_num_spatial_layers =
-        parameters_.config.rtp.ssrcs.size();
-    const size_t num_spatial_layers =
-        GetVp9SpatialLayersFromFieldTrial(call_->trials())
-            .value_or(default_num_spatial_layers);
-
-    const size_t default_num_temporal_layers =
-        num_spatial_layers > 1 ? kConferenceDefaultNumTemporalLayers : 1;
-    const size_t num_temporal_layers =
-        GetVp9TemporalLayersFromFieldTrial(call_->trials())
-            .value_or(default_num_temporal_layers);
 
     vp9_settings.numberOfSpatialLayers = std::min<unsigned char>(
-        num_spatial_layers, kConferenceMaxNumSpatialLayers);
-    vp9_settings.numberOfTemporalLayers = std::min<unsigned char>(
-        num_temporal_layers, kConferenceMaxNumTemporalLayers);
+        parameters_.config.rtp.ssrcs.size(), kConferenceMaxNumSpatialLayers);
+    vp9_settings.numberOfTemporalLayers =
+        std::min<unsigned char>(parameters_.config.rtp.ssrcs.size() > 1
+                                    ? kConferenceDefaultNumTemporalLayers
+                                    : 1,
+                                kConferenceMaxNumTemporalLayers);
 
     // VP9 denoising is disabled by default.
     vp9_settings.denoisingOn = codec_default_denoising ? true : denoising;
diff --git a/media/engine/webrtc_video_engine_unittest.cc b/media/engine/webrtc_video_engine_unittest.cc
index 339e360c61..5307f63497 100644
--- a/media/engine/webrtc_video_engine_unittest.cc
+++ b/media/engine/webrtc_video_engine_unittest.cc
@@ -3791,14 +3791,6 @@ INSTANTIATE_TEST_SUITE_P(
     Vp9SettingsTestWithFieldTrial,
     Values(
         std::make_tuple("", 1, 1, webrtc::InterLayerPredMode::kOnKeyPic),
-        std::make_tuple("WebRTC-SupportVP9SVC/Default/",
-                        1,
-                        1,
-                        webrtc::InterLayerPredMode::kOnKeyPic),
-        std::make_tuple("WebRTC-SupportVP9SVC/EnabledByFlag_2SL3TL/",
-                        2,
-                        3,
-                        webrtc::InterLayerPredMode::kOnKeyPic),
         std::make_tuple("WebRTC-Vp9InterLayerPred/Default/",
                         1,
                         1,