AEC3: Add multichannel configuration and multichannel detection

The features have two safety fallbacks:
- multichannel config has a killswitch WebRTC-Aec3SetupSpecificDefaultConfigDefaultsKillSwitch
- stereo detection has a killswitch WebRTC-Aec3StereoContentDetectionKillSwitch

Both features are enabled by default in the AEC3 config.

Tested: Bitexact on a large number of aecdumps.
Bug: chromium:1295710
Change-Id: I340cdc9140dacd4ca22d0911eb9f732b6cf8b226
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/258129
Reviewed-by: Per Åhgren <peah@webrtc.org>
Commit-Queue: Sam Zackrisson <saza@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#36482}

api/audio/echo_canceller3_config.h

@@ -236,6 +236,11 @@ struct RTC_EXPORT EchoCanceller3Config {
     float floor_first_increase = 0.00001f;
     bool conservative_hf_suppression = false;
   } suppressor;
+
+  struct MultiChannel {
+    bool detect_stereo_content = true;
+    float stereo_detection_threshold = 0.0f;
+  } multi_channel;
 };
 }  // namespace webrtc
 

api/audio/echo_canceller3_config_json.cc

@@ -415,6 +415,13 @@ void Aec3ConfigFromJsonString(absl::string_view json_string,
     ReadParam(section, "conservative_hf_suppression",
               &cfg.suppressor.conservative_hf_suppression);
   }
+
+  if (rtc::GetValueFromJsonObject(aec3_root, "multi_channel", &section)) {
+    ReadParam(section, "detect_stereo_content",
+              &cfg.multi_channel.detect_stereo_content);
+    ReadParam(section, "stereo_detection_threshold",
+              &cfg.multi_channel.stereo_detection_threshold);
+  }
 }
 
 EchoCanceller3Config Aec3ConfigFromJsonString(absl::string_view json_string) {
@@ -574,7 +581,8 @@ std::string Aec3ConfigToJsonString(const EchoCanceller3Config& config) {
   ost << "\"erle_onset_compensation_in_dominant_nearend\": "
       << (config.ep_strength.erle_onset_compensation_in_dominant_nearend
               ? "true"
-              : "false") << ",";
+              : "false")
+      << ",";
   ost << "\"use_conservative_tail_frequency_response\": "
       << (config.ep_strength.use_conservative_tail_frequency_response
               ? "true"
@@ -736,7 +744,15 @@ std::string Aec3ConfigToJsonString(const EchoCanceller3Config& config) {
       << ",";
   ost << "\"conservative_hf_suppression\": "
       << config.suppressor.conservative_hf_suppression;
+  ost << "},";
+
+  ost << "\"multi_channel\": {";
+  ost << "\"detect_stereo_content\": "
+      << (config.multi_channel.detect_stereo_content ? "true" : "false") << ",";
+  ost << "\"stereo_detection_threshold\": "
+      << config.multi_channel.stereo_detection_threshold;
   ost << "}";
+
   ost << "}";
   ost << "}";
 

api/audio/echo_canceller3_factory.cc

@@ -25,7 +25,8 @@ std::unique_ptr<EchoControl> EchoCanceller3Factory::Create(
     int num_render_channels,
     int num_capture_channels) {
   return std::make_unique<EchoCanceller3>(
-      config_, sample_rate_hz, num_render_channels, num_capture_channels);
+      config_, /*multichannel_config=*/absl::nullopt, sample_rate_hz,
+      num_render_channels, num_capture_channels);
 }
 
 }  // namespace webrtc

api/audio/test/echo_canceller3_config_json_unittest.cc

@@ -31,6 +31,10 @@ TEST(EchoCanceller3JsonHelpers, ToStringAndParseJson) {
   cfg.suppressor.subband_nearend_detection.subband1 = {4, 5};
   cfg.suppressor.subband_nearend_detection.nearend_threshold = 2.f;
   cfg.suppressor.subband_nearend_detection.snr_threshold = 100.f;
+  cfg.multi_channel.detect_stereo_content =
+      !cfg.multi_channel.detect_stereo_content;
+  cfg.multi_channel.stereo_detection_threshold =
+      cfg.multi_channel.stereo_detection_threshold + 1.0f;
   std::string json_string = Aec3ConfigToJsonString(cfg);
   EchoCanceller3Config cfg_transformed = Aec3ConfigFromJsonString(json_string);
 
@@ -75,5 +79,9 @@ TEST(EchoCanceller3JsonHelpers, ToStringAndParseJson) {
       cfg_transformed.suppressor.subband_nearend_detection.nearend_threshold);
   EXPECT_EQ(cfg.suppressor.subband_nearend_detection.snr_threshold,
             cfg_transformed.suppressor.subband_nearend_detection.snr_threshold);
+  EXPECT_EQ(cfg.multi_channel.detect_stereo_content,
+            cfg_transformed.multi_channel.detect_stereo_content);
+  EXPECT_EQ(cfg.multi_channel.stereo_detection_threshold,
+            cfg_transformed.multi_channel.stereo_detection_threshold);
 }
 }  // namespace webrtc