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}

modules/audio_processing/aec3/config_selector_unittest.cc

@@ -0,0 +1,116 @@
+/*
+ *  Copyright (c) 2022 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/audio_processing/aec3/config_selector.h"
+
+#include <tuple>
+
+#include "absl/types/optional.h"
+#include "api/audio/echo_canceller3_config.h"
+#include "test/gtest.h"
+
+namespace webrtc {
+
+class ConfigSelectorChannelsAndContentDetection
+    : public ::testing::Test,
+      public ::testing::WithParamInterface<std::tuple<int, bool>> {};
+
+INSTANTIATE_TEST_SUITE_P(ConfigSelectorMultiParameters,
+                         ConfigSelectorChannelsAndContentDetection,
+                         ::testing::Combine(::testing::Values(1, 2, 8),
+                                            ::testing::Values(false, true)));
+
+class ConfigSelectorChannels : public ::testing::Test,
+                               public ::testing::WithParamInterface<int> {};
+
+INSTANTIATE_TEST_SUITE_P(ConfigSelectorMultiParameters,
+                         ConfigSelectorChannels,
+                         ::testing::Values(1, 2, 8));
+
+TEST_P(ConfigSelectorChannelsAndContentDetection,
+       MonoConfigIsSelectedWhenNoMultiChannelConfigPresent) {
+  const auto [num_channels, detect_stereo_content] = GetParam();
+  EchoCanceller3Config config;
+  config.multi_channel.detect_stereo_content = detect_stereo_content;
+  absl::optional<EchoCanceller3Config> multichannel_config;
+
+  config.delay.default_delay = config.delay.default_delay + 1;
+  const size_t custom_delay_value_in_config = config.delay.default_delay;
+
+  ConfigSelector cs(config, multichannel_config,
+                    /*num_render_input_channels=*/num_channels);
+  EXPECT_EQ(cs.active_config().delay.default_delay,
+            custom_delay_value_in_config);
+
+  cs.Update(/*multichannel_content=*/false);
+  EXPECT_EQ(cs.active_config().delay.default_delay,
+            custom_delay_value_in_config);
+
+  cs.Update(/*multichannel_content=*/true);
+  EXPECT_EQ(cs.active_config().delay.default_delay,
+            custom_delay_value_in_config);
+}
+
+TEST_P(ConfigSelectorChannelsAndContentDetection,
+       CorrectInitialConfigIsSelected) {
+  const auto [num_channels, detect_stereo_content] = GetParam();
+  EchoCanceller3Config config;
+  config.multi_channel.detect_stereo_content = detect_stereo_content;
+  absl::optional<EchoCanceller3Config> multichannel_config = config;
+
+  config.delay.default_delay += 1;
+  const size_t custom_delay_value_in_config = config.delay.default_delay;
+  multichannel_config->delay.default_delay += 2;
+  const size_t custom_delay_value_in_multichannel_config =
+      multichannel_config->delay.default_delay;
+
+  ConfigSelector cs(config, multichannel_config,
+                    /*num_render_input_channels=*/num_channels);
+
+  if (num_channels == 1 || detect_stereo_content) {
+    EXPECT_EQ(cs.active_config().delay.default_delay,
+              custom_delay_value_in_config);
+  } else {
+    EXPECT_EQ(cs.active_config().delay.default_delay,
+              custom_delay_value_in_multichannel_config);
+  }
+}
+
+TEST_P(ConfigSelectorChannels, CorrectConfigUpdateBehavior) {
+  const int num_channels = GetParam();
+  EchoCanceller3Config config;
+  config.multi_channel.detect_stereo_content = true;
+  absl::optional<EchoCanceller3Config> multichannel_config = config;
+
+  config.delay.default_delay += 1;
+  const size_t custom_delay_value_in_config = config.delay.default_delay;
+  multichannel_config->delay.default_delay += 2;
+  const size_t custom_delay_value_in_multichannel_config =
+      multichannel_config->delay.default_delay;
+
+  ConfigSelector cs(config, multichannel_config,
+                    /*num_render_input_channels=*/num_channels);
+
+  cs.Update(/*multichannel_content=*/false);
+  EXPECT_EQ(cs.active_config().delay.default_delay,
+            custom_delay_value_in_config);
+
+  if (num_channels == 1) {
+    cs.Update(/*multichannel_content=*/false);
+    EXPECT_EQ(cs.active_config().delay.default_delay,
+              custom_delay_value_in_config);
+  } else {
+    cs.Update(/*multichannel_content=*/true);
+    EXPECT_EQ(cs.active_config().delay.default_delay,
+              custom_delay_value_in_multichannel_config);
+  }
+}
+
+}  // namespace webrtc