AGC2: max output noise level now part of config

Tested: bit-exactness verified with audioproc_f

Bug: webrtc:7494
Change-Id: Ic42f09dc13560494963cdcd338a0c52a729e108d
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/186266
Commit-Queue: Alessio Bazzica <alessiob@webrtc.org>
Reviewed-by: Jakob Ivarsson <jakobi@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#32282}

modules/audio_processing/agc2/adaptive_agc.cc

@@ -30,6 +30,7 @@ void DumpDebugData(const AdaptiveDigitalGainApplier::FrameInfo& info,
 
 constexpr int kGainApplierAdjacentSpeechFramesThreshold = 1;
 constexpr float kMaxGainChangePerSecondDb = 3.f;
+constexpr float kMaxOutputNoiseLevelDbfs = -50.f;
 
 }  // namespace
 
@@ -37,7 +38,8 @@ AdaptiveAgc::AdaptiveAgc(ApmDataDumper* apm_data_dumper)
     : speech_level_estimator_(apm_data_dumper),
       gain_applier_(apm_data_dumper,
                     kGainApplierAdjacentSpeechFramesThreshold,
-                    kMaxGainChangePerSecondDb),
+                    kMaxGainChangePerSecondDb,
+                    kMaxOutputNoiseLevelDbfs),
       apm_data_dumper_(apm_data_dumper),
       noise_level_estimator_(apm_data_dumper) {
   RTC_DCHECK(apm_data_dumper);
@@ -56,7 +58,8 @@ AdaptiveAgc::AdaptiveAgc(ApmDataDumper* apm_data_dumper,
       gain_applier_(
           apm_data_dumper,
           config.adaptive_digital.gain_applier_adjacent_speech_frames_threshold,
-          config.adaptive_digital.max_gain_change_db_per_second),
+          config.adaptive_digital.max_gain_change_db_per_second,
+          config.adaptive_digital.max_output_noise_level_dbfs),
       apm_data_dumper_(apm_data_dumper),
       noise_level_estimator_(apm_data_dumper) {
   RTC_DCHECK(apm_data_dumper);

modules/audio_processing/agc2/adaptive_digital_gain_applier.cc

@@ -44,12 +44,16 @@ float ComputeGainDb(float input_level_dbfs) {
   return 0.f;
 }
 
-// We require 'gain + noise_level <= kMaxNoiseLevelDbfs'.
+// Returns `target_gain` if the output noise level is below
+// `max_output_noise_level_dbfs`; otherwise returns a capped gain so that the
+// output noise level equals `max_output_noise_level_dbfs`.
 float LimitGainByNoise(float target_gain,
                        float input_noise_level_dbfs,
-                       ApmDataDumper* apm_data_dumper) {
+                       float max_output_noise_level_dbfs,
-  const float noise_headroom_db = kMaxNoiseLevelDbfs - input_noise_level_dbfs;
+                       ApmDataDumper& apm_data_dumper) {
-  apm_data_dumper->DumpRaw("agc2_noise_headroom_db", noise_headroom_db);
+  const float noise_headroom_db =
+      max_output_noise_level_dbfs - input_noise_level_dbfs;
+  apm_data_dumper.DumpRaw("agc2_noise_headroom_db", noise_headroom_db);
   return std::min(target_gain, std::max(noise_headroom_db, 0.f));
 }
 
@@ -89,7 +93,8 @@ float ComputeGainChangeThisFrameDb(float target_gain_db,
 AdaptiveDigitalGainApplier::AdaptiveDigitalGainApplier(
     ApmDataDumper* apm_data_dumper,
     int adjacent_speech_frames_threshold,
-    float max_gain_change_db_per_second)
+    float max_gain_change_db_per_second,
+    float max_output_noise_level_dbfs)
     : apm_data_dumper_(apm_data_dumper),
       gain_applier_(
           /*hard_clip_samples=*/false,
@@ -97,11 +102,14 @@ AdaptiveDigitalGainApplier::AdaptiveDigitalGainApplier(
       adjacent_speech_frames_threshold_(adjacent_speech_frames_threshold),
       max_gain_change_db_per_10ms_(max_gain_change_db_per_second *
                                    kFrameDurationMs / 1000.f),
+      max_output_noise_level_dbfs_(max_output_noise_level_dbfs),
       calls_since_last_gain_log_(0),
       frames_to_gain_increase_allowed_(adjacent_speech_frames_threshold_),
       last_gain_db_(kInitialAdaptiveDigitalGainDb) {
   RTC_DCHECK_GT(max_gain_change_db_per_second, 0.f);
   RTC_DCHECK_GE(frames_to_gain_increase_allowed_, 1);
+  RTC_DCHECK_GE(max_output_noise_level_dbfs_, -90.f);
+  RTC_DCHECK_LE(max_output_noise_level_dbfs_, 0.f);
 }
 
 void AdaptiveDigitalGainApplier::Process(const FrameInfo& info,
@@ -126,7 +134,8 @@ void AdaptiveDigitalGainApplier::Process(const FrameInfo& info,
 
   const float target_gain_db = LimitGainByLowConfidence(
       LimitGainByNoise(ComputeGainDb(std::min(info.input_level_dbfs, 0.f)),
-                       info.input_noise_level_dbfs, apm_data_dumper_),
+                       info.input_noise_level_dbfs,
+                       max_output_noise_level_dbfs_, *apm_data_dumper_),
       last_gain_db_, info.limiter_envelope_dbfs, info.estimate_is_confident);
 
   // Forbid increasing the gain until enough adjacent speech frames are

modules/audio_processing/agc2/adaptive_digital_gain_applier.h

@@ -34,12 +34,15 @@ class AdaptiveDigitalGainApplier {
     bool estimate_is_confident;
   };
 
+  // Ctor.
   // `adjacent_speech_frames_threshold` indicates how many speech frames are
   // required before a gain increase is allowed. `max_gain_change_db_per_second`
   // limits the adaptation speed (uniformly operated across frames).
+  // `max_output_noise_level_dbfs` limits the output noise level.
   AdaptiveDigitalGainApplier(ApmDataDumper* apm_data_dumper,
                              int adjacent_speech_frames_threshold,
-                             float max_gain_change_db_per_second);
+                             float max_gain_change_db_per_second,
+                             float max_output_noise_level_dbfs);
   AdaptiveDigitalGainApplier(const AdaptiveDigitalGainApplier&) = delete;
   AdaptiveDigitalGainApplier& operator=(const AdaptiveDigitalGainApplier&) =
       delete;
@@ -54,6 +57,7 @@ class AdaptiveDigitalGainApplier {
 
   const int adjacent_speech_frames_threshold_;
   const float max_gain_change_db_per_10ms_;
+  const float max_output_noise_level_dbfs_;
 
   int calls_since_last_gain_log_;
   int frames_to_gain_increase_allowed_;

modules/audio_processing/agc2/adaptive_digital_gain_applier_unittest.cc

@@ -36,14 +36,18 @@ constexpr VadLevelAnalyzer::Result kVadSpeech{1.f, -20.f, 0.f};
 constexpr float kMaxGainChangePerSecondDb = 3.f;
 constexpr float kMaxGainChangePerFrameDb =
     kMaxGainChangePerSecondDb * kFrameDurationMs / 1000.f;
+constexpr float kMaxOutputNoiseLevelDbfs = -50.f;
 
 // Helper to instance `AdaptiveDigitalGainApplier`.
 struct GainApplierHelper {
   GainApplierHelper()
+      : GainApplierHelper(/*adjacent_speech_frames_threshold=*/1) {}
+  explicit GainApplierHelper(int adjacent_speech_frames_threshold)
       : apm_data_dumper(0),
         gain_applier(&apm_data_dumper,
-                     /*adjacent_speech_frames_threshold=*/1,
+                     adjacent_speech_frames_threshold,
-                     kMaxGainChangePerSecondDb) {}
+                     kMaxGainChangePerSecondDb,
+                     kMaxOutputNoiseLevelDbfs) {}
   ApmDataDumper apm_data_dumper;
   AdaptiveDigitalGainApplier gain_applier;
 };
@@ -185,7 +189,8 @@ TEST(AutomaticGainController2AdaptiveGainApplier, NoiseLimitsGain) {
       kInitialAdaptiveDigitalGainDb / kMaxGainChangePerFrameDb;
   constexpr int num_frames = 50;
 
-  ASSERT_GT(kWithNoiseDbfs, kMaxNoiseLevelDbfs) << "kWithNoiseDbfs is too low";
+  ASSERT_GT(kWithNoiseDbfs, kMaxOutputNoiseLevelDbfs)
+      << "kWithNoiseDbfs is too low";
 
   for (int i = 0; i < num_initial_frames + num_frames; ++i) {
     VectorFloatFrame fake_audio(kMono, kFrameLen10ms48kHz, 1.f);
@@ -223,7 +228,8 @@ TEST(AutomaticGainController2GainApplier, AudioLevelLimitsGain) {
       kInitialAdaptiveDigitalGainDb / kMaxGainChangePerFrameDb;
   constexpr int num_frames = 50;
 
-  ASSERT_GT(kWithNoiseDbfs, kMaxNoiseLevelDbfs) << "kWithNoiseDbfs is too low";
+  ASSERT_GT(kWithNoiseDbfs, kMaxOutputNoiseLevelDbfs)
+      << "kWithNoiseDbfs is too low";
 
   for (int i = 0; i < num_initial_frames + num_frames; ++i) {
     VectorFloatFrame fake_audio(kMono, kFrameLen10ms48kHz, 1.f);
@@ -252,10 +258,8 @@ class AdaptiveDigitalGainApplierTest : public ::testing::TestWithParam<int> {
 TEST_P(AdaptiveDigitalGainApplierTest,
        DoNotIncreaseGainWithTooFewSpeechFrames) {
   const int adjacent_speech_frames_threshold = AdjacentSpeechFramesThreshold();
-  ApmDataDumper apm_data_dumper(0);
+  GainApplierHelper helper(adjacent_speech_frames_threshold);
-  AdaptiveDigitalGainApplier gain_applier(&apm_data_dumper,
+
-                                          adjacent_speech_frames_threshold,
-                                          kMaxGainChangePerFrameDb);
   AdaptiveDigitalGainApplier::FrameInfo info = kFrameInfo;
   info.input_level_dbfs = -25.0;
 
@@ -263,7 +267,7 @@ TEST_P(AdaptiveDigitalGainApplierTest,
   for (int i = 0; i < adjacent_speech_frames_threshold; ++i) {
     SCOPED_TRACE(i);
     VectorFloatFrame audio(kMono, kFrameLen10ms48kHz, 1.f);
-    gain_applier.Process(info, audio.float_frame_view());
+    helper.gain_applier.Process(info, audio.float_frame_view());
     const float gain = audio.float_frame_view().channel(0)[0];
     if (i > 0) {
       EXPECT_EQ(prev_gain, gain);  // No gain increase.
@@ -274,23 +278,21 @@ TEST_P(AdaptiveDigitalGainApplierTest,
 
 TEST_P(AdaptiveDigitalGainApplierTest, IncreaseGainWithEnoughSpeechFrames) {
   const int adjacent_speech_frames_threshold = AdjacentSpeechFramesThreshold();
-  ApmDataDumper apm_data_dumper(0);
+  GainApplierHelper helper(adjacent_speech_frames_threshold);
-  AdaptiveDigitalGainApplier gain_applier(&apm_data_dumper,
+
-                                          adjacent_speech_frames_threshold,
-                                          kMaxGainChangePerFrameDb);
   AdaptiveDigitalGainApplier::FrameInfo info = kFrameInfo;
   info.input_level_dbfs = -25.0;
 
   float prev_gain = 0.f;
   for (int i = 0; i < adjacent_speech_frames_threshold; ++i) {
     VectorFloatFrame audio(kMono, kFrameLen10ms48kHz, 1.f);
-    gain_applier.Process(info, audio.float_frame_view());
+    helper.gain_applier.Process(info, audio.float_frame_view());
     prev_gain = audio.float_frame_view().channel(0)[0];
   }
 
   // Process one more speech frame.
   VectorFloatFrame audio(kMono, kFrameLen10ms48kHz, 1.f);
-  gain_applier.Process(info, audio.float_frame_view());
+  helper.gain_applier.Process(info, audio.float_frame_view());
 
   // The gain has increased.
   EXPECT_GT(audio.float_frame_view().channel(0)[0], prev_gain);

modules/audio_processing/agc2/agc2_common.h

@@ -32,9 +32,6 @@ constexpr float kInitialAdaptiveDigitalGainDb = 8.f;
 // At what limiter levels should we start decreasing the adaptive digital gain.
 constexpr float kLimiterThresholdForAgcGainDbfs = -kHeadroomDbfs;
 
-// This parameter must be tuned together with the noise estimator.
-constexpr float kMaxNoiseLevelDbfs = -50.f;
-
 // This is the threshold for speech. Speech frames are used for updating the
 // speech level, measuring the amount of speech, and decide when to allow target
 // gain reduction.

modules/audio_processing/include/audio_processing.h

@@ -354,6 +354,7 @@ class RTC_EXPORT AudioProcessing : public rtc::RefCountInterface {
         float extra_saturation_margin_db = 2.f;
         int gain_applier_adjacent_speech_frames_threshold = 1;
         float max_gain_change_db_per_second = 3.f;
+        float max_output_noise_level_dbfs = -50.f;
       } adaptive_digital;
     } gain_controller2;