1 /* 2 * Copyright (c) 2021 The WebRTC project authors. All Rights Reserved. 3 * 4 * Use of this source code is governed by a BSD-style license 5 * that can be found in the LICENSE file in the root of the source 6 * tree. An additional intellectual property rights grant can be found 7 * in the file PATENTS. All contributing project authors may 8 * be found in the AUTHORS file in the root of the source tree. 9 */ 10 11 #ifndef MODULES_AUDIO_PROCESSING_AGC2_CLIPPING_PREDICTOR_H_ 12 #define MODULES_AUDIO_PROCESSING_AGC2_CLIPPING_PREDICTOR_H_ 13 14 #include <memory> 15 #include <vector> 16 17 #include "absl/types/optional.h" 18 #include "modules/audio_processing/include/audio_frame_view.h" 19 #include "modules/audio_processing/include/audio_processing.h" 20 21 namespace webrtc { 22 23 // Frame-wise clipping prediction and clipped level step estimation. Analyzes 24 // 10 ms multi-channel frames and estimates an analog mic level decrease step 25 // to possibly avoid clipping when predicted. `Analyze()` and 26 // `EstimateClippedLevelStep()` can be called in any order. 27 class ClippingPredictor { 28 public: 29 virtual ~ClippingPredictor() = default; 30 31 virtual void Reset() = 0; 32 33 // Analyzes a 10 ms multi-channel audio frame. 34 virtual void Analyze(const AudioFrameView<const float>& frame) = 0; 35 36 // Predicts if clipping is going to occur for the specified `channel` in the 37 // near-future and, if so, it returns a recommended analog mic level decrease 38 // step. Returns absl::nullopt if clipping is not predicted. 39 // `level` is the current analog mic level, `default_step` is the amount the 40 // mic level is lowered by the analog controller with every clipping event and 41 // `min_mic_level` and `max_mic_level` is the range of allowed analog mic 42 // levels. 43 virtual absl::optional<int> EstimateClippedLevelStep( 44 int channel, 45 int level, 46 int default_step, 47 int min_mic_level, 48 int max_mic_level) const = 0; 49 }; 50 51 // Creates a ClippingPredictor based on the provided `config`. When enabled, 52 // the following must hold for `config`: 53 // `window_length < reference_window_length + reference_window_delay`. 54 // Returns `nullptr` if `config.enabled` is false. 55 std::unique_ptr<ClippingPredictor> CreateClippingPredictor( 56 int num_channels, 57 const AudioProcessing::Config::GainController1::AnalogGainController:: 58 ClippingPredictor& config); 59 60 } // namespace webrtc 61 62 #endif // MODULES_AUDIO_PROCESSING_AGC2_CLIPPING_PREDICTOR_H_ 63