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_CAPTURE_LEVELS_ADJUSTER_AUDIO_SAMPLES_SCALER_H_ 12 #define MODULES_AUDIO_PROCESSING_CAPTURE_LEVELS_ADJUSTER_AUDIO_SAMPLES_SCALER_H_ 13 14 #include <stddef.h> 15 16 #include "modules/audio_processing/audio_buffer.h" 17 18 namespace webrtc { 19 20 // Handles and applies a gain to the samples in an audio buffer. 21 // The gain is applied for each sample and any changes in the gain take effect 22 // gradually (in a linear manner) over one frame. 23 class AudioSamplesScaler { 24 public: 25 // C-tor. The supplied `initial_gain` is used immediately at the first call to 26 // Process(), i.e., in contrast to the gain supplied by SetGain(...) there is 27 // no gradual change to the `initial_gain`. 28 explicit AudioSamplesScaler(float initial_gain); 29 AudioSamplesScaler(const AudioSamplesScaler&) = delete; 30 AudioSamplesScaler& operator=(const AudioSamplesScaler&) = delete; 31 32 // Applies the specified gain to the audio in `audio_buffer`. 33 void Process(AudioBuffer& audio_buffer); 34 35 // Sets the gain to apply to each sample. SetGain(float gain)36 void SetGain(float gain) { target_gain_ = gain; } 37 38 private: 39 float previous_gain_ = 1.f; 40 float target_gain_ = 1.f; 41 int samples_per_channel_ = -1; 42 float one_by_samples_per_channel_ = -1.f; 43 }; 44 } // namespace webrtc 45 46 #endif // MODULES_AUDIO_PROCESSING_CAPTURE_LEVELS_ADJUSTER_AUDIO_SAMPLES_SCALER_H_ 47