1 /* 2 * Copyright 2022 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #ifndef FLOWGRAPH_WHITE_NOISE_H 18 #define FLOWGRAPH_WHITE_NOISE_H 19 20 #include <unistd.h> 21 22 #include "flowgraph/FlowGraphNode.h" 23 24 #include "../analyzer/PseudoRandom.h" 25 26 /** 27 * White noise with equal energy in all frequencies up to the Nyquist. 28 * This is a based on random numbers with a uniform distribution. 29 */ 30 class WhiteNoise : public oboe::flowgraph::FlowGraphNode { 31 public: 32 WhiteNoise()33 WhiteNoise() 34 : oboe::flowgraph::FlowGraphNode() 35 , amplitude(*this, 1) 36 , output(*this, 1) 37 { 38 } 39 40 virtual ~WhiteNoise() = default; 41 42 int32_t onProcess(int32_t numFrames) override; 43 44 /** 45 * Control the amplitude amplitude of the noise. 46 * Silence is 0.0. 47 * A typical full amplitude would be 1.0. 48 */ 49 oboe::flowgraph::FlowGraphPortFloatInput amplitude; 50 51 oboe::flowgraph::FlowGraphPortFloatOutput output; 52 53 private: 54 PseudoRandom mPseudoRandom; 55 }; 56 57 #endif //FLOWGRAPH_WHITE_NOISE_H 58