1 /* 2 * Copyright 2018 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 SHARED_MONOTOSTEREO_H 18 #define SHARED_MONOTOSTEREO_H 19 20 #include "IRenderableAudio.h" 21 22 23 class MonoToStereo : public IRenderableAudio { 24 25 public: 26 MonoToStereo(IRenderableAudio * input)27 MonoToStereo(IRenderableAudio *input) : mInput(input){}; 28 renderAudio(float * audioData,int32_t numFrames)29 void renderAudio(float *audioData, int32_t numFrames) override { 30 31 constexpr int kChannelCountStereo = 2; 32 33 mInput->renderAudio(audioData, numFrames); 34 35 // We assume that audioData has sufficient frames to hold the stereo output, so copy each 36 // frame in the input to the output twice, working our way backwards through the input array 37 // e.g. 123 => 112233 38 for (int i = numFrames - 1; i >= 0; --i) { 39 40 audioData[i * kChannelCountStereo] = audioData[i]; 41 audioData[i * kChannelCountStereo + 1] = audioData[i]; 42 } 43 } 44 45 IRenderableAudio *mInput; 46 }; 47 48 49 #endif //SHARED_MONOTOSTEREO_H 50