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/*
* Copyright 2018 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef SHARED_MIXER_H
#define SHARED_MIXER_H
#include <array>
#include "IRenderableAudio.h"
constexpr int32_t kBufferSize = 192*10; // Temporary buffer is used for mixing
constexpr uint8_t kMaxTracks = 100;
/**
* A Mixer object which sums the output from multiple tracks into a single output. The number of
* input channels on each track must match the number of output channels (default 1=mono). This can
* be changed by calling `setChannelCount`.
* The inputs to the mixer are not owned by the mixer, they should not be deleted while rendering.
*/
class Mixer : public IRenderableAudio {
public:
void renderAudio(float *audioData, int32_t numFrames) {
// Zero out the incoming container array
memset(audioData, 0, sizeof(float) * numFrames * mChannelCount);
for (int i = 0; i < mNextFreeTrackIndex; ++i) {
mTracks[i]->renderAudio(mixingBuffer, numFrames);
for (int j = 0; j < numFrames * mChannelCount; ++j) {
audioData[j] += mixingBuffer[j];
}
}
}
void addTrack(IRenderableAudio *renderer){
mTracks[mNextFreeTrackIndex++] = renderer;
}
void setChannelCount(int32_t channelCount){ mChannelCount = channelCount; }
void removeAllTracks(){
for (int i = 0; i < mNextFreeTrackIndex; i++){
mTracks[i] = nullptr;
}
mNextFreeTrackIndex = 0;
}
private:
float mixingBuffer[kBufferSize];
std::array<IRenderableAudio*, kMaxTracks> mTracks;
uint8_t mNextFreeTrackIndex = 0;
int32_t mChannelCount = 1; // Default to mono
};
#endif //SHARED_MIXER_H
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