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