/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ /* This Source Code Form is subject to the terms of the Mozilla Public * License, v. 2.0. If a copy of the MPL was not distributed with this file, * You can obtain one at http://mozilla.org/MPL/2.0/. */ #ifndef MOZILLA_AUDIOMIXER_H_ #define MOZILLA_AUDIOMIXER_H_ #include "AudioSampleFormat.h" #include "nsTArray.h" #include "mozilla/PodOperations.h" #include "mozilla/LinkedList.h" #include "AudioStream.h" namespace mozilla { struct MixerCallbackReceiver { virtual void MixerCallback(AudioDataValue* aMixedBuffer, AudioSampleFormat aFormat, uint32_t aChannels, uint32_t aFrames, uint32_t aSampleRate) = 0; }; /** * This class mixes multiple streams of audio together to output a single audio * stream. * * AudioMixer::Mix is to be called repeatedly with buffers that have the same * length, sample rate, sample format and channel count. This class works with * interleaved and plannar buffers, but the buffer mixed must be of the same * type during a mixing cycle. * * When all the tracks have been mixed, calling FinishMixing will call back with * a buffer containing the mixed audio data. * * This class is not thread safe. */ class AudioMixer { public: AudioMixer() : mFrames(0), mChannels(0), mSampleRate(0) { } ~AudioMixer() { MixerCallback* cb; while ((cb = mCallbacks.popFirst())) { delete cb; } } void StartMixing() { mSampleRate = mChannels = mFrames = 0; } /* Get the data from the mixer. This is supposed to be called when all the * tracks have been mixed in. The caller should not hold onto the data. */ void FinishMixing() { MOZ_ASSERT(mChannels && mFrames && mSampleRate, "Mix not called for this cycle?"); for (MixerCallback* cb = mCallbacks.getFirst(); cb != nullptr; cb = cb->getNext()) { cb->mReceiver->MixerCallback(mMixedAudio.Elements(), AudioSampleTypeToFormat<AudioDataValue>::Format, mChannels, mFrames, mSampleRate); } PodZero(mMixedAudio.Elements(), mMixedAudio.Length()); mSampleRate = mChannels = mFrames = 0; } /* Add a buffer to the mix. */ void Mix(AudioDataValue* aSamples, uint32_t aChannels, uint32_t aFrames, uint32_t aSampleRate) { if (!mFrames && !mChannels) { mFrames = aFrames; mChannels = aChannels; mSampleRate = aSampleRate; EnsureCapacityAndSilence(); } MOZ_ASSERT(aFrames == mFrames); MOZ_ASSERT(aChannels == mChannels); MOZ_ASSERT(aSampleRate == mSampleRate); for (uint32_t i = 0; i < aFrames * aChannels; i++) { mMixedAudio[i] += aSamples[i]; } } void AddCallback(MixerCallbackReceiver* aReceiver) { mCallbacks.insertBack(new MixerCallback(aReceiver)); } bool FindCallback(MixerCallbackReceiver* aReceiver) { for (MixerCallback* cb = mCallbacks.getFirst(); cb != nullptr; cb = cb->getNext()) { if (cb->mReceiver == aReceiver) { return true; } } return false; } bool RemoveCallback(MixerCallbackReceiver* aReceiver) { for (MixerCallback* cb = mCallbacks.getFirst(); cb != nullptr; cb = cb->getNext()) { if (cb->mReceiver == aReceiver) { cb->remove(); delete cb; return true; } } return false; } private: void EnsureCapacityAndSilence() { if (mFrames * mChannels > mMixedAudio.Length()) { mMixedAudio.SetLength(mFrames* mChannels); } PodZero(mMixedAudio.Elements(), mMixedAudio.Length()); } class MixerCallback : public LinkedListElement<MixerCallback> { public: explicit MixerCallback(MixerCallbackReceiver* aReceiver) : mReceiver(aReceiver) { } MixerCallbackReceiver* mReceiver; }; /* Function that is called when the mixing is done. */ LinkedList<MixerCallback> mCallbacks; /* Number of frames for this mixing block. */ uint32_t mFrames; /* Number of channels for this mixing block. */ uint32_t mChannels; /* Sample rate the of the mixed data. */ uint32_t mSampleRate; /* Buffer containing the mixed audio data. */ nsTArray<AudioDataValue> mMixedAudio; }; } // namespace mozilla #endif // MOZILLA_AUDIOMIXER_H_