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