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comparison: content/media/AudioMixer.h
content/media/AudioMixer.h
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- TOR_BUG_9701
- changeset 8
- 97036ab72558
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| -1:000000000000 | 0:6880996d8e70 |
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| 1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ | |
| 2 /* This Source Code Form is subject to the terms of the Mozilla Public | |
| 3 * License, v. 2.0. If a copy of the MPL was not distributed with this file, | |
| 4 * You can obtain one at http://mozilla.org/MPL/2.0/. */ | |
| 5 | |
| 6 #ifndef MOZILLA_AUDIOMIXER_H_ | |
| 7 #define MOZILLA_AUDIOMIXER_H_ | |
| 8 | |
| 9 #include "AudioSampleFormat.h" | |
| 10 #include "nsTArray.h" | |
| 11 #include "mozilla/PodOperations.h" | |
| 12 | |
| 13 namespace mozilla { | |
| 14 typedef void(*MixerFunc)(AudioDataValue* aMixedBuffer, | |
| 15 AudioSampleFormat aFormat, | |
| 16 uint32_t aChannels, | |
| 17 uint32_t aFrames, | |
| 18 uint32_t aSampleRate); | |
| 19 | |
| 20 /** | |
| 21 * This class mixes multiple streams of audio together to output a single audio | |
| 22 * stream. | |
| 23 * | |
| 24 * AudioMixer::Mix is to be called repeatedly with buffers that have the same | |
| 25 * length, sample rate, sample format and channel count. | |
| 26 * | |
| 27 * When all the tracks have been mixed, calling FinishMixing will call back with | |
| 28 * a buffer containing the mixed audio data. | |
| 29 * | |
| 30 * This class is not thread safe. | |
| 31 */ | |
| 32 class AudioMixer | |
| 33 { | |
| 34 public: | |
| 35 AudioMixer(MixerFunc aCallback) | |
| 36 : mCallback(aCallback), | |
| 37 mFrames(0), | |
| 38 mChannels(0), | |
| 39 mSampleRate(0) | |
| 40 { } | |
| 41 | |
| 42 /* Get the data from the mixer. This is supposed to be called when all the | |
| 43 * tracks have been mixed in. The caller should not hold onto the data. */ | |
| 44 void FinishMixing() { | |
| 45 mCallback(mMixedAudio.Elements(), | |
| 46 AudioSampleTypeToFormat<AudioDataValue>::Format, | |
| 47 mChannels, | |
| 48 mFrames, | |
| 49 mSampleRate); | |
| 50 PodZero(mMixedAudio.Elements(), mMixedAudio.Length()); | |
| 51 mSampleRate = mChannels = mFrames = 0; | |
| 52 } | |
| 53 | |
| 54 /* Add a buffer to the mix. aSamples is interleaved. */ | |
| 55 void Mix(AudioDataValue* aSamples, | |
| 56 uint32_t aChannels, | |
| 57 uint32_t aFrames, | |
| 58 uint32_t aSampleRate) { | |
| 59 if (!mFrames && !mChannels) { | |
| 60 mFrames = aFrames; | |
| 61 mChannels = aChannels; | |
| 62 mSampleRate = aSampleRate; | |
| 63 EnsureCapacityAndSilence(); | |
| 64 } | |
| 65 | |
| 66 MOZ_ASSERT(aFrames == mFrames); | |
| 67 MOZ_ASSERT(aChannels == mChannels); | |
| 68 MOZ_ASSERT(aSampleRate == mSampleRate); | |
| 69 | |
| 70 for (uint32_t i = 0; i < aFrames * aChannels; i++) { | |
| 71 mMixedAudio[i] += aSamples[i]; | |
| 72 } | |
| 73 } | |
| 74 private: | |
| 75 void EnsureCapacityAndSilence() { | |
| 76 if (mFrames * mChannels > mMixedAudio.Length()) { | |
| 77 mMixedAudio.SetLength(mFrames* mChannels); | |
| 78 } | |
| 79 PodZero(mMixedAudio.Elements(), mMixedAudio.Length()); | |
| 80 } | |
| 81 | |
| 82 /* Function that is called when the mixing is done. */ | |
| 83 MixerFunc mCallback; | |
| 84 /* Number of frames for this mixing block. */ | |
| 85 uint32_t mFrames; | |
| 86 /* Number of channels for this mixing block. */ | |
| 87 uint32_t mChannels; | |
| 88 /* Sample rate the of the mixed data. */ | |
| 89 uint32_t mSampleRate; | |
| 90 /* Buffer containing the mixed audio data. */ | |
| 91 nsTArray<AudioDataValue> mMixedAudio; | |
| 92 }; | |
| 93 } | |
| 94 | |
| 95 #endif // MOZILLA_AUDIOMIXER_H_ |
