The Tor Browser: content/media/AudioMixer.h@97036ab72558

Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

     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/. */

     6 #ifndef MOZILLA_AUDIOMIXER_H_

     7 #define MOZILLA_AUDIOMIXER_H_

     9 #include "AudioSampleFormat.h"

    10 #include "nsTArray.h"

    11 #include "mozilla/PodOperations.h"

    13 namespace mozilla {

    14 typedef void(*MixerFunc)(AudioDataValue* aMixedBuffer,

    15                          AudioSampleFormat aFormat,

    16                          uint32_t aChannels,

    17                          uint32_t aFrames,

    18                          uint32_t aSampleRate);

    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   { }

    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   }

    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     }

    66     MOZ_ASSERT(aFrames == mFrames);

    67     MOZ_ASSERT(aChannels == mChannels);

    68     MOZ_ASSERT(aSampleRate == mSampleRate);

    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   }

    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 }

    95 #endif // MOZILLA_AUDIOMIXER_H_

The Tor Browser / file revision

content/media/AudioMixer.h@97036ab72558

content/media/AudioMixer.h