Source/WebCore/platform/audio/ios/AudioOutputUnitAdaptorIOS.cpp

/*
 * Copyright (C) 2010 Google Inc. All rights reserved.
 * Copyright (C) 2011, 2014, 2020 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
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 *     notice, this list of conditions and the following disclaimer.
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 *     from this software without specific prior written permission.
 *
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#include "config.h"
#include "AudioOutputUnitAdaptor.h"

#if ENABLE(WEB_AUDIO) && PLATFORM(IOS_FAMILY)

#include "AudioSession.h"
#include <pal/cf/AudioToolboxSoftLink.h>

namespace WebCore {

void AudioOutputUnitAdaptor::configure(float hardwareSampleRate, unsigned numberOfOutputChannels)
{
    const int kPreferredBufferSize = 256;

    // Open and initialize DefaultOutputUnit
    AudioComponent comp;
    AudioComponentDescription desc;

    desc.componentType = kAudioUnitType_Output;
    desc.componentSubType = kAudioUnitSubType_RemoteIO;
    desc.componentManufacturer = kAudioUnitManufacturer_Apple;
    desc.componentFlags = 0;
    desc.componentFlagsMask = 0;
    comp = PAL::AudioComponentFindNext(0, &desc);

    ASSERT(comp);

    OSStatus result = PAL::AudioComponentInstanceNew(comp, &m_outputUnit);
    ASSERT(!result);

    UInt32 flag = 1;
    result = PAL::AudioUnitSetProperty(m_outputUnit,
        kAudioOutputUnitProperty_EnableIO,
        kAudioUnitScope_Output,
        0,
        &flag,
        sizeof(flag));
    ASSERT(!result);

    result = PAL::AudioUnitInitialize(m_outputUnit);
    ASSERT(!result);
    // Set render callback
    AURenderCallbackStruct input;
    input.inputProc = inputProc;
    input.inputProcRefCon = this;
    result = PAL::AudioUnitSetProperty(m_outputUnit, kAudioUnitProperty_SetRenderCallback, kAudioUnitScope_Input, 0, &input, sizeof(input));
    ASSERT(!result);

    // Set stream format
    AudioStreamBasicDescription streamFormat;

    UInt32 size = sizeof(AudioStreamBasicDescription);
    result = PAL::AudioUnitGetProperty(m_outputUnit, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Output, 0, (void*)&streamFormat, &size);
    ASSERT(!result);

    constexpr int bytesPerFloat = sizeof(Float32);
    constexpr int bitsPerByte = 8;
    streamFormat.mSampleRate = hardwareSampleRate;
    streamFormat.mFormatID = kAudioFormatLinearPCM;
    streamFormat.mFormatFlags = kAudioFormatFlagsNativeFloatPacked | kAudioFormatFlagIsNonInterleaved;
    streamFormat.mBytesPerPacket = bytesPerFloat;
    streamFormat.mFramesPerPacket = 1;
    streamFormat.mBytesPerFrame = bytesPerFloat;
    streamFormat.mChannelsPerFrame = numberOfOutputChannels;
    streamFormat.mBitsPerChannel = bitsPerByte * bytesPerFloat;

    result = PAL::AudioUnitSetProperty(m_outputUnit, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Input, 0, (void*)&streamFormat, sizeof(AudioStreamBasicDescription));
    ASSERT(!result);

    AudioSession::sharedSession().setPreferredBufferSize(kPreferredBufferSize);
}

} // namespace WebCore

#endif // ENABLE(WEB_AUDIO) && PLATFORM(IOS_FAMILY)