Source/WebCore/platform/audio/cocoa/WebAudioBufferList.cpp

/*
 * Copyright (C) 2017 Apple Inc. All rights reserved.
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 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
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 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
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#include "config.h"
#include "WebAudioBufferList.h"

#include "CAAudioStreamDescription.h"
#include <pal/cf/CoreMediaSoftLink.h>

namespace WebCore {
using namespace PAL;

WebAudioBufferList::WebAudioBufferList(const CAAudioStreamDescription& format)
{
    // AudioBufferList is a variable-length struct, so create on the heap with a generic new() operator
    // with a custom size, and initialize the struct manually.
    uint32_t bufferCount = format.numberOfChannelStreams();
    uint32_t channelCount = format.numberOfInterleavedChannels();

    uint64_t bufferListSize = offsetof(AudioBufferList, mBuffers) + (sizeof(AudioBuffer) * std::max(1U, bufferCount));
    ASSERT(bufferListSize <= SIZE_MAX);

    m_listBufferSize = static_cast<size_t>(bufferListSize);
    m_canonicalList = std::unique_ptr<AudioBufferList>(static_cast<AudioBufferList*>(::operator new (m_listBufferSize)));
    memset(m_canonicalList.get(), 0, m_listBufferSize);
    m_canonicalList->mNumberBuffers = bufferCount;
    for (uint32_t buffer = 0; buffer < bufferCount; ++buffer)
        m_canonicalList->mBuffers[buffer].mNumberChannels = channelCount;

    reset();
}

WebAudioBufferList::WebAudioBufferList(const CAAudioStreamDescription& format, uint32_t sampleCount)
    : WebAudioBufferList(format)
{
    if (!sampleCount)
        return;

    uint32_t bufferCount = format.numberOfChannelStreams();
    uint32_t channelCount = format.numberOfInterleavedChannels();

    size_t bytesPerBuffer = sampleCount * channelCount * format.bytesPerFrame();
    m_flatBuffer.reserveInitialCapacity(bufferCount * bytesPerBuffer);
    auto data = m_flatBuffer.data();

    for (uint32_t buffer = 0; buffer < m_canonicalList->mNumberBuffers; ++buffer) {
        m_canonicalList->mBuffers[buffer].mData = data;
        m_canonicalList->mBuffers[buffer].mDataByteSize = bytesPerBuffer;
        data += bytesPerBuffer;
    }

    reset();
}

WebAudioBufferList::WebAudioBufferList(const CAAudioStreamDescription& format, CMSampleBufferRef sampleBuffer)
    : WebAudioBufferList(format)
{

    if (!sampleBuffer)
        return;

    CMBlockBufferRef buffer = nullptr;
    if (noErr == CMSampleBufferGetAudioBufferListWithRetainedBlockBuffer(sampleBuffer, nullptr, m_canonicalList.get(), m_listBufferSize, kCFAllocatorSystemDefault, kCFAllocatorSystemDefault, kCMSampleBufferFlag_AudioBufferList_Assure16ByteAlignment, &buffer))
        m_blockBuffer = adoptCF(buffer);

    reset();
}

void WebAudioBufferList::reset()
{
    if (!m_list)
        m_list = std::unique_ptr<AudioBufferList>(static_cast<AudioBufferList*>(::operator new (m_listBufferSize)));
    memcpy(m_list.get(), m_canonicalList.get(), m_listBufferSize);
}

WTF::IteratorRange<AudioBuffer*> WebAudioBufferList::buffers() const
{
    return WTF::makeIteratorRange(&m_list->mBuffers[0], &m_list->mBuffers[m_list->mNumberBuffers]);
}

uint32_t WebAudioBufferList::bufferCount() const
{
    return m_list->mNumberBuffers;
}

AudioBuffer* WebAudioBufferList::buffer(uint32_t index) const
{
    ASSERT(index < m_list->mNumberBuffers);
    if (index < m_list->mNumberBuffers)
        return &m_list->mBuffers[index];
    return nullptr;
}

}