qwasmaudiodevice.cpp

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// Copyright (C) 2021 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
#include "qwasmaudiodevice_p.h"
#include <emscripten.h>
#include <emscripten/val.h>
#include <emscripten/bind.h>
 
#include <AL/al.h>
#include <AL/alc.h>
 
QT_BEGIN_NAMESPACE
 
QWasmAudioDevice::QWasmAudioDevice(const char *device,
                                   const char *desc,
                                   bool isDef,
                                   QAudioDevice::Mode mode)
    : QAudioDevicePrivate(device, mode, QString::fromUtf8(desc))
{
    isDefault = isDef;
    minimumChannelCount = 1;
    maximumChannelCount = 2;
    minimumSampleRate = 8000;
    maximumSampleRate = 96000; // js AudioContext max according to docs
 
    // native openAL formats
    supportedSampleFormats.append(QAudioFormat::UInt8);
    supportedSampleFormats.append(QAudioFormat::Int16);
 
    // Browsers use 32bit floats as native, but emscripten reccomends checking for the exension.
    if (alIsExtensionPresent("AL_EXT_float32"))
        supportedSampleFormats.append(QAudioFormat::Float);
 
    preferredFormat.setChannelCount(2);
 
    // FIXME: firefox
    // An AudioContext was prevented from starting automatically.
    // It must be created or resumed after a user gesture on the page.
    emscripten::val audioContext = emscripten::val::global("window")["AudioContext"].new_();
    if (audioContext == emscripten::val::undefined())
        audioContext = emscripten::val::global("window")["webkitAudioContext"].new_();
 
    if (audioContext != emscripten::val::undefined()) {
        audioContext.call<void>("resume");
        int sRate = audioContext["sampleRate"].as<int>();
        audioContext.call<void>("close");
        preferredFormat.setSampleRate(sRate);
    }
 
    auto f = QAudioFormat::Float;
 
    if (!supportedSampleFormats.contains(f))
        f = QAudioFormat::Int16;
    preferredFormat.setSampleFormat(f);
}
 
QT_END_NAMESPACE