openal-soft/alc/backends/wasapi.cpp

/**
 * OpenAL cross platform audio library
 * Copyright (C) 2011 by authors.
 * This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Library General Public
 *  License as published by the Free Software Foundation; either
 *  version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 *  License along with this library; if not, write to the
 *  Free Software Foundation, Inc.,
 *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 * Or go to http://www.gnu.org/copyleft/lgpl.html
 */

#include "config.h"

#include "backends/wasapi.h"

#define WIN32_LEAN_AND_MEAN
#include <windows.h>

#include <stdlib.h>
#include <stdio.h>
#include <memory.h>

#include <wtypes.h>
#include <mmdeviceapi.h>
#include <audioclient.h>
#include <cguid.h>
#include <devpropdef.h>
#include <mmreg.h>
#include <propsys.h>
#include <propkey.h>
#include <devpkey.h>
#ifndef _WAVEFORMATEXTENSIBLE_
#include <ks.h>
#include <ksmedia.h>
#endif

#include <algorithm>
#include <atomic>
#include <chrono>
#include <condition_variable>
#include <deque>
#include <functional>
#include <future>
#include <mutex>
#include <string>
#include <thread>
#include <vector>

#include "albit.h"
#include "alcmain.h"
#include "alu.h"
#include "compat.h"
#include "converter.h"
#include "core/logging.h"
#include "ringbuffer.h"
#include "strutils.h"
#include "threads.h"


/* Some headers seem to define these as macros for __uuidof, which is annoying
 * since some headers don't declare them at all. Hopefully the ifdef is enough
 * to tell if they need to be declared.
 */
#ifndef KSDATAFORMAT_SUBTYPE_PCM
DEFINE_GUID(KSDATAFORMAT_SUBTYPE_PCM, 0x00000001, 0x0000, 0x0010, 0x80, 0x00, 0x00, 0xaa, 0x00, 0x38, 0x9b, 0x71);
#endif
#ifndef KSDATAFORMAT_SUBTYPE_IEEE_FLOAT
DEFINE_GUID(KSDATAFORMAT_SUBTYPE_IEEE_FLOAT, 0x00000003, 0x0000, 0x0010, 0x80, 0x00, 0x00, 0xaa, 0x00, 0x38, 0x9b, 0x71);
#endif

DEFINE_DEVPROPKEY(DEVPKEY_Device_FriendlyName, 0xa45c254e, 0xdf1c, 0x4efd, 0x80,0x20, 0x67,0xd1,0x46,0xa8,0x50,0xe0, 14);
DEFINE_PROPERTYKEY(PKEY_AudioEndpoint_FormFactor, 0x1da5d803, 0xd492, 0x4edd, 0x8c,0x23, 0xe0,0xc0,0xff,0xee,0x7f,0x0e, 0);
DEFINE_PROPERTYKEY(PKEY_AudioEndpoint_GUID, 0x1da5d803, 0xd492, 0x4edd, 0x8c, 0x23,0xe0, 0xc0,0xff,0xee,0x7f,0x0e, 4 );


namespace {

using std::chrono::milliseconds;
using std::chrono::seconds;

using ReferenceTime = std::chrono::duration<REFERENCE_TIME,std::ratio<1,10000000>>;

inline constexpr ReferenceTime operator "" _reftime(unsigned long long int n) noexcept
{ return ReferenceTime{static_cast<REFERENCE_TIME>(n)}; }


#define MONO SPEAKER_FRONT_CENTER
#define STEREO (SPEAKER_FRONT_LEFT|SPEAKER_FRONT_RIGHT)
#define QUAD (SPEAKER_FRONT_LEFT|SPEAKER_FRONT_RIGHT|SPEAKER_BACK_LEFT|SPEAKER_BACK_RIGHT)
#define X5DOT1 (SPEAKER_FRONT_LEFT|SPEAKER_FRONT_RIGHT|SPEAKER_FRONT_CENTER|SPEAKER_LOW_FREQUENCY|SPEAKER_SIDE_LEFT|SPEAKER_SIDE_RIGHT)
#define X5DOT1REAR (SPEAKER_FRONT_LEFT|SPEAKER_FRONT_RIGHT|SPEAKER_FRONT_CENTER|SPEAKER_LOW_FREQUENCY|SPEAKER_BACK_LEFT|SPEAKER_BACK_RIGHT)
#define X6DOT1 (SPEAKER_FRONT_LEFT|SPEAKER_FRONT_RIGHT|SPEAKER_FRONT_CENTER|SPEAKER_LOW_FREQUENCY|SPEAKER_BACK_CENTER|SPEAKER_SIDE_LEFT|SPEAKER_SIDE_RIGHT)
#define X7DOT1 (SPEAKER_FRONT_LEFT|SPEAKER_FRONT_RIGHT|SPEAKER_FRONT_CENTER|SPEAKER_LOW_FREQUENCY|SPEAKER_BACK_LEFT|SPEAKER_BACK_RIGHT|SPEAKER_SIDE_LEFT|SPEAKER_SIDE_RIGHT)

constexpr inline DWORD MaskFromTopBits(DWORD b) noexcept
{
    b |= b>>1;
    b |= b>>2;
    b |= b>>4;
    b |= b>>8;
    b |= b>>16;
    return b;
}
constexpr DWORD MonoMask{MaskFromTopBits(MONO)};
constexpr DWORD StereoMask{MaskFromTopBits(STEREO)};
constexpr DWORD QuadMask{MaskFromTopBits(QUAD)};
constexpr DWORD X51Mask{MaskFromTopBits(X5DOT1)};
constexpr DWORD X51RearMask{MaskFromTopBits(X5DOT1REAR)};
constexpr DWORD X61Mask{MaskFromTopBits(X6DOT1)};
constexpr DWORD X71Mask{MaskFromTopBits(X7DOT1)};

#define DEVNAME_HEAD "OpenAL Soft on "


/* Scales the given reftime value, rounding the result. */
inline uint RefTime2Samples(const ReferenceTime &val, uint srate)
{
    const auto retval = (val*srate + ReferenceTime{seconds{1}}/2) / seconds{1};
    return static_cast<uint>(mini64(retval, std::numeric_limits<uint>::max()));
}


template<typename T>
class ComPtr {
    T *mPtr{nullptr};

public:
    ComPtr() noexcept = default;
    ComPtr(const ComPtr &rhs) : mPtr{rhs.mPtr} { if(mPtr) mPtr->AddRef(); }
    ComPtr(ComPtr&& rhs) noexcept : mPtr{rhs.mPtr} { rhs.mPtr = nullptr; }
    ComPtr(std::nullptr_t) noexcept { }
    explicit ComPtr(T *ptr) noexcept : mPtr{ptr} { }
    ~ComPtr() { if(mPtr) mPtr->Release(); }

    ComPtr& operator=(const ComPtr &rhs)
    {
        if(!rhs.mPtr)
        {
            if(mPtr)
                mPtr->Release();
            mPtr = nullptr;
        }
        else
        {
            rhs.mPtr->AddRef();
            try {
                if(mPtr)
                    mPtr->Release();
                mPtr = rhs.mPtr;
            }
            catch(...) {
                rhs.mPtr->Release();
                throw;
            }
        }
        return *this;
    }
    ComPtr& operator=(ComPtr&& rhs)
    {
        if(mPtr)
            mPtr->Release();
        mPtr = rhs.mPtr;
        rhs.mPtr = nullptr;
        return *this;
    }

    operator bool() const noexcept { return mPtr != nullptr; }

    T& operator*() const noexcept { return *mPtr; }
    T* operator->() const noexcept { return mPtr; }
    T* get() const noexcept { return mPtr; }
    T** getPtr() noexcept { return &mPtr; }

    T* release() noexcept
    {
        T *ret{mPtr};
        mPtr = nullptr;
        return ret;
    }

    void swap(ComPtr &rhs) noexcept { std::swap(mPtr, rhs.mPtr); }
    void swap(ComPtr&& rhs) noexcept { std::swap(mPtr, rhs.mPtr); }
};


class GuidPrinter {
    char mMsg[64];

public:
    GuidPrinter(const GUID &guid)
    {
        std::snprintf(mMsg, al::size(mMsg), "{%08lx-%04x-%04x-%02x%02x-%02x%02x%02x%02x%02x%02x}",
            DWORD{guid.Data1}, guid.Data2, guid.Data3, guid.Data4[0], guid.Data4[1], guid.Data4[2],
            guid.Data4[3], guid.Data4[4], guid.Data4[5], guid.Data4[6], guid.Data4[7]);
    }
    const char *c_str() const { return mMsg; }
};

struct PropVariant {
    PROPVARIANT mProp;

public:
    PropVariant() { PropVariantInit(&mProp); }
    ~PropVariant() { clear(); }

    void clear() { PropVariantClear(&mProp); }

    PROPVARIANT* get() noexcept { return &mProp; }

    PROPVARIANT& operator*() noexcept { return mProp; }
    const PROPVARIANT& operator*() const noexcept { return mProp; }

    PROPVARIANT* operator->() noexcept { return &mProp; }
    const PROPVARIANT* operator->() const noexcept { return &mProp; }
};

struct DevMap {
    std::string name;
    std::string endpoint_guid; // obtained from PKEY_AudioEndpoint_GUID , set to "Unknown device GUID" if absent.
    std::wstring devid;

    template<typename T0, typename T1, typename T2>
    DevMap(T0&& name_, T1&& guid_, T2&& devid_)
      : name{std::forward<T0>(name_)}
      , endpoint_guid{std::forward<T1>(guid_)}
      , devid{std::forward<T2>(devid_)}
    { }
};

bool checkName(const al::vector<DevMap> &list, const std::string &name)
{
    auto match_name = [&name](const DevMap &entry) -> bool
    { return entry.name == name; };
    return std::find_if(list.cbegin(), list.cend(), match_name) != list.cend();
}

al::vector<DevMap> PlaybackDevices;
al::vector<DevMap> CaptureDevices;


using NameGUIDPair = std::pair<std::string,std::string>;
NameGUIDPair get_device_name_and_guid(IMMDevice *device)
{
    static constexpr char UnknownName[]{"Unknown Device Name"};
    static constexpr char UnknownGuid[]{"Unknown Device GUID"};
    std::string name{DEVNAME_HEAD};
    std::string guid;

    ComPtr<IPropertyStore> ps;
    HRESULT hr = device->OpenPropertyStore(STGM_READ, ps.getPtr());
    if(FAILED(hr))
    {
        WARN("OpenPropertyStore failed: 0x%08lx\n", hr);
        return std::make_pair(UnknownName, UnknownGuid);
    }

    PropVariant pvprop;
    hr = ps->GetValue(reinterpret_cast<const PROPERTYKEY&>(DEVPKEY_Device_FriendlyName), pvprop.get());
    if(FAILED(hr))
    {
        WARN("GetValue Device_FriendlyName failed: 0x%08lx\n", hr);
        name += UnknownName;
    }
    else if(pvprop->vt == VT_LPWSTR)
        name += wstr_to_utf8(pvprop->pwszVal);
    else
    {
        WARN("Unexpected PROPVARIANT type: 0x%04x\n", pvprop->vt);
        name += UnknownName;
    }

    pvprop.clear();
    hr = ps->GetValue(reinterpret_cast<const PROPERTYKEY&>(PKEY_AudioEndpoint_GUID), pvprop.get());
    if(FAILED(hr))
    {
        WARN("GetValue AudioEndpoint_GUID failed: 0x%08lx\n", hr);
        guid = UnknownGuid;
    }
    else if(pvprop->vt == VT_LPWSTR)
        guid = wstr_to_utf8(pvprop->pwszVal);
    else
    {
        WARN("Unexpected PROPVARIANT type: 0x%04x\n", pvprop->vt);
        guid = UnknownGuid;
    }

    return std::make_pair(std::move(name), std::move(guid));
}

EndpointFormFactor get_device_formfactor(IMMDevice *device)
{
    ComPtr<IPropertyStore> ps;
    HRESULT hr{device->OpenPropertyStore(STGM_READ, ps.getPtr())};
    if(FAILED(hr))
    {
        WARN("OpenPropertyStore failed: 0x%08lx\n", hr);
        return UnknownFormFactor;
    }

    EndpointFormFactor formfactor{UnknownFormFactor};
    PropVariant pvform;
    hr = ps->GetValue(PKEY_AudioEndpoint_FormFactor, pvform.get());
    if(FAILED(hr))
        WARN("GetValue AudioEndpoint_FormFactor failed: 0x%08lx\n", hr);
    else if(pvform->vt == VT_UI4)
        formfactor = static_cast<EndpointFormFactor>(pvform->ulVal);
    else if(pvform->vt != VT_EMPTY)
        WARN("Unexpected PROPVARIANT type: 0x%04x\n", pvform->vt);
    return formfactor;
}


void add_device(IMMDevice *device, const WCHAR *devid, al::vector<DevMap> &list)
{
    for(auto &entry : list)
    {
        if(entry.devid == devid)
            return;
    }

    auto name_guid = get_device_name_and_guid(device);

    int count{1};
    std::string newname{name_guid.first};
    while(checkName(list, newname))
    {
        newname = name_guid.first;
        newname += " #";
        newname += std::to_string(++count);
    }
    list.emplace_back(std::move(newname), std::move(name_guid.second), devid);
    const DevMap &newentry = list.back();

    TRACE("Got device \"%s\", \"%s\", \"%ls\"\n", newentry.name.c_str(),
          newentry.endpoint_guid.c_str(), newentry.devid.c_str());
}

WCHAR *get_device_id(IMMDevice *device)
{
    WCHAR *devid;

    const HRESULT hr{device->GetId(&devid)};
    if(FAILED(hr))
    {
        ERR("Failed to get device id: %lx\n", hr);
        return nullptr;
    }

    return devid;
}

void probe_devices(IMMDeviceEnumerator *devenum, EDataFlow flowdir, al::vector<DevMap> &list)
{
    al::vector<DevMap>{}.swap(list);

    ComPtr<IMMDeviceCollection> coll;
    HRESULT hr{devenum->EnumAudioEndpoints(flowdir, DEVICE_STATE_ACTIVE, coll.getPtr())};
    if(FAILED(hr))
    {
        ERR("Failed to enumerate audio endpoints: 0x%08lx\n", hr);
        return;
    }

    UINT count{0};
    hr = coll->GetCount(&count);
    if(SUCCEEDED(hr) && count > 0)
        list.reserve(count);

    ComPtr<IMMDevice> device;
    hr = devenum->GetDefaultAudioEndpoint(flowdir, eMultimedia, device.getPtr());
    if(SUCCEEDED(hr))
    {
        if(WCHAR *devid{get_device_id(device.get())})
        {
            add_device(device.get(), devid, list);
            CoTaskMemFree(devid);
        }
        device = nullptr;
    }

    for(UINT i{0};i < count;++i)
    {
        hr = coll->Item(i, device.getPtr());
        if(FAILED(hr)) continue;

        if(WCHAR *devid{get_device_id(device.get())})
        {
            add_device(device.get(), devid, list);
            CoTaskMemFree(devid);
        }
        device = nullptr;
    }
}


bool MakeExtensible(WAVEFORMATEXTENSIBLE *out, const WAVEFORMATEX *in)
{
    *out = WAVEFORMATEXTENSIBLE{};
    if(in->wFormatTag == WAVE_FORMAT_EXTENSIBLE)
    {
        *out = *CONTAINING_RECORD(in, const WAVEFORMATEXTENSIBLE, Format);
        out->Format.cbSize = sizeof(*out) - sizeof(out->Format);
    }
    else if(in->wFormatTag == WAVE_FORMAT_PCM)
    {
        out->Format = *in;
        out->Format.cbSize = 0;
        out->Samples.wValidBitsPerSample = out->Format.wBitsPerSample;
        if(out->Format.nChannels == 1)
            out->dwChannelMask = MONO;
        else if(out->Format.nChannels == 2)
            out->dwChannelMask = STEREO;
        else
            ERR("Unhandled PCM channel count: %d\n", out->Format.nChannels);
        out->SubFormat = KSDATAFORMAT_SUBTYPE_PCM;
    }
    else if(in->wFormatTag == WAVE_FORMAT_IEEE_FLOAT)
    {
        out->Format = *in;
        out->Format.cbSize = 0;
        out->Samples.wValidBitsPerSample = out->Format.wBitsPerSample;
        if(out->Format.nChannels == 1)
            out->dwChannelMask = MONO;
        else if(out->Format.nChannels == 2)
            out->dwChannelMask = STEREO;
        else
            ERR("Unhandled IEEE float channel count: %d\n", out->Format.nChannels);
        out->SubFormat = KSDATAFORMAT_SUBTYPE_IEEE_FLOAT;
    }
    else
    {
        ERR("Unhandled format tag: 0x%04x\n", in->wFormatTag);
        return false;
    }
    return true;
}

void TraceFormat(const char *msg, const WAVEFORMATEX *format)
{
    constexpr size_t fmtex_extra_size{sizeof(WAVEFORMATEXTENSIBLE)-sizeof(WAVEFORMATEX)};
    if(format->wFormatTag == WAVE_FORMAT_EXTENSIBLE && format->cbSize >= fmtex_extra_size)
    {
        const WAVEFORMATEXTENSIBLE *fmtex{
            CONTAINING_RECORD(format, const WAVEFORMATEXTENSIBLE, Format)};
        TRACE("%s:\n"
            "    FormatTag      = 0x%04x\n"
            "    Channels       = %d\n"
            "    SamplesPerSec  = %lu\n"
            "    AvgBytesPerSec = %lu\n"
            "    BlockAlign     = %d\n"
            "    BitsPerSample  = %d\n"
            "    Size           = %d\n"
            "    Samples        = %d\n"
            "    ChannelMask    = 0x%lx\n"
            "    SubFormat      = %s\n",
            msg, fmtex->Format.wFormatTag, fmtex->Format.nChannels, fmtex->Format.nSamplesPerSec,
            fmtex->Format.nAvgBytesPerSec, fmtex->Format.nBlockAlign, fmtex->Format.wBitsPerSample,
            fmtex->Format.cbSize, fmtex->Samples.wReserved, fmtex->dwChannelMask,
            GuidPrinter{fmtex->SubFormat}.c_str());
    }
    else
        TRACE("%s:\n"
            "    FormatTag      = 0x%04x\n"
            "    Channels       = %d\n"
            "    SamplesPerSec  = %lu\n"
            "    AvgBytesPerSec = %lu\n"
            "    BlockAlign     = %d\n"
            "    BitsPerSample  = %d\n"
            "    Size           = %d\n",
            msg, format->wFormatTag, format->nChannels, format->nSamplesPerSec,
            format->nAvgBytesPerSec, format->nBlockAlign, format->wBitsPerSample, format->cbSize);
}


enum class MsgType {
    OpenDevice,
    ReopenDevice,
    ResetDevice,
    StartDevice,
    StopDevice,
    CloseDevice,
    EnumeratePlayback,
    EnumerateCapture,
    QuitThread,

    Count
};

constexpr char MessageStr[static_cast<size_t>(MsgType::Count)][20]{
    "Open Device",
    "Reopen Device",
    "Reset Device",
    "Start Device",
    "Stop Device",
    "Close Device",
    "Enumerate Playback",
    "Enumerate Capture",
    "Quit"
};


/* Proxy interface used by the message handler. */
struct WasapiProxy {
    virtual ~WasapiProxy() = default;

    virtual HRESULT openProxy(const char *name) = 0;
    virtual void closeProxy() = 0;

    virtual HRESULT resetProxy() = 0;
    virtual HRESULT startProxy() = 0;
    virtual void  stopProxy() = 0;

    struct Msg {
        MsgType mType;
        WasapiProxy *mProxy;
        const char *mParam;
        std::promise<HRESULT> mPromise;
    };
    static std::deque<Msg> mMsgQueue;
    static std::mutex mMsgQueueLock;
    static std::condition_variable mMsgQueueCond;

    std::future<HRESULT> pushMessage(MsgType type, const char *param=nullptr)
    {
        std::promise<HRESULT> promise;
        std::future<HRESULT> future{promise.get_future()};
        {
            std::lock_guard<std::mutex> _{mMsgQueueLock};
            mMsgQueue.emplace_back(Msg{type, this, param, std::move(promise)});
        }
        mMsgQueueCond.notify_one();
        return future;
    }

    static std::future<HRESULT> pushMessageStatic(MsgType type)
    {
        std::promise<HRESULT> promise;
        std::future<HRESULT> future{promise.get_future()};
        {
            std::lock_guard<std::mutex> _{mMsgQueueLock};
            mMsgQueue.emplace_back(Msg{type, nullptr, nullptr, std::move(promise)});
        }
        mMsgQueueCond.notify_one();
        return future;
    }

    static bool popMessage(Msg &msg)
    {
        std::unique_lock<std::mutex> lock{mMsgQueueLock};
        mMsgQueueCond.wait(lock, []{return !mMsgQueue.empty();});
        msg = std::move(mMsgQueue.front());
        mMsgQueue.pop_front();
        return msg.mType != MsgType::QuitThread;
    }

    static int messageHandler(std::promise<HRESULT> *promise);
};
std::deque<WasapiProxy::Msg> WasapiProxy::mMsgQueue;
std::mutex WasapiProxy::mMsgQueueLock;
std::condition_variable WasapiProxy::mMsgQueueCond;

int WasapiProxy::messageHandler(std::promise<HRESULT> *promise)
{
    TRACE("Starting message thread\n");

    HRESULT cohr{CoInitializeEx(nullptr, COINIT_MULTITHREADED)};
    if(FAILED(cohr))
    {
        WARN("Failed to initialize COM: 0x%08lx\n", cohr);
        promise->set_value(cohr);
        return 0;
    }

    void *ptr{};
    HRESULT hr{CoCreateInstance(CLSID_MMDeviceEnumerator, nullptr, CLSCTX_INPROC_SERVER,
        IID_IMMDeviceEnumerator, &ptr)};
    if(FAILED(hr))
    {
        WARN("Failed to create IMMDeviceEnumerator instance: 0x%08lx\n", hr);
        promise->set_value(hr);
        CoUninitialize();
        return 0;
    }
    static_cast<IMMDeviceEnumerator*>(ptr)->Release();
    CoUninitialize();

    TRACE("Message thread initialization complete\n");
    promise->set_value(S_OK);
    promise = nullptr;

    TRACE("Starting message loop\n");
    uint deviceCount{0};
    Msg msg;
    while(popMessage(msg))
    {
        TRACE("Got message \"%s\" (0x%04x, this=%p, param=%p)\n",
            MessageStr[static_cast<size_t>(msg.mType)], static_cast<uint>(msg.mType),
            static_cast<void*>(msg.mProxy), static_cast<const void*>(msg.mParam));

        switch(msg.mType)
        {
        case MsgType::OpenDevice:
            hr = cohr = S_OK;
            if(++deviceCount == 1)
                hr = cohr = CoInitializeEx(nullptr, COINIT_MULTITHREADED);
            if(SUCCEEDED(hr))
                hr = msg.mProxy->openProxy(msg.mParam);
            msg.mPromise.set_value(hr);

            if(FAILED(hr))
            {
                if(--deviceCount == 0 && SUCCEEDED(cohr))
                    CoUninitialize();
            }
            continue;

        case MsgType::ReopenDevice:
            hr = msg.mProxy->openProxy(msg.mParam);
            msg.mPromise.set_value(hr);
            continue;

        case MsgType::ResetDevice:
            hr = msg.mProxy->resetProxy();
            msg.mPromise.set_value(hr);
            continue;

        case MsgType::StartDevice:
            hr = msg.mProxy->startProxy();
            msg.mPromise.set_value(hr);
            continue;

        case MsgType::StopDevice:
            msg.mProxy->stopProxy();
            msg.mPromise.set_value(S_OK);
            continue;

        case MsgType::CloseDevice:
            msg.mProxy->closeProxy();
            msg.mPromise.set_value(S_OK);

            if(--deviceCount == 0)
                CoUninitialize();
            continue;

        case MsgType::EnumeratePlayback:
        case MsgType::EnumerateCapture:
            hr = cohr = S_OK;
            if(++deviceCount == 1)
                hr = cohr = CoInitializeEx(nullptr, COINIT_MULTITHREADED);
            if(SUCCEEDED(hr))
                hr = CoCreateInstance(CLSID_MMDeviceEnumerator, nullptr, CLSCTX_INPROC_SERVER,
                    IID_IMMDeviceEnumerator, &ptr);
            if(FAILED(hr))
                msg.mPromise.set_value(hr);
            else
            {
                ComPtr<IMMDeviceEnumerator> enumerator{static_cast<IMMDeviceEnumerator*>(ptr)};

                if(msg.mType == MsgType::EnumeratePlayback)
                    probe_devices(enumerator.get(), eRender, PlaybackDevices);
                else if(msg.mType == MsgType::EnumerateCapture)
                    probe_devices(enumerator.get(), eCapture, CaptureDevices);
                msg.mPromise.set_value(S_OK);
            }

            if(--deviceCount == 0 && SUCCEEDED(cohr))
                CoUninitialize();
            continue;

        default:
            ERR("Unexpected message: %u\n", static_cast<uint>(msg.mType));
            msg.mPromise.set_value(E_FAIL);
            continue;
        }
    }
    TRACE("Message loop finished\n");

    return 0;
}


struct WasapiPlayback final : public BackendBase, WasapiProxy {
    WasapiPlayback(ALCdevice *device) noexcept : BackendBase{device} { }
    ~WasapiPlayback() override;

    int mixerProc();

    void open(const char *name) override;
    HRESULT openProxy(const char *name) override;
    void closeProxy() override;

    bool reset() override;
    HRESULT resetProxy() override;
    void start() override;
    HRESULT startProxy() override;
    void stop() override;
    void stopProxy() override;

    ClockLatency getClockLatency() override;

    HRESULT mOpenStatus{E_FAIL};
    ComPtr<IMMDevice> mMMDev{nullptr};
    ComPtr<IAudioClient> mClient{nullptr};
    ComPtr<IAudioRenderClient> mRender{nullptr};
    HANDLE mNotifyEvent{nullptr};

    UINT32 mFrameStep{0u};
    std::atomic<UINT32> mPadding{0u};

    std::mutex mMutex;

    std::atomic<bool> mKillNow{true};
    std::thread mThread;

    DEF_NEWDEL(WasapiPlayback)
};

WasapiPlayback::~WasapiPlayback()
{
    if(SUCCEEDED(mOpenStatus))
        pushMessage(MsgType::CloseDevice).wait();
    mOpenStatus = E_FAIL;

    if(mNotifyEvent != nullptr)
        CloseHandle(mNotifyEvent);
    mNotifyEvent = nullptr;
}


FORCE_ALIGN int WasapiPlayback::mixerProc()
{
    HRESULT hr{CoInitializeEx(nullptr, COINIT_MULTITHREADED)};
    if(FAILED(hr))
    {
        ERR("CoInitializeEx(nullptr, COINIT_MULTITHREADED) failed: 0x%08lx\n", hr);
        mDevice->handleDisconnect("COM init failed: 0x%08lx", hr);
        return 1;
    }

    SetRTPriority();
    althrd_setname(MIXER_THREAD_NAME);

    const uint update_size{mDevice->UpdateSize};
    const UINT32 buffer_len{mDevice->BufferSize};
    while(!mKillNow.load(std::memory_order_relaxed))
    {
        UINT32 written;
        hr = mClient->GetCurrentPadding(&written);
        if(FAILED(hr))
        {
            ERR("Failed to get padding: 0x%08lx\n", hr);
            mDevice->handleDisconnect("Failed to retrieve buffer padding: 0x%08lx", hr);
            break;
        }
        mPadding.store(written, std::memory_order_relaxed);

        uint len{buffer_len - written};
        if(len < update_size)
        {
            DWORD res{WaitForSingleObjectEx(mNotifyEvent, 2000, FALSE)};
            if(res != WAIT_OBJECT_0)
                ERR("WaitForSingleObjectEx error: 0x%lx\n", res);
            continue;
        }

        BYTE *buffer;
        hr = mRender->GetBuffer(len, &buffer);
        if(SUCCEEDED(hr))
        {
            {
                std::lock_guard<std::mutex> _{mMutex};
                mDevice->renderSamples(buffer, len, mFrameStep);
                mPadding.store(written + len, std::memory_order_relaxed);
            }
            hr = mRender->ReleaseBuffer(len, 0);
        }
        if(FAILED(hr))
        {
            ERR("Failed to buffer data: 0x%08lx\n", hr);
            mDevice->handleDisconnect("Failed to send playback samples: 0x%08lx", hr);
            break;
        }
    }
    mPadding.store(0u, std::memory_order_release);

    CoUninitialize();
    return 0;
}


void WasapiPlayback::open(const char *name)
{
    HRESULT hr{S_OK};

    if(!mNotifyEvent)
    {
        mNotifyEvent = CreateEventW(nullptr, FALSE, FALSE, nullptr);
        if(mNotifyEvent == nullptr)
        {
            ERR("Failed to create notify events: %lu\n", GetLastError());
            hr = E_FAIL;
        }
    }

    if(SUCCEEDED(hr))
    {
        if(name && PlaybackDevices.empty())
            pushMessage(MsgType::EnumeratePlayback).wait();

        if(SUCCEEDED(mOpenStatus))
            hr = pushMessage(MsgType::ReopenDevice, name).get();
        else
        {
            hr = pushMessage(MsgType::OpenDevice, name).get();
            mOpenStatus = hr;
        }
    }

    if(FAILED(hr))
        throw al::backend_exception{al::backend_error::DeviceError, "Device init failed: 0x%08lx",
            hr};
}

HRESULT WasapiPlayback::openProxy(const char *name)
{
    const wchar_t *devid{nullptr};
    if(name)
    {
        auto iter = std::find_if(PlaybackDevices.cbegin(), PlaybackDevices.cend(),
            [name](const DevMap &entry) -> bool
            { return entry.name == name || entry.endpoint_guid == name; });
        if(iter == PlaybackDevices.cend())
        {
            const std::wstring wname{utf8_to_wstr(name)};
            iter = std::find_if(PlaybackDevices.cbegin(), PlaybackDevices.cend(),
                [&wname](const DevMap &entry) -> bool
                { return entry.devid == wname; });
        }
        if(iter == PlaybackDevices.cend())
        {
            WARN("Failed to find device name matching \"%s\"\n", name);
            return E_FAIL;
        }
        name = iter->name.c_str();
        devid = iter->devid.c_str();
    }

    void *ptr;
    HRESULT hr{CoCreateInstance(CLSID_MMDeviceEnumerator, nullptr, CLSCTX_INPROC_SERVER,
        IID_IMMDeviceEnumerator, &ptr)};
    ComPtr<IMMDeviceEnumerator> enumerator{static_cast<IMMDeviceEnumerator*>(ptr)};
    ComPtr<IMMDevice> mmdev;
    if(!devid)
        hr = enumerator->GetDefaultAudioEndpoint(eRender, eMultimedia, mmdev.getPtr());
    else
        hr = enumerator->GetDevice(devid, mmdev.getPtr());
    enumerator = nullptr;
    if(FAILED(hr))
    {
        WARN("Failed to open device \"%s\"\n", name?name:"(default)");
        return hr;
    }

    hr = mmdev->Activate(IID_IAudioClient, CLSCTX_INPROC_SERVER, nullptr, &ptr);
    if(FAILED(hr))
    {
        WARN("Failed to activate device \"%s\"\n", name?name:"(default)");
        return hr;
    }

    mClient = ComPtr<IAudioClient>{static_cast<IAudioClient*>(ptr)};
    mMMDev = std::move(mmdev);
    if(name) mDevice->DeviceName = name;
    else mDevice->DeviceName = get_device_name_and_guid(mMMDev.get()).first;

    return hr;
}

void WasapiPlayback::closeProxy()
{
    mClient = nullptr;
    mMMDev = nullptr;
}


bool WasapiPlayback::reset()
{
    HRESULT hr{pushMessage(MsgType::ResetDevice).get()};
    if(FAILED(hr))
        throw al::backend_exception{al::backend_error::DeviceError, "0x%08lx", hr};
    return true;
}

HRESULT WasapiPlayback::resetProxy()
{
    mClient = nullptr;

    void *ptr;
    HRESULT hr{mMMDev->Activate(IID_IAudioClient, CLSCTX_INPROC_SERVER, nullptr, &ptr)};
    if(FAILED(hr))
    {
        ERR("Failed to reactivate audio client: 0x%08lx\n", hr);
        return hr;
    }
    mClient = ComPtr<IAudioClient>{static_cast<IAudioClient*>(ptr)};

    WAVEFORMATEX *wfx;
    hr = mClient->GetMixFormat(&wfx);
    if(FAILED(hr))
    {
        ERR("Failed to get mix format: 0x%08lx\n", hr);
        return hr;
    }

    WAVEFORMATEXTENSIBLE OutputType;
    if(!MakeExtensible(&OutputType, wfx))
    {
        CoTaskMemFree(wfx);
        return E_FAIL;
    }
    CoTaskMemFree(wfx);
    wfx = nullptr;

    const ReferenceTime per_time{ReferenceTime{seconds{mDevice->UpdateSize}} / mDevice->Frequency};
    const ReferenceTime buf_time{ReferenceTime{seconds{mDevice->BufferSize}} / mDevice->Frequency};

    if(!mDevice->Flags.test(FrequencyRequest))
        mDevice->Frequency = OutputType.Format.nSamplesPerSec;
    if(!mDevice->Flags.test(ChannelsRequest))
    {
        const uint32_t chancount{OutputType.Format.nChannels};
        const DWORD chanmask{OutputType.dwChannelMask};
        if(chancount >= 8 && (chanmask&X71Mask) == X7DOT1)
            mDevice->FmtChans = DevFmtX71;
        else if(chancount >= 7 && (chanmask&X61Mask) == X6DOT1)
            mDevice->FmtChans = DevFmtX61;
        else if(chancount >= 6 && (chanmask&X51Mask) == X5DOT1)
            mDevice->FmtChans = DevFmtX51;
        else if(chancount >= 6 && (chanmask&X51RearMask) == X5DOT1REAR)
            mDevice->FmtChans = DevFmtX51Rear;
        else if(chancount >= 4 && (chanmask&QuadMask) == QUAD)
            mDevice->FmtChans = DevFmtQuad;
        else if(chancount >= 2 && (chanmask&StereoMask) == STEREO)
            mDevice->FmtChans = DevFmtStereo;
        else if(chancount >= 1 && (chanmask&MonoMask) == MONO)
            mDevice->FmtChans = DevFmtMono;
        else
            ERR("Unhandled channel config: %d -- 0x%08lx\n", chancount, chanmask);
    }

    OutputType.Format.wFormatTag = WAVE_FORMAT_EXTENSIBLE;
    switch(mDevice->FmtChans)
    {
    case DevFmtMono:
        OutputType.Format.nChannels = 1;
        OutputType.dwChannelMask = MONO;
        break;
    case DevFmtAmbi3D:
        mDevice->FmtChans = DevFmtStereo;
        /*fall-through*/
    case DevFmtStereo:
        OutputType.Format.nChannels = 2;
        OutputType.dwChannelMask = STEREO;
        break;
    case DevFmtQuad:
        OutputType.Format.nChannels = 4;
        OutputType.dwChannelMask = QUAD;
        break;
    case DevFmtX51:
        OutputType.Format.nChannels = 6;
        OutputType.dwChannelMask = X5DOT1;
        break;
    case DevFmtX51Rear:
        OutputType.Format.nChannels = 6;
        OutputType.dwChannelMask = X5DOT1REAR;
        break;
    case DevFmtX61:
        OutputType.Format.nChannels = 7;
        OutputType.dwChannelMask = X6DOT1;
        break;
    case DevFmtX71:
        OutputType.Format.nChannels = 8;
        OutputType.dwChannelMask = X7DOT1;
        break;
    }
    switch(mDevice->FmtType)
    {
    case DevFmtByte:
        mDevice->FmtType = DevFmtUByte;
        /* fall-through */
    case DevFmtUByte:
        OutputType.Format.wBitsPerSample = 8;
        OutputType.Samples.wValidBitsPerSample = 8;
        OutputType.SubFormat = KSDATAFORMAT_SUBTYPE_PCM;
        break;
    case DevFmtUShort:
        mDevice->FmtType = DevFmtShort;
        /* fall-through */
    case DevFmtShort:
        OutputType.Format.wBitsPerSample = 16;
        OutputType.Samples.wValidBitsPerSample = 16;
        OutputType.SubFormat = KSDATAFORMAT_SUBTYPE_PCM;
        break;
    case DevFmtUInt:
        mDevice->FmtType = DevFmtInt;
        /* fall-through */
    case DevFmtInt:
        OutputType.Format.wBitsPerSample = 32;
        OutputType.Samples.wValidBitsPerSample = 32;
        OutputType.SubFormat = KSDATAFORMAT_SUBTYPE_PCM;
        break;
    case DevFmtFloat:
        OutputType.Format.wBitsPerSample = 32;
        OutputType.Samples.wValidBitsPerSample = 32;
        OutputType.SubFormat = KSDATAFORMAT_SUBTYPE_IEEE_FLOAT;
        break;
    }
    OutputType.Format.nSamplesPerSec = mDevice->Frequency;

    OutputType.Format.nBlockAlign = static_cast<WORD>(OutputType.Format.nChannels *
        OutputType.Format.wBitsPerSample / 8);
    OutputType.Format.nAvgBytesPerSec = OutputType.Format.nSamplesPerSec *
        OutputType.Format.nBlockAlign;

    TraceFormat("Requesting playback format", &OutputType.Format);
    hr = mClient->IsFormatSupported(AUDCLNT_SHAREMODE_SHARED, &OutputType.Format, &wfx);
    if(FAILED(hr))
    {
        ERR("Failed to check format support: 0x%08lx\n", hr);
        hr = mClient->GetMixFormat(&wfx);
    }
    if(FAILED(hr))
    {
        ERR("Failed to find a supported format: 0x%08lx\n", hr);
        return hr;
    }

    if(wfx != nullptr)
    {
        TraceFormat("Got playback format", wfx);
        if(!MakeExtensible(&OutputType, wfx))
        {
            CoTaskMemFree(wfx);
            return E_FAIL;
        }
        CoTaskMemFree(wfx);
        wfx = nullptr;

        mDevice->Frequency = OutputType.Format.nSamplesPerSec;
        const uint32_t chancount{OutputType.Format.nChannels};
        const DWORD chanmask{OutputType.dwChannelMask};
        if(chancount >= 8 && (chanmask&X71Mask) == X7DOT1)
            mDevice->FmtChans = DevFmtX71;
        else if(chancount >= 7 && (chanmask&X61Mask) == X6DOT1)
            mDevice->FmtChans = DevFmtX61;
        else if(chancount >= 6 && (chanmask&X51Mask) == X5DOT1)
            mDevice->FmtChans = DevFmtX51;
        else if(chancount >= 6 && (chanmask&X51RearMask) == X5DOT1REAR)
            mDevice->FmtChans = DevFmtX51Rear;
        else if(chancount >= 4 && (chanmask&QuadMask) == QUAD)
            mDevice->FmtChans = DevFmtQuad;
        else if(chancount >= 2 && (chanmask&StereoMask) == STEREO)
            mDevice->FmtChans = DevFmtStereo;
        else if(chancount >= 1 && (chanmask&MonoMask) == MONO)
            mDevice->FmtChans = DevFmtMono;
        else
        {
            ERR("Unhandled extensible channels: %d -- 0x%08lx\n", OutputType.Format.nChannels,
                OutputType.dwChannelMask);
            mDevice->FmtChans = DevFmtStereo;
            OutputType.Format.nChannels = 2;
            OutputType.dwChannelMask = STEREO;
        }

        if(IsEqualGUID(OutputType.SubFormat, KSDATAFORMAT_SUBTYPE_PCM))
        {
            if(OutputType.Format.wBitsPerSample == 8)
                mDevice->FmtType = DevFmtUByte;
            else if(OutputType.Format.wBitsPerSample == 16)
                mDevice->FmtType = DevFmtShort;
            else if(OutputType.Format.wBitsPerSample == 32)
                mDevice->FmtType = DevFmtInt;
            else
            {
                mDevice->FmtType = DevFmtShort;
                OutputType.Format.wBitsPerSample = 16;
            }
        }
        else if(IsEqualGUID(OutputType.SubFormat, KSDATAFORMAT_SUBTYPE_IEEE_FLOAT))
        {
            mDevice->FmtType = DevFmtFloat;
            OutputType.Format.wBitsPerSample = 32;
        }
        else
        {
            ERR("Unhandled format sub-type: %s\n", GuidPrinter{OutputType.SubFormat}.c_str());
            mDevice->FmtType = DevFmtShort;
            if(OutputType.Format.wFormatTag != WAVE_FORMAT_EXTENSIBLE)
                OutputType.Format.wFormatTag = WAVE_FORMAT_PCM;
            OutputType.Format.wBitsPerSample = 16;
            OutputType.SubFormat = KSDATAFORMAT_SUBTYPE_PCM;
        }
        OutputType.Samples.wValidBitsPerSample = OutputType.Format.wBitsPerSample;
    }
    mFrameStep = OutputType.Format.nChannels;

    const EndpointFormFactor formfactor{get_device_formfactor(mMMDev.get())};
    mDevice->IsHeadphones = (mDevice->FmtChans == DevFmtStereo
        && (formfactor == Headphones || formfactor == Headset));

    setChannelOrderFromWFXMask(OutputType.dwChannelMask);

    hr = mClient->Initialize(AUDCLNT_SHAREMODE_SHARED, AUDCLNT_STREAMFLAGS_EVENTCALLBACK,
        buf_time.count(), 0, &OutputType.Format, nullptr);
    if(FAILED(hr))
    {
        ERR("Failed to initialize audio client: 0x%08lx\n", hr);
        return hr;
    }

    UINT32 buffer_len{};
    ReferenceTime min_per{};
    hr = mClient->GetDevicePeriod(&reinterpret_cast<REFERENCE_TIME&>(min_per), nullptr);
    if(SUCCEEDED(hr))
        hr = mClient->GetBufferSize(&buffer_len);
    if(FAILED(hr))
    {
        ERR("Failed to get audio buffer info: 0x%08lx\n", hr);
        return hr;
    }

    /* Find the nearest multiple of the period size to the update size */
    if(min_per < per_time)
        min_per *= maxi64((per_time + min_per/2) / min_per, 1);
    mDevice->UpdateSize = minu(RefTime2Samples(min_per, mDevice->Frequency), buffer_len/2);
    mDevice->BufferSize = buffer_len;

    hr = mClient->SetEventHandle(mNotifyEvent);
    if(FAILED(hr))
    {
        ERR("Failed to set event handle: 0x%08lx\n", hr);
        return hr;
    }

    return hr;
}


void WasapiPlayback::start()
{
    const HRESULT hr{pushMessage(MsgType::StartDevice).get()};
    if(FAILED(hr))
        throw al::backend_exception{al::backend_error::DeviceError,
            "Failed to start playback: 0x%lx", hr};
}

HRESULT WasapiPlayback::startProxy()
{
    ResetEvent(mNotifyEvent);

    HRESULT hr{mClient->Start()};
    if(FAILED(hr))
    {
        ERR("Failed to start audio client: 0x%08lx\n", hr);
        return hr;
    }

    void *ptr;
    hr = mClient->GetService(IID_IAudioRenderClient, &ptr);
    if(SUCCEEDED(hr))
    {
        mRender = ComPtr<IAudioRenderClient>{static_cast<IAudioRenderClient*>(ptr)};
        try {
            mKillNow.store(false, std::memory_order_release);
            mThread = std::thread{std::mem_fn(&WasapiPlayback::mixerProc), this};
        }
        catch(...) {
            mRender = nullptr;
            ERR("Failed to start thread\n");
            hr = E_FAIL;
        }
    }

    if(FAILED(hr))
        mClient->Stop();

    return hr;
}


void WasapiPlayback::stop()
{ pushMessage(MsgType::StopDevice).wait(); }

void WasapiPlayback::stopProxy()
{
    if(!mRender || !mThread.joinable())
        return;

    mKillNow.store(true, std::memory_order_release);
    mThread.join();

    mRender = nullptr;
    mClient->Stop();
}


ClockLatency WasapiPlayback::getClockLatency()
{
    ClockLatency ret;

    std::lock_guard<std::mutex> _{mMutex};
    ret.ClockTime = GetDeviceClockTime(mDevice);
    ret.Latency  = std::chrono::seconds{mPadding.load(std::memory_order_relaxed)};
    ret.Latency /= mDevice->Frequency;

    return ret;
}


struct WasapiCapture final : public BackendBase, WasapiProxy {
    WasapiCapture(ALCdevice *device) noexcept : BackendBase{device} { }
    ~WasapiCapture() override;

    int recordProc();

    void open(const char *name) override;
    HRESULT openProxy(const char *name) override;
    void closeProxy() override;

    HRESULT resetProxy() override;
    void start() override;
    HRESULT startProxy() override;
    void stop() override;
    void stopProxy() override;

    void captureSamples(al::byte *buffer, uint samples) override;
    uint availableSamples() override;

    HRESULT mOpenStatus{E_FAIL};
    ComPtr<IMMDevice> mMMDev{nullptr};
    ComPtr<IAudioClient> mClient{nullptr};
    ComPtr<IAudioCaptureClient> mCapture{nullptr};
    HANDLE mNotifyEvent{nullptr};

    ChannelConverter mChannelConv{};
    SampleConverterPtr mSampleConv;
    RingBufferPtr mRing;

    std::atomic<bool> mKillNow{true};
    std::thread mThread;

    DEF_NEWDEL(WasapiCapture)
};

WasapiCapture::~WasapiCapture()
{
    if(SUCCEEDED(mOpenStatus))
        pushMessage(MsgType::CloseDevice).wait();
    mOpenStatus = E_FAIL;

    if(mNotifyEvent != nullptr)
        CloseHandle(mNotifyEvent);
    mNotifyEvent = nullptr;
}


FORCE_ALIGN int WasapiCapture::recordProc()
{
    HRESULT hr{CoInitializeEx(nullptr, COINIT_MULTITHREADED)};
    if(FAILED(hr))
    {
        ERR("CoInitializeEx(nullptr, COINIT_MULTITHREADED) failed: 0x%08lx\n", hr);
        mDevice->handleDisconnect("COM init failed: 0x%08lx", hr);
        return 1;
    }

    althrd_setname(RECORD_THREAD_NAME);

    al::vector<float> samples;
    while(!mKillNow.load(std::memory_order_relaxed))
    {
        UINT32 avail;
        hr = mCapture->GetNextPacketSize(&avail);
        if(FAILED(hr))
            ERR("Failed to get next packet size: 0x%08lx\n", hr);
        else if(avail > 0)
        {
            UINT32 numsamples;
            DWORD flags;
            BYTE *rdata;

            hr = mCapture->GetBuffer(&rdata, &numsamples, &flags, nullptr, nullptr);
            if(FAILED(hr))
                ERR("Failed to get capture buffer: 0x%08lx\n", hr);
            else
            {
                if(mChannelConv.is_active())
                {
                    samples.resize(numsamples*2);
                    mChannelConv.convert(rdata, samples.data(), numsamples);
                    rdata = reinterpret_cast<BYTE*>(samples.data());
                }

                auto data = mRing->getWriteVector();

                size_t dstframes;
                if(mSampleConv)
                {
                    const void *srcdata{rdata};
                    uint srcframes{numsamples};

                    dstframes = mSampleConv->convert(&srcdata, &srcframes, data.first.buf,
                        static_cast<uint>(minz(data.first.len, INT_MAX)));
                    if(srcframes > 0 && dstframes == data.first.len && data.second.len > 0)
                    {
                        /* If some source samples remain, all of the first dest
                         * block was filled, and there's space in the second
                         * dest block, do another run for the second block.
                         */
                        dstframes += mSampleConv->convert(&srcdata, &srcframes, data.second.buf,
                            static_cast<uint>(minz(data.second.len, INT_MAX)));
                    }
                }
                else
                {
                    const uint framesize{mDevice->frameSizeFromFmt()};
                    size_t len1{minz(data.first.len, numsamples)};
                    size_t len2{minz(data.second.len, numsamples-len1)};

                    memcpy(data.first.buf, rdata, len1*framesize);
                    if(len2 > 0)
                        memcpy(data.second.buf, rdata+len1*framesize, len2*framesize);
                    dstframes = len1 + len2;
                }

                mRing->writeAdvance(dstframes);

                hr = mCapture->ReleaseBuffer(numsamples);
                if(FAILED(hr)) ERR("Failed to release capture buffer: 0x%08lx\n", hr);
            }
        }

        if(FAILED(hr))
        {
            mDevice->handleDisconnect("Failed to capture samples: 0x%08lx", hr);
            break;
        }

        DWORD res{WaitForSingleObjectEx(mNotifyEvent, 2000, FALSE)};
        if(res != WAIT_OBJECT_0)
            ERR("WaitForSingleObjectEx error: 0x%lx\n", res);
    }

    CoUninitialize();
    return 0;
}


void WasapiCapture::open(const char *name)
{
    HRESULT hr{S_OK};

    mNotifyEvent = CreateEventW(nullptr, FALSE, FALSE, nullptr);
    if(mNotifyEvent == nullptr)
    {
        ERR("Failed to create notify event: %lu\n", GetLastError());
        hr = E_FAIL;
    }

    if(SUCCEEDED(hr))
    {
        if(name && CaptureDevices.empty())
            pushMessage(MsgType::EnumerateCapture).wait();
        hr = pushMessage(MsgType::OpenDevice, name).get();
    }
    mOpenStatus = hr;

    if(FAILED(hr))
        throw al::backend_exception{al::backend_error::DeviceError, "Device init failed: 0x%08lx",
            hr};

    hr = pushMessage(MsgType::ResetDevice).get();
    if(FAILED(hr))
    {
        if(hr == E_OUTOFMEMORY)
            throw al::backend_exception{al::backend_error::OutOfMemory, "Out of memory"};
        throw al::backend_exception{al::backend_error::DeviceError, "Device reset failed"};
    }
}

HRESULT WasapiCapture::openProxy(const char *name)
{
    const wchar_t *devid{nullptr};
    if(name)
    {
        auto iter = std::find_if(CaptureDevices.cbegin(), CaptureDevices.cend(),
            [name](const DevMap &entry) -> bool
            { return entry.name == name || entry.endpoint_guid == name; });
        if(iter == CaptureDevices.cend())
        {
            const std::wstring wname{utf8_to_wstr(name)};
            iter = std::find_if(CaptureDevices.cbegin(), CaptureDevices.cend(),
                [&wname](const DevMap &entry) -> bool
                { return entry.devid == wname; });
        }
        if(iter == CaptureDevices.cend())
        {
            WARN("Failed to find device name matching \"%s\"\n", name);
            return E_FAIL;
        }
        name = iter->name.c_str();
        devid = iter->devid.c_str();
    }

    void *ptr;
    HRESULT hr{CoCreateInstance(CLSID_MMDeviceEnumerator, nullptr, CLSCTX_INPROC_SERVER,
        IID_IMMDeviceEnumerator, &ptr)};
    ComPtr<IMMDeviceEnumerator> enumerator{static_cast<IMMDeviceEnumerator*>(ptr)};
    if(!devid)
        hr = enumerator->GetDefaultAudioEndpoint(eCapture, eMultimedia, mMMDev.getPtr());
    else
        hr = enumerator->GetDevice(devid, mMMDev.getPtr());
    enumerator = nullptr;
    if(FAILED(hr))
    {
        WARN("Failed to open device \"%s\"\n", name?name:"(default)");
        return hr;
    }

    hr = mMMDev->Activate(IID_IAudioClient, CLSCTX_INPROC_SERVER, nullptr, &ptr);
    if(FAILED(hr))
    {
        WARN("Failed to activate device \"%s\"\n", name?name:"(default)");
        mMMDev = nullptr;
        return hr;
    }

    mClient = ComPtr<IAudioClient>{static_cast<IAudioClient*>(ptr)};
    if(name) mDevice->DeviceName = name;
    else mDevice->DeviceName = get_device_name_and_guid(mMMDev.get()).first;

    return hr;
}

void WasapiCapture::closeProxy()
{
    mClient = nullptr;
    mMMDev = nullptr;
}

HRESULT WasapiCapture::resetProxy()
{
    mClient = nullptr;

    void *ptr;
    HRESULT hr{mMMDev->Activate(IID_IAudioClient, CLSCTX_INPROC_SERVER, nullptr, &ptr)};
    if(FAILED(hr))
    {
        ERR("Failed to reactivate audio client: 0x%08lx\n", hr);
        return hr;
    }
    mClient = ComPtr<IAudioClient>{static_cast<IAudioClient*>(ptr)};

    // Make sure buffer is at least 100ms in size
    ReferenceTime buf_time{ReferenceTime{seconds{mDevice->BufferSize}} / mDevice->Frequency};
    buf_time = std::max(buf_time, ReferenceTime{milliseconds{100}});

    WAVEFORMATEXTENSIBLE InputType{};
    InputType.Format.wFormatTag = WAVE_FORMAT_EXTENSIBLE;
    switch(mDevice->FmtChans)
    {
    case DevFmtMono:
        InputType.Format.nChannels = 1;
        InputType.dwChannelMask = MONO;
        break;
    case DevFmtStereo:
        InputType.Format.nChannels = 2;
        InputType.dwChannelMask = STEREO;
        break;
    case DevFmtQuad:
        InputType.Format.nChannels = 4;
        InputType.dwChannelMask = QUAD;
        break;
    case DevFmtX51:
        InputType.Format.nChannels = 6;
        InputType.dwChannelMask = X5DOT1;
        break;
    case DevFmtX51Rear:
        InputType.Format.nChannels = 6;
        InputType.dwChannelMask = X5DOT1REAR;
        break;
    case DevFmtX61:
        InputType.Format.nChannels = 7;
        InputType.dwChannelMask = X6DOT1;
        break;
    case DevFmtX71:
        InputType.Format.nChannels = 8;
        InputType.dwChannelMask = X7DOT1;
        break;

    case DevFmtAmbi3D:
        return E_FAIL;
    }
    switch(mDevice->FmtType)
    {
    /* NOTE: Signedness doesn't matter, the converter will handle it. */
    case DevFmtByte:
    case DevFmtUByte:
        InputType.Format.wBitsPerSample = 8;
        InputType.SubFormat = KSDATAFORMAT_SUBTYPE_PCM;
        break;
    case DevFmtShort:
    case DevFmtUShort:
        InputType.Format.wBitsPerSample = 16;
        InputType.SubFormat = KSDATAFORMAT_SUBTYPE_PCM;
        break;
    case DevFmtInt:
    case DevFmtUInt:
        InputType.Format.wBitsPerSample = 32;
        InputType.SubFormat = KSDATAFORMAT_SUBTYPE_PCM;
        break;
    case DevFmtFloat:
        InputType.Format.wBitsPerSample = 32;
        InputType.SubFormat = KSDATAFORMAT_SUBTYPE_IEEE_FLOAT;
        break;
    }
    InputType.Samples.wValidBitsPerSample = InputType.Format.wBitsPerSample;
    InputType.Format.nSamplesPerSec = mDevice->Frequency;

    InputType.Format.nBlockAlign = static_cast<WORD>(InputType.Format.nChannels *
        InputType.Format.wBitsPerSample / 8);
    InputType.Format.nAvgBytesPerSec = InputType.Format.nSamplesPerSec *
        InputType.Format.nBlockAlign;
    InputType.Format.cbSize = sizeof(InputType) - sizeof(InputType.Format);

    TraceFormat("Requesting capture format", &InputType.Format);
    WAVEFORMATEX *wfx;
    hr = mClient->IsFormatSupported(AUDCLNT_SHAREMODE_SHARED, &InputType.Format, &wfx);
    if(FAILED(hr))
    {
        ERR("Failed to check format support: 0x%08lx\n", hr);
        return hr;
    }

    mSampleConv = nullptr;
    mChannelConv = {};

    if(wfx != nullptr)
    {
        TraceFormat("Got capture format", wfx);
        if(!MakeExtensible(&InputType, wfx))
        {
            CoTaskMemFree(wfx);
            return E_FAIL;
        }
        CoTaskMemFree(wfx);
        wfx = nullptr;

        auto validate_fmt = [](ALCdevice *device, uint32_t chancount, DWORD chanmask) noexcept
            -> bool
        {
            switch(device->FmtChans)
            {
            /* If the device wants mono, we can handle any input. */
            case DevFmtMono:
                return true;
            /* If the device wants stereo, we can handle mono or stereo input. */
            case DevFmtStereo:
                return (chancount == 2 && (chanmask == 0 || (chanmask&StereoMask) == STEREO))
                    || (chancount == 1 && (chanmask&MonoMask) == MONO);
            /* Otherwise, the device must match the input type. */
            case DevFmtQuad:
                return (chancount == 4 && (chanmask == 0 || (chanmask&QuadMask) == QUAD));
            /* 5.1 (Side) and 5.1 (Rear) are interchangeable here. */
            case DevFmtX51:
            case DevFmtX51Rear:
                return (chancount == 6 && (chanmask == 0 || (chanmask&X51Mask) == X5DOT1
                        || (chanmask&X51RearMask) == X5DOT1REAR));
            case DevFmtX61:
                return (chancount == 7 && (chanmask == 0 || (chanmask&X61Mask) == X6DOT1));
            case DevFmtX71:
                return (chancount == 8 && (chanmask == 0 || (chanmask&X71Mask) == X7DOT1));
            case DevFmtAmbi3D: return (chanmask == 0 && device->channelsFromFmt());
            }
            return false;
        };
        if(!validate_fmt(mDevice, InputType.Format.nChannels, InputType.dwChannelMask))
        {
            ERR("Failed to match format, wanted: %s %s %uhz, got: 0x%08lx mask %d channel%s %d-bit %luhz\n",
                DevFmtChannelsString(mDevice->FmtChans), DevFmtTypeString(mDevice->FmtType),
                mDevice->Frequency, InputType.dwChannelMask, InputType.Format.nChannels,
                (InputType.Format.nChannels==1)?"":"s", InputType.Format.wBitsPerSample,
                InputType.Format.nSamplesPerSec);
            return E_FAIL;
        }
    }

    DevFmtType srcType{};
    if(IsEqualGUID(InputType.SubFormat, KSDATAFORMAT_SUBTYPE_PCM))
    {
        if(InputType.Format.wBitsPerSample == 8)
            srcType = DevFmtUByte;
        else if(InputType.Format.wBitsPerSample == 16)
            srcType = DevFmtShort;
        else if(InputType.Format.wBitsPerSample == 32)
            srcType = DevFmtInt;
        else
        {
            ERR("Unhandled integer bit depth: %d\n", InputType.Format.wBitsPerSample);
            return E_FAIL;
        }
    }
    else if(IsEqualGUID(InputType.SubFormat, KSDATAFORMAT_SUBTYPE_IEEE_FLOAT))
    {
        if(InputType.Format.wBitsPerSample == 32)
            srcType = DevFmtFloat;
        else
        {
            ERR("Unhandled float bit depth: %d\n", InputType.Format.wBitsPerSample);
            return E_FAIL;
        }
    }
    else
    {
        ERR("Unhandled format sub-type: %s\n", GuidPrinter{InputType.SubFormat}.c_str());
        return E_FAIL;
    }

    if(mDevice->FmtChans == DevFmtMono && InputType.Format.nChannels != 1)
    {
        uint chanmask{(1u<<InputType.Format.nChannels) - 1u};
        /* Exclude LFE from the downmix. */
        if((InputType.dwChannelMask&SPEAKER_LOW_FREQUENCY))
        {
            constexpr auto lfemask = MaskFromTopBits(SPEAKER_LOW_FREQUENCY);
            const int lfeidx{al::popcount(InputType.dwChannelMask&lfemask) - 1};
            chanmask &= ~(1u << lfeidx);
        }

        mChannelConv = ChannelConverter{srcType, InputType.Format.nChannels, chanmask,
            mDevice->FmtChans};
        TRACE("Created %s multichannel-to-mono converter\n", DevFmtTypeString(srcType));
        /* The channel converter always outputs float, so change the input type
         * for the resampler/type-converter.
         */
        srcType = DevFmtFloat;
    }
    else if(mDevice->FmtChans == DevFmtStereo && InputType.Format.nChannels == 1)
    {
        mChannelConv = ChannelConverter{srcType, 1, 0x1, mDevice->FmtChans};
        TRACE("Created %s mono-to-stereo converter\n", DevFmtTypeString(srcType));
        srcType = DevFmtFloat;
    }

    if(mDevice->Frequency != InputType.Format.nSamplesPerSec || mDevice->FmtType != srcType)
    {
        mSampleConv = CreateSampleConverter(srcType, mDevice->FmtType, mDevice->channelsFromFmt(),
            InputType.Format.nSamplesPerSec, mDevice->Frequency, Resampler::FastBSinc24);
        if(!mSampleConv)
        {
            ERR("Failed to create converter for %s format, dst: %s %uhz, src: %s %luhz\n",
                DevFmtChannelsString(mDevice->FmtChans), DevFmtTypeString(mDevice->FmtType),
                mDevice->Frequency, DevFmtTypeString(srcType), InputType.Format.nSamplesPerSec);
            return E_FAIL;
        }
        TRACE("Created converter for %s format, dst: %s %uhz, src: %s %luhz\n",
            DevFmtChannelsString(mDevice->FmtChans), DevFmtTypeString(mDevice->FmtType),
            mDevice->Frequency, DevFmtTypeString(srcType), InputType.Format.nSamplesPerSec);
    }

    hr = mClient->Initialize(AUDCLNT_SHAREMODE_SHARED, AUDCLNT_STREAMFLAGS_EVENTCALLBACK,
        buf_time.count(), 0, &InputType.Format, nullptr);
    if(FAILED(hr))
    {
        ERR("Failed to initialize audio client: 0x%08lx\n", hr);
        return hr;
    }

    UINT32 buffer_len{};
    ReferenceTime min_per{};
    hr = mClient->GetDevicePeriod(&reinterpret_cast<REFERENCE_TIME&>(min_per), nullptr);
    if(SUCCEEDED(hr))
        hr = mClient->GetBufferSize(&buffer_len);
    if(FAILED(hr))
    {
        ERR("Failed to get buffer size: 0x%08lx\n", hr);
        return hr;
    }
    mDevice->UpdateSize = RefTime2Samples(min_per, mDevice->Frequency);
    mDevice->BufferSize = buffer_len;

    mRing = RingBuffer::Create(buffer_len, mDevice->frameSizeFromFmt(), false);

    hr = mClient->SetEventHandle(mNotifyEvent);
    if(FAILED(hr))
    {
        ERR("Failed to set event handle: 0x%08lx\n", hr);
        return hr;
    }

    return hr;
}


void WasapiCapture::start()
{
    const HRESULT hr{pushMessage(MsgType::StartDevice).get()};
    if(FAILED(hr))
        throw al::backend_exception{al::backend_error::DeviceError,
            "Failed to start recording: 0x%lx", hr};
}

HRESULT WasapiCapture::startProxy()
{
    ResetEvent(mNotifyEvent);

    HRESULT hr{mClient->Start()};
    if(FAILED(hr))
    {
        ERR("Failed to start audio client: 0x%08lx\n", hr);
        return hr;
    }

    void *ptr;
    hr = mClient->GetService(IID_IAudioCaptureClient, &ptr);
    if(SUCCEEDED(hr))
    {
        mCapture = ComPtr<IAudioCaptureClient>{static_cast<IAudioCaptureClient*>(ptr)};
        try {
            mKillNow.store(false, std::memory_order_release);
            mThread = std::thread{std::mem_fn(&WasapiCapture::recordProc), this};
        }
        catch(...) {
            mCapture = nullptr;
            ERR("Failed to start thread\n");
            hr = E_FAIL;
        }
    }

    if(FAILED(hr))
    {
        mClient->Stop();
        mClient->Reset();
    }

    return hr;
}


void WasapiCapture::stop()
{ pushMessage(MsgType::StopDevice).wait(); }

void WasapiCapture::stopProxy()
{
    if(!mCapture || !mThread.joinable())
        return;

    mKillNow.store(true, std::memory_order_release);
    mThread.join();

    mCapture = nullptr;
    mClient->Stop();
    mClient->Reset();
}


void WasapiCapture::captureSamples(al::byte *buffer, uint samples)
{ mRing->read(buffer, samples); }

uint WasapiCapture::availableSamples()
{ return static_cast<uint>(mRing->readSpace()); }

} // namespace


bool WasapiBackendFactory::init()
{
    static HRESULT InitResult{E_FAIL};

    if(FAILED(InitResult)) try
    {
        std::promise<HRESULT> promise;
        auto future = promise.get_future();

        std::thread{&WasapiProxy::messageHandler, &promise}.detach();
        InitResult = future.get();
    }
    catch(...) {
    }

    return SUCCEEDED(InitResult);
}

bool WasapiBackendFactory::querySupport(BackendType type)
{ return type == BackendType::Playback || type == BackendType::Capture; }

std::string WasapiBackendFactory::probe(BackendType type)
{
    std::string outnames;
    auto add_device = [&outnames](const DevMap &entry) -> void
    {
        /* +1 to also append the null char (to ensure a null-separated list and
         * double-null terminated list).
         */
        outnames.append(entry.name.c_str(), entry.name.length()+1);
    };

    switch(type)
    {
    case BackendType::Playback:
        WasapiProxy::pushMessageStatic(MsgType::EnumeratePlayback).wait();
        std::for_each(PlaybackDevices.cbegin(), PlaybackDevices.cend(), add_device);
        break;

    case BackendType::Capture:
        WasapiProxy::pushMessageStatic(MsgType::EnumerateCapture).wait();
        std::for_each(CaptureDevices.cbegin(), CaptureDevices.cend(), add_device);
        break;
    }

    return outnames;
}

BackendPtr WasapiBackendFactory::createBackend(ALCdevice *device, BackendType type)
{
    if(type == BackendType::Playback)
        return BackendPtr{new WasapiPlayback{device}};
    if(type == BackendType::Capture)
        return BackendPtr{new WasapiCapture{device}};
    return nullptr;
}

BackendFactory &WasapiBackendFactory::getFactory()
{
    static WasapiBackendFactory factory{};
    return factory;
}