First Commit

externals/openal-soft/alc/backends/coreaudio.cpp

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+/**
+ * OpenAL cross platform audio library
+ * Copyright (C) 1999-2007 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 "coreaudio.h"
+
+#include <inttypes.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <cmath>
+#include <memory>
+#include <string>
+
+#include "alnumeric.h"
+#include "core/converter.h"
+#include "core/device.h"
+#include "core/logging.h"
+#include "ringbuffer.h"
+
+#include <AudioUnit/AudioUnit.h>
+#include <AudioToolbox/AudioToolbox.h>
+
+
+namespace {
+
+#if TARGET_OS_IOS || TARGET_OS_TV
+#define CAN_ENUMERATE 0
+#else
+#define CAN_ENUMERATE 1
+#endif
+
+constexpr auto OutputElement = 0;
+constexpr auto InputElement = 1;
+
+#if CAN_ENUMERATE
+struct DeviceEntry {
+    AudioDeviceID mId;
+    std::string mName;
+};
+
+std::vector<DeviceEntry> PlaybackList;
+std::vector<DeviceEntry> CaptureList;
+
+
+OSStatus GetHwProperty(AudioHardwarePropertyID propId, UInt32 dataSize, void *propData)
+{
+    const AudioObjectPropertyAddress addr{propId, kAudioObjectPropertyScopeGlobal,
+        kAudioObjectPropertyElementMaster};
+    return AudioObjectGetPropertyData(kAudioObjectSystemObject, &addr, 0, nullptr, &dataSize,
+        propData);
+}
+
+OSStatus GetHwPropertySize(AudioHardwarePropertyID propId, UInt32 *outSize)
+{
+    const AudioObjectPropertyAddress addr{propId, kAudioObjectPropertyScopeGlobal,
+        kAudioObjectPropertyElementMaster};
+    return AudioObjectGetPropertyDataSize(kAudioObjectSystemObject, &addr, 0, nullptr, outSize);
+}
+
+OSStatus GetDevProperty(AudioDeviceID devId, AudioDevicePropertyID propId, bool isCapture,
+    UInt32 elem, UInt32 dataSize, void *propData)
+{
+    static const AudioObjectPropertyScope scopes[2]{kAudioDevicePropertyScopeOutput,
+        kAudioDevicePropertyScopeInput};
+    const AudioObjectPropertyAddress addr{propId, scopes[isCapture], elem};
+    return AudioObjectGetPropertyData(devId, &addr, 0, nullptr, &dataSize, propData);
+}
+
+OSStatus GetDevPropertySize(AudioDeviceID devId, AudioDevicePropertyID inPropertyID,
+    bool isCapture, UInt32 elem, UInt32 *outSize)
+{
+    static const AudioObjectPropertyScope scopes[2]{kAudioDevicePropertyScopeOutput,
+        kAudioDevicePropertyScopeInput};
+    const AudioObjectPropertyAddress addr{inPropertyID, scopes[isCapture], elem};
+    return AudioObjectGetPropertyDataSize(devId, &addr, 0, nullptr, outSize);
+}
+
+
+std::string GetDeviceName(AudioDeviceID devId)
+{
+    std::string devname;
+    CFStringRef nameRef;
+
+    /* Try to get the device name as a CFString, for Unicode name support. */
+    OSStatus err{GetDevProperty(devId, kAudioDevicePropertyDeviceNameCFString, false, 0,
+        sizeof(nameRef), &nameRef)};
+    if(err == noErr)
+    {
+        const CFIndex propSize{CFStringGetMaximumSizeForEncoding(CFStringGetLength(nameRef),
+            kCFStringEncodingUTF8)};
+        devname.resize(static_cast<size_t>(propSize)+1, '\0');
+
+        CFStringGetCString(nameRef, &devname[0], propSize+1, kCFStringEncodingUTF8);
+        CFRelease(nameRef);
+    }
+    else
+    {
+        /* If that failed, just get the C string. Hopefully there's nothing bad
+         * with this.
+         */
+        UInt32 propSize{};
+        if(GetDevPropertySize(devId, kAudioDevicePropertyDeviceName, false, 0, &propSize))
+            return devname;
+
+        devname.resize(propSize+1, '\0');
+        if(GetDevProperty(devId, kAudioDevicePropertyDeviceName, false, 0, propSize, &devname[0]))
+        {
+            devname.clear();
+            return devname;
+        }
+    }
+
+    /* Clear extraneous nul chars that may have been written with the name
+     * string, and return it.
+     */
+    while(!devname.back())
+        devname.pop_back();
+    return devname;
+}
+
+UInt32 GetDeviceChannelCount(AudioDeviceID devId, bool isCapture)
+{
+    UInt32 propSize{};
+    auto err = GetDevPropertySize(devId, kAudioDevicePropertyStreamConfiguration, isCapture, 0,
+        &propSize);
+    if(err)
+    {
+        ERR("kAudioDevicePropertyStreamConfiguration size query failed: %u\n", err);
+        return 0;
+    }
+
+    auto buflist_data = std::make_unique<char[]>(propSize);
+    auto *buflist = reinterpret_cast<AudioBufferList*>(buflist_data.get());
+
+    err = GetDevProperty(devId, kAudioDevicePropertyStreamConfiguration, isCapture, 0, propSize,
+        buflist);
+    if(err)
+    {
+        ERR("kAudioDevicePropertyStreamConfiguration query failed: %u\n", err);
+        return 0;
+    }
+
+    UInt32 numChannels{0};
+    for(size_t i{0};i < buflist->mNumberBuffers;++i)
+        numChannels += buflist->mBuffers[i].mNumberChannels;
+
+    return numChannels;
+}
+
+
+void EnumerateDevices(std::vector<DeviceEntry> &list, bool isCapture)
+{
+    UInt32 propSize{};
+    if(auto err = GetHwPropertySize(kAudioHardwarePropertyDevices, &propSize))
+    {
+        ERR("Failed to get device list size: %u\n", err);
+        return;
+    }
+
+    auto devIds = std::vector<AudioDeviceID>(propSize/sizeof(AudioDeviceID), kAudioDeviceUnknown);
+    if(auto err = GetHwProperty(kAudioHardwarePropertyDevices, propSize, devIds.data()))
+    {
+        ERR("Failed to get device list: %u\n", err);
+        return;
+    }
+
+    std::vector<DeviceEntry> newdevs;
+    newdevs.reserve(devIds.size());
+
+    AudioDeviceID defaultId{kAudioDeviceUnknown};
+    GetHwProperty(isCapture ? kAudioHardwarePropertyDefaultInputDevice :
+        kAudioHardwarePropertyDefaultOutputDevice, sizeof(defaultId), &defaultId);
+
+    if(defaultId != kAudioDeviceUnknown)
+    {
+        newdevs.emplace_back(DeviceEntry{defaultId, GetDeviceName(defaultId)});
+        const auto &entry = newdevs.back();
+        TRACE("Got device: %s = ID %u\n", entry.mName.c_str(), entry.mId);
+    }
+    for(const AudioDeviceID devId : devIds)
+    {
+        if(devId == kAudioDeviceUnknown)
+            continue;
+
+        auto match_devid = [devId](const DeviceEntry &entry) noexcept -> bool
+        { return entry.mId == devId; };
+        auto match = std::find_if(newdevs.cbegin(), newdevs.cend(), match_devid);
+        if(match != newdevs.cend()) continue;
+
+        auto numChannels = GetDeviceChannelCount(devId, isCapture);
+        if(numChannels > 0)
+        {
+            newdevs.emplace_back(DeviceEntry{devId, GetDeviceName(devId)});
+            const auto &entry = newdevs.back();
+            TRACE("Got device: %s = ID %u\n", entry.mName.c_str(), entry.mId);
+        }
+    }
+
+    if(newdevs.size() > 1)
+    {
+        /* Rename entries that have matching names, by appending '#2', '#3',
+         * etc, as needed.
+         */
+        for(auto curitem = newdevs.begin()+1;curitem != newdevs.end();++curitem)
+        {
+            auto check_match = [curitem](const DeviceEntry &entry) -> bool
+            { return entry.mName == curitem->mName; };
+            if(std::find_if(newdevs.begin(), curitem, check_match) != curitem)
+            {
+                std::string name{curitem->mName};
+                size_t count{1};
+                auto check_name = [&name](const DeviceEntry &entry) -> bool
+                { return entry.mName == name; };
+                do {
+                    name = curitem->mName;
+                    name += " #";
+                    name += std::to_string(++count);
+                } while(std::find_if(newdevs.begin(), curitem, check_name) != curitem);
+                curitem->mName = std::move(name);
+            }
+        }
+    }
+
+    newdevs.shrink_to_fit();
+    newdevs.swap(list);
+}
+
+#else
+
+static constexpr char ca_device[] = "CoreAudio Default";
+#endif
+
+
+struct CoreAudioPlayback final : public BackendBase {
+    CoreAudioPlayback(DeviceBase *device) noexcept : BackendBase{device} { }
+    ~CoreAudioPlayback() override;
+
+    OSStatus MixerProc(AudioUnitRenderActionFlags *ioActionFlags,
+        const AudioTimeStamp *inTimeStamp, UInt32 inBusNumber, UInt32 inNumberFrames,
+        AudioBufferList *ioData) noexcept;
+    static OSStatus MixerProcC(void *inRefCon, AudioUnitRenderActionFlags *ioActionFlags,
+        const AudioTimeStamp *inTimeStamp, UInt32 inBusNumber, UInt32 inNumberFrames,
+        AudioBufferList *ioData) noexcept
+    {
+        return static_cast<CoreAudioPlayback*>(inRefCon)->MixerProc(ioActionFlags, inTimeStamp,
+            inBusNumber, inNumberFrames, ioData);
+    }
+
+    void open(const char *name) override;
+    bool reset() override;
+    void start() override;
+    void stop() override;
+
+    AudioUnit mAudioUnit{};
+
+    uint mFrameSize{0u};
+    AudioStreamBasicDescription mFormat{}; // This is the OpenAL format as a CoreAudio ASBD
+
+    DEF_NEWDEL(CoreAudioPlayback)
+};
+
+CoreAudioPlayback::~CoreAudioPlayback()
+{
+    AudioUnitUninitialize(mAudioUnit);
+    AudioComponentInstanceDispose(mAudioUnit);
+}
+
+
+OSStatus CoreAudioPlayback::MixerProc(AudioUnitRenderActionFlags*, const AudioTimeStamp*, UInt32,
+    UInt32, AudioBufferList *ioData) noexcept
+{
+    for(size_t i{0};i < ioData->mNumberBuffers;++i)
+    {
+        auto &buffer = ioData->mBuffers[i];
+        mDevice->renderSamples(buffer.mData, buffer.mDataByteSize/mFrameSize,
+            buffer.mNumberChannels);
+    }
+    return noErr;
+}
+
+
+void CoreAudioPlayback::open(const char *name)
+{
+#if CAN_ENUMERATE
+    AudioDeviceID audioDevice{kAudioDeviceUnknown};
+    if(!name)
+        GetHwProperty(kAudioHardwarePropertyDefaultOutputDevice, sizeof(audioDevice),
+            &audioDevice);
+    else
+    {
+        if(PlaybackList.empty())
+            EnumerateDevices(PlaybackList, false);
+
+        auto find_name = [name](const DeviceEntry &entry) -> bool
+        { return entry.mName == name; };
+        auto devmatch = std::find_if(PlaybackList.cbegin(), PlaybackList.cend(), find_name);
+        if(devmatch == PlaybackList.cend())
+            throw al::backend_exception{al::backend_error::NoDevice,
+                "Device name \"%s\" not found", name};
+
+        audioDevice = devmatch->mId;
+    }
+#else
+    if(!name)
+        name = ca_device;
+    else if(strcmp(name, ca_device) != 0)
+        throw al::backend_exception{al::backend_error::NoDevice, "Device name \"%s\" not found",
+            name};
+#endif
+
+    /* open the default output unit */
+    AudioComponentDescription desc{};
+    desc.componentType = kAudioUnitType_Output;
+#if CAN_ENUMERATE
+    desc.componentSubType = (audioDevice == kAudioDeviceUnknown) ?
+        kAudioUnitSubType_DefaultOutput : kAudioUnitSubType_HALOutput;
+#else
+    desc.componentSubType = kAudioUnitSubType_RemoteIO;
+#endif
+    desc.componentManufacturer = kAudioUnitManufacturer_Apple;
+    desc.componentFlags = 0;
+    desc.componentFlagsMask = 0;
+
+    AudioComponent comp{AudioComponentFindNext(NULL, &desc)};
+    if(comp == nullptr)
+        throw al::backend_exception{al::backend_error::NoDevice, "Could not find audio component"};
+
+    AudioUnit audioUnit{};
+    OSStatus err{AudioComponentInstanceNew(comp, &audioUnit)};
+    if(err != noErr)
+        throw al::backend_exception{al::backend_error::NoDevice,
+            "Could not create component instance: %u", err};
+
+#if CAN_ENUMERATE
+    if(audioDevice != kAudioDeviceUnknown)
+        AudioUnitSetProperty(audioUnit, kAudioOutputUnitProperty_CurrentDevice,
+            kAudioUnitScope_Global, OutputElement, &audioDevice, sizeof(AudioDeviceID));
+#endif
+
+    err = AudioUnitInitialize(audioUnit);
+    if(err != noErr)
+        throw al::backend_exception{al::backend_error::DeviceError,
+            "Could not initialize audio unit: %u", err};
+
+    /* WARNING: I don't know if "valid" audio unit values are guaranteed to be
+     * non-0. If not, this logic is broken.
+     */
+    if(mAudioUnit)
+    {
+        AudioUnitUninitialize(mAudioUnit);
+        AudioComponentInstanceDispose(mAudioUnit);
+    }
+    mAudioUnit = audioUnit;
+
+#if CAN_ENUMERATE
+    if(name)
+        mDevice->DeviceName = name;
+    else
+    {
+        UInt32 propSize{sizeof(audioDevice)};
+        audioDevice = kAudioDeviceUnknown;
+        AudioUnitGetProperty(audioUnit, kAudioOutputUnitProperty_CurrentDevice,
+            kAudioUnitScope_Global, OutputElement, &audioDevice, &propSize);
+
+        std::string devname{GetDeviceName(audioDevice)};
+        if(!devname.empty()) mDevice->DeviceName = std::move(devname);
+        else mDevice->DeviceName = "Unknown Device Name";
+    }
+#else
+    mDevice->DeviceName = name;
+#endif
+}
+
+bool CoreAudioPlayback::reset()
+{
+    OSStatus err{AudioUnitUninitialize(mAudioUnit)};
+    if(err != noErr)
+        ERR("-- AudioUnitUninitialize failed.\n");
+
+    /* retrieve default output unit's properties (output side) */
+    AudioStreamBasicDescription streamFormat{};
+    UInt32 size{sizeof(streamFormat)};
+    err = AudioUnitGetProperty(mAudioUnit, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Output,
+        OutputElement, &streamFormat, &size);
+    if(err != noErr || size != sizeof(streamFormat))
+    {
+        ERR("AudioUnitGetProperty failed\n");
+        return false;
+    }
+
+#if 0
+    TRACE("Output streamFormat of default output unit -\n");
+    TRACE("  streamFormat.mFramesPerPacket = %d\n", streamFormat.mFramesPerPacket);
+    TRACE("  streamFormat.mChannelsPerFrame = %d\n", streamFormat.mChannelsPerFrame);
+    TRACE("  streamFormat.mBitsPerChannel = %d\n", streamFormat.mBitsPerChannel);
+    TRACE("  streamFormat.mBytesPerPacket = %d\n", streamFormat.mBytesPerPacket);
+    TRACE("  streamFormat.mBytesPerFrame = %d\n", streamFormat.mBytesPerFrame);
+    TRACE("  streamFormat.mSampleRate = %5.0f\n", streamFormat.mSampleRate);
+#endif
+
+    /* Use the sample rate from the output unit's current parameters, but reset
+     * everything else.
+     */
+    if(mDevice->Frequency != streamFormat.mSampleRate)
+    {
+        mDevice->BufferSize = static_cast<uint>(mDevice->BufferSize*streamFormat.mSampleRate/
+            mDevice->Frequency + 0.5);
+        mDevice->Frequency = static_cast<uint>(streamFormat.mSampleRate);
+    }
+
+    /* FIXME: How to tell what channels are what in the output device, and how
+     * to specify what we're giving? e.g. 6.0 vs 5.1
+     */
+    streamFormat.mChannelsPerFrame = mDevice->channelsFromFmt();
+
+    streamFormat.mFramesPerPacket = 1;
+    streamFormat.mFormatFlags = kAudioFormatFlagsNativeEndian | kLinearPCMFormatFlagIsPacked;
+    streamFormat.mFormatID = kAudioFormatLinearPCM;
+    switch(mDevice->FmtType)
+    {
+        case DevFmtUByte:
+            mDevice->FmtType = DevFmtByte;
+            /* fall-through */
+        case DevFmtByte:
+            streamFormat.mFormatFlags |= kLinearPCMFormatFlagIsSignedInteger;
+            streamFormat.mBitsPerChannel = 8;
+            break;
+        case DevFmtUShort:
+            mDevice->FmtType = DevFmtShort;
+            /* fall-through */
+        case DevFmtShort:
+            streamFormat.mFormatFlags |= kLinearPCMFormatFlagIsSignedInteger;
+            streamFormat.mBitsPerChannel = 16;
+            break;
+        case DevFmtUInt:
+            mDevice->FmtType = DevFmtInt;
+            /* fall-through */
+        case DevFmtInt:
+            streamFormat.mFormatFlags |= kLinearPCMFormatFlagIsSignedInteger;
+            streamFormat.mBitsPerChannel = 32;
+            break;
+        case DevFmtFloat:
+            streamFormat.mFormatFlags |= kLinearPCMFormatFlagIsFloat;
+            streamFormat.mBitsPerChannel = 32;
+            break;
+    }
+    streamFormat.mBytesPerFrame = streamFormat.mChannelsPerFrame*streamFormat.mBitsPerChannel/8;
+    streamFormat.mBytesPerPacket = streamFormat.mBytesPerFrame*streamFormat.mFramesPerPacket;
+
+    err = AudioUnitSetProperty(mAudioUnit, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Input,
+        OutputElement, &streamFormat, sizeof(streamFormat));
+    if(err != noErr)
+    {
+        ERR("AudioUnitSetProperty failed\n");
+        return false;
+    }
+
+    setDefaultWFXChannelOrder();
+
+    /* setup callback */
+    mFrameSize = mDevice->frameSizeFromFmt();
+    AURenderCallbackStruct input{};
+    input.inputProc = CoreAudioPlayback::MixerProcC;
+    input.inputProcRefCon = this;
+
+    err = AudioUnitSetProperty(mAudioUnit, kAudioUnitProperty_SetRenderCallback,
+        kAudioUnitScope_Input, OutputElement, &input, sizeof(AURenderCallbackStruct));
+    if(err != noErr)
+    {
+        ERR("AudioUnitSetProperty failed\n");
+        return false;
+    }
+
+    /* init the default audio unit... */
+    err = AudioUnitInitialize(mAudioUnit);
+    if(err != noErr)
+    {
+        ERR("AudioUnitInitialize failed\n");
+        return false;
+    }
+
+    return true;
+}
+
+void CoreAudioPlayback::start()
+{
+    const OSStatus err{AudioOutputUnitStart(mAudioUnit)};
+    if(err != noErr)
+        throw al::backend_exception{al::backend_error::DeviceError,
+            "AudioOutputUnitStart failed: %d", err};
+}
+
+void CoreAudioPlayback::stop()
+{
+    OSStatus err{AudioOutputUnitStop(mAudioUnit)};
+    if(err != noErr)
+        ERR("AudioOutputUnitStop failed\n");
+}
+
+
+struct CoreAudioCapture final : public BackendBase {
+    CoreAudioCapture(DeviceBase *device) noexcept : BackendBase{device} { }
+    ~CoreAudioCapture() override;
+
+    OSStatus RecordProc(AudioUnitRenderActionFlags *ioActionFlags,
+        const AudioTimeStamp *inTimeStamp, UInt32 inBusNumber,
+        UInt32 inNumberFrames, AudioBufferList *ioData) noexcept;
+    static OSStatus RecordProcC(void *inRefCon, AudioUnitRenderActionFlags *ioActionFlags,
+        const AudioTimeStamp *inTimeStamp, UInt32 inBusNumber, UInt32 inNumberFrames,
+        AudioBufferList *ioData) noexcept
+    {
+        return static_cast<CoreAudioCapture*>(inRefCon)->RecordProc(ioActionFlags, inTimeStamp,
+            inBusNumber, inNumberFrames, ioData);
+    }
+
+    void open(const char *name) override;
+    void start() override;
+    void stop() override;
+    void captureSamples(al::byte *buffer, uint samples) override;
+    uint availableSamples() override;
+
+    AudioUnit mAudioUnit{0};
+
+    uint mFrameSize{0u};
+    AudioStreamBasicDescription mFormat{};  // This is the OpenAL format as a CoreAudio ASBD
+
+    SampleConverterPtr mConverter;
+
+    al::vector<char> mCaptureData;
+
+    RingBufferPtr mRing{nullptr};
+
+    DEF_NEWDEL(CoreAudioCapture)
+};
+
+CoreAudioCapture::~CoreAudioCapture()
+{
+    if(mAudioUnit)
+        AudioComponentInstanceDispose(mAudioUnit);
+    mAudioUnit = 0;
+}
+
+
+OSStatus CoreAudioCapture::RecordProc(AudioUnitRenderActionFlags *ioActionFlags,
+    const AudioTimeStamp *inTimeStamp, UInt32 inBusNumber, UInt32 inNumberFrames,
+    AudioBufferList*) noexcept
+{
+    union {
+        al::byte _[maxz(sizeof(AudioBufferList), offsetof(AudioBufferList, mBuffers[1]))];
+        AudioBufferList list;
+    } audiobuf{};
+
+    audiobuf.list.mNumberBuffers = 1;
+    audiobuf.list.mBuffers[0].mNumberChannels = mFormat.mChannelsPerFrame;
+    audiobuf.list.mBuffers[0].mData = mCaptureData.data();
+    audiobuf.list.mBuffers[0].mDataByteSize = static_cast<UInt32>(mCaptureData.size());
+
+    OSStatus err{AudioUnitRender(mAudioUnit, ioActionFlags, inTimeStamp, inBusNumber,
+        inNumberFrames, &audiobuf.list)};
+    if(err != noErr)
+    {
+        ERR("AudioUnitRender capture error: %d\n", err);
+        return err;
+    }
+
+    mRing->write(mCaptureData.data(), inNumberFrames);
+    return noErr;
+}
+
+
+void CoreAudioCapture::open(const char *name)
+{
+#if CAN_ENUMERATE
+    AudioDeviceID audioDevice{kAudioDeviceUnknown};
+    if(!name)
+        GetHwProperty(kAudioHardwarePropertyDefaultInputDevice, sizeof(audioDevice),
+            &audioDevice);
+    else
+    {
+        if(CaptureList.empty())
+            EnumerateDevices(CaptureList, true);
+
+        auto find_name = [name](const DeviceEntry &entry) -> bool
+        { return entry.mName == name; };
+        auto devmatch = std::find_if(CaptureList.cbegin(), CaptureList.cend(), find_name);
+        if(devmatch == CaptureList.cend())
+            throw al::backend_exception{al::backend_error::NoDevice,
+                "Device name \"%s\" not found", name};
+
+        audioDevice = devmatch->mId;
+    }
+#else
+    if(!name)
+        name = ca_device;
+    else if(strcmp(name, ca_device) != 0)
+        throw al::backend_exception{al::backend_error::NoDevice, "Device name \"%s\" not found",
+            name};
+#endif
+
+    AudioComponentDescription desc{};
+    desc.componentType = kAudioUnitType_Output;
+#if CAN_ENUMERATE
+    desc.componentSubType = (audioDevice == kAudioDeviceUnknown) ?
+        kAudioUnitSubType_DefaultOutput : kAudioUnitSubType_HALOutput;
+#else
+    desc.componentSubType = kAudioUnitSubType_RemoteIO;
+#endif
+    desc.componentManufacturer = kAudioUnitManufacturer_Apple;
+    desc.componentFlags = 0;
+    desc.componentFlagsMask = 0;
+
+    // Search for component with given description
+    AudioComponent comp{AudioComponentFindNext(NULL, &desc)};
+    if(comp == NULL)
+        throw al::backend_exception{al::backend_error::NoDevice, "Could not find audio component"};
+
+    // Open the component
+    OSStatus err{AudioComponentInstanceNew(comp, &mAudioUnit)};
+    if(err != noErr)
+        throw al::backend_exception{al::backend_error::NoDevice,
+            "Could not create component instance: %u", err};
+
+    // Turn off AudioUnit output
+    UInt32 enableIO{0};
+    err = AudioUnitSetProperty(mAudioUnit, kAudioOutputUnitProperty_EnableIO,
+        kAudioUnitScope_Output, OutputElement, &enableIO, sizeof(enableIO));
+    if(err != noErr)
+        throw al::backend_exception{al::backend_error::DeviceError,
+            "Could not disable audio unit output property: %u", err};
+
+    // Turn on AudioUnit input
+    enableIO = 1;
+    err = AudioUnitSetProperty(mAudioUnit, kAudioOutputUnitProperty_EnableIO,
+        kAudioUnitScope_Input, InputElement, &enableIO, sizeof(enableIO));
+    if(err != noErr)
+        throw al::backend_exception{al::backend_error::DeviceError,
+            "Could not enable audio unit input property: %u", err};
+
+#if CAN_ENUMERATE
+    if(audioDevice != kAudioDeviceUnknown)
+        AudioUnitSetProperty(mAudioUnit, kAudioOutputUnitProperty_CurrentDevice,
+            kAudioUnitScope_Global, InputElement, &audioDevice, sizeof(AudioDeviceID));
+#endif
+
+    // set capture callback
+    AURenderCallbackStruct input{};
+    input.inputProc = CoreAudioCapture::RecordProcC;
+    input.inputProcRefCon = this;
+
+    err = AudioUnitSetProperty(mAudioUnit, kAudioOutputUnitProperty_SetInputCallback,
+        kAudioUnitScope_Global, InputElement, &input, sizeof(AURenderCallbackStruct));
+    if(err != noErr)
+        throw al::backend_exception{al::backend_error::DeviceError,
+            "Could not set capture callback: %u", err};
+
+    // Disable buffer allocation for capture
+    UInt32 flag{0};
+    err = AudioUnitSetProperty(mAudioUnit, kAudioUnitProperty_ShouldAllocateBuffer,
+        kAudioUnitScope_Output, InputElement, &flag, sizeof(flag));
+    if(err != noErr)
+        throw al::backend_exception{al::backend_error::DeviceError,
+            "Could not disable buffer allocation property: %u", err};
+
+    // Initialize the device
+    err = AudioUnitInitialize(mAudioUnit);
+    if(err != noErr)
+        throw al::backend_exception{al::backend_error::DeviceError,
+            "Could not initialize audio unit: %u", err};
+
+    // Get the hardware format
+    AudioStreamBasicDescription hardwareFormat{};
+    UInt32 propertySize{sizeof(hardwareFormat)};
+    err = AudioUnitGetProperty(mAudioUnit, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Input,
+        InputElement, &hardwareFormat, &propertySize);
+    if(err != noErr || propertySize != sizeof(hardwareFormat))
+        throw al::backend_exception{al::backend_error::DeviceError,
+            "Could not get input format: %u", err};
+
+    // Set up the requested format description
+    AudioStreamBasicDescription requestedFormat{};
+    switch(mDevice->FmtType)
+    {
+    case DevFmtByte:
+        requestedFormat.mBitsPerChannel = 8;
+        requestedFormat.mFormatFlags = kAudioFormatFlagIsSignedInteger | kAudioFormatFlagIsPacked;
+        break;
+    case DevFmtUByte:
+        requestedFormat.mBitsPerChannel = 8;
+        requestedFormat.mFormatFlags = kAudioFormatFlagIsPacked;
+        break;
+    case DevFmtShort:
+        requestedFormat.mBitsPerChannel = 16;
+        requestedFormat.mFormatFlags = kAudioFormatFlagIsSignedInteger
+            | kAudioFormatFlagsNativeEndian | kAudioFormatFlagIsPacked;
+        break;
+    case DevFmtUShort:
+        requestedFormat.mBitsPerChannel = 16;
+        requestedFormat.mFormatFlags = kAudioFormatFlagsNativeEndian | kAudioFormatFlagIsPacked;
+        break;
+    case DevFmtInt:
+        requestedFormat.mBitsPerChannel = 32;
+        requestedFormat.mFormatFlags = kAudioFormatFlagIsSignedInteger
+            | kAudioFormatFlagsNativeEndian | kAudioFormatFlagIsPacked;
+        break;
+    case DevFmtUInt:
+        requestedFormat.mBitsPerChannel = 32;
+        requestedFormat.mFormatFlags = kAudioFormatFlagsNativeEndian | kAudioFormatFlagIsPacked;
+        break;
+    case DevFmtFloat:
+        requestedFormat.mBitsPerChannel = 32;
+        requestedFormat.mFormatFlags = kLinearPCMFormatFlagIsFloat | kAudioFormatFlagsNativeEndian
+            | kAudioFormatFlagIsPacked;
+        break;
+    }
+
+    switch(mDevice->FmtChans)
+    {
+    case DevFmtMono:
+        requestedFormat.mChannelsPerFrame = 1;
+        break;
+    case DevFmtStereo:
+        requestedFormat.mChannelsPerFrame = 2;
+        break;
+
+    case DevFmtQuad:
+    case DevFmtX51:
+    case DevFmtX61:
+    case DevFmtX71:
+    case DevFmtX714:
+    case DevFmtX3D71:
+    case DevFmtAmbi3D:
+        throw al::backend_exception{al::backend_error::DeviceError, "%s not supported",
+            DevFmtChannelsString(mDevice->FmtChans)};
+    }
+
+    requestedFormat.mBytesPerFrame = requestedFormat.mChannelsPerFrame * requestedFormat.mBitsPerChannel / 8;
+    requestedFormat.mBytesPerPacket = requestedFormat.mBytesPerFrame;
+    requestedFormat.mSampleRate = mDevice->Frequency;
+    requestedFormat.mFormatID = kAudioFormatLinearPCM;
+    requestedFormat.mReserved = 0;
+    requestedFormat.mFramesPerPacket = 1;
+
+    // save requested format description for later use
+    mFormat = requestedFormat;
+    mFrameSize = mDevice->frameSizeFromFmt();
+
+    // Use intermediate format for sample rate conversion (outputFormat)
+    // Set sample rate to the same as hardware for resampling later
+    AudioStreamBasicDescription outputFormat{requestedFormat};
+    outputFormat.mSampleRate = hardwareFormat.mSampleRate;
+
+    // The output format should be the requested format, but using the hardware sample rate
+    // This is because the AudioUnit will automatically scale other properties, except for sample rate
+    err = AudioUnitSetProperty(mAudioUnit, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Output,
+        InputElement, &outputFormat, sizeof(outputFormat));
+    if(err != noErr)
+        throw al::backend_exception{al::backend_error::DeviceError,
+            "Could not set input format: %u", err};
+
+    /* Calculate the minimum AudioUnit output format frame count for the pre-
+     * conversion ring buffer. Ensure at least 100ms for the total buffer.
+     */
+    double srateScale{outputFormat.mSampleRate / mDevice->Frequency};
+    auto FrameCount64 = maxu64(static_cast<uint64_t>(std::ceil(mDevice->BufferSize*srateScale)),
+        static_cast<UInt32>(outputFormat.mSampleRate)/10);
+    FrameCount64 += MaxResamplerPadding;
+    if(FrameCount64 > std::numeric_limits<int32_t>::max())
+        throw al::backend_exception{al::backend_error::DeviceError,
+            "Calculated frame count is too large: %" PRIu64, FrameCount64};
+
+    UInt32 outputFrameCount{};
+    propertySize = sizeof(outputFrameCount);
+    err = AudioUnitGetProperty(mAudioUnit, kAudioUnitProperty_MaximumFramesPerSlice,
+        kAudioUnitScope_Global, OutputElement, &outputFrameCount, &propertySize);
+    if(err != noErr || propertySize != sizeof(outputFrameCount))
+        throw al::backend_exception{al::backend_error::DeviceError,
+            "Could not get input frame count: %u", err};
+
+    mCaptureData.resize(outputFrameCount * mFrameSize);
+
+    outputFrameCount = static_cast<UInt32>(maxu64(outputFrameCount, FrameCount64));
+    mRing = RingBuffer::Create(outputFrameCount, mFrameSize, false);
+
+    /* Set up sample converter if needed */
+    if(outputFormat.mSampleRate != mDevice->Frequency)
+        mConverter = SampleConverter::Create(mDevice->FmtType, mDevice->FmtType,
+            mFormat.mChannelsPerFrame, static_cast<uint>(hardwareFormat.mSampleRate),
+            mDevice->Frequency, Resampler::FastBSinc24);
+
+#if CAN_ENUMERATE
+    if(name)
+        mDevice->DeviceName = name;
+    else
+    {
+        UInt32 propSize{sizeof(audioDevice)};
+        audioDevice = kAudioDeviceUnknown;
+        AudioUnitGetProperty(mAudioUnit, kAudioOutputUnitProperty_CurrentDevice,
+            kAudioUnitScope_Global, InputElement, &audioDevice, &propSize);
+
+        std::string devname{GetDeviceName(audioDevice)};
+        if(!devname.empty()) mDevice->DeviceName = std::move(devname);
+        else mDevice->DeviceName = "Unknown Device Name";
+    }
+#else
+    mDevice->DeviceName = name;
+#endif
+}
+
+
+void CoreAudioCapture::start()
+{
+    OSStatus err{AudioOutputUnitStart(mAudioUnit)};
+    if(err != noErr)
+        throw al::backend_exception{al::backend_error::DeviceError,
+            "AudioOutputUnitStart failed: %d", err};
+}
+
+void CoreAudioCapture::stop()
+{
+    OSStatus err{AudioOutputUnitStop(mAudioUnit)};
+    if(err != noErr)
+        ERR("AudioOutputUnitStop failed\n");
+}
+
+void CoreAudioCapture::captureSamples(al::byte *buffer, uint samples)
+{
+    if(!mConverter)
+    {
+        mRing->read(buffer, samples);
+        return;
+    }
+
+    auto rec_vec = mRing->getReadVector();
+    const void *src0{rec_vec.first.buf};
+    auto src0len = static_cast<uint>(rec_vec.first.len);
+    uint got{mConverter->convert(&src0, &src0len, buffer, samples)};
+    size_t total_read{rec_vec.first.len - src0len};
+    if(got < samples && !src0len && rec_vec.second.len > 0)
+    {
+        const void *src1{rec_vec.second.buf};
+        auto src1len = static_cast<uint>(rec_vec.second.len);
+        got += mConverter->convert(&src1, &src1len, buffer + got*mFrameSize, samples-got);
+        total_read += rec_vec.second.len - src1len;
+    }
+
+    mRing->readAdvance(total_read);
+}
+
+uint CoreAudioCapture::availableSamples()
+{
+    if(!mConverter) return static_cast<uint>(mRing->readSpace());
+    return mConverter->availableOut(static_cast<uint>(mRing->readSpace()));
+}
+
+} // namespace
+
+BackendFactory &CoreAudioBackendFactory::getFactory()
+{
+    static CoreAudioBackendFactory factory{};
+    return factory;
+}
+
+bool CoreAudioBackendFactory::init() { return true; }
+
+bool CoreAudioBackendFactory::querySupport(BackendType type)
+{ return type == BackendType::Playback || type == BackendType::Capture; }
+
+std::string CoreAudioBackendFactory::probe(BackendType type)
+{
+    std::string outnames;
+#if CAN_ENUMERATE
+    auto append_name = [&outnames](const DeviceEntry &entry) -> void
+    {
+        /* Includes null char. */
+        outnames.append(entry.mName.c_str(), entry.mName.length()+1);
+    };
+    switch(type)
+    {
+    case BackendType::Playback:
+        EnumerateDevices(PlaybackList, false);
+        std::for_each(PlaybackList.cbegin(), PlaybackList.cend(), append_name);
+        break;
+    case BackendType::Capture:
+        EnumerateDevices(CaptureList, true);
+        std::for_each(CaptureList.cbegin(), CaptureList.cend(), append_name);
+        break;
+    }
+
+#else
+
+    switch(type)
+    {
+    case BackendType::Playback:
+    case BackendType::Capture:
+        /* Includes null char. */
+        outnames.append(ca_device, sizeof(ca_device));
+        break;
+    }
+#endif
+    return outnames;
+}
+
+BackendPtr CoreAudioBackendFactory::createBackend(DeviceBase *device, BackendType type)
+{
+    if(type == BackendType::Playback)
+        return BackendPtr{new CoreAudioPlayback{device}};
+    if(type == BackendType::Capture)
+        return BackendPtr{new CoreAudioCapture{device}};
+    return nullptr;
+}