qpipewire_audiosink.cpp

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// Copyright (C) 2025 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 "qpipewire_audiosink_p.h"
 
#include <QtMultimedia/private/qpipewire_audiocontextmanager_p.h>
#include <QtMultimedia/private/qpipewire_audiodevice_p.h>
#include <QtMultimedia/private/qpipewire_support_p.h>
#include <QtCore/qcoreapplication.h>
#include <QtCore/qdebug.h>
#include <QtCore/qloggingcategory.h>
 
#include <pipewire/pipewire.h>
#include <pipewire/stream.h>
#include <spa/pod/builder.h>
 
#include <thread>
#include <utility>
 
QT_BEGIN_NAMESPACE
 
namespace QtPipeWire {
 
Q_STATIC_LOGGING_CATEGORY(lcPipewireAudioSink, "qt.multimedia.pipewire.audiosink");
static constexpr bool pipewireRealtimeTracing = false;
 
using namespace Qt::Literals;
 
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 
QPipewireAudioSinkStream::QPipewireAudioSinkStream(QAudioDevice device,
                                                   const QAudioFormat &format,
                                                   std::optional<qsizetype> ringbufferSize,
                                                   QPipewireAudioSink *parent,
                                                   float volume,
                                                   std::optional<NativePeriodFrames> nativePeriodFrames,
                                                   AudioEndpointRole role
                                                   ):
    QPipewireAudioStream {
        format,
    },
    QPlatformAudioSinkStream {
        std::move(device),
        format,
        ringbufferSize,
        nativePeriodFrames,
        volume,
    },
    m_role {
        role,
    },
    m_parent{
        parent,
    }
{
    m_xrunNotification = m_xrunOccurred.callOnActivated(&m_xrunOccurred, [this, parent] {
        if (isStopRequested())
            return;
        parent->reportXRuns(m_xrunCount.exchange(0));
    });
}
 
QPipewireAudioSinkStream::~QPipewireAudioSinkStream()
{
    Q_ASSERT(!m_ringbufferDrained.thread() || m_ringbufferDrained.thread()->isCurrentThread());
    resetStream();
    Q_ASSERT(!m_deviceRemovalObserver);
}
 
bool QPipewireAudioSinkStream::open()
{
    return true;
}
 
bool QPipewireAudioSinkStream::start(QIODevice *device)
{
    createStream(StreamType::Ringbuffer);
 
    Q_ASSERT(hasStream());
    auto sinkNodeSerial = findSinkNodeSerial();
    if (!sinkNodeSerial) {
        requestStop();
        return false;
    }
 
    setQIODevice(device);
    pullFromQIODevice();
 
    createQIODeviceConnections(device);
 
    bool connected = connectStream(*sinkNodeSerial, SPA_DIRECTION_OUTPUT);
    if (!connected) {
        requestStop();
        return false;
    }
 
    // keep instance alive until PW_STREAM_STATE_UNCONNECTED
    m_self = shared_from_this();
    QAudioContextManager::instance()->registerStreamReference(m_self);
 
    return true;
}
 
QIODevice *QPipewireAudioSinkStream::start()
{
    QIODevice *device = createRingbufferWriterDevice();
 
    setIdleState(true);
    bool started = start(device);
    if (!started)
        return nullptr;
 
    return device;
}
 
bool QPipewireAudioSinkStream::start(AudioCallback audioCallback)
{
    createStream(StreamType::Callback);
 
    Q_ASSERT(hasStream());
    auto sinkNodeSerial = findSinkNodeSerial();
    if (!sinkNodeSerial) {
        requestStop();
        return false;
    }
 
    m_audioCallback = std::move(audioCallback);
 
    bool connected = connectStream(*sinkNodeSerial, SPA_DIRECTION_OUTPUT);
    if (!connected) {
        requestStop();
        return false;
    }
 
    // keep instance alive until PW_STREAM_STATE_UNCONNECTED
    m_self = shared_from_this();
    QAudioContextManager::instance()->registerStreamReference(m_self);
    return true;
}
 
void QPipewireAudioSinkStream::stop(ShutdownPolicy shutdownPolicy)
{
    m_shutdownPolicy.store(shutdownPolicy, std::memory_order_relaxed);
    if (shutdownPolicy == ShutdownPolicy::DrainRingbuffer) {
        // disconnect when ringbuffer is drained
        m_ringbufferDrained.callOnActivated([this] {
            disconnectStream();
        });
    }
 
    requestStop();
    m_parent = nullptr;
 
    disconnectQIODeviceConnections();
    if (m_deviceRemovalObserver)
        unregisterDeviceObserver();
 
    if (shutdownPolicy == ShutdownPolicy::DiscardRingbuffer || m_audioCallback) {
        // disconnect immediately
        disconnectStream();
    }
 
    if (m_audioCallback)
        // ensure that no callback is sent after we stop the stream
        m_disconnectSemaphore.acquire();
}
 
void QPipewireAudioSinkStream::updateStreamIdle(bool idle)
{
    if (m_parent)
        m_parent->updateStreamIdle(idle);
}
 
void QPipewireAudioSinkStream::createStream(StreamType streamType)
{
    const char *roleString = [&] {
        switch (m_role) {
        case AudioEndpointRole::MediaPlayback:
        case AudioEndpointRole::Other:
            return "Music";
        case AudioEndpointRole::Accessibility:
            return "Accessibility";
        case AudioEndpointRole::SoundEffect:
            return "Notification";
        default:
            Q_UNREACHABLE_RETURN("Music");
        }
    }();
 
    auto extraProperties = std::array{
        spa_dict_item{ PW_KEY_MEDIA_CATEGORY, "Playback" },
        spa_dict_item{ PW_KEY_MEDIA_ROLE, roleString },
    };
 
    QString applicationName = qApp->applicationName();
    if (applicationName.isNull())
        applicationName = u"QPipewireAudioSink"_s;
 
    QPipewireAudioStream::createStream(extraProperties, m_nativePeriodFrames,
                                       applicationName.toUtf8().constData(), streamType);
}
 
std::optional<ObjectSerial> QPipewireAudioSinkStream::findSinkNodeSerial()
{
    const QPipewireAudioDevicePrivate *device =
            QAudioDevicePrivate::handle<QPipewireAudioDevicePrivate>(m_audioDevice);
 
    QByteArray nodeName = device->nodeName();
    auto ret = QAudioContextManager::deviceMonitor().findSinkNodeSerial(std::string_view{
            nodeName.data(),
            size_t(nodeName.size()),
    });
 
    if (!ret)
        qWarning() << "Cannot find device: " << nodeName;
    return ret;
}
 
void QPipewireAudioSinkStream::handleDeviceRemoved()
{
    if (isStopRequested())
        return;
    requestStop();
    disconnectQIODeviceConnections();
    handleIOError(std::exchange(m_parent, nullptr));
}
 
static auto resolveHostBuffer(pw_buffer *b, const QAudioFormat &format)
{
    struct spa_buffer *buf = b->buffer;
    uint64_t strideBytes = format.bytesPerSample() * format.channelCount();
    Q_ASSERT(strideBytes > 0);
    uint64_t totalNumberOfFrames = buf->datas[0].maxsize / strideBytes;
 
#if PW_CHECK_VERSION(0, 3, 49)
    if (pw_check_library_version(0, 3, 49))
        // LATER: drop support for 0.3.49
        if (b->requested)
            totalNumberOfFrames = std::min(b->requested, totalNumberOfFrames);
#endif
 
    const uint64_t requestedSamples = totalNumberOfFrames * format.channelCount();
 
    QSpan<std::byte> writeBuffer{
        reinterpret_cast<std::byte *>(buf->datas[0].data),
        qsizetype(requestedSamples * format.bytesPerSample()),
    };
 
    struct HostBufferData
    {
        QSpan<std::byte> writeBuffer;
        const uint64_t requestedSamples{};
        const uint64_t totalNumberOfFrames{};
    };
 
    return HostBufferData{
        writeBuffer,
        requestedSamples,
        totalNumberOfFrames,
    };
}
 
void QPipewireAudioSinkStream::processRingbuffer() noexcept Q_DECL_NONBLOCKING_FUNCTION
{
    struct pw_buffer *b = pw_stream_dequeue_buffer(m_stream.get());
    if (!b) {
        qCritical() << "pw_stream_dequeue_buffer failed";
        return;
    }
 
    auto [writeBuffer, requestedSamples, totalNumberOfFrames] = resolveHostBuffer(b, m_format);
 
    bool stopRequested = isStopRequested(std::memory_order_acquire);
    ShutdownPolicy shutdownPolicy = stopRequested ? m_shutdownPolicy.load(std::memory_order_relaxed)
                                                  : ShutdownPolicy::DrainRingbuffer;
 
    if (stopRequested && shutdownPolicy == ShutdownPolicy::DiscardRingbuffer) {
        // discarding ringbuffer: we silence the last block and exit early
        QAudioHelperInternal::fillSilence(writeBuffer, m_format);
        queueBuffer(b, requestedSamples);
 
        if constexpr (pipewireRealtimeTracing)
            qCDebug(lcPipewireAudioSink)
                    << "QPipewireAudioSinkStream: shutdown with DiscardRingbuffer";
        return;
    }
 
    performXRunDetection(totalNumberOfFrames);
 
    uint64_t framesWritten = QPlatformAudioSinkStream::process(writeBuffer, totalNumberOfFrames);
    uint64_t samplesWritten = framesWritten * m_format.channelCount();
 
    if (stopRequested) {
        if (samplesWritten < requestedSamples) {
            if constexpr (pipewireRealtimeTracing)
                qCDebug(lcPipewireAudioSink)
                        << "QPipewireAudioSinkStream: shutdown after draining ringbuffer";
            m_ringbufferDrained.set();
        }
    }
 
    queueBuffer(b, samplesWritten);
    addFramesHandled(samplesWritten);
}
 
void QPipewireAudioSinkStream::processCallback() noexcept Q_DECL_NONBLOCKING_FUNCTION
{
    using namespace QtMultimediaPrivate;
    struct pw_buffer *b = pw_stream_dequeue_buffer(m_stream.get());
    if (!b) {
        qCritical() << "pw_stream_dequeue_buffer failed";
        return;
    }
 
    auto [writeBuffer, requestedSamples, totalNumberOfFrames] = resolveHostBuffer(b, m_format);
 
    runAudioCallback(*m_audioCallback, writeBuffer, m_format, volume());
 
    queueBuffer(b, requestedSamples);
}
 
void QPipewireAudioSinkStream::stateChanged(pw_stream_state oldState, pw_stream_state state,
                                            const char *)
{
    qCDebug(lcPipewireAudioSink) << "QPipewireAudioSinkStream::stateChanged" << oldState << state;
 
    switch (state) {
    case pw_stream_state::PW_STREAM_STATE_UNCONNECTED: {
        m_disconnectSemaphore.release();
        QAudioContextManager::instance()->unregisterStreamReference(m_self);
        invokeOnAppThread([self = std::move(m_self)] {
            // drop refcount on app thread
        });
        break;
 
    default:
        break;
    }
    }
}
 
void QPipewireAudioSinkStream::finalizeStream()
{
    requestStop();
}
 
void QPipewireAudioSinkStream::disconnectStream()
{
    auto self = shared_from_this(); // extend lifetime until this function returns;
 
    QPipewireAudioStream::disconnectStream();
 
    QObject::disconnect(m_xrunNotification);
}
 
void QPipewireAudioSinkStream::queueBuffer(pw_buffer *b, uint64_t samplesWritten) noexcept Q_DECL_NONBLOCKING_FUNCTION
{
    struct spa_buffer *buf = b->buffer;
    buf->datas[0].chunk->offset = 0;
    buf->datas[0].chunk->stride = m_format.bytesPerSample() * m_format.channelCount();
    buf->datas[0].chunk->size = samplesWritten * m_format.bytesPerSample();
 
    pw_stream_queue_buffer(m_stream.get(), b);
}
 
void QPipewireAudioSinkStream::fakeXRun()
{
    constexpr bool forceXRun = true;
    if constexpr (forceXRun) {
        // force xrun
        static int i = 0;
        if (++i == 10)
            std::this_thread::sleep_for(std::chrono::milliseconds(500));
    }
}
 
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// QPipewireAudioSink
 
QPipewireAudioSink::QPipewireAudioSink(QAudioDevice device, const QAudioFormat &format,
                                       QObject *parent)
    : BaseClass(std::move(device), format, parent)
{
}
 
QPipewireAudioSink::~QPipewireAudioSink()
    = default;
 
void QPipewireAudioSink::reportXRuns(int numberOfXruns)
{
    qDebug() << "XRuns occurred:" << numberOfXruns;
}
 
} // namespace QtPipeWire
 
QT_END_NAMESPACE