qvideoframeinput.cpp

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// Copyright (C) 2024 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 "qaudiobuffer.h"
#include "qvideoframeinput.h"
#include "qmediaframeinput_p.h"
#include "qmediainputencoderinterface_p.h"
#include "qplatformvideoframeinput_p.h"
 
QT_BEGIN_NAMESPACE
 
class QVideoFrameInputPrivate : public QMediaFrameInputPrivate
{
public:
    QVideoFrameInputPrivate(QVideoFrameInput *q) : q(q) { }
 
    bool sendVideoFrame(const QVideoFrame &frame)
    {
        return sendMediaFrame([&]() { emit m_platfromVideoFrameInput->newVideoFrame(frame); });
    }
 
    void initialize(QVideoFrameFormat format = {})
    {
        m_platfromVideoFrameInput = std::make_unique<QPlatformVideoFrameInput>(std::move(format));
        addUpdateSignal(m_platfromVideoFrameInput.get(), &QPlatformVideoFrameInput::encoderUpdated);
    }
 
    void uninitialize()
    {
        m_platfromVideoFrameInput.reset();
 
        if (captureSession())
            captureSession()->setVideoFrameInput(nullptr);
    }
 
    QPlatformVideoFrameInput *platfromVideoFrameInput() const
    {
        return m_platfromVideoFrameInput.get();
    }
 
protected:
    void updateCaptureSessionConnections(QMediaCaptureSession *prevSession,
                                         QMediaCaptureSession *newSession) override
    {
        if (prevSession)
            removeUpdateSignal(prevSession, &QMediaCaptureSession::videoOutputChanged);
 
        if (newSession)
            addUpdateSignal(newSession, &QMediaCaptureSession::videoOutputChanged);
    }
 
    bool checkIfCanSendMediaFrame() const override
    {
        if (auto encoderInterface = m_platfromVideoFrameInput->encoderInterface())
            return encoderInterface->canPushFrame();
 
        return captureSession()->videoOutput() || captureSession()->videoSink();
    }
 
    void emitReadyToSendMediaFrame() override { emit q->readyToSendVideoFrame(); }
 
private:
    QVideoFrameInput *q = nullptr;
    std::unique_ptr<QPlatformVideoFrameInput> m_platfromVideoFrameInput;
};
 
/*!
    \class QVideoFrameInput
    \inmodule QtMultimedia
    \ingroup multimedia
    \ingroup multimedia_video
    \since 6.8
 
    \brief The QVideoFrameInput class is used for providing custom video frames
    to \l QMediaRecorder or a video output through \l QMediaCaptureSession.
 
    QVideoFrameInput is only supported with the FFmpeg backend.
 
    Custom video frames can be recorded by connecting a \l QVideoFrameInput and a
    \l QMediaRecorder to a \l QMediaCaptureSession. For a pull mode implementation,
    call \l sendVideoFrame() in response to the \l readyToSendVideoFrame() signal. In
    the snippet below this is done by connecting the signal to a slot in a custom media
    generator class. The slot function emits another signal with a new video frame, which
    is connected to \l sendVideoFrame():
 
    \snippet custommediainputsnippets/custommediainputsnippets.cpp QVideoFrameInput setup
 
    Here's a minimal implementation of the slot function that provides video frames:
 
    \snippet custommediainputsnippets/custommediainputsnippets.cpp nextVideoFrame()
 
    For more details see readyToSendVideoFrame() and sendVideoFrame().
 
    \sa QMediaRecorder, QMediaCaptureSession and QVideoSink.
*/
 
/*!
    Constructs a new QVideoFrameInput object with \a parent.
*/
QVideoFrameInput::QVideoFrameInput(QObject *parent) : QVideoFrameInput({}, parent) { }
 
/*!
    Constructs a new QVideoFrameInput object with video frame \a format and \a parent.
 
    The specified \a format will work as a hint for the initialization of the matching
    video encoder upon invoking \l QMediaRecorder::record().
    If the format is not specified or not valid, the video encoder will be initialized
    upon sending the first frame.
    Sending of video frames with another pixel format and size after initialization
    of the matching video encoder might cause a performance penalty during recording.
 
    We recommend specifying the format if you know in advance what kind of frames you're
    going to send.
*/
QVideoFrameInput::QVideoFrameInput(const QVideoFrameFormat &format, QObject *parent)
    : QObject(*new QVideoFrameInputPrivate(this), parent)
{
    Q_D(QVideoFrameInput);
    d->initialize(format);
}
 
/*!
    Destroys the object.
 */
QVideoFrameInput::~QVideoFrameInput()
{
    Q_D(QVideoFrameInput);
    d->uninitialize();
}
 
/*!
    Sends \l QVideoFrame to \l QMediaRecorder or a video output
    through \l QMediaCaptureSession.
 
    Returns \c true if the specified \a frame has been sent successfully
    to the destination. Returns \c false, if the frame hasn't been sent,
    which can happen if the instance is not assigned to
    \l QMediaCaptureSession, the session doesn't have video outputs or
    a media recorder, the media recorder is not started or its queue is full.
    The signal \l readyToSendVideoFrame will be sent as soon as
    the destination is able to handle a new frame.
 
    Sending of an empty video frame is treated by \l QMediaRecorder
    as an end of the input stream. QMediaRecorder stops the recording
    automatically if \l QMediaRecorder::autoStop is \c true and
    all the inputs have reported the end of the stream.
*/
bool QVideoFrameInput::sendVideoFrame(const QVideoFrame &frame)
{
    Q_D(QVideoFrameInput);
    return d->sendVideoFrame(frame);
}
 
/*!
    Returns the video frame format that was specified
    upon construction of the video frame input.
*/
QVideoFrameFormat QVideoFrameInput::format() const
{
    Q_D(const QVideoFrameInput);
    return d->platfromVideoFrameInput()->frameFormat();
}
 
/*!
    Returns the capture session this video frame input is connected to, or
    a \c nullptr if the video frame input is not connected to a capture session.
 
    Use QMediaCaptureSession::setVideoFrameInput() to connect
    the video frame input to a session.
*/
QMediaCaptureSession *QVideoFrameInput::captureSession() const
{
    Q_D(const QVideoFrameInput);
    return d->captureSession();
}
 
void QVideoFrameInput::setCaptureSession(QMediaCaptureSession *captureSession)
{
    Q_D(QVideoFrameInput);
    d->setCaptureSession(captureSession);
}
 
QPlatformVideoFrameInput *QVideoFrameInput::platformVideoFrameInput() const
{
    Q_D(const QVideoFrameInput);
    return d->platfromVideoFrameInput();
}
 
/*!
    \fn void QVideoFrameInput::readyToSendVideoFrame()
 
    Signals that a new frame can be sent to the video frame input.
    After receiving the signal, if you have frames to be sent, invoke \l sendVideoFrame
    once or in a loop until it returns \c false.
 
    \sa sendVideoFrame()
*/
 
QT_END_NAMESPACE