Recap: I am setting up a QML element to intercept frames from a VideoSource
going to a VideoOutput. It looks like:
{VideoSource}-frames-> {MySurfaceImplementation}-frames->{VideoOutput}
Thanks to all the people here, I got the first part of it working. Now I'm
confused on the last half.
MySurfaceImplementation (called VideoSurface):
1. takes a source (MediaPlayer or Camera}
2. takes various settings related to the frame/image grabbing and processing
3. takes the frame from source and relays them to a dest (VideoOutput)
Currently 1 & 2 work 3 is proving problematic.
When VideoSurface::present is called, I attempt to present frames to dest,
immediately and always, but these never appear. And present() does not indicate
an error. In fact, I don't get any errors.
I am wondering what is needed to get this working. I investigated
QMediaService, which reads: "In general, implementing a QMediaService is
outside of the scope of this documentation and support on the relevant mailing
lists or IRC channels should be sought."
So now I am here. I just want to provide frames to QVideoOutput, the same ones
from the MediaPlayer. I don't care about sound.
One thing that might be very useful and gereral is a MediaTee element and
class, where you take one source, and have two dests, so that I can get a frame
and process it and the VideoOutput can continue unrestricted. Without it, I'm
trying to patch my VideoSurface class the media graph.
What do I need to do to send the frame I have to the VideoOutput?
Many, many thanks in advance!
------
void VideoSurface::setSource(QObject *source)
{
m_source = source;
if (m_source)
{
QMediaPlayer *player =
qvariant_cast<QMediaPlayer*>(m_source->property("mediaObject"));
qDebug() << "videoSurface::setDest() player" << player;
if (player)
{
QVideoRendererControl* rendererControl =
player->service()->requestControl<QVideoRendererControl*>();
if (rendererControl)
{
rendererControl->setSurface(this);
} else {
qDebug() << "VideoSurface::setSource()" << source << " Unable to get
QVideoRenderControl for video integration.";
}
} else {
qDebug() << "VideoSurface::setSource()" << source << " Unable to get player "
<< player;
}
}
}
------
bool VideoSurface::start ( const QVideoSurfaceFormat & format )
{
qDebug() << "videoSurface::start()";
if (m_dest)
{
bool ret = ((QAbstractVideoSurface*)m_dest)->start(format);
if (!ret)
{
qDebug() << "VideoSurface::start() dest: " << m_dest << " start() failed";
}
return ret && QAbstractVideoSurface::start(format);
}
return QAbstractVideoSurface::start(format);
}
------
bool VideoSurface::present ( const QVideoFrame & videoFrame )
{
// qDebug() << "videoSurface::present()" << m_frameCount << m_emitRate;
// present the frame to the destiantion first, some don't block, so this might
be quick. At least on those
if (m_dest) // cases we won't slow it down.
{
bool ret = ((QAbstractVideoSurface*)m_dest)->present(videoFrame);
if (!ret)
{
qDebug() << "VideoSurface::present() dest: " << m_dest << " present() failed,
reason:" << ((QAbstractVideoSurface*)m_dest)->error();
}
}
/* conversion code follows */
}
------
-QML--
Rectangle{
width:360
height:360
MediaPlayer{ id:player; source:"vin4.mp4"; autoPlay:true }
VideoSurface{ id:surface; source:player; dest:viewer ;emitRate:10
emitImages:true}
VideoOutput{ id:viewer; source:surface; anchors.fill:parent}
}
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