Using QVideoProbe from QML

[Scorp2us]

I am trying to do the following: Using a camera (Well, a video for testing purposes, but will eventually be a QML Camera) decode a bar code. I have the barcode working for static images (VinScanner. C++, exposed to QML, works). Work want me to use the live camera feed so no capture is needed. It will just use the live feed. VideoProbe is my C++ class which wraps QVideoProbe. What I expect to see, at least, are several "frame" messages logged to the console. Nothing happens.

Here is the QML:

Video {
		id: video
		anchors.fill: parent
		autoLoad: true
		autoPlay: true
		source: "vin1.mp4"
		onPlaying: {
			probe.source = video
			console.log("source="+video.source)
			console.log("has video=" + video.hasVideo + " status="+video.status+ " playstate="+video.playbackState)
			console.log("videoCodec="+ video.metaData.videoCodec)
		}
	}
VideoProbe {
		id: probe
		source: video
		onFrame: {
			console.log("frame\n")
			scanner.decode(videoFrame)
		}
	}
VinScanner {
		id: scanner
		onDecoded: vinText.text = vin
	}

Video {
		id: video
		anchors.fill: parent
		autoLoad: true
		autoPlay: true
		source: "vin1.mp4"
		onPlaying: {
			probe.source = video
			console.log("source="+video.source)
			console.log("has video=" + video.hasVideo + " status="+video.status+ " playstate="+video.playbackState)
			console.log("videoCodec="+ video.metaData.videoCodec)
		}
	}
VideoProbe {
		id: probe
		source: video
		onFrame: {
			console.log("frame\n")
			scanner.decode(videoFrame)
		}
	}
VinScanner {
		id: scanner
		onDecoded: vinText.text = vin
	}

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Now, what happens is a variety of things.
First application output:
VideoProbe::setSource() not a QMediaObject, got a: Video_QMLTYPE_0
source=file:///home/xxx/Projects/build-vinscan-Desktop_Qt_5_2_1_GCC_64bit-Debug/qml/vinscan/vin1.mp4
has video=false status=2 playstate=1
videoCodec=undefined

Now, what happens on the screen (QML window) is fine. I see the video I collected of me hovering over a bar code. However the hasVideo property is false.
When I take this Video object and pass it to C++, I get a "Video_QMLTYPE_0" classname from obj->metaObject()->className() or, when it is a Camera, I get a QDeclarativeCamera (not part of QT API!) . Neither of which I expected to get. I expected to get a QObject* that I could promote to a QMediaObject*. But the qobject_cast<>() fails. Both the QCamera an QMediaPlayer inherit QMediaObject. I based my approach on that.

I think the rest of what I have will work once I get the setSource(QObject*) function squared away.

--VIDEOPROBE.H--

class VideoProbe : public QVideoProbe
{
	Q_OBJECT
 
	QObject *m_source; Q_PROPERTY(QObject* source READ source WRITE setSource)
	//QObject *m_dest;		Q_PROPERTY(QObject* dest READ dest WRITE setDest)
	bool m_active;			Q_PROPERTY(bool active READ isActive WRITE setActive)
 
public:
	explicit VideoProbe(QObject *parent = 0);
	bool isActive();		void setActive(bool);
	QObject* source();		bool setSource(QObject *);
 
signals:
	void frame(QVideoFrame videoFrame);
 
public slots:
	void emitFrame(QVideoFrame videoFrame);
 
};

class VideoProbe : public QVideoProbe
{
	Q_OBJECT

	QObject *m_source; Q_PROPERTY(QObject* source READ source WRITE setSource)
	//QObject *m_dest;		Q_PROPERTY(QObject* dest READ dest WRITE setDest)
	bool m_active;			Q_PROPERTY(bool active READ isActive WRITE setActive)

public:
	explicit VideoProbe(QObject *parent = 0);
	bool isActive();		void setActive(bool);
	QObject* source();		bool setSource(QObject *);

signals:
	void frame(QVideoFrame videoFrame);

public slots:
	void emitFrame(QVideoFrame videoFrame);

};

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----- SET SOURCE----

bool VideoProbe::setSource(QObject* sourceObj)
{
	m_source = sourceObj;
	bool ret =false;
	if (qobject_cast<QMediaObject*>(sourceObj))
	{
		ret = QVideoProbe::setSource((QMediaObject*)sourceObj);
		qDebug() << "VideoProbe::setSource()" << sourceObj << ret;
	} else {
		qDebug() << "VideoProbe::setSource() not a QMediaObject, got a:" << sourceObj->metaObject()->className();
	}
	return ret;
 
}

bool VideoProbe::setSource(QObject* sourceObj)
{
	m_source = sourceObj;
	bool ret =false;
	if (qobject_cast<QMediaObject*>(sourceObj))
	{
		ret = QVideoProbe::setSource((QMediaObject*)sourceObj);
		qDebug() << "VideoProbe::setSource()" << sourceObj << ret;
	} else {
		qDebug() << "VideoProbe::setSource() not a QMediaObject, got a:" << sourceObj->metaObject()->className();
	}
	return ret;

}

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