Streaming Video Out

mrdebug

It's very easy but hard too.
I have a Qt video surveillance application. I'm using OpenCV to grab images from cameras, FFMpeg to store video and a own http server Qt based to broadcast the video using h264 or mjpeg.
If you want to use broadcast (one server to more clients) I suggest to use udp.
If you want to send more than one stream I suggest you to use an own protocol similar to avi format (little package with header and data).

Bouriquo

I tried to get QVideoFrame from QAbstractVideoSurface. But I can't get the QVideoFrame buffer to send it to my UdpSocket. I just used QVideoFrame.bits(), but it's seems is empty.

? Offline

@Bouriquo How did you go about getting it? Did you subclass QAbstractVideoSurface like in the link i gave you?

Bouriquo

@raf924 Yes I was already find this class.

#include "myvideosurface.h"

MyVideoSurface::MyVideoSurface()
{
writer = new QUdpSocket();
}

QListQVideoFrame::PixelFormat MyVideoSurface::supportedPixelFormats( QAbstractVideoBuffer::HandleType handleType) const
{
Q_UNUSED(handleType);

// Return the formats you will support
return QList<QVideoFrame::PixelFormat>() << QVideoFrame::Format_RGB565;

}

bool MyVideoSurface::present(const QVideoFrame &frame)
{
Q_UNUSED(frame);

//statusLabel->setText(tr("Now broadcasting datagram %1").arg(messageNo));
QVideoFrame *clone = new QVideoFrame(frame);
clone->map(QAbstractVideoBuffer::ReadOnly);
qDebug() << clone->isMapped();
//frame.map(QAbstractVideoBuffer::ReadOnly);
QByteArray *datagram = new QByteArray((char*)(clone->bits()),clone->mappedBytes());
//QByteArray datagram = "Broadcast message ";
//qDebug() << "Write bytes1 : " << frame.mappedBytes() << frame.mapMode();
//qDebug() << "Write bytes2 : " << clone->mappedBytes() << clone->mapMode();
qDebug() << clone->bits();
writer->writeDatagram(datagram->data(), datagram->size(),QHostAddress::Broadcast, 45454);
//writer->writeDatagram((char*)clone->bits(),clone->mappedBytes(),QHostAddress::Broadcast, 45454);
clone->unmap();
return true;

}

SGaist

Out of curiosity, why not use something that's designed for that task ? GStreamer allows to do everything you need: get the camera stream, add overlay, stream using standard protocol and if you use QtGStreamer you also have a widget or QtQuick element to visualize that.

Bouriquo

Yes I know. But I just would like to try by myself :D.

Bouriquo

This post is deleted!

Pietrko

Is using GStreamer still recommended solution for streaming out through network?
EDIT: relevant -> recommended

SGaist

Why wouldn't it be ?

Pietrko

@SGaist said in Streaming Video Out:

Why wouldn't it be ?

My mistake, made post most precise.

SGaist

What exactly do you want to do ?

Pietrko

I need a simple way to send frames from camera over network, while at the same time providing real-time 30FPS camera preview in QML widget.
Simple - means as little coding as possible.
The way I'm trying to do it now is to derive C++ class from QObject with "mediaObject" property expose it as a source for VideoOutput in QML.
The C++ class would catch the frames and save them into buffer (and sent over network).

Unfortunately its impossible (afaik) using just QML, beacuse imageCapture object inside Camera does not allow to save frame into buffers (only into files).

SGaist

Then QtGStreamer is likely what you want.

Pietrko

But, would it work if I would create a class with Q_PROPERTY mediaObject - that hold QCamera instance?
And pass this class to QML videoOutput ?

SGaist

QCamera is a class to get video stream or images from a camera. The QML VideoOutput type is designed to render video onscreen.

alpat

This post is deleted!