How to convert QImage to QVideoFrame so I would set it as frame for VideoSink Qt6.2

[Christian Ehrlicher]

@UbiMiles said in How to convert QImage to QVideoFrame so I would set it as frame for VideoSink Qt6.2:

how can I convert the image to a QVideoFrame

Maybe by using the correct ctor?

[SGaist]

Hi,

@Christian-Ehrlicher except that it's not the case anymore for Qt 6 since the class has heavily changed.

From an educated guess, you shall create a QVideoFrame with a format compatible with your QImage and then memcpy the data from one to the other.

[Christian Ehrlicher]

Oh sorry. Don't know why they removed it (or why they made QAbstractVideoBuffer private so creating an own is no longer possible...)

Then emulate the ctor with something similar to (untested):

auto format = QVideoFrameFormat(img.size(), QVideoFrameFormat::pixelFormatFromImageFormat(img.format());
auto frame = new QVideoFrame(format);
frame.map(QVideoFrame::ReadWrite);
memcpy(frame.bits(), img.bits(), img.sizeInBytes());

[UbiMiles]

@Christian-Ehrlicher

The app crashes when I try to execute that block of code..
I get the idea but I do not seem to have an implementation of it in mind so far.

[jsulm]

@UbiMiles said in How to convert QImage to QVideoFrame so I would set it as frame for VideoSink Qt6.2:

The app crashes

Did you debug to see where exactly and why it crashes?

[UbiMiles]

@jsulm
it throws an access violation when executing memcpy, trying to set frame for Sink, or when I try to unmap the frame

[UbiMiles]

@UbiMiles I think the problem is with the memcpy statement

[UbiMiles]

the generated frame seems to be invalid would it have to do with my QImage format not being compatible?

[UbiMiles]

the image format is "Format_RGB888"

[imironchik]

QImage img( QStringLiteral( "sample_640×426.png" ) );
QVideoFrameFormat fmt( img.size(), QVideoFrameFormat::Format_YUYV );
QVideoFrame vf( fmt );

vf.map( QVideoFrame::WriteOnly );

libyuv::ARGBToYUY2( (const uint8_t*) img.bits(), img.bytesPerLine(), vf.bits( 0 ),
	vf.bytesPerLine( 0 ), img.width(), img.height() );

vf.unmap();

Only be sure that QImage pixel format is ARGB32...

[UbiMiles]

@imironchik My QImage pixel type is RGB888
memcpy managed to get the job done , yet if I try declaring a video frame with the format of my QImage an invalid frame is returned, Explicitly providing the format shows that it does indeed work yet it's messed up do to incompatible formats,

I submitted this question on stackoverflow and provided an answer myself, now I am trying to find a way to get it to work with RGB888
https://stackoverflow.com/questions/71407367/how-to-convert-qimage-to-qvideoframe-so-i-would-set-it-as-frame-for-videosink-qt/71409775#71409775

[imironchik]

@UbiMiles You can convert any valid QImage to ARGB32 with QImage::convertToFormat(). then use above code.

[UbiMiles]

@imironchik
I see, thanks
one last question is where is "libyuv" namespace coming from

[imironchik]

@UbiMiles libyuv is a Google's Open Source small library. Just google its name.