Receiving NV21 pixel format from camera using an implemented QAbstractVideoSurface class but result is gray not colorful

Jafar.Sag.Sibil

The following code is used to write every video frame.
but the result is gray.

problem 1 :

frame.image().isNull();// true forever

problem 2 :

frame.image().convertToFormat(someFormat).isNull();//true forever

problem 3 :

QImage	defaultImage ( frame.bits ( ), frame.width ( ), frame.height ( ), frame.bytesPerLine ( ), QImage::Format_Grayscale8 );// this operation does not work for every format and many of those make our result image null other than Alpha8, Mono, MonoLSB (all make our image terrible), Indexed, grayscale8 (gray style)

videosurface.cpp

bool VideoSurfacer::present ( const QVideoFrame & f )
{
	QVideoFrame frame ( f );
	if ( frame.isValid ( ) && frame.map ( QAbstractVideoBuffer::MapMode::ReadWrite ) )
		{
			QImage	defaultImage ( frame.bits ( ), frame.width ( ), frame.height ( ), frame.bytesPerLine ( ), QImage::Format_Grayscale8 );
			QString path = QStandardPaths::writableLocation ( QStandardPaths::GenericDataLocation ) + "/download/" + QString::number ( ++i );
			QFile ( path + ".jpg" ).remove ( );
			defaultImage.save ( path + ".jpg", "JPG" );

			frame.unmap ( );
		}
	return true;
}

attention : QVideoFrame::imageFormatFromPixelformat(frame.pixelFormat());
returns Format_Invalid which makes our image terrible like Mono etc

SGaist

So from the documentation you can only access it when mapping the frame. So you have to manage the data yourself.

SGaist

Hi,

Did you check the handle type ?

Jafar.Sag.Sibil

Handle type is NoHandle

SGaist

So from the documentation you can only access it when mapping the frame. So you have to manage the data yourself.