Qt iOS: change format of received frames from camera - ios

Question

Frames received from QVideoFilterRunnable::run method has format QVideoFrame::Format_NV12 so before load it to GPU texture using glTexImage I need to convert it to BGRA first. Is there any way to change the output format of camera?
Here is original problem:
Qt iOS: how to return QVideoFrame with type GLTextureHandle from QVideoFilterRunnable

Answer 1

Since I'm using QML this is instructions about getting QML object and using it in C++ code. I guess pure C++ stuff will be the same.
First you need to highlight camera object in QML source:
Camera {
id: camera
objectName: "CameraObject"
}
Get root object of QQuickView:
QQuickView view;
QQuickItem* root = view.rootObject();
assert(root != nullptr);
Get QML camera:
QObject* qmlCamera = root->findChild<QObject*>("CameraObject");
assert(qmlCamera != nullptr);
Get C++ camera from QML camera object:
QCamera* camera = qvariant_cast<QCamera*>(qmlCamera->property("mediaObject"));
assert(camera != nullptr);
Find format you need:
QCameraViewfinderSettings bestSetting;
assert(bestSetting.isNull()); // sanity check
auto viewfinderSettings = camera->supportedViewfinderSettings();
for (auto i: viewfinderSettings) {
if (i.pixelFormat() != QVideoFrame::Format_ARGB32) {
// skip non-ARGB formats
continue;
}
// check i.resolution()
// several settings with Format_ARGB32 will be available
// pick the one with resolution which fits best for you
bestSetting = i;
}
Check that something found and apply settings:
assert(bestSetting.pixelFormat() == QVideoFrame::Format_ARGB32);
camera->setViewfinderSettings(bestSetting);
Now view can be shown:
view.show();
return app.exec();