[Development] New Qt Multimedia

[Jason H]

> There are still open issues and gaps in the implementation that need fixing, but the code is now in a decent enough shape to merge it back to dev and continue on that branch. We will however now have everything ready in Qt Multimedia for the 6.2 feature freeze, and will be working with an exception on this module. Especially the support for camera and media capture on Windows and the Android backend still need more work. The gstreamer backend for Linux and AVFoundation for iOS and macOS should be in a pretty decent shape. QNX support is missing right now, and is planned after 6.2.

So the changes listed in the bullet points look great!

As someone who has attempted to work with Qt Multimedia on the mobile platforms, I can say that I was looking forward to this.

I do have a few questions (mobile focused):

1. On Android, it looks like you're using the old Camera API and not Camera2? (https://developer.android.com/reference/android/hardware/camera2/package-summary) I found that Camera2 paralleled AVFoundation, so between Camera being deprecated and Camera2 resembling AV Foundation, I am surprised Camera (old) was targeted?

2. Recording WAV on Android was a problem.  I get that this was not Qt's fault, but having universal WAV recording would be good. Is it in scope? (Solution was to just do it in Java, grabbing raw PCM data), but iOS could deliver WAV if you told it to in the container format.

3. Support for image/video depth data? On iOS, these are mini-images embedded within the image itself. Is it in scope? (Can be from disparity or LIDAR, IR, etc)

4. On the removal of QAbstractVideoFilter AND QVideoProbe: Disappointed to hear this. I previously used this for read-only frames for analysis, i.e. Barcode reading and object detection. How do we do that now?