How to grab video frames in Qt?

Question

I am new to Qt, I only know the basics: create interfaces and connect slots. In a few words, my knowledge is not deep at all.

I need to open a video file and capture all of its frames to get the R, G, B channels and, later on, process optical flow (this is already done) frame to frame to finally represent it on a window.

Is it possible to get the video frames with Qt? I have researched a lot but not found anything conclusive.

Answer 1

You can use QMediaPlayer to achieve this.

1. Instantiate the QMediaPlayer.
2. Subclass the QAbstractVideoSurface.
3. Set your implementation as the output for the media player via QMediaPlayer::setVideoOutput.
4. Feed the media player the needed file and eventually it will start calling QAbstractVideoSurface::present(const QVideoFrame & frame) on your implementation of QAbstractVideoSurface if the video was loaded successfully. Then you can access the channels and everything from the QVideoFrame and draw the frame on a widget.