How to BoxFit.cover a fullscreen VideoPlayer widget with specific aspect ratio

Using the video_player package, the initial setup is:

VideoPlayerController _controller;

  @override
  void initState() {
    super.initState();
    _controller =
        VideoPlayerController.asset("assets/video/home_background.mp4")
          ..initialize().then((value) => {setState(() {})});
    _controller.setLooping(true);
    _controller.setVolume(0.0);
    _controller.play();
  }

and then, in your widget tree:

Stack(
  children: <Widget>[
    SizedBox.expand(
      child: FittedBox(
        fit: BoxFit.cover,
        child: SizedBox(
          width: _controller.value.size?.width ?? 0,
          height: _controller.value.size?.height ?? 0,
          child: VideoPlayer(_controller),
        ),
      ),
    ),
    //FURTHER IMPLEMENTATION
  ],
)

Old question, answering for reference. This is an open issue on Flutter (as of 2020/04/23) : https://github.com/flutter/flutter/issues/31911

Good workaround is provided in the comments of the issue, using a SizedBox instead of an AspectRatio. Your code would be like this :

  @override
  Widget build(BuildContext context) {
    return Stack(
      children: <Widget>[
        FittedBox(
          fit: BoxFit.cover,
          child: SizedBox(
            width: _aspectRatio,
            height: 1,
            child: VideoPlayer(_playerController),
          ),
        ),
        _buildText(),
      ],
    );
  }