iOS Swift - 如何获取本地和远程视频的纵横比？

Question

场景： 我正在应用程序中构建 WebRTC 视图 视频容器的高度始终为 160。

在容器的中心应显示最大高度为 160 的远程视频，宽度应按视频的纵横比进行缩放。宽度也不能大于视图宽度，在这种情况下宽度将等于视图宽度，高度应适应纵横比。

右上角应显示来自前置摄像头的本地视频，最大宽度为 100，高度应根据本地视频的纵横比进行调整

到目前为止我的代码：

func createPeerConnection () {
    // some other code

    self.localStream = self.factory.mediaStream(withStreamId: "stream")
    let videoSource = self.factory.videoSource()

    let devices = RTCCameraVideoCapturer.captureDevices()
    if let camera = devices.last,
        let format = RTCCameraVideoCapturer.supportedFormats(for: camera).last,
        let fps = format.videoSupportedFrameRateRanges.first?.maxFrameRate {
        let intFps = Int(fps)
        self.capturer = RTCCameraVideoCapturer(delegate: videoSource)
        self.capturer?.startCapture(with: camera, format: format, fps: intFps)
        videoSource.adaptOutputFormat(toWidth: 100, height: 160, fps: Int32(fps))
    }

    let videoTrack = self.factory.videoTrack(with: videoSource, trackId: "video")
    self.localStream.addVideoTrack(videoTrack)

    DispatchQueue.main.async {
        if self.localView == nil {
            let videoView = RTCEAGLVideoView(frame: CGRect(x: self.view.frame.size.width - 105, y: 5, width: 100, height: 160))
            videoView.backgroundColor = UIColor.red

            self.view.addSubview(videoView)
            self.localView = videoView
        }
        videoTrack.add(self.localView!)
    }
}

func peerConnection(_ peerConnection: RTCPeerConnection, didAdd stream: RTCMediaStream) {
    self.remoteStream = stream
    if let videoTrack = stream.videoTracks.first {
        DispatchQueue.main.async {
            if self.remoteView == nil {
                let videoView = RTCEAGLVideoView(frame: CGRect(x: self.view.frame.size.width - 50, y: 0, width: 100, height: 160))
                videoView.backgroundColor = UIColor.green
                if let local = self.localView {
                    self.view.insertSubview(videoView, belowSubview: local)
                } else {
                    self.view.addSubview(videoView)
                }
                self.remoteView = videoView
            }
            videoTrack.add(self.remoteView!)
        }
    }
}

我不知道如何获取本地或远程视频的纵横比。如果我有这个，我可以为每个人计算适当的宽度和高度

// 使用解决方案编辑：

我没有找到获得确切尺寸的方法，但我找到了一种按比例渲染视频的方法 我所要做的就是：

let videoView = RTCEAGLVideoView(frame: CGRect(x: self.view.frame.size.width - 105, y: 5, width: 100, height: 134))
videoView.contentMode = .scaleAspectFill

现在视频会根据容器大小自行缩放

Answer 1

您可以使用AVURLAsset 和CGSize 来获取视频的分辨率

private func resolutionForLocalVideo(url: URL) -> CGSize? {
   guard let track = AVURLAsset(url: url).tracks(withMediaType: AVMediaTypeVideo).first else { return nil }
   let size = track.naturalSize.applying(track.preferredTransform)
   return CGSize(width: fabs(size.width), height: fabs(size.height))
} 

现在，使用 natural size 和 preferredTransform

var mediaAspectRatio: Double! // <- here the aspect ratio for video with url will be set

func initAspectRatioOfVideo(with fileURL: URL) {
  let resolution = resolutionForLocalVideo(url: fileURL)

  guard let width = resolution?.width, let height = resolution?.height else { 
     return 
  }

  mediaAspectRatio = Double(height / width)
}

另外，你可以找到比例因子

float xScale = destination.size.width / imageSize.width; //destination is the max image drawing area.

float yScale = destination.size.height / imageSize.height;

float scaleFactor = xScale < yScale ? xScale : yScale;

这也可以通过GPUImageMovie、GPUImageCropFilter和GPUImageMovieWriter实现