iOS中的方形视频输出

有没有办法在iOS中通过AVFoundation获得方形视频输出?

我使用OpenGL处理​​视频的每一帧(CMSampleBuffer).每一帧
旋转,所以我需要裁剪和旋转CMSampleBuffer.但我不知道该怎么做,所以我相信有一种方法可以通过在AVCaptureVideoDataOutput中设置属性(videoSettings)来获取已裁剪和旋转的帧.

我用谷歌搜索,用Google搜索谷歌,但没有发现任何东西.
swift中的代码示例很棒.

更新:

我在Swift中的完整最终解决方案:

override func viewWillAppear(animated: Bool) {
    super.viewWillAppear(animated)

    captureSession = AVCaptureSession()
    captureSession!.sessionPreset = AVCaptureSessionPreset640x480

    let backCamera = AVCaptureDevice.defaultDeviceWithMediaType(AVMediaTypeVideo)
    var error: NSError?
    var input: AVCaptureDeviceInput!
    do {
        input = try AVCaptureDeviceInput(device: backCamera)
    } catch let error1 as NSError {
        error = error1
        input = nil
    }
    if error == nil && captureSession!.canAddInput(input) {
        captureSession!.addInput(input)
        stillImageOutput = AVCaptureStillImageOutput()
        stillImageOutput!.outputSettings = [AVVideoCodecKey: AVVideoCodecJPEG, kCVPixelBufferPixelFormatTypeKey: Int(kCVPixelFormatType_32BGRA)]
        if captureSession!.canAddOutput(stillImageOutput) {
            captureSession!.addOutput(stillImageOutput)
        }
    }
    videoOutput = AVCaptureVideoDataOutput()
    videoOutput!.videoSettings = [kCVPixelBufferPixelFormatTypeKey: Int(kCVPixelFormatType_32BGRA), AVVideoWidthKey : 100, AVVideoHeightKey: 100]
    videoOutput!.setSampleBufferDelegate(self, queue: dispatch_queue_create("sample buffer delegate", DISPATCH_QUEUE_SERIAL))

    if captureSession!.canAddOutput(self.videoOutput) {
        captureSession!.addOutput(self.videoOutput)
    }

    videoOutput!.connectionWithMediaType(AVMediaTypeVideo).videoOrientation = AVCaptureVideoOrientation.PortraitUpsideDown
    videoOutput!.connectionWithMediaType(AVMediaTypeVideo).videoMirrored = true
    captureSession!.startRunning();
}

这对我来说是完美的镜像和旋转视频输出!但它不是裁剪!

最佳答案 要旋转CMSampleBuffer,您应该参加此Apple技术说明:

https://developer.apple.com/library/ios/qa/qa1744/_index.html

特别是,如果你想物理旋转视频(而不是只设置方向标志),你可以..

例如在回调中:

- (void)captureOutput:(AVCaptureOutput *)captureOutput 
didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer 
       fromConnection:(AVCaptureConnection *)connection 

如果你这样做:

    [connection setVideoOrientation:AVCaptureVideoOrientationPortraitUpsideDown];

你会得到一个颠倒的视频.

要裁剪视频,您需要使用AVAssetWriterInput,您可以使用videoSettings字典设置裁剪.

例如:

NSDictionary *videoSettings = @{
      AVVideoCodecKey  : AVVideoCodecH264
    , AVVideoWidthKey  : @(100)
    , AVVideoHeightKey : @(100)
         };

用于这里:

  self.assetWriterVideoInput = [[AVAssetWriterInput alloc]
                               initWithMediaType:AVMediaTypeVideo
                                  outputSettings:videoSettings];

会给你一个大小为100 x 100像素的视频,全宽,但裁剪高度到正方形.

查看AVVideoSettings.h以获取完整的密钥列表

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