如何使用AVFoundation设置逐帧生成的视频的方向？

关于如何使用AVFoundation设置逐帧生成的视频的方向，以下是一些建议和步骤：

首先，确保你已经导入了AVFoundation框架。
创建一个AVAssetWriter和AVAssetWriterInput对象，用于处理视频帧。
设置AVAssetWriterInput的输出设置，包括视频的编码格式、分辨率和颜色空间等。
将AVAssetWriterInput添加到AVAssetWriter对象中。
开始写入视频帧。在这个过程中，你需要设置每个视频帧的方向。可以通过修改CGAffineTransformMakeRotation()函数中的角度参数来实现。
完成写入后，调用AVAssetWriter的finishWriting方法，将生成的视频保存到指定的URL中。

以下是一个简单的示例代码：

import AVFoundation

func generateVideo(withFrames frames: [UIImage], outputURL: URL, orientation: AVCaptureVideoOrientation) {
    let videoSettings: [String: Any] = [
        AVVideoCodecKey: AVVideoCodecType.h264,
        AVVideoWidthKey: 720,
        AVVideoHeightKey: 1280,
        AVVideoCompressionPropertiesKey: [
            AVVideoAverageBitRateKey: 2300000
        ]
    ]

    let assetWriter = try! AVAssetWriter(outputURL: outputURL, fileType: .mp4)
    let input = AVAssetWriterInput(mediaType: .video, outputSettings: videoSettings)
    input.expectsMediaDataInRealTime = true

    assetWriter.add(input)
    assetWriter.startWriting()
    assetWriter.startSession(atSourceTime: CMTime.zero)

    let pixelBufferAdaptor = AVAssetWriterInputPixelBufferAdaptor(assetWriterInput: input, sourcePixelBufferAttributes: nil)

    for (index, frame) in frames.enumerated() {
        var pixelBuffer: CVPixelBuffer?
        let options = [kCVPixelBufferCGImageCompatibilityKey as String: true, kCVPixelBufferCGBitmapContextCompatibilityKey as String: true]
        let status = CVPixelBufferCreate(kCFAllocatorDefault, Int(frame.size.width), Int(frame.size.height), kCVPixelFormatType_32ARGB, options as CFDictionary, &pixelBuffer)

        if status == kCVReturnSuccess {
            let managedBuffer = pixelBuffer!
            CVPixelBufferLockBaseAddress(managedBuffer, CVPixelBufferLockFlags(rawValue: 0))
            let pixelData = CVPixelBufferGetBaseAddress(managedBuffer)
            let rgbColorSpace = CGColorSpaceCreateDeviceRGB()
            let context = CGContext(data: pixelData, width: Int(frame.size.width), height: Int(frame.size.height), bitsPerComponent: 8, bytesPerRow: CVPixelBufferGetBytesPerRow(managedBuffer), space: rgbColorSpace, bitmapInfo: CGImageAlphaInfo.noneSkipFirst.rawValue)

            context?.translateBy(x: 0, y: frame.size.height)
            context?.scaleBy(x: 1.0, y: -1.0)
            context?.concatenate(CGAffineTransform(rotationAngle: orientation.rawValue))
            context?.draw(frame.cgImage!, in: CGRect(x: 0, y: 0, width: frame.size.width, height: frame.size.height))

            CVPixelBufferUnlockBaseAddress(managedBuffer, CVPixelBufferLockFlags(rawValue: 0))
            pixelBufferAdaptor.append(managedBuffer, withPresentationTime: CMTimeMake(value: index, timescale: 30))
        }
    }

    input.markAsFinished()
    assetWriter.finishWriting {
        print("Video generated successfully")
    }
}

在这个示例中，你可以通过调整AVCaptureVideoOrientation参数来设置视频的方向。希望这些信息对你有所帮助！