我在正方形UIView中录制视频但是当我导出视频时全屏1080x1920现在我想知道如何将视频从全屏缩小为1：1的平方比...
以下是我设置摄像机的方法：
session = AVCaptureSession()
for device in AVCaptureDevice.devices() {
if let device = device as? AVCaptureDevice , device.position == AVCaptureDevicePosition.back {
self.device = device
}
}
for device in AVCaptureDevice.devices(withMediaType: AVMediaTypeAudio) {
let device = device as? AVCaptureDevice
let audioInput = try! AVCaptureDeviceInput(device: device)
session?.addInput(audioInput)
}
do {
if let session = session {
videoInput = try AVCaptureDeviceInput(device: device)
session.addInput(videoInput)
videoOutput = AVCaptureMovieFileOutput()
let totalSeconds = 60.0 //Total Seconds of capture time
let timeScale: Int32 = 30 //FPS
let maxDuration = CMTimeMakeWithSeconds(totalSeconds, timeScale)
videoOutput?.maxRecordedDuration = maxDuration
videoOutput?.minFreeDiskSpaceLimit = 1024 * 1024//SET MIN FREE SPACE IN BYTES FOR RECORDING TO CONTINUE ON A VOLUME
if session.canAddOutput(videoOutput) {
session.addOutput(videoOutput)
}
let videoLayer = AVCaptureVideoPreviewLayer(session: session)
videoLayer?.frame = self.videoPreview.bounds
videoLayer?.videoGravity = AVLayerVideoGravityResizeAspectFill
self.videoPreview.layer.addSublayer(videoLayer!)
session.startRunning()
我已经看过其他一些帖子，但没有发现它们非常有用，而且大多数都在Obj C ...
如果有人可以帮助我或让我朝着正确的方向前进，我们非常感激！
答案 0 :(得分：4)
首先，您需要使用AVCaptureFileOutputRecordingDelegate。
视频完成录制后，您专门使用func capture( _ captureOutput: AVCaptureFileOutput!, didFinishRecordingToOutputFileAt outputFileURL: URL!, fromConnections connections: [Any]!, error: Error! )方法执行裁剪过程。
这是我曾经实施过的裁剪功能的一个例子。您需要传入录制的视频的网址以及用于在裁剪过程完成后返回裁剪视频的新网址的回调。
func cropVideo( _ outputFileUrl: URL, callback: @escaping ( _ newUrl: URL ) -> () )
{
// Get input clip
let videoAsset: AVAsset = AVAsset( url: outputFileUrl )
let clipVideoTrack = videoAsset.tracks( withMediaType: AVMediaTypeVideo ).first! as AVAssetTrack
// Make video to square
let videoComposition = AVMutableVideoComposition()
videoComposition.renderSize = CGSize( width: clipVideoTrack.naturalSize.height, height: clipVideoTrack.naturalSize.height )
videoComposition.frameDuration = CMTimeMake( 1, self.framesPerSecond )
// Rotate to portrait
let transformer = AVMutableVideoCompositionLayerInstruction( assetTrack: clipVideoTrack )
let transform1 = CGAffineTransform( translationX: clipVideoTrack.naturalSize.height, y: -( clipVideoTrack.naturalSize.width - clipVideoTrack.naturalSize.height ) / 2 )
let transform2 = transform1.rotated(by: CGFloat( M_PI_2 ) )
transformer.setTransform( transform2, at: kCMTimeZero)
let instruction = AVMutableVideoCompositionInstruction()
instruction.timeRange = CMTimeRangeMake(kCMTimeZero, CMTimeMakeWithSeconds( self.intendedVideoLength, self.framesPerSecond ) )
instruction.layerInstructions = [transformer]
videoComposition.instructions = [instruction]
// Export
let croppedOutputFileUrl = URL( fileURLWithPath: FileManager.getOutputPath( String.random() ) )
let exporter = AVAssetExportSession(asset: videoAsset, presetName: AVAssetExportPresetHighestQuality)!
exporter.videoComposition = videoComposition
exporter.outputURL = croppedOutputFileUrl
exporter.outputFileType = AVFileTypeQuickTimeMovie
exporter.exportAsynchronously( completionHandler: { () -> Void in
DispatchQueue.main.async(execute: {
callback( croppedOutputFileUrl )
})
})
}
此外，这是我的getOutputPath方法的实现：
func getOutputPath( _ name: String ) -> String
{
let documentPath = NSSearchPathForDirectoriesInDomains( .documentDirectory, .userDomainMask, true )[ 0 ] as NSString
let outputPath = "\(documentPath)/\(name).mov"
return outputPath
}
希望这有帮助。
答案 1 :(得分：0)
func cropFrame(videoAsset:AVAsset, animation:Bool) -> Void {
var insertTime = kCMTimeZero
var arrayLayerInstructions:[AVMutableVideoCompositionLayerInstruction] = []
var outputSize = CGSize.init(width: 0, height: 0)
// Determine video output size
let videoTrack = videoAsset.tracks(withMediaType: AVMediaType.video)[0]
let assetInfo = orientationFromTransform(transform: videoTrack.preferredTransform)
var videoSize = videoTrack.naturalSize
if assetInfo.isPortrait == true {
videoSize.width = videoTrack.naturalSize.height
videoSize.height = videoTrack.naturalSize.width
}
if videoSize.height > outputSize.height {
outputSize = videoSize
}
let defaultSize = CGSize(width: 1920, height: 1080) // Default video size
if outputSize.width == 0 || outputSize.height == 0 {
outputSize = defaultSize
}
// Silence sound (in case of video has no sound track)
let silenceURL = Bundle.main.url(forResource: "silence", withExtension: "mp3")
let silenceAsset = AVAsset(url:silenceURL!)
let silenceSoundTrack = silenceAsset.tracks(withMediaType: AVMediaType.audio).first
// Init composition
let mixComposition = AVMutableComposition.init()
// Get audio track
var audioTrack:AVAssetTrack?
if videoAsset.tracks(withMediaType: AVMediaType.audio).count > 0 {
audioTrack = videoAsset.tracks(withMediaType: AVMediaType.audio).first
}
else {
audioTrack = silenceSoundTrack
}
// Init video & audio composition track
let videoCompositionTrack = mixComposition.addMutableTrack(withMediaType: AVMediaType.video,
preferredTrackID: Int32(kCMPersistentTrackID_Invalid))
let audioCompositionTrack = mixComposition.addMutableTrack(withMediaType: AVMediaType.audio,
preferredTrackID: Int32(kCMPersistentTrackID_Invalid))
do {
let startTime = kCMTimeZero
let duration = videoAsset.duration
// Add video track to video composition at specific time
try videoCompositionTrack?.insertTimeRange(CMTimeRangeMake(startTime, duration),
of: videoTrack,
at: insertTime)
// Add audio track to audio composition at specific time
if let audioTrack = audioTrack {
try audioCompositionTrack?.insertTimeRange(CMTimeRangeMake(startTime, duration),
of: audioTrack,
at: insertTime)
}
// Add instruction for video track
let layerInstruction = videoCompositionInstructionForTrack(track: videoCompositionTrack!,
asset: videoAsset,
standardSize: outputSize,
atTime: insertTime)
// Hide video track before changing to new track
let endTime = CMTimeAdd(insertTime, duration)
//let finalTimer = CMTimeAdd(CMTime(seconds: 5, preferredTimescale: videoAsset.duration.timescale), CMTime(seconds: 5, preferredTimescale: videoAsset.duration.timescale))
//Kalpesh crop video frames
if animation {
let timeScale = videoAsset.duration.timescale
let durationAnimation = CMTime.init(seconds: 1, preferredTimescale: timeScale)
layerInstruction.setOpacityRamp(fromStartOpacity: 1.0, toEndOpacity: 0.0, timeRange: CMTimeRange.init(start: endTime, duration: durationAnimation))
//**********======== CROP YOUR VIDEO FRAME HERE MANUALLY ========**********
layerInstruction.setCropRectangle(CGRect(x: 0, y: 0, width: videoTrack.naturalSize.width, height: 300.0), at: startTime)
} else {
layerInstruction.setOpacity(0, at: endTime)
}
arrayLayerInstructions.append(layerInstruction)
// Increase the insert time
insertTime = CMTimeAdd(insertTime, duration)
}
catch {
print("Load track error")
}
// Main video composition instruction
let mainInstruction = AVMutableVideoCompositionInstruction()
mainInstruction.timeRange = CMTimeRangeMake(kCMTimeZero, insertTime)
mainInstruction.layerInstructions = arrayLayerInstructions
// Main video composition
let mainComposition = AVMutableVideoComposition()
mainComposition.instructions = [mainInstruction]
mainComposition.frameDuration = CMTimeMake(1, 30)
mainComposition.renderSize = outputSize
// Export to file
let path = NSTemporaryDirectory().appending("mergedVideo.mp4")
let exportURL = URL.init(fileURLWithPath: path)
// Init exporter
let exporter = AVAssetExportSession.init(asset: mixComposition, presetName: AVAssetExportPresetHighestQuality)
exporter?.outputURL = exportURL
exporter?.outputFileType = AVFileType.mp4
exporter?.shouldOptimizeForNetworkUse = true
exporter?.videoComposition = mainComposition
// Do export
exporter?.exportAsynchronously(completionHandler: {
})
}
func videoCompositionInstructionForTrack(track: AVCompositionTrack, asset: AVAsset, standardSize:CGSize, atTime: CMTime) -> AVMutableVideoCompositionLayerInstruction {
let instruction = AVMutableVideoCompositionLayerInstruction(assetTrack: track)
let assetTrack = asset.tracks(withMediaType: AVMediaType.video)[0]
let transform = assetTrack.preferredTransform
let assetInfo = orientationFromTransform(transform: transform)
var aspectFillRatio:CGFloat = 1
if assetTrack.naturalSize.height < assetTrack.naturalSize.width {
aspectFillRatio = standardSize.height / assetTrack.naturalSize.height
}
else {
aspectFillRatio = standardSize.width / assetTrack.naturalSize.width
}
if assetInfo.isPortrait {
let scaleFactor = CGAffineTransform(scaleX: aspectFillRatio, y: aspectFillRatio)
let posX = standardSize.width/2 - (assetTrack.naturalSize.height * aspectFillRatio)/2
let posY = standardSize.height/2 - (assetTrack.naturalSize.width * aspectFillRatio)/2
let moveFactor = CGAffineTransform(translationX: posX, y: posY)
instruction.setTransform(assetTrack.preferredTransform.concatenating(scaleFactor).concatenating(moveFactor), at: atTime)
} else {
let scaleFactor = CGAffineTransform(scaleX: aspectFillRatio, y: aspectFillRatio)
let posX = standardSize.width/2 - (assetTrack.naturalSize.width * aspectFillRatio)/2
let posY = standardSize.height/2 - (assetTrack.naturalSize.height * aspectFillRatio)/2
let moveFactor = CGAffineTransform(translationX: posX, y: posY)
var concat = assetTrack.preferredTransform.concatenating(scaleFactor).concatenating(moveFactor)
if assetInfo.orientation == .down {
let fixUpsideDown = CGAffineTransform(rotationAngle: CGFloat(Double.pi))
concat = fixUpsideDown.concatenating(scaleFactor).concatenating(moveFactor)
}
instruction.setTransform(concat, at: atTime)
}
return instruction
}
func orientationFromTransform(transform: CGAffineTransform) -> (orientation: UIImageOrientation, isPortrait: Bool) {
var assetOrientation = UIImageOrientation.up
var isPortrait = false
if transform.a == 0 && transform.b == 1.0 && transform.c == -1.0 && transform.d == 0 {
assetOrientation = .right
isPortrait = true
} else if transform.a == 0 && transform.b == -1.0 && transform.c == 1.0 && transform.d == 0 {
assetOrientation = .left
isPortrait = true
} else if transform.a == 1.0 && transform.b == 0 && transform.c == 0 && transform.d == 1.0 {
assetOrientation = .up
} else if transform.a == -1.0 && transform.b == 0 && transform.c == 0 && transform.d == -1.0 {
assetOrientation = .down
}
return (assetOrientation, isPortrait)
}
以这种方式致电：
let avssets = AVAsset(url: VideoURL)
self.cropFrame(videoAsset: avssets, animation: true)