帧持续时间 - UIImage 数组到电影 [英] Frame Duration time - UIImage array to movie

问题描述

我已经通过这段代码成功完成了将 UIImage 数组导出为电影"的部分.在导出的视频中，每个图像显示 1 秒钟.但我需要，导出的视频中每张图像都会显示 5 秒.我需要这样做的最小变化是什么?这是我的代码...

I have successfully completed the part "Export UIImage array as movie" through this code. In the exported video every image is shown for 1 second. But I need, every image will be shown for 5 seconds in the exported video. What is the minimal change I need to do so ? Here is my code...

var outputSize = CGSize(width: 1920, height: 1280)

func build(outputSize outputSize: CGSize) {
        let fileManager = NSFileManager.defaultManager()
        let urls = fileManager.URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask)
        guard let documentDirectory: NSURL = urls.first else {
            fatalError("documentDir Error")
        }
        let videoOutputURL = documentDirectory.URLByAppendingPathComponent("OutputVideo.mp4")
       if NSFileManager.defaultManager().fileExistsAtPath(videoOutputURL!.path!) {
            do {
                try NSFileManager.defaultManager().removeItemAtPath(videoOutputURL!.path!)
            } catch {
                fatalError("Unable to delete file: \(error) : \(#function).")
            }
        }
        guard let videoWriter = try? AVAssetWriter(URL: videoOutputURL!, fileType: AVFileTypeMPEG4) else {
            fatalError("AVAssetWriter error")
        }
        let outputSettings = [AVVideoCodecKey : AVVideoCodecH264, AVVideoWidthKey : NSNumber(float: Float(outputSize.width)), AVVideoHeightKey : NSNumber(float: Float(outputSize.height))]
        guard videoWriter.canApplyOutputSettings(outputSettings, forMediaType: AVMediaTypeVideo) else {
            fatalError("Negative : Can't apply the Output settings...")
        }
        let videoWriterInput = AVAssetWriterInput(mediaType: AVMediaTypeVideo, outputSettings: outputSettings)
        let sourcePixelBufferAttributesDictionary = [kCVPixelBufferPixelFormatTypeKey as String : NSNumber(unsignedInt: kCVPixelFormatType_32ARGB), kCVPixelBufferWidthKey as String: NSNumber(float: Float(outputSize.width)), kCVPixelBufferHeightKey as String: NSNumber(float: Float(outputSize.height))]
        let pixelBufferAdaptor = AVAssetWriterInputPixelBufferAdaptor(assetWriterInput: videoWriterInput, sourcePixelBufferAttributes: sourcePixelBufferAttributesDictionary)
        if videoWriter.canAddInput(videoWriterInput) {
            videoWriter.addInput(videoWriterInput)
        }
        if videoWriter.startWriting() {
            videoWriter.startSessionAtSourceTime(kCMTimeZero)
            assert(pixelBufferAdaptor.pixelBufferPool != nil)
            let media_queue = dispatch_queue_create("mediaInputQueue", nil)
            videoWriterInput.requestMediaDataWhenReadyOnQueue(media_queue, usingBlock: { () -> Void in
                let fps: Int32 = 1
                let frameDuration = CMTimeMake(1, fps)
                var frameCount: Int64 = 0
                var appendSucceeded = true
                while (!self.choosenPhotos.isEmpty) {
                    if (videoWriterInput.readyForMoreMediaData) {
                        let nextPhoto = self.choosenPhotos.removeAtIndex(0)
                        let lastFrameTime = CMTimeMake(frameCount, fps)
                        let presentationTime = frameCount == 0 ? lastFrameTime : CMTimeAdd(lastFrameTime, frameDuration)
                        var pixelBuffer: CVPixelBuffer? = nil
                        let status: CVReturn = CVPixelBufferPoolCreatePixelBuffer(kCFAllocatorDefault, pixelBufferAdaptor.pixelBufferPool!, &pixelBuffer)
                        if let pixelBuffer = pixelBuffer where status == 0 {
                            let managedPixelBuffer = pixelBuffer
                            CVPixelBufferLockBaseAddress(managedPixelBuffer, CVPixelBufferLockFlags(rawValue: CVOptionFlags(0)))
                            let data = CVPixelBufferGetBaseAddress(managedPixelBuffer)
                            let rgbColorSpace = CGColorSpaceCreateDeviceRGB()
                            let context = CGBitmapContextCreate(data, Int(self.outputSize.width), Int(self.outputSize.height), 8, CVPixelBufferGetBytesPerRow(managedPixelBuffer), rgbColorSpace, CGImageAlphaInfo.PremultipliedFirst.rawValue)
                            CGContextClearRect(context!, CGRectMake(0, 0, CGFloat(self.outputSize.width), CGFloat(self.outputSize.height)))
                            let horizontalRatio = CGFloat(self.outputSize.width) / nextPhoto.size.width
                            let verticalRatio = CGFloat(self.outputSize.height) / nextPhoto.size.height
                            let aspectRatio = min(horizontalRatio, verticalRatio) // ScaleAspectFit
                            let newSize:CGSize = CGSizeMake(nextPhoto.size.width * aspectRatio, nextPhoto.size.height * aspectRatio)
                            let x = newSize.width < self.outputSize.width ? (self.outputSize.width - newSize.width) / 2 : 0
                            let y = newSize.height < self.outputSize.height ? (self.outputSize.height - newSize.height) / 2 : 0
                            CGContextDrawImage(context!, CGRectMake(x, y, newSize.width, newSize.height), nextPhoto.CGImage!)
                            CVPixelBufferUnlockBaseAddress(managedPixelBuffer, CVPixelBufferLockFlags(rawValue: CVOptionFlags(0)))
                            appendSucceeded = pixelBufferAdaptor.appendPixelBuffer(pixelBuffer, withPresentationTime: presentationTime)
                        } else {
                            print("Failed to allocate pixel buffer")
                            appendSucceeded = false
                        }
                    }
                    if !appendSucceeded {
                        break
                    }
                    frameCount += 1
                }
                videoWriterInput.markAsFinished()
                videoWriter.finishWritingWithCompletionHandler { () -> Void in
                    print("FINISHED!!!!!")
                }
            })
        }
    }

推荐答案

只需更改:

let frameDuration = CMTimeMake(5, fps)

并将这一行从:

 let lastFrameTime = CMTimeMake(frameCount, fps)

到

let lastFrameTime = CMTimeMake(frameCount*5, fps)

或

let lastFrameTime = frameDuration

希望这会有所帮助.

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