如何解决从SwiftiOS视频创建帧
有一个视频文件,时长为3秒。我需要创建30帧-UIImages。每隔0.1秒捕获一次图像。 我尝试使用AVAssetimageGenerator和CMTimeMake,但是我总是得到30张相似的图像,或者15张相似的图像,另外15张相似的图像。
请帮助了解如何从该视频中制作这种幻灯片。也许还有更好的方法。
请参见下面的代码:
static func generate_Thumbnails(forVideoWithURL url : URL) -> [UIImage]? {
let asset = AVAsset(url: url)
var result: [UIImage] = []
let assetImgGenerator = AVAssetimageGenerator(asset: asset)
assetImgGenerator.appliesPreferredTrackTransform = true
for i in 1...30 {
let time: CMTime = CMTimeMake(value: Int64(i),timescale: 10)
do {
let img: CGImage = try assetImgGenerator.copyCGImage(at: time,actualTime: nil)
let frameImg: UIImage = UIImage(cgImage: img)
result.append(frameImg)
} catch {
//return nil
}
}
return result
}
解决方法
我还没有阅读AVAssetImageGenerator的文档,但实际上,我每秒只能生成1张图像。因此,您应该能够在1、2和3秒(而不是30秒)上获得图像。这是我用来生成图像的代码,与您的代码非常相似。
private func getPreviewImage(forURL url: URL,atSeconds seconds: Double) -> UIImage? {
let asset = AVURLAsset(url: url)
let generator = AVAssetImageGenerator(asset: asset)
generator.appliesPreferredTrackTransform = true
let timestamp = CMTime(seconds: seconds,preferredTimescale: 100)
do {
let imageRef = try generator.copyCGImage(at: timestamp,actualTime: nil)
return UIImage(cgImage: imageRef)
}
catch let error as NSError
{
print("Image generation failed with error \(error)")
return nil
}
}
,
我尝试了Amin Benarieb的解决方案,但似乎可行:
static func toImages(fromVideoUrl url: URL) -> [UIImage]? {
let asset = AVAsset(url: url)
guard let reader = try? AVAssetReader(asset: asset) else { return nil }
let videoTrack = asset.tracks(withMediaType: .video).first!
let outputSettings = [String(kCVPixelBufferPixelFormatTypeKey): NSNumber(value: kCVPixelFormatType_32BGRA)]
let trackReaderOutput = AVAssetReaderTrackOutput(track: videoTrack,outputSettings: outputSettings)
reader.add(trackReaderOutput)
reader.startReading()
var images = [UIImage]()
while reader.status == .reading {
autoreleasepool {
if let sampleBuffer = trackReaderOutput.copyNextSampleBuffer() {
if let imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer) {
let ciImage = CIImage(cvImageBuffer: imageBuffer)
images.append(UIImage(ciImage: ciImage))
}
}
}
}
return images
}
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