Swift4.2 从视频中抓取截图答案

【问题标题】：Swift4.2 grab screenshot from VideoSwift4.2 从视频中抓取截图
【发布时间】：2019-03-07 17:55:09
【问题描述】：

在 Swift 4.2 中，我正在尝试从视频中截取屏幕截图

func thumbnailImageFor(fileUrl:URL) -> UIImage? {

        let asset = AVAsset(url: fileUrl)
        let assetImgGenerate = AVAssetImageGenerator(asset: asset)
        assetImgGenerate.appliesPreferredTrackTransform = true

        let time = CMTimeMakeWithSeconds(1.0, preferredTimescale: 600)
        do {
            let img = try assetImgGenerate.copyCGImage(at: time, actualTime: nil)
            let thumbnail = UIImage(cgImage: img)
            return thumbnail
        } catch {
            print(error)
            return nil
        }   
 }

但出现错误：

Error Domain=AVFoundationErrorDomain Code=-11800 "该操作可能未完成” UserInfo={NSLocalizedFailureReason=未知错误发生 (-12792), NSLocalizedDescription=操作不能完成，NSUnderlyingError=0x600000f46580 {错误 Domain=NSOSStatusErrorDomain Code=-12792 "(null)"}}

视频的网址： https://firebasestorage.googleapis.com/v0/b/lailaichatapp.appspot.com/o/message_movies%2F8A61AC4E-4A08-4EC7-BC78-A5D861BE48C5.mov?alt=media&token=8906971d-59d7-4880-988e-135615c10f22

我错过了什么吗？

【问题讨论】：

AFAIK AVAsset 需要内部文件 URL 而不是外部 Web URL
你能试试直接用AVURLAsset代替抽象的AVAsset吗？
这能回答你的问题吗？ Failed to get video thumbnail from AVPlayer using Fairplay HLS

标签： swift avasset

【解决方案1】：

我认为这可能是电影文件类型的问题，因为这样可以：

import UIKit
import AVFoundation

func thumbnailImageFor(fileUrl:URL) -> UIImage? {

    let video = AVURLAsset(url: fileUrl, options: [:])
    let assetImgGenerate = AVAssetImageGenerator(asset: video)
    assetImgGenerate.appliesPreferredTrackTransform = true

    let videoDuration:CMTime = video.duration
    let durationInSeconds:Float64 = CMTimeGetSeconds(videoDuration)

    let numerator = Int64(1)
    let denominator = videoDuration.timescale
    let time = CMTimeMake(value: numerator, timescale: denominator)

    do {
        let img = try assetImgGenerate.copyCGImage(at: time, actualTime: nil)
        let thumbnail = UIImage(cgImage: img)
        return thumbnail
    } catch {
        print(error)
        return nil
    }
}

let url: URL = URL(string: "http://commondatastorage.googleapis.com/gtv-videos-bucket/sample/ElephantsDream.mp4")!

let image: UIImage? = thumbnailImageFor(fileUrl: url)
print("Image: \(image)")

【讨论】：