快速从本地视频创建缩略图

Question

如何从本地视频文件中快速创建缩略图？

例如，如果视频文件路径位于此处：

file:///Users/Dev/Library/Developer/CoreSimulator/Devices/F33222DF-D8F0-448B-A127-C5B03C64D0DC/data/Containers/Data/Application/4BC62DBF-0108-453C-9324-5BC0E356FE24/tmp/trim.059D11E6-F0EF-43DB-9E97-CA4F1F95D6B6.MOV

谢谢。

Answer 1

这是在 swift 5 中生成视频缩略图（第一帧）的方法：

import UIKit
import AVFoundation

class ViewController: UIViewController {

    @IBOutlet weak var imageView: UIImageView!
    override func viewDidLoad() {
        super.viewDidLoad()
    
        let video = AVURLAsset(url: URL(fileURLWithPath: Bundle.main.path(forResource: "sampleVideo", ofType: "mov")!))
        let thumbnailGenerator = AVAssetImageGenerator(asset: video)
    
        do
        {
            let cgImage = try thumbnailGenerator.copyCGImage(at: CMTimeMake(value: 0, timescale: 1), actualTime: nil)
            let UiImage = UIImage(cgImage: cgImage)
            imageView.image = UiImage
        }
        catch
        { print(error) }
    
    }

}

在此示例中，视频名称为 sampleVideo.mov（将文件 url 更改为视频文件的名称），确保将视频导入本地 Xcode 项目并将其添加到应用程序的目标中。

我制作了一个 youtube 来解释这个 here

Answer 2

Swift 5.3

作为其他答案的替代方案，稍作修改后，我决定进行 URL 扩展。

import AVFoundation

extension URL {
    func generateThumbnail() -> UIImage? {
        do {
            let asset = AVURLAsset(url: self)
            let imageGenerator = AVAssetImageGenerator(asset: asset)
            imageGenerator.appliesPreferredTrackTransform = true
            
            // Swift 5.3
            let cgImage = try imageGenerator.copyCGImage(at: .zero,
                                                         actualTime: nil)

            return UIImage(cgImage: cgImage)
        } catch {
            print(error.localizedDescription)

            return nil
        }
    }
}

用法：

let image = someURL.generateThumbnail()

Answer 3

最好少写一些简单的代码便于理解。 这就是我在 Swift (3.1 ... 5.2) 中转换的解决方案

import AVFoundation

func imagePreview(from moviePath: URL, in seconds: Double) -> UIImage? {
    let timestamp = CMTime(seconds: seconds, preferredTimescale: 60)
    let asset = AVURLAsset(url: moviePath)
    let generator = AVAssetImageGenerator(asset: asset)
    generator.appliesPreferredTrackTransform = true

    guard let imageRef = try? generator.copyCGImage(at: timestamp, actualTime: nil) else {
        return nil
    }
    return UIImage(cgImage: imageRef)
}

希望对某人有所帮助。

Answer 4

func saveImageDocumentDirectoryWithDate(tempImage:UIImage, block : @escaping (_ url: URL?) -> Void ){

    let documentsDirectoryURL = try! FileManager().url(for: .documentDirectory, in: .userDomainMask, appropriateFor: nil, create: true)

    let random : String =  randomString(length: 5)

    let fileURL = documentsDirectoryURL.appendingPathComponent(String(format:"CPImage%@.png",random))
    do { try tempImage.pngData()?.write(to: fileURL) }
    catch { block(nil) }
    block(fileURL)}

Answer 5

这是大卫答案的清理版本，并针对 iOS 11 / Swift 4.x 进行了测试。

请注意根据您使用的 Swift 版本处理初始时间的不同调用。

func generateThumbnail(url: URL) -> UIImage? {
    do {
        let asset = AVURLAsset(url: url)
        let imageGenerator = AVAssetImageGenerator(asset: asset)
        imageGenerator.appliesPreferredTrackTransform = true
        // Select the right one based on which version you are using
        // Swift 4.2
        let cgImage = try imageGenerator.copyCGImage(at: .zero,
                                                     actualTime: nil)
        // Swift 4.0
        let cgImage = try imageGenerator.copyCGImage(at: kCMTimeZero,
                                                     actualTime: nil)


        return UIImage(cgImage: cgImage)
    } catch {
        print(error.localizedDescription)

        return nil
    }
}

1. 从提供的URL 创建一个AVURLAsset
2. 使用新创建的AVURLAsset创建一个AVAssetImageGenerator，负责制作缩略图
3. appliesPreferredTrackTransform 通知生成器将矩阵应用于缩略图生成。默认值为 false。
4. 尝试在视频轨道的第一帧创建CGImage
5. 使用新创建的 CGImage 创建 UIImage 并返回它
6. 如果图像生成步骤失败，则会捕获错误并将其与 nil UIImage 一起呈现给控制台

Answer 6

翻译自：

First frame of a video using AVFoundation

    var err: NSError? = nil
    let asset = AVURLAsset(URL: NSURL(fileURLWithPath: "/that/long/path"), options: nil)
    let imgGenerator = AVAssetImageGenerator(asset: asset)
    let cgImage = imgGenerator.copyCGImageAtTime(CMTimeMake(0, 1), actualTime: nil, error: &err)
    // !! check the error before proceeding
    let uiImage = UIImage(CGImage: cgImage)
    let imageView = UIImageView(image: uiImage)
    // lay out this image view, or if it already exists, set its image property to uiImage

Answer 7

BaseZen 的答案翻译为 Swift 3 / Swift 4

您需要将要制作缩略图的视频的位置设置为url资产路径，例如：

别忘了import AVFoundation

func generateThumbnail(path: URL) -> UIImage? {
    do {
        let asset = AVURLAsset(url: path, options: nil)
        let imgGenerator = AVAssetImageGenerator(asset: asset)
        imgGenerator.appliesPreferredTrackTransform = true
        let cgImage = try imgGenerator.copyCGImage(at: CMTimeMake(value: 0, timescale: 1), actualTime: nil)
        let thumbnail = UIImage(cgImage: cgImage)
        return thumbnail
    } catch let error {
        print("*** Error generating thumbnail: \(error.localizedDescription)")
        return nil
    }
}

对于所有对此有疑问的人，我创建了以下托管在 Github 上的示例

Answer 8

BaseZen 的答案翻译成 Swift 2：

import UIKit
import AVFoundation

do {
    let asset = AVURLAsset(URL: NSURL(fileURLWithPath: "/that/long/path"), options: nil)
    let imgGenerator = AVAssetImageGenerator(asset: asset)
    imgGenerator.appliesPreferredTrackTransform = true
    let cgImage = try imgGenerator.copyCGImageAtTime(CMTimeMake(0, 1), actualTime: nil)
    let uiImage = UIImage(CGImage: cgImage)
    let imageView = UIImageView(image: uiImage)
    // lay out this image view, or if it already exists, set its image property to uiImage
} catch let error as NSError {
    print("Error generating thumbnail: \(error)")
}